Research On Through-Flow Structural Performance Of Centrifugal Compressor For WD095 Micro Gas Turbine

The micro gas turbine(MGT) is a type of low-cost and combined heat and power generation,widely used in minitype distributed power generation,for its advantages of more agility,safety and low emission.It meets the great diversified demand of the development of our country's energy supply.Moreover,the MGT can be used in the water-scarce area,which accords with the strategy of 21^st sustainable development.But owing to its compactness and relatively small size of the through-flow structure,the efficiency of the components of MGT is relatively low.Thus,this paper is mainly focused on the research and the performance under designed conditions of a centrifugal compressor of high pressure ratio and high rotating speed,a pivotal component of WD095 micro gas turbine,with the purpose of reducing flow loss and further advancing efficiency.In this paper,a series of investigations were carried out with regard to the impeller and the diffuser,two core parts of the centrifugal compressor.For the unshrouded impeller,the size of blade tip clearance and the circumferential position of splitter blades were studied and analyzed.Based on the aerodynamics and the structure analysis theory,the through-flow structure was investigated numerically in detail,by using the CFD software-NUMECA and the finite-element analysis software-ANSYS.According to the numerical results,0.2mm tip clearance was recommended for this impeller.The investigation also shows that:reasonable circumferential position of splitter blades can availably restrain the secondary flow in the through flow cross section,and apparently improve the internal flow condition in the impeller. The performance of the impeller is the best in all design projects,while the circumferential distance of the splitter blade trailing edge between splitter blade and the pressure side of main blade is 44.4%of the distance between two main blades,and its leading edge is located in the middle of two main blades.Then two types of staggered arrangement cascade diffusers were designed respectively with the similarly reduced blade profile of the initial design and NACA-65.The internal flow condition was numerically simulated and analyzed for the two types of diffusers respectively with the similarly reduced blade profile of the initial design and NACA-65.The simulation results indicate that the staggered arrangement cascade diffusers can restrain the flow separation effectively,decrease flow loss and increase efficiency.And the efficiency of the combining structure of the impeller and the staggered arrangement cascade diffuser is increased by more than 2 percentage points compared with the initial design.It is shown the staggered arrangement cascade diffuser is worth to further study.