Numerical Study On Flowfield And The Rotor’s Film Cooling Of Radial-inflow Turbine In CCHP System

As a kind of typical distributed power generation technology, the CCHP system will occupy a more important role in the 21 st century’s electric power industry. This kind of energy-supplying system whose core is micro gas turbine can greatly enhance the energy utilization rate, so it attracted a lot of scholars abroad in developed countries to study and apply the technology. However, in our country the micro gas turbine technology need more exploration and exist a great market demand because of a series factors, such as energy distribution, domestic consumption, technology, and so on. To meet the requirement of flow, efficiency, performance aspects, the micro gas turbine always take the radial inflow turbine as the core work component. But there is strongly three dimensional flow in its passage, and turbine’s high rotating speed will make the brother’s larger force and centrifugal force bigger. So it is difficult to design and experimental study on the radial inflow turbine. At the same time it has great challenge on material strength because of the thermal stress caused by high-temperature inflow, so it is necessary to design cooling structure to make sure the turbine’s normal work.This paper focuses on the high-temperature radial turbine of CCHP system and makes an efficient solution. Then the turbine efficiency is elevated through modifying the impeller inlet contour line. And this kind of inlet contour line’s acting mechanism is analyzed. At last a reasonable cooling structure solution is designed on the turbine surface and enwall to reduce the thermal stress.The result shows that the wheel efficiency of the designed radial turbine reached 79.3%, leakage flow loss which is created by pressure gradient is the main loss of the turbine passage. Using a reasonable front blend angle for the impeller inlet contour line can enhance the blade loading in the suction side on bottom of the blades, and reduce the leakage flow loss, and enhance the turbine working efficiency by 1.1% It is reasonable to design film cooling structure on the turbine surface and enwall and reduce the temperature availably. The cooling flow is affected by main flow nearly blade wall with the same regular of the wall limited streamline. The temperature on the suction side is the same as the temperature on the pressure side because of a low thickness and high heat conduction of the designed radial turbine, but the cooling efficiency on the suction side is better than the pressure side. The most reasonable cooling mass flow can reach 2.5% of the main flow.