航空发动机多设计点热力循环分析方法的构建及应用

Construction and application of multi-design point method to perform thermodynamic cycle analysis for aero-engine

针对航空发动机设计中涉及多性能需求与多约束条件的问题,提出一种以多个工作状态作为设计点进行热力循环分析的实现方法,并介绍了多设计点方法的构建及求解过程。采用单设计点方法和多设计点方法对大涵道比涡扇发动机进行热力循环分析,并对比了两种方法得到的设计域。结果表明,由于单设计点方法需假设某些热力参数在循环分析过程中不变,使设计域内部分区域不能满足性能需求或技术限制,且该区域内可能包含性能最优点。多设计点方法考虑了全部技术限制和所有工作状态的性能需求,在单设计点方法中不变的循环参数,在多设计点方法中作为非线性方程组中的迭代变量,确保了多设计点方法的设计域总是可以满足所有的性能需求和技术限制。

An approach to perform thermodynamic cycle analysis at multiple design points was developed to investigate the situation utilizing multiple performance requirements and multiple constraints in the aero-engine design process.The construction and solution process to perform design cycle analysis at more than one operating condition was illustrated.Cycle design spaces of a large bypass ratio turbofan engine created by two different design methods were examined.The analysis demonstrates that the constant assumption for cycle parameters of single design point method will make some region in the design space conflict with technology limits or performance requirements and this will make the region maybe contains the optimum candidate engine infeasible.The design space of multi-design point method,which incorporates all operating conditions and constrains,always meet the technology limits and performance requirements because of the use of the cycle parameters included in the system of nonlinear equations.