Performance of mixed flow compressor with un-shrouded impeller strongly depends upon unsteady, asymmetrical flow fields in the axial directions. The flow through the mixed flow impeller is complex due to three-dimensi...Performance of mixed flow compressor with un-shrouded impeller strongly depends upon unsteady, asymmetrical flow fields in the axial directions. The flow through the mixed flow impeller is complex due to three-dimensional nature of geometry. In mixed flow impeller, there are clearances between the rotating impeller blades and the casing as the high pressure ratio compressors are usually open shrouded impellers. As a result, certain amount of reduction in the performance is unavoidable due to clearance flows. In the present investigations, numerical analysis is performed using a commercial code to investigate tip clearance effects on through flow. The performance of mixed flow impeller with four different clearances between impeller and stationary shroud are evaluated and compared with experimental results. The impeller performance map was obtained for different operating speeds and mass flow rates with different tip clearances. The result shows that the tip leakage flow strongly interacts with mainstream and contributes to total pressure loss and performance reduction. The pressure and performance decrement are approximately linearly proportional to the gap between impeller and stationary shroud.The analysis showed scope for improvement in design of the compressor for better performance in terms of efficiency and operating range.展开更多
In this paper,the simultaneous effects of the sweep and lean of the blades in one stage of a transonic compressor on its performance have been investigated.Then,with the help of numerical solution,fluid flows over the...In this paper,the simultaneous effects of the sweep and lean of the blades in one stage of a transonic compressor on its performance have been investigated.Then,with the help of numerical solution,fluid flows over these two modified geometries generated from the original sample were analyzed.Considering the applied constraints,the two generated rotor geometries have different geometrical characteristics;so that in rotor No.1,the blade has a backward sweep and it is less affected by lean,while in the modified rotor No.2,the blade has a forward sweep and it is more affected by lean.In the first sample,it is observed that the stage efficiency increases by 0.5%for operating design,while the stall margin reduces,and the chocking mass flow rate diminishes by 1.5%.Also regarding the second modified blade,the results indicate that the stall margin increases,the choking flow rate at the nominal rotational speed of the stage increases by 0.18%and the stage efficiency increases by 1%.The comparison of numerical results also shows that,in the first modified rotor,the pressure ratio of the stage diminishes by 0.01%;while in the second sample,the pressure ratio of the stage increases by the same amount.These results were then compared with the experimental results,showing a good agreement.展开更多
文摘Performance of mixed flow compressor with un-shrouded impeller strongly depends upon unsteady, asymmetrical flow fields in the axial directions. The flow through the mixed flow impeller is complex due to three-dimensional nature of geometry. In mixed flow impeller, there are clearances between the rotating impeller blades and the casing as the high pressure ratio compressors are usually open shrouded impellers. As a result, certain amount of reduction in the performance is unavoidable due to clearance flows. In the present investigations, numerical analysis is performed using a commercial code to investigate tip clearance effects on through flow. The performance of mixed flow impeller with four different clearances between impeller and stationary shroud are evaluated and compared with experimental results. The impeller performance map was obtained for different operating speeds and mass flow rates with different tip clearances. The result shows that the tip leakage flow strongly interacts with mainstream and contributes to total pressure loss and performance reduction. The pressure and performance decrement are approximately linearly proportional to the gap between impeller and stationary shroud.The analysis showed scope for improvement in design of the compressor for better performance in terms of efficiency and operating range.
文摘In this paper,the simultaneous effects of the sweep and lean of the blades in one stage of a transonic compressor on its performance have been investigated.Then,with the help of numerical solution,fluid flows over these two modified geometries generated from the original sample were analyzed.Considering the applied constraints,the two generated rotor geometries have different geometrical characteristics;so that in rotor No.1,the blade has a backward sweep and it is less affected by lean,while in the modified rotor No.2,the blade has a forward sweep and it is more affected by lean.In the first sample,it is observed that the stage efficiency increases by 0.5%for operating design,while the stall margin reduces,and the chocking mass flow rate diminishes by 1.5%.Also regarding the second modified blade,the results indicate that the stall margin increases,the choking flow rate at the nominal rotational speed of the stage increases by 0.18%and the stage efficiency increases by 1%.The comparison of numerical results also shows that,in the first modified rotor,the pressure ratio of the stage diminishes by 0.01%;while in the second sample,the pressure ratio of the stage increases by the same amount.These results were then compared with the experimental results,showing a good agreement.
