深冷组合发动机吸气模态最大状态控制规律研究

Maximum State Control Schedule Research on Deeply Precooled Combined Cycle Engine in Airbreathing Mode

关键词:  深冷组合循环发动机  最大状态  控制规律  工作包线  控制规律分界线

Key words:  Deeply precooled combined cycle engine  Maximum state  Control schedule  Operating envelop  Control schedule demarcation line

摘要:

为了研究深冷组合循环发动机吸气模态最大状态控制规律，基于部件法建立了发动机热力学计算模型，依据整机共同工作条件确定了发动机非设计点计算的变量与平衡方程。根据工质间的相互影响关系，提出了以氦压气机转速和氦涡轮前温度为控制变量的双变量控制规律。在考虑发动机机械负荷、气动负荷、热负荷及压气机稳定裕度等限制的条件下，根据制定的最大状态控制规律，完成了高度特性和速度特性的计算。根据限制条件计算得到了发动机的工作包线，并指出了最大状态控制规律的区域划分。最后，将控制规律应用于工作包线内，获得了压气机转速、换算转速及工质流量等参数的分布规律。结果表明：工作包线上下边界分别取决于氦压气机喘振裕度限制和空气压气机换算转速下限，右边界限制取决于换热器1氦气出口温度上限。深冷组合循环发动机最大状态控制规律应划分为2个区域，分界线满足以下条件：空气压气机和氦压气机换算转速同时达到最大值。分界线以上空气压气机达到最大工作状态，分界线以下氦压气机达到最大工作状态。空气压气机进口参数是决定控制规律分界线的主要因素。

Abstract:

In order to study the maximum state control schedule of the deeply precooled combined cycle engine in airbreathing mode， the engine thermodynamic calculation model was established based on the component method， and the variables and equilibrium equations of the engine at off-design points were determined according to the co-operation conditions of the engine. According to the interaction between working fluids， a two-variable control schedule was proposed with the rotational speed of the helium compressor and the helium turbine inlet temperature as controlled variables. Taking into account constraints such as mechanics load， aerodynamics load， thermal load and surge margin， engine performance at different altitudes and speeds were calculated according to the maximum state control schedule established. The operating envelop of the engine was obtained according to the constraints， and the regional division of the control schedule was indicated. Finally， the control schedule is applied to the operating envelope， and the distribution of parameters such as compressor rotational speed， corrected rotational speed and flow rate of working fluids were obtained. The results show that the upper and lower boundaries of the operating envelop are determined by the helium compressor surge margin and the air compressor corrected rotational speed lower bound， while the right boundary is determined by the upper limit of the heat exchanger 1 helium outlet temperature. The maximum state control schedule of the deeply precooled combined cycle engine can be divided into two regions， and the demarcation line meets the following conditions： the air compressor and helium compressor corrected rotational speeds reach their maximum value simultaneously. Above the demarcation line the air compressor reaches its maximum working state， while below the demarcation line the helium compressor reaches its maximum working state. The air compressor inlet pressure is the main factor that determines the control schedule demarcation line.