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The purpose of this paper is to introduce a design and fabrication procedure for a solid propellant gas generator. Based on this procedure a gas generator was designed to supply the required operating fluid of a controllable flying object’s gaseous actuator of control surface which results of that design is presented in this paper as well. Supplying required pressure during the mission and gas flow rate with expected chemical characteristics are requirements of the design. At first the amount of necessary parameters like flow rate and pressure were specified. Then the design calculations were done according to proposed approach. In order to evaluate the design process and achieved data, a full scale gas generator set was built. Since this study includes specifying a proper formula for solid propellant of gas generator, a lab scale motor was used to qualify the propellant’s characteristics experimentally. After doing tests and comparing the results with output data of gas generator design procedure, convenient consistency was observed. Besides by doing several tests it was found that PSAN as oxidizer, HTPB as binder and chromium oxide as catalyst is a proper composition for solid propellant of gas generator. Finally, covering basic requirements of a solid propellant gas generator such as uniform flow rate and less presence of solid phase and corrosive components in combustion products by means of designed gas generator is an approval to show the validity of presented design method.

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This study is a try to design a spike nozzle and simulate its flow-field in different conditions. Hence, spike nozzle design methods were studied and accordingly the design code was developed. Then the behavior of flow in this type of nozzle was simulated numerically by means of computational fluid dynamics. In order to conduct the simulations, four turbulence models suitable for solving the flow-field of spike nozzle were used, not only to model the performance of the nozzle in design and off-design conditions, but also to identify the best model for the accuracy of the solutions. To ensure the accuracy of the simulations, numerical results and experimental data were compared. It was found that applied models in case of using high quality grids with proper dimension near the nozzle walls, can predict the nozzle flow pattern with acceptable approximation. Also the comparisons revealed that the amount of pressure on the spike wall calculated by Realizable k-ε model, is generally identical with experimental results and in the worst condition the difference between them is 15%, so this model has the best agreement with experimental results. Besides, comparison of taken photos during experiments and extracted contours from numerical analysis, shows the high ability of applied numerical method to predict spike nozzle flow-field. Therefor it can be claimed that by using the proposed method in this research, there is no need to perform cold-flow tests during the design and construction of spike nozzles.