Influence study of flow separation on the nozzle vibration response

Li, Geng; Q, Liu; Han, Xuequn; Guo, Yunqiang

doi:10.1016/j.jppr.2016.05.002

Cited by 3 publications

(1 citation statement)

References 5 publications

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“…n order to experimentally evaluate the highaltitude performance of the said nozzles, a high altitude test (HAT) facility system consisting of a supersonic exhaust diffuser is generally employed [1,2,3,4]. The main purpose is to reduce the nozzle back pressure sufficiently to have full flow at the design pressure [5].…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigations At High Altitudes For Nozzles Performance Monitoring

Qureshi¹,

Ozair²,

Ahmad³

et al. 2023

JISR-C

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Large area ratio nozzles that are employed for space propulsion applications are not meant to be tested at the ground-level conditions because of the flow conditions that occurs in their divergent section due to their low exhaust pressures. Therefore, it is desired to perform the experimental evaluation at high-altitude to evaluate the performance of the said nozzles. Generally, a high-altitude test facility, consisting of a supersonic exhaust diffuser, is generally employed. In thispaper, a second-throat exhaust diffuser has been numerically investigated to predict its minimum starting pressure, and to understand the flow physics in the diffuser using Computational Fluid Dynamics (CFD). Numerical computation of the flow field in the diffuser system is done for the two cases: 1) when the nozzle and the diffuser system are initially evacuated to a low pressure, and 2) when the nozzle and the diffuser system are initially at ambient pressure (1 bar). Simulations have been carried out for cold flow situation (Ȗ=1.4) over a range of nozzle inlet stagnation pressures. Numerical results compare favorably with the theoretical and experimental results and provide adequate insight to the flow physics and internal shock structures formed in thediffuser in addition to minimum starting pressure, diffuser wall pressure and vacuum thrust.

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Section: Introductionmentioning

confidence: 99%

Numerical Investigations At High Altitudes For Nozzles Performance Monitoring

Qureshi¹,

Ozair²,

Ahmad³

et al. 2023

JISR-C

View full text Add to dashboard Cite

show abstract

A detailed modelling on spray atomisation and combustion of LOX/GCH4 in variable area pintle injector rocket engines

Radhakrishnan

Lee

Koo

2021

Combustion Theory and Modelling

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Study on Separation Characteristics of Nozzles with Large Expansion Ratio of Solid Rocket Motors

Wang

Tian

2022

Aerospace

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In order to study the flow characteristics of a nozzle with large expansion ratio and its influence on the force on the nozzle, ground cold flow test research and a fluid–structure coupling simulation analysis were carried out (maximum expansion ratio ε = 30.25). The variation and pulsation characteristics of the pressure near the measuring point area and the inlet pressure were obtained through experiments. Through the analysis of the peak-to-peak value and average value, it was found that the average pressure after separation increases by 90%, but the peak-to-peak value increases by about five times, indicating that the pressure fluctuation after separation is much larger than before separation. The separation flow field under cold flow conditions was simulated using the CFD commercial calculation software Fluent to verify the correctness of the numerical calculations. The fluid–structure coupling analysis was carried out on a large expansion ratio (maximum expansion ratio ε = 48) full-scale nozzle, and the structural deformation characteristics of the nozzle under the separation conditions were studied. The research results show that flow separation occurs in the nozzle with a large expansion ratio under ground conditions. Before the separation point, the pressure pulsation on the nozzle wall is small, and the turbulent pulsation effect is weak. After the separation point, the pressure pulsation increases, and the turbulent pulsation effect is enhanced. When the total pressure decreases, the separation area of the nozzle increases, and the separation flow field presents a strong asymmetry. Reducing the total inlet pressure by half resulted in approximately 50 times the lateral load. Under the combined influence of the ground conditions and low total pressure, the large lateral load caused by the asymmetry of the separation flow field will cause the deformation of the nozzle structure to increase by 5.5 times. This research provides an important reference for the design and experiment of nozzles with a large expansion ratio.

show abstract

Influence study of flow separation on the nozzle vibration response

Cited by 3 publications

References 5 publications

Numerical Investigations At High Altitudes For Nozzles Performance Monitoring

Numerical Investigations At High Altitudes For Nozzles Performance Monitoring

A detailed modelling on spray atomisation and combustion of LOX/GCH4 in variable area pintle injector rocket engines

Study on Separation Characteristics of Nozzles with Large Expansion Ratio of Solid Rocket Motors

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