Incipient thermal choking and stable shock-train formation in the heat-release region of a scramjet combustor. Part I: Shock-tunnel experiments

2015 ◽  
Vol 162 (4) ◽  
pp. 921-931 ◽  
Author(s):  
S.J. Laurence ◽  
D. Lieber ◽  
J. Martinez Schramm ◽  
K. Hannemann ◽  
J. Larsson
Keyword(s):  
Heat Release ◽  
Shock Tunnel ◽  
Shock Train ◽  
Scramjet Combustor

scholarly journals Incipient thermal choking and stable shock-train formation in the heat-release region of a scramjet combustor. Part II: Large eddy simulations

2015 ◽  
Vol 162 (4) ◽  
pp. 907-920 ◽  
Author(s):  
Johan Larsson ◽  
Stuart Laurence ◽  
Iván Bermejo-Moreno ◽  
Julien Bodart ◽  
Sebastian Karl ◽  
...  
Keyword(s):  
Heat Release ◽  
Large Eddy Simulations ◽  
Shock Train ◽  
Scramjet Combustor ◽  
Large Eddy

Influence of lobe geometry on mixing and heat release characteristics of solid fuel rocket scramjet combustor

2019 ◽  
Vol 164 ◽  
pp. 212-229
Author(s):  
Gao Yonggang ◽  
Liu Yang ◽  
Chai Zexin ◽  
Li Xiaocong ◽  
Hu Chunbo ◽  
...  
Keyword(s):  
Heat Release ◽  
Solid Fuel ◽  
Scramjet Combustor

Experimental study on the effect of air throttling on supersonic combustion

2016 ◽  
Vol 232 (3) ◽  
pp. 472-480 ◽  
Author(s):  
Ye Tian ◽  
Shunhua Yang ◽  
Baoguo Xiao ◽  
Jialing Le
Keyword(s):  
Experimental Study ◽  
Mass Flux ◽  
Equivalence Ratio ◽  
Flame Stabilization ◽  
Wall Pressure ◽  
Supersonic Combustion ◽  
Reacting Flow ◽  
Flux Rate ◽  
Shock Train ◽  
Scramjet Combustor

The effect of air throttling on supersonic combustion was investigated by experiments in the present paper. Our results indicated that, in the non-reacting flow, a shock train could be generated in the scramjet combustor due to the increased backpressure caused by air throttling, and the wall pressure increased obviously. But when the mass flux rate of air throttling was not large enough, the shock train would oscillate with the flow. In the reacting flow, the flame stabilization was achieved in the combustor without air throttling when the equivalence ratio of kerosene was 0.2 and 0.31, but the flame was blown off when the equivalence ratio of kerosene was 0.45. On the contrary, the kerosene (equivalence ratio: 0.45) was ignited successfully in the combustor with air throttling, and it kept burning all the time in the cases with air throttling −5% (the flux of air throttling was 5% of the inflow flux) and with air throttling −14% (the flux of air throttling was 14% of the inflow flux), but the flame was blown off in the case with air throttling −1.1% after kerosene had burnt 70 ms. The flux of air throttling should be large enough to achieve flame stabilization, and the hydrogen and air throttling should both exist all the time in order to keep the flame burning steadily.

scholarly journals Study on the Effect of Air Throttling on Flame Stabilization of an Ethylene Fueled Scramjet Combustor

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Ye Tian ◽  
Shunhua Yang ◽  
Jialing Le
Keyword(s):  
Numerical Simulation ◽  
Total Pressure ◽  
Time Sequence ◽  
Flame Stabilization ◽  
Shock Train ◽  
Lower Velocity ◽  
Scramjet Combustor ◽  
Inflow Condition ◽  
Total Temperature ◽  
Simulation Results

The effect of air throttling on flame stabilization of an ethylene fueled scramjet combustor was investigated by numerical simulation and experiments in this paper. The results were obtained under the inflow condition with Mach number of 2.0, total temperature of 900 K, total pressure of 0.8 MPa, and total equivalence ratio of 0.5. The shock train generated by air throttling had a big effect on the flow structure of the scramjet combustor. Compared with the combustor without air throttling, the flow field with air throttling had a lower velocity and higher pressure, temperature, and vortices intensity. Air throttling was an effective way to achieve flame stabilization; the combustion in the combustor without air throttling was nearly blowout. In the experiment, the combustion was nearly blowout with air throttling location of 745 mm, and the fuel/air mixture in the combustor with air throttling location of 875 mm was burned intensively. It was important to choose the location and time sequence of air throttling for fuel ignition and flame stabilization. The numerical simulation results agreed well with experimental measurements.

Effect of heat release on movement characteristics of shock train in an isolator

2017 ◽  
Vol 133 ◽  
pp. 185-194 ◽  
Author(s):  
Chenlin Zhang ◽  
Juntao Chang ◽  
MengMeng Liu ◽  
Shuo Feng ◽  
Wen Shi ◽  
...  
Keyword(s):  
Heat Release ◽  
Shock Train ◽  
Movement Characteristics

scholarly journals Transient fluid-combustion phenomena in a model scramjet

2013 ◽  
Vol 722 ◽  
pp. 85-120 ◽  
Author(s):  
S. J. Laurence ◽  
S. Karl ◽  
J. Martinez Schramm ◽  
K. Hannemann
Keyword(s):  
Numerical Simulations ◽  
Equivalence Ratio ◽  
Transient Flow ◽  
Shock Propagation ◽  
Shock Train ◽  
Limited Region ◽  
Maximum Heat ◽  
Reflected Shock ◽  
Scramjet Combustor ◽  
Shock System

AbstractAn experimental and numerical investigation of the unsteady phenomena induced in a hydrogen-fuelled scramjet combustor under high-equivalence-ratio conditions is carried out, focusing on the processes leading up to unstart. The configuration for the study is the fuelled flow path of the HyShot II flight experiment. Experiments are performed in the HEG reflected-shock wind tunnel, and results are compared with those obtained from unsteady numerical simulations. High-speed schlieren and OH∗ chemiluminescence visualization, together with time-resolved surface pressure measurements, allow links to be drawn between the experimentally observed flow and combustion features. The transient flow structures signalling the onset of unstart are observed to take the form of an upstream-propagating shock train. Both the speed of propagation and the downstream location at which the shock train originates depend strongly on the equivalence ratio. The physical nature of the incipient shock system, however, appears to be similar for different equivalence ratios. Both experiments and computations indicate that the primary mechanism responsible for the transient behaviour is thermal choking, though localized boundary-layer separation is observed to accompany the shock system as it moves upstream. In the numerical simulations, the global choking behaviour is dictated by the limited region of maximum heat release around the shear layer between the injected hydrogen and the incoming air flow. This leads to the idea of ‘local’ thermal choking and results in a lower choking limit than is predicted by a simple integral analysis. Such localized choking makes it possible for new quasi-steady flow topologies to arise, and these are observed in both experiments and simulation. Finally, a quasi-unsteady one-dimensional analytical model is proposed to explain elements of the shock-propagation behaviour.

Numerical Investigation on the Cold Flow Field of a Typical Cavity-based Scramjet Combustor with Double Ramp Entry

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
S. Periyasamy ◽  
S. Ragul ◽  
K. Sundararaj ◽  
P. S. Premkumar
Keyword(s):  
Flow Field ◽  
Static Pressure ◽  
Wave Structure ◽  
Back Pressure ◽  
Pressure Waves ◽  
Shock Train ◽  
Shock Wave Structure ◽  
Cold Flow ◽  
Scramjet Combustor ◽  
Inlet Conditions

AbstractThe effects of back pressure and cavity L/D ratio on the shock wave structure in the cold flow field of a typical cavity-based scramjet combustor with combined inlet and isolator is investigated numerically in the selected scramjet models. The scramjet with a throat ratio of TR 0.0 and cavity L/D 6.04 was analyzed. To perform such analysis, steady, 2-D RANS was used with SST k-ω. From the analysis, the value of static pressure along the cowl surface, contours of Mach number and pressure were obtained. The scramjet was modeled with different TR 0.1, 0.2, 0.25 and 0.3 with the same cavity L/D 6.04 and different cavity L/D 4.04, 9.04 and 12.04 with the same TR 0.25. All the models were analyzed with the same inlet conditions and the results were obtained. From the analysis, it was observed that the increase in back pressure moves the shock train towards the inlet of the isolator which leads to ‘engine unstart’ after the throat ratio of TR 0.1. Also, it is observed that there is an optimal L/D ratio of the cavity L/D 9.04 which restricts the propagation of high-pressure waves obtained in the combustor.

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