Development and Assessment of a Backward Facing Steps Planar Rocket Nozzle

Magdi Abdelrazig Elhag Mohamed ,Our ,S Abdallah

doi:10.4172/2229-8711.1000160

Magdi Abdelrazig Elhag Mohamed , Our + Show 1 more

Open Access

https://doi.org/10.4172/2229-8711.1000160

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Abstract

Large Rocket engine nozzles performance deteriorate because of asymmetric flow separation that lead to side loads. The dual-bell nozzle is a promising two operating modes nozzle which consists of a base nozzle with low area ratio and a nozzle extension with high area ratio. Although the dual-bell nozzle improves the performance of large rocket engines, it suffers from side loads that occur during the transition between the two operating modes. This paper presents and assess a new nozzle that consist of backward facing steps to minimize/eliminate side loads. The backward facing steps geometry guarantees fixed stable local separation at the steps edges at all altitudes, thus eliminates the possibility of side loads as the rocket ascends. The assessment of the nozzle performance is carried out using CFD simulation of turbulent Navier-Stokes equations solver (fluent 14.5). The computed results for both dual-bell and backward facing steps nozzles are compared with the dual-bell nozzle experimental data.

Highlights

Classical bell nozzles that have fixed expansion area ratio cannot yield the maximum performance along a whole rocket trajectory
The dual-bell nozzle is a promising two operating modes nozzle which consists of a base nozzle with low area ratio and a nozzle extension with high area ratio
The dual-bell nozzle improves the performance of large rocket engines, it suffers from side loads that occur during the transition between the two operating modes

Summary

Introduction

Classical bell nozzles that have fixed expansion area ratio cannot yield the maximum performance along a whole rocket trajectory. A controlled flow separation occurs at the wall inflection leading to lower nozzle exit area (base nozzle area) which increases thrust gain and guarantees lower side loads. In ref [3,4] a planar dual bell nozzle has been tested experimentally and numerically under different flow conditions.

Results

Conclusion