Abstract:
High performance Axial Flow compressors are the lifeline of an aircraft. Due to its importence its aerodynamical study is a high leavrage area for the reasearchers. These compressors normally have optimum efficiency at the location which is near to stall point. Moreover due to increased loading with minimum number of stages compressors are forced to operate near the stall regime which can led the engine in Flameout state. In order to have the satisfactory perfomance of engine the stall line should be avoided during transients i.e accelaration and decelartion.
The fluid flow in axial flow Compressor is under termendus strain and its behaviour is highly sensitive to adverse pressure gradiant.To reduce the weight and length of an axial flow compressor the number of stages are to be minimized, which leads to present day demand of high pressure ratio and high efficiency per stage.
Various techiniques have been used to control the stall and surge of compressor. These techniques can be classified into active and passive control techniques. Active control techniques include bleed valve and air injection whereas in passive techniques the Variable guide vanes, Casing treatment and multiple spools are incorporated. Some of these techniques are used for widening the stall margin and other are used to increase the Performance of the compressor while the combination of different techniques effectively enhance the operation range and efficiency
