Topology optimization design of regenerative cooling channels around the inserted pylon in hypersonic engine

The regenerative cooling technique is widely used in the active thermal protection systems for air-breathing hypersonic engines due to its high energy utilization efficiency. However, the design of regenerative channels is complicated by the presence of several components inserted through the combustor wall of hypersonic engine like pylons. With the conventional method, the bypassing cooling channel would cause large pressure loss and nonuniform flow distribution. In this paper, an innovative topology optimization method is proposed to design the cooling channels bypassing the inserted pylon. The optimization results show that with the constraint of low power dissipation, the coolant tends to flow out through the unaffected area and the isolated outlet is easy to occur under the boundary condition of multiple flow inlets and outlets. The isolated outlet would lead to significant nonuniformity of flow distribution and local overheating. To avoid these phenomena, the fluid area fraction and power dissipation constraints should be increased. Subsequently, the topology- optimized bypassing cooling channel structure is simulated numerically, and the results show that, compared to the conventional design of bypassing cooling channel, the optimized channel's pressure drop, maximum temperature and temperature distribution uniformity are improved by 23.2%, 10.4% and 3.5%, respectively, and the flow stagnation is avoided.