Investigation On Design And Optimization Of Fan/Compressor Splitter

With the unceasing performance improvement and structure innovation of the modern aero-engine, the fan/compressor splitter gradually performs a geometrical diversity and number growth. As a consequence, the design of fan/compressor splitter is faced with more stringent requirements. However, very few investigations about splitter were conducted previously, and nearly focused on the surrounding flow field or impact on the overall performance. The individual design theory and method exploration is still nearly blank for the fan/compressor splitter. Therefore, a set of mature splitter design and optimization method is developed in the present work based on two-dimensional model.Summary of the relevant researches contained as below:(1) An initial design method of "meanline distribution + area distribution + thickness overlay" is developed for the core duct with a large radial drop. Initial design methods of Curve Fitting, Airfoil Modifying et al are proposed for the complex splitter leading edge. Numerical results show that: the core duct generated by c2+a1 type has a small exit static pressure distortion and strong total pressure recovery ability; Airfoil Modifying method leads to the largest static pressure coefficient on splitter wall, while Circular parameterized method performs the contrary.(2) The CST method is developed and tested for complex splitter parameterized design. A combinatorial optimization strategy of "Design of Experimental + ASA global optimization" is proposed for splitter optimization design. The Quadratic Regression Model is developed for DOE results analysis, and the influence law of different design variables on the design objectives is explored.(3) Multi-objective direct optimization design and combinatorial optimization design platforms are respectively built up based on Isight environment. Core task modules such as parameterized design program are carried out. Program interfaces between the grid generation, CFD evaluation et al are set up by edited batch scripts, and the automatic running of whole optimization process is achieved.(4) The direct optimization design is conducted on a splitter example with bypass ratio of 2.8 and radius drop to length ratio of 0.5. Results show that the blunt feature of splitter leading edge is strengthened in optimal design; the low pressure area and pressure gradient decreases in the core duct. The combinatorial optimization design is conducted on another splitter example with bypass ratio of 0.366 and radius drop to length ratio of 0.3. Results show that DOE is helpful to adjust the number and scope of design variables; the optimized performance gain of core duct is larger than bypass duct; the static pressure recovery region expands and the radial mixing loss decreases.