航空发动机涡轮特性转换方法

针对以落压比为横坐标,流量与效率为纵坐标,并按不同等转速线区分所表示的涡轮特性在涡轮处于临界状态时换算流量几乎保持不变,使得在航空发动机数学模型中应用该形式涡轮特性通过插值求解共同工作点时存在计算效率降低的不足,根据相似理论及等熵条件下涡轮膨胀功与落压比对应关系,推导了涡轮落压比、涡轮效率与涡轮当量功的关系,并结合抛物线插值方法给出了向以转速为横坐标,涡轮当量功与效率为纵坐标,并按不同等流量线区分所表示的涡轮特性转换方法。实例转换计算表明:采用所提出的转换计算方法,可有效解决以往涡轮特性插值流量基本不变的局限,并且两种格式的涡轮特性转换相对误差小于0.65%,满足工程要求。

Turbine characteristics conversion method of aeroengine

For the turbine characteristics expressed by taking the nozzle pressure ratio as the abscissa, the corrected mass flow and efficiency as the ordinate, and differentiated by different equal rotation speed lines, when the turbine works at critical state, the corrected mass flow of this form of turbine characteristics almost remain unchanged, and had the disadvantage of reducing computational efficiency in solving common working point when it was used in aeroengine mathematical model by interpolation of turbine characteristics. According to similarity theory and the corresponding relationship between turbine expansion work and nozzle pressure ratio under isentropic conditions, the calculation formula between turbine nozzle pressure ratio, turbine efficiency and turbine equivalent work was derived; combined with the parabolic interpolation method, a method for transforming turbine characteristics expressed in the above form was presented, the converted turbine characteristics were expressed by the equal rotation speed as the abscissa, the turbine equivalent work and efficiency as the ordinate, and differentiated by different equal corrected mass flow lines. The conversion calculation shows that with the proposed conversion calculation method, the relative error is less than 0.65% between two forms of turbine characteristics, which meets the engineering requirements, and can effectively avoid the disadvantage of previous turbine characteristics.