2010 Vol. 25, No. 11

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Display Method:
The boundary transition research of scramjet inlet based on the T-S wave syntony
Zhao Jun-bo
2010, 25(11): .
Abstract PDF(841KB) icon2061 icon573
Abstract:
For the boundary separation and block of the scramjet inlet by the shock wave and boundary interacting, a kind of boundary control method based on the T-S wave syntony principle is presented, and the method is calibrated by the wind tunnel test for a typical 2D inlet. The results of the example showed that the boundary control method could eliminate the boundary separation efficiently, and decrease the negative influence of boundary separation, so the inlet’s capability could be maintained. The research coinstantaneous shows that the boundary transition should be considered, and effective transition method should be adopted to ensure the normal work of the scramjet engine.
Numerical Simulation on Inlet Distortion of Centrifugal Compressor with 90 degree Bent Pipe
Li Du
2010, 25(11)
Abstract PDF(3031KB) icon1958 icon657
Abstract:
To understand the effects of centrifugal compressor inlet distortion caused by 90°bent pipe, two different axial position inlet bent pipe were numerically simulated with compressor and the influence on compressor performance was analyzed. The results show different performance deterioration between different bent pipes, the larger distance between bent pipe outlet and impeller inlet creates more decrease. The bent pipe makes the flow field of impeller inlet strongly disordered. The distortion causes a noticeable decline in compressor performance under large mass flow and a slightly drop under low mass flow. The affect of inlet distortion amplifies and develops to the volute inlet while the mass flow rate increases, which function with circumferential distortion caused by volute tongue, makes the performance decreased. When the mass flow rate is low, the inlet distortion reduces the flow loss in impeller passage, which could maintain the performance of compressor at low mass flow.
Method to achieve compressor characteristics maps based on SVM and PSO
Jiang Ai-wu
2010, 25(11)
Abstract PDF(459KB) icon1433 icon608
Abstract:
An algorithm for support vector regression is improved and implemented as in computer programming. And this new algorithm, together with the particle swarm optimization, is used to regress the nonlinear function about how would compressor efficiency or corrected inlet air flow vary when the rotor speed, pressure ratio and compressor inlet flow angle changed. Here the inlet flow angle is considered as one of the independent variables, so this is the improvement for the method to achieve the compressor characteristics maps only depending on rotor speed and pressure ratio. The nonlinear relationship between the dependent variables and independent ones described above was regressed by support vector machine, and its degree of approximation was optimized by particle swarm optimization. Finally, the method was tested to be effective to achieve the nonlinear function describing the compressor characteristics maps.

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