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

Abstract

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.

Unified algorithm of chemically reacting flows at all speeds

“…The computational model is the single-grooved combustor model. 12 It has four expansive parts, the area of its inlet cross-section is 50 mm × 100 mm, and its total length is 1700 mm. It can be seen from Figure 1 The three fuel injection points are set at the front and back of the external part of the groove, and in the groove, with mass flows rate 1:3:2.…”

“…The corresponding inflows condition at the separation section of the scramjet is listed in Table 2. The incoming air is set to be polluted air, and its mole ratio of nitrogen, oxygen, and water is set to be 69:21:10 12 .…”

“…It has a variety of turbulence models and has been studied extensively for scramjet with satisfactory results through comparing with the experiments. [12][13][14] It was widely considered to be reliable. However, as the Mach gradually decreases and approaches zero, the compressibility of the fluid becomes smaller and smaller, and gradually presents a trend of incompressibility.…”

Numerical Investigation of an Axisymmetric Model Scramjet Assisted with Cavity of Different Aft Wall Angles

“…Under this special condition, the flameholder could be removed. However, the flameholder, such as cavity [8] and strut [9], is essential under Mach 5 flight condition. The cavity flameholder [10], which evolves from the backward-facing step [11], has advantages over other flameholding schemes due to its low resistance and structural simplicity.…”