Gas Turbine Engine Fundamentals PDF (EASA Part-66)

Fundamentals M15 GAS TURBINE ENGINE Rev.-ID: 1SEP2014 Author: DaC For Training Purposes Only ELTT Release: Sep. 19, 2014 M15.1 Fundamentals EASA Part-66 CAT A M15.01_A E Training Manual...

Fundamentals M15 GAS TURBINE ENGINE Rev.-ID: 1SEP2014 Author: DaC For Training Purposes Only ELTT Release: Sep. 19, 2014 M15.1 Fundamentals EASA Part-66 CAT A M15.01_A E Training Manual For training purposes and internal use only. E Copyright by Lufthansa Technical Training (LTT). LTT is the owner of all rights to training documents and training software. Any use outside the training measures, especially reproduction and/or copying of training documents and software − also extracts there of − in any format at all (photocopying, using electronic systems or with the aid of other methods) is prohibited. Passing on training material and training software to third parties for the purpose of reproduction and/or copying is prohibited without the express written consent of LTT. Copyright endorsements, trademarks or brands may not be removed. A tape or video recording of training courses or similar services is only permissible with the written consent of LTT. In other respects, legal requirements, especially under copyright and criminal law, apply. Lufthansa Technical Training Dept HAM US Lufthansa Base Hamburg Weg beim Jäger 193 22335 Hamburg Germany Tel: +49 (0)40 5070 2520 Fax: +49 (0)40 5070 4746 E-Mail: [email protected] www.Lufthansa-Technical-Training.com Revision Identification: S The date given in the column ”Revision” on the face of S Dates and author’s ID, which may be given at the base S The LTT production process ensures that the Training this cover is binding for the complete Training Manual. of the individual pages, are for information about the Manual contains a complete set of all necessary pages latest revision of that page(s) only. in the latest finalized revision. Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE M15.01 | M14.01 M15 GAS TURBINE ENGINE M15.1 FUNDAMENTALS FOR TRAINING PURPOSES ONLY! FRA US/O-5 DaC May 23, 2013 ATA DOC Page 1 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Gas Turbine Engine − Introduction M15.01 | M14.01 GAS TURBINE ENGINES - INTRODUCTION Introduction to Aircraft Engines Controlled flight over long distances is only possible with a suitable aircraft engine. From the aerodynamics lesson you remember that the lift force, which keeps an aircraft in the air, is only created when the aircraft moves through the atmosphere fast enough. It is clear that the main function of an aircraft engine is to create the necessary movement of the aircraft. In addition the aircraft engine also supplies hydraulic power, electric power and bleed air for the pneumatic system. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 01|Intro|L1|A/B1/B2 Page 2 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Gas Turbine Engine − Introduction M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 1 Main Tasks of Jet Engines HAM US/F SwD 01.04.2008 01|Intro|L1|A/B1/B2 Page 3 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Gas Turbine Engine − Introduction M15.01 | M14.01 Introduction to Aircraft Engines cont. There are 2 different types of aircraft engines; S piston type engines and S gas turbine engines. The first airplanes were powered by piston type engines that turned a propeller. These engines are simple in design and more fuel efficient than gas turbine engines, but piston type engines have some big disadvantages compared with gas turbine engines. The performance of piston engines decreases at higher altitudes and they cannot be large for aircraft because the ratio of weight and power decreases with the size of the piston engines. Therefore, piston type engines are only used on very small aircraft. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 02|Intro|L1|A/B1/B2 Page 4 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Gas Turbine Engine − Introduction M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 2 Advantages /Disadvantages of Piston Type Engines HAM US/F SwD 01.04.2008 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Operation and Constructional Arrangement M15.01 | M14.01 OPERATION AND CONSTRUCTIONAL ARRANGEMENT Types of Gas Turbine Engines Gas turbine engines, however, can operate at very high altitudes. They easily provide thrust, torque and bleed air and they let aircraft fly at high speeds. There are different types of gas turbine engines on aircraft: S turbojet engines, S turbofan engines, S turboprop engines S and auxiliary power units (APU) The turbofan engine is usually used on modern aircraft. This engine is better because it makes high aircraft speeds possible with good engine efficiency. The turbofan engine was developed from the turbojet engine. Turbojet engines were the first type of gas turbine engines used on aircraft. These engines give very high aircraft speeds, but they are very loud because of the extremely high exhaust gas velocities. They also need too much fuel. Another type of engine, which was developed from the turbojet, is the turboprop engine. Turboprop engines are specially designed to produce shaft horsepower only, which is used to drive a propeller. This engine type is usually installed on small commuter aircraft. It is a good compromise between achievable aircraft speed and fuel efficiency. Another type of gas turbine engine that you will find on modern aircraft is the auxiliary power unit. This small gas turbine engine is usually called APU. It is FOR TRAINING PURPOSES ONLY! used to supply the aircraft with electric and pneumatic power if the engines are not available. With the APU the aircraft is independent of airport equipment. HAM US/F SwD 01.04.2008 03|Gas Turb Eng Types|L1|A/B1/B2 Page 6 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Operation and Constructional Arrangement M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 3 Types of Gas Turbine Engines HAM US/F SwD 01.04.2008 03|Gas Turb Eng Types|L1|A/B1/B2 Page 7 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Newton’s Laws of Motion M15.01 | M14.01 NEWTON‘S LAWS OF MOTION Principles of Jet Propulsion All aircraft engines work in the same way. They create a propulsion force, which moves the aircraft. If you hold a water hose, which is spraying water, you can feel that the hose pushes in the opposite direction of the water which is spraying out of it. Jet propulsion is the propelling force, which is generated in the opposite direction to the flow of mass through the jet nozzle. An engine which uses jet propulsion is called a reaction engine. These engines use the third Newton’s law of motion, which states that for every force which acts on a body there is an opposite and equal reaction. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 04|Princp Jet Prop|L1|A/B1/B2 Page 8 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Newton’s Laws of Motion M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 4 Jet Propulsion Principle HAM US/F SwD 01.04.2008 04|Princp Jet Prop|L1|A/B1/B2 Page 9 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Acceleration M15.01 | M14.01 ACCELERATION Principles of Jet Propulsion A force is always created when a body of mass is accelerated. This body can be any kind of matter such as fluids and gasses, or it can be a solid mass. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 05|Princp Jet Prop|L1|A/B1/B2 Page 10 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Acceleration M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 5 Force Equation HAM US/F SwD 01.04.2008 05|Princp Jet Prop|L1|A/B1/B2 Page 11 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Acceleration and Work M15.01 | M14.01 ACCELERATION AND WORK Principles of Jet Propulsion cont. To accelerate air, the air pressure must be increased. This can be done mechanically with a compressor or thermally by increasing the volume of air when a fuel / air mixture is burned or heated. However, the combination of both methods guarantees acceptable thrust for aircraft engines. You see that the idea of using jet propulsion to move an aircraft is simple but the application was difficult. Until the late 1930s there was no compressor which could supply a continuous and large enough airflow to produce suitable thrust. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 06|Princp Jet Prop|L1|A/B1/B2 Page 12 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Acceleration and Work M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 6 Air Acceleration Methods HAM US/F SwD 01.04.2008 06|Princp Jet Prop|L1|A/B1/B2 Page 13 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Acceleration M15.01 | M14.01 Principles of Jet Propulsion cont. Centrifugal flow compressors driven by turbines finally made propulsion engines for aircraft possible. In 1937 Hans von Ohain built a gas turbine engine with a centrifugal flow compressor driven by a radial turbine and in 1941 Frank Whittle built his first engine which had a centrifugal flow compressor driven by an axial turbine. Whittle’s and von Ohain’s engines became the base for all gas turbine engines. Note that these engines were only possible after the development of materials that were heat-resistant enough for continuous combustion. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 07|Princp Jet Prop|L1|A/B1/B2 Page 14 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Acceleration M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 7 Compressors for Gas Turbine Engines HAM US/F SwD 01.04.2008 07|Princp Jet Prop|L1|A/B1/B2 Page 15 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Power. Force and Velocity M15.01 | M14.01 POWER, FORCE AND VELOCITY The Thrust Force Thrust force is generated by the acceleration of ambient air which is forced through the engine. This means that the thrust is determined by 2 parameters. One is the mass of ambient air which is accelerated and the other parameter is the quantity of acceleration itself. The definition of mass is the quantity of matter in a body. In this example it is the airflow through the engine in a given time and the acceleration of the airflow is the difference between the outlet velocity of the air at the jet nozzle compared with the inlet velocity of the air entering the engine. The letter F is the thrust force. Today this force is measured in N (Newton) or kN (Kilo Newton). 10kN for example are equal to a force of 1020kg or 2249lbs (pounds) pushing down because of the gravity of the earth. The letter m is the mass of air. The dot above the letter m shows that this is a flow rate in kg/s. V1 is the velocity of the air at the engine inlet. V2 is the outlet velocity of the air at the engine jet nozzle. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 08|Thr Force|L2|B1/B2 Page 16 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Power. Force and Velocity M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 8 The Thrust Force HAM US/F SwD 01.04.2008 08|Thr Force|L2|B1/B2 Page 17 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Brayton Cycle M15.01 | M14.01 BRAYTON CYCLE Pressure-Volume Diagram In thermodynamics, a cyclic process is referred to as a series of changes of state of a working medium (liquid, steam, gas, generally called fluid) which occur periodically. Thereby, the initial state specified by state variables such as T 4 + T max pressure, temperature and density, etc. is repeatedly reached. Thermodynamic. cycles are technical processes usually used for converting heat into p Q zu mechanical work (e.g. combustion engines) or for heating and cooling by performing work. Here you can see a pressure−volume diagram of a thermodynamic cycle of a turbojet engine, also called Brayton Cycle. 3 ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ 4 ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ p max d p3 + p4 ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ c ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ 5 ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ p5 ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ. Wi + Pi ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ 2 ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ p2 b 8 p min a ÉÉÉÉÉÉÉÉÉÉÉÉÉÉ 0 p0 + p8 FOR TRAINING PURPOSES ONLY!. T 0 + T min Q ab... V V min V max Figure 9 Brayton cycle FRA US/O-5 DaC Jun 24, 2013 08a|Brayton cycle|L1/A/B1/B2 Page 18 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Brayton Cycle M15.01 | M14.01 THIS PAGE INTENTIONALLY LEFT BLANK FOR TRAINING PURPOSES ONLY! FRA US/O-5 DaC Jun 24, 2013 08a|Brayton cycle|L1/A/B1/B2 Page 19 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Brayton Cycle M15.01 | M14.01 DETAILED BRAYTON CYCLE B. Along curve 5 to 8, the exhaust nozzle allows the remaining energy at 1. Point 0 represents the atmospheric conditions on which the mass airflow the turbine exit to be converted into kinetic energy, i. e. the mass of gas enters the engine intake at velocity vF. is accelerated in a mere flow process. 2. Curve 0 ? 3 indicates the isentropic compression process of the mass Area c−5−8−a−c indicates this energy conversion. airflow; its volume decreases with increasing pressure. To ensure an ideal output velocity (c8 > vF) the mass airflow must reach As no heat transfer occurs across the system boundaries, the temperature the atmospheric pressure level when passing the nozzle cross section. of the compressed working fluid increases. 5. The isobaric heat rejection 8 ? 0 takes place in the atmosphere. A. Section 0 to 1 refers to the process in front of the diffuser−shaped air As the temperature of the airflow is still relatively high at the exhaust nozzle, intake of the engine. Section 1 to 2 refers to the process inside the together with the exhaust gas the heat flow also leaves the engine. This diffuser−shaped air intake of the engine. energy loss (for the engine) is inevitable due to the engine’s principle of In the air intake (above a certain vF) the velocity of the airflow decreases operation, but it should be as minimal as possible. and the static pressure increases. B. Section 2 to 3 takes place in the compressor which is driven by a Isobars are lines of equal pressure. turbine via a shaft system. At the end of the compressor, the pressure reaches the maximum value of the entire cyclic process. With increasing pressure the temperature also increases. The volume flow reaches its minimum at the end of the Isentropes are referred to as lines of equal entropy. If the entropy in a process compressor. remains constant, it is called isentropic. According to thermodynamics, a change of state of gases during which there is no change in entropy is called The compressor driving power, i. e. the required technical work per time isentropic. The energy content is constant. unit, is indicated by area b−2−3−d−b. 3. Process 3 to 4 is called isobaric heat addition, which takes place in the combustion section. An adiabatic change of state is a thermodynamic process during which a system In this process, the chemical energy of the fuel is converted into thermal is transferred from one state into another without exchanging thermal energy with energy which is then transferred to the airflow. This process involves a high its environment. increase in temperature and a considerable volume increase of the working fluid. Therefore, the mass airflow reaches its highest energy level at the end of the combustion chamber. FOR TRAINING PURPOSES ONLY! 4. Curve 4 to 8 represents the isentropic expansion process during which the gases are expanded to atmospheric pressure again. A. In section 4 ? 5, in the turbine, part of the airflow’s energy is converted into technical work per time unit. This rotation power is used to drive the compressor and the auxiliary engine equipment. It is indicated by the content of area d−4−5−c−d. With decreasing pressure and decreasing temperature the volume of the mass airflow increases FRA US/O-5 DaC Jun 24, 2013 08b|Brayton cycle|L2/B1/B2 Page 20 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Brayton Cycle M15.01 | M14.01 T 4 (TIT) + T max LEGENDE: T 3 (CDT) CIP – COMPRESSOR INLET PRESSURE (p2) p CDP – COMPRESSOR DISCHARGE PRESSURE (p3).. Q zu + Q 34 CIT – COMPRESSOR INLET TEMPERATURE (T2) CDT – COMPRESSOR DISCHARGE TEMPERATURE (T3) 3 TIT – TURBINE INLET TEMPERATURE (T4) 4 p 3 (CDP) + d EGT – EXHAUST GAS TEMPERATURE (T5) + p 4 + p max 5 c p5 T 5 (EGT) b 2 p 2 (CIP) FOR TRAINING PURPOSES ONLY! 8 T8 p 0 + p 8 + p min a 0.. T 0 + T min Q ab + Q 80 T 2 (CIT)..... V 3 + V min V 8 + V max V Figure 10 detailed brayton cycle FRA US/O-5 DaC Jun 24, 2013 08b|Brayton cycle|L2/B1/B2 Page 21 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Energy and Velocity M15.01 | M14.01 ENERGY AND VELOCITY What is Thrust On a test model we will explore what thrust is. On the graphic you can see a small jet engine model which is free to move forward and backwards. The engine model is supplied with air by an external compressor. The quantity of airflow to the engine can be changed by a control valve. A pointer on the engine shows the generated thrust on a scale below. If the airflow is constant and you change the diameter of the jet nozzle, the outlet velocity changes. If you install different jet nozzles on the engine model, you see what happens to the thrust when the outlet velocity changes. The nozzle with a small diameter creates a high outlet velocity and therefore a high thrust. A nozzle with a medium diameter creates a medium outlet velocity and therefore a medium thrust. The nozzle with a large diameter creates a low outlet velocity resulting in a low thrust. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 09|Whats Thr|L2|B1/B2 Page 22 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Energy and Velocity M15.01 | M14.01 large diameter small diameter FOR TRAINING PURPOSES ONLY! Figure 11 Thrust Test Model HAM US/F SwD 01.04.2008 09|Whats Thr|L2|B1/B2 Page 23 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Energy and Acceleration M15.01 | M14.01 What Is Thrust cont. You can see here that if you put a deflector plate into the outlet airflow, the thrust of the jet nozzle does not change. This shows that the thrust is generated by acceleration of airflow and not by pushing against the atmosphere or some other object. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 10|Whats Thr|L1|B1/B2 Page 24 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Energy and Acceleration M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 12 Deflector Plate in Outlet Airflow HAM US/F SwD 01.04.2008 10|Whats Thr|L1|B1/B2 Page 25 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Influence of Environmental Effects M15.01 | M14.01 INFLUENCE OF ENVIRONMENTAL EFFECTS Environmental Effects on Thrust There are 4 main environmental parameters that cause a change in the thrust of a jet engine: S the ambient air pressure, S the air temperature, S the operating altitude S and finally the air speed of the aircraft. The most important factors that cause a change of the mass airflow, are air temperature and air pressure because these factors determine the density of air. The density is the mass per unit of volume. In other words, it is the number of molecules in a given volume. Generally the density is measured in kg/m3 or lbs/ft3. When the density of a gas increases, there are more molecules in a given volume and vice versa. A lower air density creates lower thrust because the airflow contains less mass than a high density airflow. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 11|Env Thr Effects|L2|B1/B2 Page 26 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Influence of Environmental Effects M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 13 Environmental Effects on Thrust HAM US/F SwD 01.04.2008 11|Env Thr Effects|L2|B1/B2 Page 27 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Influence of Environmental Effects M15.01 | M14.01 Environmental Effects on Thrust cont. The air temperature changes the density. The thrust of a jet engine decreases when the temperature of the air increases. Pressure changes of the ambient air also change its density and therefore the thrust of an engine. The higher the air pressure gets, the higher the resulting thrust is. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 12|Env Thr Effects|L2|B1/B2 Page 28 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Influence of Environmental Effects M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 14 Relation Thrust vs. Air Pressure and Air Temperature HAM US/F SwD 01.04.2008 12|Env Thr Effects|L2|B1/B2 Page 29 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Influence of Environmental Effects M15.01 | M14.01 Environmental Effects on Thrust cont. A much bigger effect on air pressure changes can be seen when the altitude changes. With increasing altitudes, the ambient pressure decreases and the temperature decreases continuously until 36000ft (10973m) is reached. From 36000ft up to 65000ft (19812m), the air temperature stays constant at approximately -70° F (-57° C). The colder air temperatures at higher altitudes give a small increase in thrust but the decrease in thrust is much bigger because the decrease of air density is much bigger. The thrust which results from the 2 opposite conditions is shown by the highlighted curve on the diagram. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 13|Env Thr Effects|L2|B1/B2 Page 30 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Influence of Environmental Effects M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 15 Relation Thrust vs. Altitude HAM US/F SwD 01.04.2008 13|Env Thr Effects|L2|B1/B2 Page 31 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Influence of Environmental Effects M15.01 | M14.01 Environmental Effects on Thrust cont. One factor that changes the thrust, is the quantity of the acceleration of the airflow because of the speed of the aircraft. When the speed of the aircraft increases, the thrust decreases. You can see this in the downward slope of the thrust curve. This happens because the difference between the outlet velocity and the inlet velocity of the airflow decreases when the speed of the aircraft increases. Another factor of the airspeed causes an opposite change on the generated thrust. When the aircraft moves through the air, the airflow that is rammed into the engine inlets increases the airflow through the engine. This increases the thrust of the engine. Therefore, the net effect of the airspeed on the thrust is a combination of thrust decrease from acceleration effect and thrust increase from the ram effect. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 14|Env Thr Effects|L2|B1/B2 Page 32 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Influence of Environmental Effects M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 16 Relation Thrust vs. Aircraft Speed HAM US/F SwD 01.04.2008 14|Env Thr Effects|L2|B1/B2 Page 33 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Operation M15.01 | M14.01 OPERATION Thrust of Turbojet Engines The gas turbine engine, turbofan engine and turboprop engine produce thrust by accelerating of ambient air. However, the difference between them is how they do it. A turbojet engine is designed for one purpose and this is to produce high velocity gases. On these engines, all the gas energy which is not used to drive the compressor and the accessories is converted into thrust. The high outlet velocity of these engines give high aircraft speeds, but turbojet engines are extremely loud and not very efficient. All other engines shown earlier have been based on the turbojet engine with the primary reason to improve efficiency. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 15|A/C Thr|L1|A/B1/B2 Page 34 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Operation M15.01 | M14.01 Turbo Jet Engine FOR TRAINING PURPOSES ONLY! Figure 17 Thrust of a Turbojet Engine HAM US/F SwD 01.04.2008 15|A/C Thr|L1|A/B1/B2 Page 35 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Operation M15.01 | M14.01 Thrust of Turboprop Engines Turboprop engines produce their thrust by a small acceleration of a large quantity of air with a propeller. The propeller can be driven directly from the compressor shaft or by a free turbine and a long center drive shaft. A reduction gear is always required to reduce the high gas turbine engine rotation to speeds that can be managed by the propeller. Turboprop engines convert almost all the gas energy into torque. They are very efficient, but the propeller does not permit high aircraft speeds. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 16|A/C Thr|L1|A/B1/B2 Page 36 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Operation M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 18 Thrust of a Turboprop Engine HAM US/F SwD 01.04.2008 16|A/C Thr|L1|A/B1/B2 Page 37 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Operation M15.01 | M14.01 Thrust of Turbofan Engines The turbofan engine combines the best advantages of turbojet and turboprop engines. The turbofan engine is very much like a turboprop engine, but instead of the propeller this engine has a fan, which is enclosed in a casing. Turbofan engines are usually twin or triple spool engines. The fan is always driven by a turbine via a drive shaft. Normally these engines do not have a reduction gear to reduce the speed of the fan. Turbofan engines convert a large part of the gas energy into torque to drive the fan and the engine compressors. The remaining hot gas energy from the airflow, which discharges from the so-called core engine, is directly converted into thrust. The total thrust of the turbofan engine is the sum of the thrust developed by the core engine and by the fan. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 17|A/C Thr|L1|A/B1/B2 Page 38 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Operation M15.01 | M14.01 Turbofan Engine FOR TRAINING PURPOSES ONLY! Figure 19 Thrust of a Turbofan Engine HAM US/F SwD 01.04.2008 17|A/C Thr|L1|A/B1/B2 Page 39 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Bypass Ratio M15.01 | M14.01 BYPASS RATIO Thrust of Turbofan Engines On the turbofan engine the fan accelerates a high airflow to a relatively low outlet velocity. At the same time the core engine accelerates a small quantity of air to a high outlet velocity. Because of the high fan airflow, the fan can produce more than 80% of the total thrust. This is primarily dependent on the bypass ratio. The bypass ratio is the ratio of air that passes through the fan duct compared with the air that passes through the core engine. On modern turbofan engines the bypass ratio is between 4:1 and 9:1. In future this ratio will increase further. Older turbofan engines like the Pratt & Whitney JT8D engines have a bypass ratio of about 1:1. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 18|A/C Thr|L1|A/B1/B2 Page 40 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Bypass Ratio M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 20 Bypass Ratio HAM US/F SwD 01.04.2008 18|A/C Thr|L1|A/B1/B2 Page 41 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Construction and Operation M15.01 | M14.01 CONSTRUCTION AND OPERATION Exhaust Nozzles on Turbofan Engines Turbofan engines can be either short ducted, which is correct for most of the high bypass engines, or long ducted with combined or separate exhausts. In conclusion, you can say that the turbofan engine combines the good efficiency and high thrust capability of the turboprop with the high speed and high altitude capability of a turbojet. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 19|A/C Thr|L1|A/B1/B2 Page 42 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Construction and Operation M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 21 Exhaust Nozzles on Turbofan Engines HAM US/F SwD 01.04.2008 19|A/C Thr|L1|A/B1/B2 Page 43 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Operation M15.01 | M14.01 OPERATION Propfans Latest engine research activities are about open rotor engines or so-called propfans. The gas turbine engine powers either a single fan or a set of counter−rotating fans via a gearbox. Because of the number and shape of the fan blades, these engines have good speed and altitude capabilities. They also have the advantage of using up to 20% less fuel than high bypass engines. This is because they have bypass ratios of up to 90:1. Because of mounting difficulties, these engines are not very common on modern jet aircraft. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 20|A/C Thr|L1|A/B1/B2 Page 44 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Operation M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 22 Propfan HAM US/F SwD 01.04.2008 20|A/C Thr|L1|A/B1/B2 Page 45 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 CONSTRUCTIONAL ARRANGEMENT Non - Modular Construction The different methods of engine design are known as modular engine design and non-modular engine design. A gas turbine engine is made of many individual parts. In the early years of gas turbine engine design, parts were made by using the best manufacturing capabilities and engine materials of that time, so that the engine fulfilled its main purpose. Because of these factors, compromises were made which led to a very condensed and difficult engine design. A non−modular engine construction saved weight and was fully functional. It therefore fulfilled the main aim of the engine design, but most parts were matched individually. This meant that the design was complicated and parts were difficult to access. Often the engine was removed to gain access to a single part that had to be replaced for maintenance purposes. A non−modular engine construction is usually only found on older engine type and on some APUs. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 01|Non−mod Constr|L1|A/B1/B2 Page 46 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 23 Non-Modular Construction HAM US/F SwD 01.04.2008 01|Non−mod Constr|L1|A/B1/B2 Page 47 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 Modular Construction A modular engine construction is used on all modern aircraft. The whole engine is split up into a set of separate major modules. These engine modules are pre−assembled and balanced. They are specially designed to be removed and replaced more easily. The modules remain intact after removal and do not fall to pieces. Usually the major engine modules are further divided into individual sub-modules. The number of modules depends on the manufacturer and on the engine type. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 02|Mod Constr|L1|A/B1/B2 Page 48 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 24 Modular Construction HAM US/F SwD 01.04.2008 02|Mod Constr|L1|A/B1/B2 Page 49 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 Modular Construction cont. There are many advantages to a modular engine construction for the engine manufacturer and for the engine operator. The advantages for the engine manufacturer are: S the rotating module parts can be pre−balanced, S less spare engines are needed in stock, S there is more flexibility when changes are made to individual engine parts S and finally the main engine modules can be easily stored and transported. The advantages for the engine operator are: S the modules can be removed and replaced with a minimum of disturbance to other nearby engine parts, S no re−balancing is required after a module change, S most modules can be replaced while the engine remains on the aircraft, S there is less need for spare parts and the modules can be easily transported. Another factor of the modular design is that very often the replacement of a module is considered a minor repair and not a shop repair. This means that work may be done by a maintenance organization and not by an engine overhaul organization. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 03|Mod Constr|L1|A/B1/B2 Page 50 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 Advantages for the Manufacturer Advantages for the Operator FOR TRAINING PURPOSES ONLY! Figure 25 Advantages of Modular Engine Construction HAM US/F SwD 01.04.2008 03|Mod Constr|L1|A/B1/B2 Page 51 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 Engine Materials The main design aim for engine materials is that they must be as strong as required for their individual tasks, they must also be as light as possible and they must be as cheap as possible. Typical materials used on modern jet engines are − aluminium alloy, − ceramic material, − composite material, − cobalt base alloy, − nickel base alloy, − corrosion resistant steel alloy − and titanium base alloy. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 04|Engine Mat|L1|A/B1/B2 Page 52 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 Flow Path Liner Outlet Guide Vanes Fan Turbine Nozzle N1 Shaft Spinner Cone Engine Bearing No.1 FOR TRAINING PURPOSES ONLY! Low Pressure Compressor High Pressure High Pressure Turbine Compressor Diffuser Case Exhaust Case Main Gearbox and Combustor Low Pressure Turbine Fan Case Fan Exit Case Figure 26 Engine Materials HAM US/F SwD 01.04.2008 04|Engine Mat|L1|A/B1/B2 Page 53 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 Engine Materials cont. Aluminium alloy is mainly used for gearbox housings, fan stator casings and other low loaded parts of the fan module. Composite materials are usually used in the fan module. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 05|Engine Mat|L1|A/B1/B2 Page 54 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 27 Engine Materials - Composites and Aluminium Alloys HAM US/F SwD 01.04.2008 05|Engine Mat|L1|A/B1/B2 Page 55 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 Engine Materials cont. Ceramic coatings are used in the combustion section and in the high pressure turbine. These coatings serve as heat protection and corrosion protection. Steel alloys are used for the N1 drive shaft, the engine bearings and also for main structural frames on some engines. On the PW 4000 engine in the graphic the intermediate case and the turbine exhaust case are made of steel. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 06|Engine Mat|L1|A/B1/B2 Page 56 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 28 Engine Materials - Ceramic and Steel Alloys HAM US/F SwD 01.04.2008 06|Engine Mat|L1|A/B1/B2 Page 57 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 Engine Materials cont. Cobalt base alloys are very heat resistant. They can be found in the stator of the first stage of the high pressure turbine. Titanium base alloys are as strong as steel but only half as heavy. They can withstand high centrifugal loads, but they are expensive. These materials are mainly used in the fan, the low pressure compressor and the front stages of the high pressure compressor. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 07|Engine Mat|L1|A/B1/B2 Page 58 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 29 Engine Materials - Cobalt Based Alloys and Titanium Alloys HAM US/F SwD 01.04.2008 07|Engine Mat|L1|A/B1/B2 Page 59 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 Engine Materials cont. Nickel base alloys can withstand high centrifugal loads at high temperatures. Therefore these materials are used in the high pressure compressor, in the combustion section and for the high and low pressure turbines. Note that these examples are typical and depend on the engine manufacturer. More and more engine parts will be made of composite materials in the future. FOR TRAINING PURPOSES ONLY! HAM US/F SwD 01.04.2008 08|Engine Mat|L1|A/B1/B2 Page 60 Lufthansa Technical Training GAS TURBINE ENGINE | PROPULSION EASA PART-66 M15 FUNDAMENTALS | TURBINE ENGINE Constructional Arrangement M15.01 | M14.01 FOR TRAINING PURPOSES ONLY! Figure 30 Engine Materials - Nickel Based Alloys HAM US/F SwD 01.04.2008 08|Engine Mat|L1|A/B1/B2 Page 61 M15.01 A E TABLE OF CONTENTS M15 GAS TURBINE ENGINE............. 1 NON - MODULAR CONSTRUCTION................ 46 MODULAR CONSTRUCTION...................... 48 M15.1 FUNDAMENTALS........................ 1 ENGINE MATERIALS............................. 52 GAS TURBINE ENGINES - INTRODUCTION........ 2 INTRODUCTION TO AIRCRAFT ENGINES.......... 2 OPERATION AND CONSTRUCTIONAL ARRANGEMENT...... 6 TYPES OF GAS TURBINE ENGINES............... 6 NEWTON‘S LAWS OF MOTION.................... 8 PRINCIPLES OF JET PROPULSION................ 8 ACCELERATION................................. 10 PRINCIPLES OF JET PROPULSION................ 10 ACCELERATION AND WORK..................... 12 POWER, FORCE AND VELOCITY.................. 16 THE THRUST FORCE............................. 16 BRAYTON CYCLE................................ 18 PRESSURE-VOLUME DIAGRAM................... 18 ENERGY AND VELOCITY......................... 22 WHAT IS THRUST................................ 22 INFLUENCE OF ENVIRONMENTAL EFFECTS...... 26 ENVIRONMENTAL EFFECTS ON THRUST......... 26 OPERATION..................................... 34 THRUST OF TURBOJET ENGINES................. 34 THRUST OF TURBOPROP ENGINES.............. 36 THRUST OF TURBOFAN ENGINES................ 38 BYPASS RATIO.................................. 40 THRUST OF TURBOFAN ENGINES................ 40 CONSTRUCTION AND OPERATION............... 42 EXHAUST NOZZLES ON TURBOFAN ENGINES..... 42 OPERATION..................................... 44 PROPFANS...................................... 44 CONSTRUCTIONAL ARRANGEMENT.............. 46 Page i M15.01 A E TABLE OF CONTENTS Page ii M15.01 A E TABLE OF FIGURES Figure 1 Main Tasks of Jet Engines.............................. 3 Figure 2 Advantages/ Disadvantages of Piston Type Engines........ 5 Figure 3 Types of Gas Turbine Engines........................... 7 Figure 4 Jet Propulsion Principle................................. 9 Figure 5 Force Equation........................................ 11 Figure 6 Air Acceleration Methods............................... 13 Figure 7 Compressors for Gas Turbine Engines................... 15 Figure 8 The Thrust Force...................................... 17 Figure 9 Brayton cycle......................................... 18 Figure 10 detailed brayton cycle................................. 21 Figure 11 Thrust Test Model.................................... 23 Figure 12 Deflector Plate in Outlet Airflow......................... 25 Figure 13 Environmental Effects on Thrust........................ 27 Figure 14 Relation Thrust vs. Air Pressure and Air Temperature.....