Numerical investigation on drag characteristics of the swept strut flameholder under aerodynamic and combustion heat release effects

In this paper, numerical investigations were conducted on the drag characteristics of a swept strut under aerodynamic and combustion heat release effects under the flight condition of Mach 6, with combustor inlet conditions of Ma ₀ = 2.8, T _{t 0} = 1680 K, and P _{t 0} = 1.68 MPa. The drag characteristics of struts with different swept angles were analyzed. The results indicate that, within the scope of this study, the 75° swept strut achieves the best drag reduction effect. Under single-strut kerosene injection conditions, the drag reduction of the strut is achieved through the reduction in pressure drag resulting from the combined aerodynamic and combustion effects. The drag characteristics of the 75° swept strut under strut/wall combined kerosene injection were investigated. The results show that combined injection can further reduce the strut drag, and even transform the force acting on the strut from drag to weak thrust. Furthermore, the drag reduction mechanisms of the swept strut under aerodynamic and combustion effects were explored. Aerodynamic drag reduction is achieved by increasing the strut swept angle to induce a weaker leading-edge shock, which reduces mainstream losses, and allows the mainstream to expand more fully at the strut tail edge, thereby decreasing the pressure drag of the strut. Combustion drag reduction is achieved by establishing a high backpressure in the main combustion zone at the strut tail edge through proper combustion organization to reduce the pressure drag of the strut, avoiding excessively high combustion heat release intensity in the local region near the strut, controlling the extent of flame upstream propagation along the strut surface, and consequently reducing both the pressure drag and the viscous drag of the strut. Finally, the low-drag combustion organization scheme for the swept strut combustor was investigated. The results show that adopting combined kerosene injection from the strut injector and a single wall injector can achieve favorable strut drag reduction.