Numerical simulation of the structural response of a composite rocket nozzle during the ignition transient.
Loading...
Date
2009
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The following dissertation describes an investigation of the structural response behaviour of a
composite solid rocket motor nozzle subjected to thermal and pressure loading during the motor
ignition period, derived on the basis of a multidisciplinary numerical simulation approach. To
provide quantitative and qualitative context to the results obtained, comparisons were made to
the predicted aerothermostructural response of the nozzle over the entire motor burn period.
The study considered two nozzle designs – an exploratory nozzle design used to establish the
basic simulation methodology, and a prototype nozzle design that was employed as the primary
subject for numerical experimentation work. Both designs were developed according to
fundamental solid rocket motor nozzle design principles as non-vectoring nozzles for
deployment in medium sized solid rocket booster motors. The designs feature extensive use of
spatially reinforced carbon-carbon composites for thermostructural components, complemented
by carbon-phenolic composites for thermal insulation and steel for the motor attachment substructures. All numerical simulations were conducted using the ADINA multiphysics finite element
analysis code with respect to axisymmetric computational domains. Thermal and structural
models were developed to simulate the structural response of the exploratory nozzle design in
reference to the instantaneous application of pressure and thermal loading conditions derived
from literature. Ignition and burn period response results were obtained for both quasi-static and
dynamic analysis regimes.
For the case of the prototype nozzle design, a flow model was specifically developed to simulate
the flow of the exhaust gas stream within the nozzle, for the provision of transient and steady
loading data to the associated thermal and structural models. This arrangement allowed for a
more realistic representation of the interaction between the fluid, thermal and structural fields
concerned. Results were once again obtained for short and long term scenarios with respect to
quasi-static and dynamic interpretations. In addition, the aeroelastic interaction occurring
between the nozzle and flow field during motor ignition was examined in detail. The results obtained in the present study provided significant indications with respect to a
variety of response characteristics associated with the motor ignition period, including the
magnitude and distribution of the displacement and stress responses, the importance of inertial
effects in response computations, the stress response contributions made by thermal and pressure
loading, the effect of loading condition quality, and the bearing of the rate of ignition on the calculated stress response.
Through comparisons between the response behaviour predicted during the motor ignition and
burn periods, the significance of considering the ignition period as a qualification and
optimisation criterion in the design of characteristically similar solid rocket motor nozzles was established.
Description
Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.
Keywords
Solid propellant rockets., Rockets (Aeronautics)--Nozzles., Theses--Mechanical engineering.