液氢预冷吸气式发动机建模与循环特性分析

Modeling and Cycle Characteristics Analysis of Liquid Hydrogen Pre-cooled Air-Breathing Engine

关键词:  预冷发动机  热力循环  部件法  性能模拟  特性分析

Key words:  Pre-cooled engine  Thermodynamic cycle  Components method  Performance simulation  Characteristics analysis

摘要:

为研究预冷发动机的循环特性，提出了一种结构简单、部件匹配难度低的液氢预冷吸气式发动机构型，分析了其热力循环过程，比较了与预冷膨胀式空气涡轮冲压发动机（ATREX）在循环方式上的异同。基于部件法建模，提出了一种通用的自定义部件计算顺序的方法，解决了加热器部件冷热两端的先后计算问题，发展了整机性能计算模型，计算并分析了关键循环参数对发动机性能的影响。计算结果表明：在设计点，压气机压比和燃油流量对发动机性能影响显著，而涡轮前温度主要影响燃油流路部件参数的选择。沿飞行轨迹，增大压气机设计压比、设计燃油流量可以提高低马赫数的推力，增大压气机设计压比会增大高马赫数的涡轮功率负荷，降低15%的设计燃油流量可以提高10%以上的比冲；增大涡轮前温度可以适当提高比冲，显著降低涡轮功率负荷。相比于ATREX与预冷涡轮发动机（PCTJ），液氢预冷吸气式发动机具有较大的比冲优势。

Abstract:

To study the cycle characteristics of a pre-cooled engine， liquid hydrogen pre-cooled air-breathing engine （LHPE） with simple structure and low matching difficulty was proposed. The thermodynamic cycle process of LHPE was analyzed， and the similarities and differences with Air Turbo Ramjet with Expander Cycle （ATREX） in the cycle process were compared. Based on the modeling method of component-level， a general method of user-defined component calculation sequence was proposed， which solves the sequential calculation problem of the heater’s hot side and cold side. A simulation model of LHPE was constructed and the influence of cycle variables on the overall performance of LHPE was calculated. The results show that compressor pressure ratio and fuel flow rate have a significant impact on overall performance， and turbine inlet temperature mainly affects parameter selection of fuel flow path at design point. Along the flight trajectory， net thrust at low Mach number increases by increasing design value of compressor pressure ratio and fuel flow rate， and power load of turbine increases when design value of compressor pressure ratio increases， while specific impulse increases by more than 10% when design value of fuel flow rate is reduced by 15%. Specific impulse can slightly increase， and power load of turbine can be significantly decreased by increasing turbine inlet temperature. LHPE has a greater specific impulse advantage compared with ATREX and Pre-cooled Turbojet （PCTJ）.