基于相似原理的风车状态进口空气流量和内阻力估算方法

风车状态进口流量和内阻力是试飞安全评估中必须获取的重要信息。为评估燃烧室空中复燃能力和风车状态下飞机阻力,在1维管流理论基础上,结合流量连续原理,介绍了1种通过直接测量尾喷管出口马赫数、间接获取空气流量和内阻力的测量方案,并根据相似原理,将其推广应用至不同几何的发动机,发展了1种不依赖发动机部件特性,且适用于不同几何结构的涡喷/涡扇发动机通用的风车状态空气流量和内阻力估算方法。最后以GE公司的CF34-10A发动机为例,对其风车状态下的进口空气流量和内阻力进行了估算,估算结果与GE公司提供的风车状态数据吻合,满足工程需求。该方法对多发飞机起飞、爬升、着陆以及巡航阶段单发失效时的飞机阻力性能估算和风车起动研究具有重要意义。

Estimation Method of Windmilling Inlet Air Flow and Internal Drag Based on Similarity Principle

The inlet air flow and internal drag under windmilling conditions are key information that should be achieved in safety evaluation of flight test. To estimate combustion chamber relight capability and engine drag under windmilling conditions, an measurement scheme was introduced that the windmilling air flow and internal drag can be obtained indirectly through the measurement of mach number at nozzle exit based on one-dimensional ducted flow and continuity theory. According to the similarity principle, the method was applied on different geometry engines. An estimation method was developed, which was independence on engine component characteristics, and was applied on estimating the windmilling drag and air flow of turbojet and turbofan engines in different geometries. At last, taking the GE CF34-10A as an example, the windmilling inlet air flow and internal drag were estimated. The investigation results are in good agreement with the GE test data, which meet the engineering requirement. It has important significance for estimating the assessment of aircraft drag performance and windmilling start with one or more engines inoperative during take-off, climb, landing, and cruise conditions.