| A numerical modeling computer program for predicting multistage axial compressor stage characteristics has been developed. By this program, which is relying on the general stage-characteristics and compressor design point parameters, as well as the compressor geometry parameters, the stage characteristics at the design speed can be successfi.illy simulated In the real flow condition, the stage characteristics is altered for the part-speed condition, The results for design-speed are presented. The stage characteristics for blade reset are obtained from an optional calculation, which alters the stage design flow coefficient and the pressure coefficient for the blade reset.The compressor is modeled with an overall control volume that is further divided into a set of elemental control volumes. The stage-by-stage model uses the MacoCormack predictor corrector algorithm to solve the Euler equations with source terms in the element control volume, and uses characteristic line technique to solve inlet and outlet boundaries. By increasing the outlet static pressure in every time step, the compressor will operate on the same corrected speed line with a higher pressure-ratio until the stability limit is reached. Compared to the existing data, the relative error of the surge point was found within 5%.Another application of stage-by-stage model is to investigate the post-stall behavior in the compression system which consists of one compressor and one combustion chamber. By closing the assumed choked nozzle (exit boundary) gradually, the surge phenomenon can be observed. At this time, if the mass flow of fuel in main combustion chamber is being decreased, it is found that the compressor system is gradually dropping out of surge recycle.The stage-stacking method is one basic method in the calculation of compressor performance.When compressor system enters the rotating condition, a fist-order time lag equation is introduced to obtain the dynamic stage forces... |
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