Research On Inverse Method For Compressor Blade Design In Stage Environment

There are commonly three methods for designing compressor blade: optimization method, analyzing design method, and inverse method. Analyzing method is easy to implement and its principles are simple, but it always wastes much time and the designing result is strongly depended on the designer’s experiences. Adopting optimization method the designing result has high reliability, but it’s difficult to determine the optimal principles. When using inverse method to design a compressor blade, the designers specify the target parameters according to the design index, and get the new blade, which meets the target parameters, using the inverse design algorithm. Inverse method has lots of advantages such as small resource depletion, high designing efficiency, weak dependence of designers’ experiences and so on. According to the characteristic wave theory for non-viscous flow, this paper developes a kind of effective inverse design method for full three-dimensional compressor blade, based on the work on the inverse design method for compressor blade of Von Karman Institute(VKI). This paper also discusses lots of important problems in view of the application of the inverse method in the engineering practice. Then the inverse method is used for redesigning stage35, a compressor stage from NASA Lewis research center, to get a more well-performed stage35. The main research work of this paper includes:(1) Improve the inviscid inverse design process for compressor blade design, at the same time the basic principles and realization of the inverse method are described in detail. Starting from the discrete compatible relations related to the simplified Euler equation, this paper constructs the ‘permeable wall boundary condition’, which is one of the two key technologies involved in this inverse method, and realizes this boundary condition on the CFD platform NAPA. Then this paper realizes the other key technology, called three-dimensional surface modification, based on streamline(stream surface) tracing.Demonstrate the rationality of the permeable wall boundary condition, and then prove the normalization of permeable wall boundary condition and slip wall boundary condition. Put forward the idea of regarding the grid node, who has a minimum Mach number near the blade leading edge, as the starting point of the inverse process.(2) Through error analysis(local truncation error analysis and error transfer analysis) and analyzing the flow field parameters on the sensitivity of grid structure in the 3d surface correction system, this paper explains the phenomenon that the results of inverse design are very different in different types of flow fields such as high-speed flow area, low-speed flow area near leading or trailing edge margin, and other low-speed flow area. Present the relations of the grid structure, flow field parameters and the wall correction, at the same time a solution about reducing the correction error near the wall is put forward, which is hardly increased design time.(3) Based on the MPI/Open MP hybrid parallelization NAPA, which is our research group’s independent research and development, this paper realizes the large-scale parallelization of the inverse method, raising the efficiency of the inverse design. Give three kinds of given strategies on the target parameters to enhance the practicality of the inverse method in engineering practice.(4) The 3d viscous inverse design process is constructed. Then respectively through inviscid and viscous inverse design process, stage35 is redesigned to get a new stage35 with better performance.Compared to the initial stage35, the modified stage35’s total pressure ratio increases by 0.52%, and the adiabatic efficiency increases 3.57 percentage points, at the inviscid inverse design point.Compared to the initial stage35, the modified stage35’s total pressure ratio increases by 0.93%, and the adiabatic efficiency increases 2 percentage points, at the viscous inverse design point.