关键词: 深冷组合循环发动机;循环分析;循环热效率;设计可行域;冷却燃料当量比

Abstract: To study deeply precooled combined cycle engine with the scheme similar to SABRE3, a thermodynamic calculation model of engine design point was established based on component method. A new cycle efficiency and cycle characteristic parameter were defined for the engine helium cycle. Considering the physical constraints of the engine and the interaction effects between different working fluids, the design feasible regions of air fluid and helium fluid can be obtained. The cycle analysis of air fluid and helium fluid was carried out in their feasible regions, and the distributions of main engine parameters such as cooling fuel equivalent ratio and performance were calculated. The results show that the range of air heat-to-work ratio (η_t2) is 0.02~0.746. The feasible region of the helium cycle is limited by η_t2 and the thermal load of the heat-exchanger (HX). When the initial temperature of helium cycle and the thermal load limit are determined, the lower the η_t2, the narrower the feasible region of helium cycle is. The key for reducing the cooling fuel equivalent ratio is to reduce the helium mass flow rate by increasing helium outlet temperature of HX1. When the helium outlet temperatures of HX1 and HX2 reach the maximum value simultaneously, the cooling fuel equivalent ratio takes its minimum value. When the outlet temperatures of the HX1 and HX2 are 1200K and 1300K, respectively, the cooling fuel equivalent ratio ranges from 0.917 to 2.64 in air cycle feasible regions.

Key words: Deeply precooled combined cycle engine;Cycle analysis;Thermal cycle efficiency;Design feasible region;Cooling fuel equivalent ratio