两类对转风扇的设计与气动特征数值研究

Aerodynamic design and investigation of two counter-rotating fans

采用一维设计程序分析了前后转子设计转速比的影响,研究了平均半径处的增压比、绝热效率、扩散损失和激波损失随转速比的变化规律.用计算流体力学分析了设计点与非设计状态的两个对转级流场,研究了其详细物理现象.结果表明两个对转级的设计与非设计性能均良好.发现低速风扇的两个转子均为常规跨声速转子,而高速风扇的前转子常规,后转子则为前缘激波和通道激波均贯穿全叶展的全超声速转子.同时发现,均带有与常规风扇级相当的失速裕度,低速对转级是两个转子同时达到失速点并且激波被推出叶栅,而高速对转级则是后转子先达到失速点并激波推出,从而后转子决定着级失速裕度.

The design rotating speed ratio of forward and afterward rotors was discussed based on one-dimensional analysis.The variations of pressure ratios,adiabatic efficiencies,diffusion losses and shock losses at the streamline of half-annulus-area radius against the varied design rotating speed ratios were studied.The flow fields of these two contra-stages were numerically simulated and the detailed flow physics was investigated at the design and off-design conditions.The simulations reveal that these two stages are quite well performed.For the civil engine contra-stage test fan,both rotors are conventional transonic rotors due to the low pressure ratio and low tip speed.For the military engine contra-stage fan different from the conventional transonic forward rotor,the afterward rotor is a full-span relative supersonic rotor in which both the leading edge shock and the passage shock extend from the casing to the hub.Furthermore,these two contra-stages exhibit stall margins competitive to conventional rotor-stator stages.For the civil test fan of low pressure ratio at the stall point,both the forward and afterward rotors are stall and the shocks are detached,correspondingly;for the military fan of high pressure ratio,only the afterward rotor is stall,determining the stage stall point.