Optimization For Inlet And Exhaust Of Steam Turbine Low Pressure Casing With Air Cooling

The performances of the steam turbine are decided by its economy and safety. The economy of the steam turbine is evaluated by the summation of all kinds of loss. The low pressure casing of air-cooling turbine is designed much more smaller than the wet-cooling turbine as it's steam parameter and running mode. At the same time, the moving blades are designed more wider in axial to ensure the strength. All these factors lead to the spaces of the inlet of casing and exhaust hood are narrow. This will increase the flow resistance and reduce the efficiency.The blowing tests always been used in the past to evaluate and optimize the inlet and exhaust hood of steam turbine. The first step is to build the test model in equal scale, then below the test model by compressed air, at last to get the pressure loss factor by measuring the inlet and outlet parameters. The advantages of this method is intuitionist and reliable, but the defect is that it can only measure the inlet and outlet parameters, hardly to describe the internal flow detail. The optimization design need the designer has ample experience and need a lot of try. This will cost a lot of time and money.The CFD numerical simulation technical has been used more and more prevalent theses years. It can describe the detail flow feature by the calculated pressure, temperature and velocity vector distribution, which is helpful to analyze the principle of loss and doing the optimization works. This method cost fewer money and time. We can use it to direction the bellowing test and reduce the test works.This thesis has analyze the inlet and exhaust of a low pressure casing which has been running in china using all of the two methods mentioned above. Got some design problem and tried doing some optimization work. Found some design rules which may be helpful for analyze the principle of flow loss in the inlet and exhaust of low pressure casing and design them easier and better.