Chapter 4 Combustion Section v1 PDF

Chapter 4: Combustion Section Introduction  Purpose of Combustor  Combustion chamber qualities  Combustion chamber construction (air flow)  Types of combustion chamber  Multiple can combustion chamber  Tubo annular combustion chamber  Ann...

Chapter 4: Combustion Section Introduction  Purpose of Combustor  Combustion chamber qualities  Combustion chamber construction (air flow)  Types of combustion chamber  Multiple can combustion chamber  Tubo annular combustion chamber  Annular combustion chamber  Advantages & Disadvantage of individual types 2 Purpose of Combustor  The burner section contains the combustion chamber, and provides the means for proper mixing of the fuel and air to assure good combustion and to ignite the fuel/air mixture at the start. 3 Combustion Chamber Qualities Complete combustion Low total pressure loss Stability of combustion No hot spots Short length Small cross-section No flameout Relightability Wide range of operation 4 Facts on Combustion  Fuel must be vaporized and mixed with air before combustion.  Combustion process increases the thermal energy of the gases.  Equivalence ratio ǿ is the actual fuel air ratio divided by the stoichiometric fuel air ratio  Rich mixture is when ǿ > 1  Lean mixture is when ǿ < 1  The air fuel ratio is in the range of 60 to 100 5 Air Distribution in a Combustion Chamber 6 Air Distribution in a Combustion Chamber 7 Flame Stabilizing And General Airflow Pattern 8 Types Of Combustion Chamber  There are three main types of combustion chamber in use for gas turbine engines. These are: 1. The multiple can chamber 2. The tubo-annular chamber 3. The annular chamber 9 Multiple Can Combustion Chamber 10 Can Type Combustion Chamber  The can type combustion chamber is used mainly on older centrifugal compressor engines  Airflow is ducted to individual combustion cans that are arranged around the circumference of the burner section  Each can contains its own fuel nozzle, burner liner, and casing  Advantages include its strength and durability, combined with the ease of maintenance  Disadvantages include poor use of space in the chamber for cooling, and uneven heat distribution to the turbine section 11 Tubo Annular Combustion Chamber 12 Can-annular Type  Can-annular type chambers combine the ease of maintenance of the can type with the outstanding thermodynamics cooling of the annular type  Contains cans at the front where the fuel and air are mixed and burned  Advantages are similar to can type but with additional structural stability and better utilization of space as compare to can type  Disadvantages are similar with can type and it is more expensive and heavier than can type 13 Annular Combustion Chamber 14 Annular Combustion Chamber  Annular combustion chambers consist of a circular, continuous, inner and outer shroud around the outside of the compressor drive shaft  Annular combustion chamber is most commonly used in most engines due to its size advantage  Fuel is introduced through a series of nozzles where it is mixed and ignited with the incoming air  Advantages include providing a uniform heat distribution across the face of the turbine section which aids in the prevention of heat warping or turbine blade failure, and for better mixing of air and fuel along with better use of cooling space  Disadvantages include not being able to be removed without complete disassembly of the engine from the aircraft, and possible structural problems may arise due to the large-diameter, thick-wall cylinder required with this type of chamber 15 Recap  Design qualities of combustion chamber  Air-fuel ratio range  Identify the types of combustion chamber and state the Advantages/Disadvantages for each type of chamber 16