The difference of cold/hot pitch moment will result in difficulty of vehicle attitude control when the hypersonic vehicle works at the relay point and cruising end point under the influence of cold and hot expansion conditions. To solve this problem

an adjustable cowl scheme was adopted and investigated

and also proven in effectively decreasing the difference of cold/hot pitch moment. The flow-field with different cowl angles was numerically simulated to obtain the performance parameters of nozzle. The results showed that

when the cowl angle was adjusted to 6°

the difference of cold/hot pitch moment was reduced by 29.57% and the thrust coefficient decreased only 0.42% in design Mach number 4.5. Finally

a wind tunnel experiment was carried out

and numerical simulation was performed based on the conditions of the wind tunnel experiment. The results of the simulation were in good agreement with experiment data

validating the effectiveness and correctness of the adjustment scheme and the results of numerical simulation.