Thermo-Structural Response Caused by Structure Gap and Gap Design for Solid Rocket Motor Nozzles

The coupling thermal and mechanical effect on submerged nozzles is important in the design of modern rockets upon thermal loading and aerodynamic pressure. In this paper, a simulation with the subroutine of nonuniform pressure and nonuniform heat transfer coefficient was conducted to study the thermo-structural response of a submerged nozzle at the pressure 6 MPa and stagnation temperature 3200 K. Both the aerodynamic parameters and heat coefficients were obtained through analyzing the flow field. It was found that the thermal loading had an important influence on the stress of throat insert for the solid rocket motor (SRM). The hoop stress increases at first and then decreases with the increase of time for the throat insert. The ground hot firing test of SRM with a submerged nozzle was carried out. The experimental results showed that the structural integrity of the submerged nozzle is very normal during SRM operation. The present method is reasonable, which can be applied to study the thermo-structural response of submerged nozzle for SRM.

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Structural vibrations and internal ballistic modelling of a star-grain solid rocket motor

10.32920/ryerson.14657292 ◽

2021 ◽

Author(s):

Sonny Loncaric

Keyword(s):

Finite Element ◽

Simulation Model ◽

Numerical Solutions ◽

Damping Ratio ◽

Structural Response ◽

Rocket Motor ◽

Numerical Dissipation ◽

Solid Rocket Motor ◽

Internal Ballistic ◽

Solid Rocket

A numerical model is developed to solve the governing equations for the structural dynamics and internal ballistics of a solid rocket motor (SRM). An explicit finite element method is used to solve for the structural response, and an explicit finite volume method is used to solve for the internal ballistic flow. Together, these two numerical solutions are coupled to model the nonsteady behaviour of axial combustion instability in sleeved cylindrical- and star-grain SRMs. The simulation model is used to predict the axial instability in star-grain SRMs. A parametric analysis is made to record the effects of various parameters on the simulation model. These parameters include the numerical dissipation constant, damping ratio and pulsing strength. It is found that both the numerical dissipation constant and damping ratio can, both artificially and physically, affect the finite element structural response of the motor. The pulsing strength affects only the rate at which the do pressure rises as well as how quickly the limiting wave amplitude is reached. A numerical model is developed to solve the governing equations for the structural dynamics and internal ballistics of a solid rocket motor (SRM). An explicit finite element method is used to solve for the structural response, and an explicit finite volume method is used to solve for the internal ballistic flow. Together, these two numerical solutions are coupled to model the nonsteady behaviour of axial combustion instability in sleeved cylindrical- and star-grain SRMs.The simulation model is used to predict the axial instability in star-grain SRMs. A parametric analysis is made to record the effects of various parameters on the simulation model. These parameters include the numerical dissipation constant, damping ratio and pulsing strength. It is found that both the numerical dissipation constant and damping ratio can, both artificially and physically, affect the finite element structural response of the motor. The pulsing strength affects only the rate at which the do pressure rises as well as how quickly the limiting wave amplitude is reached.The detailed analysis of simulated star-grain SRM axial instability reveals the effect of structural vibrations on burning rate augmentation and wave development in nonsteady operation. The variation in oscillation frequencies about a given grain section periphery, and along the grain with different levels of burnback, influences the means by which the local acceleration drives the combustion and flow behavior. The amount of damping also plays a role in influencing the predicted instability symptoms of the motor.

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Structural vibrations and internal ballistic modelling of a star-grain solid rocket motor

10.32920/ryerson.14657292.v1 ◽

2021 ◽

Author(s):

Sonny Loncaric

Keyword(s):

Finite Element ◽

Simulation Model ◽

Numerical Solutions ◽

Damping Ratio ◽

Structural Response ◽

Rocket Motor ◽

Numerical Dissipation ◽

Solid Rocket Motor ◽

Internal Ballistic ◽

Solid Rocket

A numerical model is developed to solve the governing equations for the structural dynamics and internal ballistics of a solid rocket motor (SRM). An explicit finite element method is used to solve for the structural response, and an explicit finite volume method is used to solve for the internal ballistic flow. Together, these two numerical solutions are coupled to model the nonsteady behaviour of axial combustion instability in sleeved cylindrical- and star-grain SRMs. The simulation model is used to predict the axial instability in star-grain SRMs. A parametric analysis is made to record the effects of various parameters on the simulation model. These parameters include the numerical dissipation constant, damping ratio and pulsing strength. It is found that both the numerical dissipation constant and damping ratio can, both artificially and physically, affect the finite element structural response of the motor. The pulsing strength affects only the rate at which the do pressure rises as well as how quickly the limiting wave amplitude is reached. A numerical model is developed to solve the governing equations for the structural dynamics and internal ballistics of a solid rocket motor (SRM). An explicit finite element method is used to solve for the structural response, and an explicit finite volume method is used to solve for the internal ballistic flow. Together, these two numerical solutions are coupled to model the nonsteady behaviour of axial combustion instability in sleeved cylindrical- and star-grain SRMs.The simulation model is used to predict the axial instability in star-grain SRMs. A parametric analysis is made to record the effects of various parameters on the simulation model. These parameters include the numerical dissipation constant, damping ratio and pulsing strength. It is found that both the numerical dissipation constant and damping ratio can, both artificially and physically, affect the finite element structural response of the motor. The pulsing strength affects only the rate at which the do pressure rises as well as how quickly the limiting wave amplitude is reached.The detailed analysis of simulated star-grain SRM axial instability reveals the effect of structural vibrations on burning rate augmentation and wave development in nonsteady operation. The variation in oscillation frequencies about a given grain section periphery, and along the grain with different levels of burnback, influences the means by which the local acceleration drives the combustion and flow behavior. The amount of damping also plays a role in influencing the predicted instability symptoms of the motor.

Download Full-text