Study On The Radial Inflow Turbine Structure Optimization For Low Temperature Waste Heat Power Generation System

The radial inflow turbine is studied by both experiment and simulation in this paper.The application background of the turbine is Organic Rankine Cycle waste heatrecovery system. A detailed analysis of the working fluid flow in original designturbine is made by applying CFD technique in design condition. The stator andimpeller of the original design turbine are optimized. The performance of optimizedturbine is proved to be better than the original turbine in design condition andoff-design condition. The numerical analysis methods are proved to be correct bycomparing numerical simulation results with experimental measurements. Theresearch results of the paper have a certain guiding significance for the optimizationof radial inflow turbine. The main research results are as follows:1. An experimental research of Organic Rankine Cycle waste heat powergeneration system with original design turbine is carried. The results indicate that theflow rate of the working fluid is positively correlated with turbine inlet pressure,impeller speed and negatively correlated with turbine inlet temperature, outlettemperature when other conditions remain unchanged.2.35kinds of stator models with different setting angles and vane numbers areestablished. A conclusion that when the setting angle is28°, vane number is19, thestator gets the best performance is drawn by analyzing the combined impact of settingangle and vane number. Compared with the original design turbine, the program notonly reduces the pressure difference between the pressure surface and the suctionsurface, avoids the generation of the secondary flow to a greater extent, but also raisesthe circumferential velocity by8.6percent and the velocity coefficient by1.3percent.3. Impeller models with different non-developable ruled paraboloids areestablished and studied by means of contrast. The results indicate that when theparabolic exponent is t=2.05, the highest efficiency of the impeller may reach to91.9%. It increases by1.0%compared with the original design impeller.4. The whole radial inflow turbine is studied before and after optimization indesign condition and off-design condition. The results indicate that the total to static efficiency of the optimized turbine increases by1.6%and the total to total efficiencyincreases by2.1%compared to the original design turbine in design condition; Thestability of the isentropic efficiency curves and reduced flow rate ratio curves of theoptimized turbine are higher than the original design in off-design conditions.5. The flow rate and power experimentally measured are compared with thenumerical simulation results respectively. The results indicate that the changes ofcalculated values are basically the same with the measured values. The calculatedflow rate is about5.5%larger than the measured flow rate, and the measured turbinepower is about80%of the calculated turbine power. The simulation values agree withthe measurements well, and the correctness of the simulation methods are proved.