Gasturbine Performance Deel 5

The order of prohibited areas in a fuel metering graph based on increasing RPM is: Rich Blow Out, Stall, Overtemp.

Oil is used in a heat exchanger to heat the fuel. It serves as the heat transfer medium between the engine oil and the fuel.

The pressure relief valve in a fuel metering system prevents excessive pressure buildup when the shut-off valve closes. It ensures safe operation by releasing excess pressure.

The blades of the High-pressure Turbine (HDT) are NOT controlled by FADEC. It primarily manages other aspects like engine speed and fuel flow.

The FADEC uses the 'Approach Configuration' signal to maintain RPM at Flight Idle for a restart. This ensures a predictable and stable restart process.

Newton's 2nd and 3rd Laws of Motion are essential for understanding aircraft propulsion. The interaction of force and mass to create acceleration (2nd Law) and the action-reaction principle (3rd Law) are key.

During one cycle of a reciprocating engine, the piston drives the shaft for only 1 stroke. This is the Power stroke where the expanding gas drives the piston.

In an ideal gas, the molecules are assumed to have zero volume. This simplifies calculations and is a reasonable assumption under certain conditions.

In a reciprocating engine, the gas is compressed during an adiabatic process. This means heat exchange with the surroundings is negligible.

In the inlet of a turbofan, the airflow temperature increases. This is due to the compression process, but the total temperature remains constant due to the conservation of energy.

A combustion chamber with a high inlet temperature and a high temperature increase requires the largest fuel/air ratio. This is because more fuel is needed to achieve the desired temperature rise.

As TAS (True Airspeed) increases, the specific thrust decreases. This is because less fuel can be supplied to a given mass of air at higher speeds.

Engine Pressure Ratio (EPR) is used as an indication of the thrust produced by a jet engine. Higher EPR means higher thrust.

The rotation of a rotor in a turbine causes a change in total temperature due to the conversion of kinetic energy into thermal energy. This results in a temperature difference across the rotor.

Surge occurs when the airflow in a compressor reverses direction. This is a dangerous condition that can occur in off-design operation.

In the stator of a 50%-reaction turbine, pressure energy is converted to velocity energy. This happens as the flow enters the turbine stages.

Due to the centrifugal force acting on a turbine blade, compressive stress occurs at both the leading and trailing edges. This is because these edges experience the highest radial forces.

The surplus of air fed to the combustion chamber ensures complete combustion in the primary zone, adequate cooling of the combustion chamber walls, and dilution of hot combustion gases.

An annular type combustion chamber is the least suitable for connection to a centrifugal compressor. Centrifugal compressors need a different flow pattern.

In a twin-spool turbofan, the starting engine is connected to the N2 shaft, providing initial power for the gas turbine. However, the starting engine does not directly drive the gas turbine with pressurized air.

Light-up, which is the initiation of fuel combustion in the combustion chamber, starts at point

In a fuel metering graph, the Stall Area indicates that the fuel-air ratio is too high. This results in excessive air expansion, potential instability, and possible flameout.

The heat exchanger in a fuel system cools oil and heats fuel. This helps regulate fuel temperature and ensures proper operation.

If the CDP (Control Displacement Piston) increases, it moves to the left, resulting in a larger fuel flow opening and increased fuel flow. This is how some engines are able to adjust fuel flow.

MEC (Mechanical Engine Control) uses fly weights to regulate engine speed. In FADEC, these fly weights are replaced by electronic sensors and actuators.

In a reciprocating engine, the SHAFT drives the PISTON for 3 strokes. This includes the Intake, Compression, and Exhaust strokes where the crankshaft rotates the connecting rod, moving the piston.

In a cylinder with a free movable piston, if a mass is removed from the piston, the piston will move up slowly, but the temperature of the gas will remain constant. This is an example of an isothermal process.

Ignition does NOT take place in a Stirling engine. It utilizes a closed cycle system with external heating and cooling, relying on heat transfer for operation.

The main advantages of a jet engine over a reciprocating engine are related to the airflow. Jet engines handle airflow more efficiently, leading to higher speeds and a more streamlined design.

When the total enthalpy of 1 kg of air increases, the total temperature also increases for sure. This is due to the direct relationship between total enthalpy and total temperature.

Specific thrust is measured in Newtons per kilogram of air per second. It represents the thrust produced per unit of mass airflow.

In the rotor of a compressor, the relative velocity of the air does NOT increase and the direction of the whirl velocity is NOT reversed. Instead, the relative velocity decreases, and the direction of the whirl velocity is changed.

Point 'a' on the compressor characteristic curve indicates the stalling point of the compressor. This occurs when the airflow is no longer stable and can lead to reduced performance or stall.

To determine the pressure difference in a centrifugal compressor, you use the change in absolute velocity in the diffuser and the change in relative velocity in the impeller. These velocity changes are linked to pressure changes.

Area B in the relight envelope represents an area where a restart is only possible using the starting engine. This is when the engine conditions are outside of normal restart capabilities.

The surplus of air fed to the combustion chamber is not to ensure complete combustion of the fuel in the primary zone. While this is a benefit, the primary functions are for cooling, dilution, and flame stabilization.

The last parameter to increase during engine startup is EGT (Exhaust Gas Temperature). This indicates that the engine has reached a stable operating condition.

An engine can accelerate from point X to Y along lines A and B. Line C represents the equilibrium line, which is the steady-state operating condition where the engine is balanced.

With increasing OAT (Outside Air Temperature), N2 increases because the turbine chokes at a higher temperature. The engine needs to work harder at higher external temperatures to maintain performance.

Component B acts as a control valve in the fuel metering system. Because of its design, the fuel flow is independent of the pressure difference across the control piston.

N1 is not used by a MEC (Mechanical Engine Control). This is a signal monitored and controlled by FADEC (Full Authority Digital Engine Control) which is more advanced.

N1 is not used by a MEC (Mechanical Engine Control). N1 is a primary control parameter in FADEC (Full Authority Digital Engine Control) which is more advanced.