The flame quenching process in combustors was observed by high speed camera and Schlieren system, at the inflow conditions of Ma = 2.64, To = 1483K, P0 = 1.65 MPa, T = 724 K and P -- 76.3 kPa. Changing process of the ...The flame quenching process in combustors was observed by high speed camera and Schlieren system, at the inflow conditions of Ma = 2.64, To = 1483K, P0 = 1.65 MPa, T = 724 K and P -- 76.3 kPa. Changing process of the flame and shock structure in the combustor was clearly observed. The results revealed that the precom- bustion shock disappeared accompanied with the process in which the flame was blown out and withdrawed from the mainflow into the cavity and vanished after a short while. The time of quenching process was extended by the cavity flame holder, and the ability of flame holding was enhanced by arranging more cavities in the downstream as well. The flame was blown from the upstream to the downstream, so the flame in the downstream of the cavity was quenched out later than that in the upstream.展开更多
Scramjet engines are used at extreme temperatures and velocity. New control problems involving distributed parameter control have been found concerning investigations of the control of scramjet engines whose physical ...Scramjet engines are used at extreme temperatures and velocity. New control problems involving distributed parameter control have been found concerning investigations of the control of scramjet engines whose physical states are spatially interacted. Succeeding the existing theoretical studies on the distributed parameter control for scramjet engines, this paper puts forward a simplified distributed parameter control approach for scramjet engines aimed at engineering application. The simplified control procedure uses the classical proportional-integral（PI） compensation to control the target pressure distribution of scramjet engines, which is effective and applicable for practical implements. Simulation results show the validation of the simplified distributed parameter control procedure.展开更多
To uncover the internal flow characteristics in an ethylene-fueled aeroramp injector/gaspilot（ARI/G-P）flame scramjet,a Reynolds-averaged Navier-Stokes（RANS）solver is constructed under a hybrid polyhedral cell fini...To uncover the internal flow characteristics in an ethylene-fueled aeroramp injector/gaspilot（ARI/G-P）flame scramjet,a Reynolds-averaged Navier-Stokes（RANS）solver is constructed under a hybrid polyhedral cell finite volume frame.The shear stress transport（SST）k-x model is used to predict the turbulence,while the Overmann’s compressibility corrected laminar flamelet model is adopted to simulate the turbulent combustion.Nonreactive computations for Case 1（G-P jet on）,Case 2（ARI jets on）,and Case 3（both ARI and G-P jets on）were conducted to analyze the mixing mechanism,while reactive Cases 4–7 at equivalent ratios of 0.380,0.278,0.199 and0.167 respectively were calculated to investigate the flame structure and combustion modes.The numerical results are compared well to those of the experiments.It is shown that the G-P jet plays significant role in both the fuel/air mixing and flame holding processes;the combustion for the four reactive cases takes place intensively in the regions downstream of the ARI/G-P unit;Cases 4 and 5are under subsonic combustion mode,whereas Cases 6 and 7 are mode transition critical and supersonic combustion cases,respectively;the mode transition equivalent ratio is approximately 0.20.展开更多
基金supported by the National Natural Science Foundation of China (10902124)
文摘The flame quenching process in combustors was observed by high speed camera and Schlieren system, at the inflow conditions of Ma = 2.64, To = 1483K, P0 = 1.65 MPa, T = 724 K and P -- 76.3 kPa. Changing process of the flame and shock structure in the combustor was clearly observed. The results revealed that the precom- bustion shock disappeared accompanied with the process in which the flame was blown out and withdrawed from the mainflow into the cavity and vanished after a short while. The time of quenching process was extended by the cavity flame holder, and the ability of flame holding was enhanced by arranging more cavities in the downstream as well. The flame was blown from the upstream to the downstream, so the flame in the downstream of the cavity was quenched out later than that in the upstream.
文摘Scramjet engines are used at extreme temperatures and velocity. New control problems involving distributed parameter control have been found concerning investigations of the control of scramjet engines whose physical states are spatially interacted. Succeeding the existing theoretical studies on the distributed parameter control for scramjet engines, this paper puts forward a simplified distributed parameter control approach for scramjet engines aimed at engineering application. The simplified control procedure uses the classical proportional-integral（PI） compensation to control the target pressure distribution of scramjet engines, which is effective and applicable for practical implements. Simulation results show the validation of the simplified distributed parameter control procedure.
基金co-supported by the National Natural Science Foundation of China (Nos. 51176003 and 51276007)the Fundamental Research Funds for the Central Universities of China (No. YWF-15-GFY)
文摘To uncover the internal flow characteristics in an ethylene-fueled aeroramp injector/gaspilot（ARI/G-P）flame scramjet,a Reynolds-averaged Navier-Stokes（RANS）solver is constructed under a hybrid polyhedral cell finite volume frame.The shear stress transport（SST）k-x model is used to predict the turbulence,while the Overmann’s compressibility corrected laminar flamelet model is adopted to simulate the turbulent combustion.Nonreactive computations for Case 1（G-P jet on）,Case 2（ARI jets on）,and Case 3（both ARI and G-P jets on）were conducted to analyze the mixing mechanism,while reactive Cases 4–7 at equivalent ratios of 0.380,0.278,0.199 and0.167 respectively were calculated to investigate the flame structure and combustion modes.The numerical results are compared well to those of the experiments.It is shown that the G-P jet plays significant role in both the fuel/air mixing and flame holding processes;the combustion for the four reactive cases takes place intensively in the regions downstream of the ARI/G-P unit;Cases 4 and 5are under subsonic combustion mode,whereas Cases 6 and 7 are mode transition critical and supersonic combustion cases,respectively;the mode transition equivalent ratio is approximately 0.20.
