Principles of naval engineering - Historic Naval Ships Association

Chapter 23. -GAS TURBINEGAS PRODUCING SECTIONPOWER TURBINE SECTIONCOMPRESSORCOMBUSTIONCHAMBERGASPRODUCINGTURBINEACCESSORYDRIVEFigure 23-4.— Gas turbine engine with single-spool axial-flow compressor.147.138disadvantages of the axial-flow compressorinclude difficulty of manufacture, high initialcost, and relatively great weight.147.139Figure 23-5.— Single-spool axial-flowcompressor.The advantages of the centrifugal compressorinclude a high pressure rise per stage, simplicityof manufacture, low initial cost, and relativelylight weight. The disadvantages of the centrifugalcompressor include the need for a relativelylarge frontal area for a given air flow and thedifficulty of using two or more stages becauseof losses that would occur between the stages.Combustion ChamberThe combustion chamber is the componentin which the fuel-air mixture is burned. Thecombustion chamber consists of a casing, aperforatedinner shell, a fuel nozzle, and a devicefor initial ignition. The number of combustionchambers used in a gas turbine engine varieswidely; as few as one and as many as sixteencombustion chambers have been used in one gasturbine engine.The combustion chamber is the most efficientcomponent of a gas turbine engine. Efficienciesbetween 95 and 98 percent can be obtained over awide operating range. To produce such efficiencies,combustion chambers are designed to operatewith low pressure losses, high combustion599