Sharif Digital Repository

The hybrid rocket motor is a kind of chemical propulsion system that has been recently given serious attention by various industries and research centers. The relative simplicity, safety and low cost of this motor, in comparison with other chemical propulsion motors, are the most important reasons for such interest. Moreover, throttle-ability and thrust variability on demand are additional advantages of this type of motor. In this paper, the result of an internal ballistic simulation of hybrid rocket motor in a zero-dimensional form is presented. Further to validate the code, an experimental setup was designed and manufactured. The simulation results are compared with the experimental data... 

Transient heat-up of a solid propellant rocket structure during motor burning time is studied, numerically. The solid phase energy equation coupled with unsteady compressible flow equations are used in this simulation. The flow-field equations are discretized and solved using upwind Roe's scheme. The results show that heat transfer from the gas phase boundaries has negligible effect on internal ballistics behavior. On the other hand, the results are suitable for a thermal stresses analysis in the chamber case and are consequently valuable from structural design viewpoints  

In this paper, the internal ballistics of a solid propellant rocket motor including a pyrogen type igniter is numerically investigated. The aim of the simulation is to calculate the chamber pressure as a function of time, during flame spreading phase. In addition, effects of the igniter flow on the propellant heat-up and ignition are studied in detail using unsteady quasi one-dimensional conservation equations for a working gas, coupled with the transient conduction within a solid propellant. The convective and radiative heat flux from the igniter flow to the solid surface is considered. The flow-field equations are solved using upwind Roe's scheme. The obtained results can be used to design... 

In this paper, the effect of viscosity on internal ballistics simulation of a solid rocket motor with an internal burning cylindrical grain is numerically investigated. Axisymmetric compressible Navier-Stokes equations are discretized by finite volume approach on structured mesh and are solved using upwind Roe's scheme. A quasi steady procedure is used to simulate the regression of the burning surface by using a steady flow solver. Grid resolution is studied to insure acceptable accuracy. It is finally shown that most physical phenomena are quite accurately simulated by using an Euler solver, while NS solvers do not increase the accuracy as much they increase the CPU time  

In this paper, the internal ballistics of a solid rocket motor (SRM) including a blast tube is investigated, numerically. Effects of the blast tube presence on the performance of the SRM are studied in detail using unsteady quasi one-dimensional conservation equations. These equations are discretized and solved using upwind Roe's scheme. Any two-dimensional grain configuration can be accounted for if an appropriate geometrical input file is generated using a grain analysis program. The results are presented for several blast tube geometries  

The performance of an HTPB/N2O hybrid motor was experimentally investigated. A hybrid motor was designed and manufactured in a laboratory with the purpose of studying the effects of various parameters on the motor's performance, including fuel regression rate and specific impulse. A series of tests were conducted to find a correlation between the fuel regression rate and the oxidizer's mass flux. The effects of chamber's pressure on the regression rate as well as other performance parameters were investigated. While the burning rate did not change dramatically, both the efficiency and ISP of the motor increased. The local fuel regression rate and the fuel port were also calculated. In... 

Time-varying structural reliability of a multistage solid-propellant launch vehicle subjected to deterministic and stochastic loads is investigated. The study is of practical importance because the launch vehicle's structure is influenced by a combination of external aerodynamics as well as inertial and internal ballistic loads emanating from the solid rocket motors. In addition, as launch-vehicle flight conditions change during flight, the vehicle will be subjected to time-varying loads. In this sense, the environmental, aerodynamic, and internal pressure fluctuations can be interpreted as stochastic forces affecting the launch-vehicle structural reliability. To account for temporal... 

Purpose - The purpose of this paper is to analyze a squared lattice cylindrical shell under compressive axial load and to optimize the geometric parameters to achieve the maximum buckling load. Also a comparison between buckling loads of a squared lattice cylinder and a solid hollow cylinder with equal weight, length and outer diameter is performed to reveal the superior performance of the squared lattice cylindrical shells. Design/methodology/ approach - A cylindrical lattice shell includes circumferential and longitudinal rods with geometric parameters such as crosssection areas of the rods, distances and angles between them. In this study, the governing differential equation for buckling...