Numerical Research On The Unsteady Combustion Characteristic Of Combustion Wave Rotor Engine

The wave rotor combustor (WRC) engine is a concept engine, which is a composite of waverotor technology, high efficiency low emissions technology and gas turbine engine combustiontechnology.The advantages of WRC include higher supercharger efficiency of pressure wave,higher thermal cycle efficiency thermal cycle efficiency of unsteady combustion (such as pulsedetonation combustion, and other content burning, etc), stratified combustion, low emissions andselfcool, edc. In this paper, analytic aerothermodynamic cycle model was established to evaluate theperformance of a combustion wave rotor, and the physical model was established for the numericallysimulation of the flow and combustion characteristics of the combustion wave rotor. Key findings areas follows:（1）By study the application of an combustion wave rotor to a turbo-shaft engine, the results showthat by the application of the combustion wave rotor, the engine output shaft power and totalefficiency increase up to35.7%,the SFC reduce up to23.6%, the maximum entropy decrease of7.6%.Considering the overall engine performance and the amount of gas remaining in the rotor channel twofactors, the combustion wave rotor engine is most appropriate to wake at the mach number of0.6ofthe channel exit. when the exit mach number is0.6,the engine shaft power output and total efficiencyincrease by19.88%,the SFC reduce by16.58%, the maximum entropy decrease of6.52%.(2) By numerical simulation of flow characteristics, It is concluded that when the pressuredifference between the inlet and outlet of WRC is87386.16Pa the flow from the compressor wascompressed by26.33%more,and the temperature increased by8.61%.An ideal fuel distribution wasobtained,which will be helpful to improve the overall efficiency of the engine, reliable ignition andthe organization of the combustion. In the wave rotor combustor exhaust, it shows a relativelyuniform velocity profile with the Mach number about0.35. The stronger turbulent dissipation rate wasfound where the inlet port join to the channel. By changing pressure difference between the inlet andexhaust ports of the wave rotor,it was found that,at lower pressure difference the pre-compressioneffect gradually weakened，and the formation of mixed gas conditions deteriorate.By add fuel at theposition of the exhaust plate,the mixed gas formed within the rotor was improved,but it change thedistribution of the pressure and the temperature within the channel.Reduce the rotor speed, the mixedgas formation has been significantly improved, the amount of fuel into the channel increased, butdiminished the role of pre-compression. Especially when the rotor speed is reduced to2000rpm, thepre-compression wave rotor pressure ratio decreased significantly.（3）Both hydrogen and propane are studied as a fuel in combustion wave rotor.The resauts showthat, for hydrogen,the detonation combustion was rapidly achieved in the rotor channel. The speedof detonation wave propagation reached2000m/s or more,and the peak pressure of1.8MPa.Whileuse propane as the fuel, despite the success achieved constant volume combustion,but no detonationcombustion,flame propagation speed of only100m/s or so.After the burning is completed, within thewave rotor pressure ratio of inlet pressure by300%or more, to achieve a pressurized combustion.Reduced the pressure difference in the inlet and exhaust ports to0.06Mpa, by reducing the rotor speed, the same to achieve a constant volume combustion, while reduce pressure difference to0.04MPa whe,It can not achieved a stable combustion process.Under the centrifugal force of400g~1600g range,with the centrifugal force increases, the flame propagation speed increased significantly and changethe shape of the flame front cover, near the arc inside the channel near the burning rate is higher.