In accordance with the flow characteristics of vortex valve variable-thrust SOLID ROCKET MOTORs, a cold flow experimental system based on Particle Image Velocimetry was established. A flow velocity vector diagram of vortex chamber was generated, and the vortex structure was analyzed. The results provided an experimental foundation for numerical simulation. The flow characteristics in vortex chamber and in the throat and divergent sections of the nozzle were modeled and simulated. The flow in the vortex chamber conformed to the complex Rankine vortex, and the flow field was divided into three different zones. The vortex core was the primary influence factor for thrust modulation. The resultant velocity reached Mach number 1 before gas arrived at nozzle throat, and the axial velocity still reached Mach number 1 at nozzle throat. Hence, the axial velocity can be used to judge the occurrence of choking at the nozzle throat. The intensity of swirl flow in divergent section of the nozzle was evidently lower than that in vortex chamber and throat. As a result, a lowpressure zone emerged around the central axis, thereby causing thrust losses.

In this study, SOLID ROCKET MOTOR internal ballistic, has been investigated. Flow field consists of internal grain space and converging-diverging nozzle. Axisymmetric, compressible and transient Euler equations have been considered as governing equations and erosive burning has been considered as an important phenomenon in SOLID ROCKET MOTORs. Fluent software and its moving mesh capability have been used to flow field modeling. At the first time, an appropriate UDF has been utilized to achieve a good simulation of erosive burning. The results show very good agreement with other numerical results.

In the present research, a new model is presented to predict the burning rate of a SOLID ROCKET MOTOR (SRM) in the presence of erosive burning phenomenon. This model is based on the Wang model and the major modification is adding the pressure change in the erosive burning rate. In addition, the necessary relations needed to calculate the velocity gradient on the propellant surface in a one-dimensional internal ballistics code was presented. To assess the new model, the test results of a laboratory MOTOR designed in this research were used. Also, to compare the performance and accuracy of this model with the other models, this MOTOR was simulated with the presented model and the six available models. The results of the comparison indicate that the new model has better accuracy than the other models. The advantage of introducing the pressure effect in the Wang model has been shown. Another advantage of the new model is that this model doesn’ t have any experimental constants dependent on the propellant composition or grain dimensions which is a common defect in popular models such as Lenoir-Robillard model.

Excessive heat transfer causes major defects on the ROCKET MOTORs. For example, it will reduce mechanical properties of materials or causes melting of internal wall layers when temperature rises. In the other hand, non-uniform distribution of temperature in SOLID propellant MOTOR shells, in addition to thermal stresses will develop mechanical stresses. Calculating the temperature distribution and thermal and mechanical stresses on the SOLID ROCKET MOTORs were interested by the designers. In this paper, the manner of calculating the mechanical and thermal wall stresses on SOLID propellant ROCKET MOTORs using dynamic coupled thermoelasticity equations relationships are presented. For this purpose, firstly differential equations governing the issue are resolved using the finite element method. The presented approach is applied and tested on a real ROCKET and the effect of thermal insulation in wall temperatures and mechanical stresses is shown.

Internal ballistics of SOLID ROCKET MOTOR is simulated by solving the axisymmetric Navier-Stokes equations on a moving unstructured grid. Then, the flow velocity, pressure, temperature, and other variables are computed for problems with complex geometries and boundary conditions. The dynamic (moving) mesh is used to model flows where the shape of the domain changes with time due to motion of the domain boundaries (burning surfaces).Updating of the mesh is handled automatically at each time step, based on the new position of the boundaries. This study showed that CFD with unstructured dynamic meshing can be a powerful tool for simulating internal ballistics of SOLID ROCKET MOTORs.

In this paper, the heat transfer and ablation thermal insulators in SOLID ROCKET MOTOR are investigated. Therefore, by collecting and solving the thermal ablation equations, a computer program, using MATLAB software, is developed which can predict the thermal response of insulators in different operating conditions and compare the performance of these insulators. The heat and mass transfer equations are considered in two dimensions in a SOLID body. We used the equations, finite volume method with implicit formulation for time dependency to solve equations. The reaction equation which written in the form of Arrhenius, is solved using Runge-Kutta method, and the density and the flux of the gas produced at each step are obtained. Also we represent a model for the rate of recession.

A systematic design of the SOLID propellant ROCKET; Analysis of characterizes and components; Manufacture of a porotype and flight test are the main purposes of study. In ROCKET MOTOR design process, the zero and one dimensional interior ballistic flow solution are used. The numerical solution is based on iterative approach for propellant combustion conditions and pressure estimation. Propellant grain geometry, combustion chamber, nozzle, MOTOR bulkhead, joints analysis and sealing are most important subsystems; so the challenge is to develop a model for their convergence. The other highlight of this approach are parts building; make SOLID propellant and finally assemble the MOTOR. This MOTOR was used for real flight test of the sounding ROCKET. The experimental data and scientific process have good convergence and its results usable for other engineering research.

Numerical simulation of grain burn back has been done in three dimensions. For numerical grain burn back analysis, a numerical code based on level set method has been developed and in order to increase accuracy, cut cell method was implemented for elements which capture interfaces. The accuracy of the code was validated by grains which have analytical solutions. It was seen that the code has acceptable accuracy. Then, the results of burn back analysis for some grain configuration were depicted. Also, an internal ballistic code in zero dimensional was generated to predict the pressure inside the MOTOR, and was linked by burn back analysis code. The simulation results were compared with experimental ones and high accuracy was achieved.

In this paper, the heat transfer and ablation thermal insulators in SOLID ROCKET MOTOR are investigated. Therefore, by collecting and solving the thermal ablation equations, a computer program, using MATLAB software, is developed which can predict the thermal response of insulators in different operating conditions and compare the performance of these insulators. The heat and mass transfer equations are considered in two dimensions in a SOLID body. We used the equations, finite volume method with implicit formulation for time dependency to solve equations. The reaction equation which written in the form of Arrhenius, is solved using Runge-Kutta method, and the density and the flux of the gas produced at each step are obtained. Also we represent a model for the rate of recession.