Variable flow ducted rockets are excellent candidates for propulsion systems in hypersonic vehicles. However, the anti-regulation characteristics of the gas flow not only decrease the stability of ducted rockets but also create difficulties in the control system design. In this study, a model predictive control (MPC)–based compound control algorithm that suppresses the anti-regulation is proposed. First, a mathematical model involving a gas flow regulation system was developed to describe and analyse the anti-regulation. Next, a fused feedback variable that included both the gas flow and the gas generator pressure signal was constructed. An MPC control system with the fused feedback variable was also designed. Then, to accurately predict the gas flow and the anti-regulation, a nonlinear disturbance observer was constructed. To evaluate the performance of the controller, two scenarios that were regulated by a tracking differentiator proportional–integral–derivative controller and a model reference adaptive control controller were constructed and compared. The theoretical results demonstrate that the proposed method exhibited a superior performance compared to previous methods by overcoming the supposed trade-off between the response rate and the anti-regulation of gas flow systems.

Variable-throat adjustment is the most practical flow regulation method of solid ducted rocket ramjet (SDR). The high-fidelity mathematical model of the interstage valve is the basis for realizing high-precision gas flow and thrust regulation. In this paper, the complex effect of gas was divided into load and throat deformation effect. The load was mainly determined by the clearance, friction torque, and pneumatic torque that the valve was subjected to during operation. And the throat deformation was determined primarily by the deposition and ablation of the valve faced in the gas. Therefore, we could divide the valve model into three parts: the servo motor model, the load characteristic model, and the deformation model of the actual acting throat (referred to as the throat). Given, we have designed a cold-air experiment program, using cold air to equalize the valve load. Furthermore, we analyzed its mechanism of action and established the load model using the experimental data and neural network. Finally, the deformation mechanism of the throat was investigated, and simultaneously, the deformation model was shown based on the flight test data. Compared with the traditional interstage valve model, the model established in this paper is closer to the actual working conditions, which is helpful to carry out the more comprehensive and practical ground simulation. It has essential reference value for further realizing the precise regulation of gas flow.