考虑部件不确定性的发动机性能裕度设计方法

Determination of Design Margins for Aeroengine Performance Targets Considering Component Uncertainties

针对部件不确定性影响整机性能达标的问题,以混合排气涡扇发动机为对象,利用总体性能参数对部件参数的敏感性系数矩阵,结合和方根原理,建立了考虑部件参数不确定性的航空发动机性能裕度设计方法。在此基础上研究了总体性能参数达标的置信度、部件参数达标的置信度对航空发动机性能裕度设计结果的影响规律。结果表明:各部件参数的置信度决定了发动机总体参数的置信度。部件参数满足设计目标的置信度越高,总体性能参数的裕度需求越小;总体性能参数满足设计要求的置信度越高,则其裕度需求越大。对于80%的总体性能参数置信度,对应不同部件参数置信度,推力的裕度需求为1.44%~5.25%,耗油率的裕度需求为-1.60%~-6.61%。相关结论为航空发动机性能稳健设计提供了理论依据。

In view of the significant impact of component uncertainties on the aeroengine performance, the robust design method was practiced on a mixed-flow turbofan engine. The sensitivity coefficient matrices derived from the nonlinear aeroengine model combined with the root sum squared method were applied to establish a design margins determination method for engine overall performance targets considering component parameter uncertainties. The effects of confidence levels of overall per-formance targets as well as the confidence levels of component performance on the design margins were revealed. The results show that confidence levels of overall performance parameters can be defined by that of component performance parameters. Furthermore, the higher the confidence levels of component performance parameters, the lower the design margins required for the overall performance targets. With the increase of confidence levels of overall performance targets, the design margins required for the overall performance targets increase monotonically. To achieve a confidence level of 80% for the perfor-mance targets, the thrust margin should be 1.44% to 5.25%, and the specific fuel consumption margin should be -1.60% to -6.61%, corresponding to different confidence levels of component performance parameters. The conclusions of this study can be used as the theoretical basis for the determination of design margins for engine overall performance targets.