关键词: 波瓣混合排气系统；波瓣高宽比；多项式响应面模型；波瓣性能参数；波瓣结构参数

Abstract: Numerical simulation based on Navier-Stokes equations was applied to the lobed forced mixing exhaust system of turbofan engine. The effects of ratio of lobe height to lobe width，when area at lobe exit equals to the one at the exhaust entrance，on the performance and structure of lobed mixer were obtained. Based on this，approximation models about change of lobe performance with ratio of lobe height to width were created by polynomial response surface methodology(RSM)with different order of polynomial. In the respect of fitting precision of polynomial response surface methodology，compared with second-order and third-order RSM methods，the forth-order RSM method can well reflect the change of thermal mixing efficiency，total pressure recovery coefficient，relative thrust and lobe relative weight with the ratio of lobe height to width. Moreover，the errors of calculation results between the forth-order RSM method and numerical simulation are very small. In the respect of effects of ratio of lobe height to weight on performance of mixing exhaust system，at the exit of mixing exhaust system，as increasing the ratio of lobe height to width，in general，the thermal mixing efficiency increases at first and then declines in the wavy changing tendency. The total pressure recovery coefficient appears to change like this “slowly increases-sharply declines-augments-quickly reduces”; as for the relative thrust of exhaust system，when ratio of lobe height to width is larger than 3，although it changes like wave，the variation is very small. For the lobe relative weight，it increases with increasing the ratio of lobe height to width.

Key words: Lobed mixing exhaust system；Ratio of lobe height to lobe width；Polynomial response surface methodology；Lobe performance parameter；Lobe structure parameter