Investigation On Cooling Characteristics Of Compound Cooling Configurations Of Reverse-flow Combustion Chamber

With the power-weight ratio of turboshaft engine increasing, the design direction of thecombustion chamber will be high temperature rise and high heat capacity. So only the advanced andefficient cooling technology can meet the cooling requirement of the flame tube wall. On one hand,with the temperature rise in reverse-flow combustion chamber improving, the air used for combustionis more and more, so the air used for cooling in chamber is less and less, on the other hand, theincrease of the compressor outlet air temperature also makes the cooing air temperature rise, so itscooing potential is dropping. Thus, the traditional methods used for combustion chamber cooling areunable to meet the future engine’s cooling needs, so more advanced cooling technology is needed tomeet the needs of the flame tube cooling.Studies show in the case that the turboshaft engine power-weight ratio continuously increasingand the amount of cooling air continuously reducing, the impingement+effusion coolingconfiguration and impingement+convection+film cooling configuration have the potential to meetthe reverse-flow combustion chamber flame tube wall cooling demand. However, there is no materialstudied how these advanced composite cooling technologies applied to the flame tube cooling in thedomestic. Based on this, six different composite cooling structures of the reverse-flow combustionchamber have been designed in this paper, and studied their cooling efficiency and pressure losscoefficient numerically and experimentally, the analysis of the effects of flow parameters on thecooling efficiency and pressure loss coefficient have been shown. And the three-dimensionalcombustion simulation of the reverse-flow combustion chamber which used impingement+effusioncooling configuration has also been studied. Within the parameter range of this paper, results showthat:(1) For different composite cooling structures, the efficiency of compound cooling all increaseswith the increase of the blowing ratio at the same wall position; Whether the straight section or thecurved section of the reverse-flow combustion chamber, the cooling efficiency of the impingement+effusion cooling configuration is lower than the cooling efficiency of the impingement+convection+film cooling configuration; The comprehensive cooling efficiency distributions along the flowdirection of six different structures are all present a downward after rising trend.(2) For the six different composite cooling structures, the discharge coefficients and pressure losscoefficients all increase with the increase of the blowing ratio. (3) On the whole, the whole impingement+reverse convection+film cooling configuration, thewhole impingement+homodromous convection+film cooling configuration and the impingement+reverse convection+film cooling configuration in straight section&impingement+effusion coolingconfiguration in curved section are better than the three others.(4) Simulation results indicate that the typical impingement+effusion cooling configurationused in reverse-flow combustion chamber is feasible, it can meet the cooling requirements of thiscombustion chamber.