Effect of Water Injection on Turbine Inlet under Different Flight Conditions

Abstract

Numerical simulations were conducted to research the pre-cooling effects of water injection on the turbine inlet of a turbine-based combined cycle (TBCC) engine under different flight conditions. Then, the performance of the water injection pre-compressor cooling (WIPCC) engine was calculated by mathematical modelling with different water to air ratios (WAR). It was the first time that the mass injection field of the turbine inlet of a TBCC engine was simulated, and it was also the first time that the performance of a subcomponent turbine engine of a TBCC was assessed. The calculation results showed the relationship of the inlet temperature with respect to WAR, inlet length and flight Mach number. The strategy for inlet length and water mass flow was proposed in order to meet the requirements of pre-cooling. When the length of the turbine inlet was 10 times the diameter of the inlet exit, the air could be cooled by 167.5 K with WAR = 0.09. The highest evaporation ratio reached at 93%. Finally, the calculation results revealed the performance of the water-pre-cooled turbine engine, of which the flight envelope was expanded to Ma3.0 from Ma2.3 by pre-cooling. The engine thrust as well as the specific impulse were significantly improved. The thrust reached at 0.9 times the characteristic thrust meeting the TBCC mode transition requirement of thrust and working speed spectrum.