The combustion modes in two different scramjet combustors with the mass flow rates of 1.8 kg/s and 3.6 kg/s are experimentally investigated to explore the scaling effects on supersonic combustion with a Mach number 2....The combustion modes in two different scramjet combustors with the mass flow rates of 1.8 kg/s and 3.6 kg/s are experimentally investigated to explore the scaling effects on supersonic combustion with a Mach number 2.0 inflow.It is found that the scramjet combustor with a larger scale can broaden the flame rich blowout limit.As the Equivalence Ratio(ER)increases,the combustion in the small-scale combustor maintains in the cavity-stabilized mode,and the flamebase moves downstream along the cavity shear layer;however,the combustion in the large-scale combustor gradually transfers from the cavity-stabilized mode to the jet-wake-stabilized mode.The differences in the cavity residence time,the ignition delay time and the Damkohler number caused by different scales of the scramjet combustor are likely to account for the scaling effects on the combustion modes.展开更多
This paper presents an experimental study into dynamics of chamber pressure and heat release rate during self-excited spinning and standing azimuthal mode in NTO/MMH (nitrogen tetroxide/monomethylhydrazine) impinging ...This paper presents an experimental study into dynamics of chamber pressure and heat release rate during self-excited spinning and standing azimuthal mode in NTO/MMH (nitrogen tetroxide/monomethylhydrazine) impinging combustion chambers.Nine cases including two combustion chamber configurations were conducted.The operating conditions of all unstable cases were located in the instability region according to Hewitt empirical correlation.The results show that chamber pressure oscillations keep pace with the corresponding OH*chemiluminescence intensity over the whole combustion region in the spinning and standing modes.It is indicated that the Rayleigh index is positive over the whole combustion area in all the unstable cases.A significant supersonic flame front structure of the first-order spinning mode was found in a cylindrical chamber,which means that a detonation wave could exist in the cylindrical chamber without a center body.The pressure and heat release rate oscillations at the pressure node are nonnegligible although their amplitudes are lower than those at the pressure antinode in the first-order standing mode with an annular chamber.Besides,the dominant frequency of pressure and heat release rate oscillations at the pressure node is twice as high as that at the pressure antinode.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11925207,11902353 and 91741205)the Foundation of Innovation-oriented Province Construction of Hunan(No.2019RS2028)。
文摘The combustion modes in two different scramjet combustors with the mass flow rates of 1.8 kg/s and 3.6 kg/s are experimentally investigated to explore the scaling effects on supersonic combustion with a Mach number 2.0 inflow.It is found that the scramjet combustor with a larger scale can broaden the flame rich blowout limit.As the Equivalence Ratio(ER)increases,the combustion in the small-scale combustor maintains in the cavity-stabilized mode,and the flamebase moves downstream along the cavity shear layer;however,the combustion in the large-scale combustor gradually transfers from the cavity-stabilized mode to the jet-wake-stabilized mode.The differences in the cavity residence time,the ignition delay time and the Damkohler number caused by different scales of the scramjet combustor are likely to account for the scaling effects on the combustion modes.
基金co-supported by the National Natural Science Foundation of China (Nos. 11502186 and 51506157)the National Key Basic Research Program of China
文摘This paper presents an experimental study into dynamics of chamber pressure and heat release rate during self-excited spinning and standing azimuthal mode in NTO/MMH (nitrogen tetroxide/monomethylhydrazine) impinging combustion chambers.Nine cases including two combustion chamber configurations were conducted.The operating conditions of all unstable cases were located in the instability region according to Hewitt empirical correlation.The results show that chamber pressure oscillations keep pace with the corresponding OH*chemiluminescence intensity over the whole combustion region in the spinning and standing modes.It is indicated that the Rayleigh index is positive over the whole combustion area in all the unstable cases.A significant supersonic flame front structure of the first-order spinning mode was found in a cylindrical chamber,which means that a detonation wave could exist in the cylindrical chamber without a center body.The pressure and heat release rate oscillations at the pressure node are nonnegligible although their amplitudes are lower than those at the pressure antinode in the first-order standing mode with an annular chamber.Besides,the dominant frequency of pressure and heat release rate oscillations at the pressure node is twice as high as that at the pressure antinode.
