Side Loads in Subscale Dual Bell Nozzles

Génin, Chloe; Stark, Ralf

doi:10.2514/1.54666

Cited by 7 publications

(12 citation statements)

References 6 publications

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“…The separation point leaves the contour inflection and starts moving down the extension, in the region close to the inflection, where the wall pressure gradient is negative. The sneak transition is comparable to the separated flow in a conventional nozzle and leads to increased side loads 5 .…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the inflection geometry on dual bell nozzle flow behavior

Génin¹,

Stark²

2011

47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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Section: Introductionmentioning

confidence: 99%

Experimental investigation of the inflection geometry on dual bell nozzle flow behavior

Génin¹,

Stark²

2011

47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

Self Cite

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“…The main advantage of the DBN is its simplicity because of absence of any movable parts and therefore, its high reliability [12]. However, the DBN suffers from a short time specific impulse loss and a high side load peak during the transition from low to high altitude mode [11,13]. The specific impulse decrease occurs because the transition from low to high altitude mode occurs at lower altitude than the optimum [11].…”

Section: Introductionmentioning

confidence: 99%

“…The specific impulse decrease occurs because the transition from low to high altitude mode occurs at lower altitude than the optimum [11]. While the high side load peak occurs during transition because the flow is potentially separates asymmetrically within the nozzle extension [13]. Many studies have been done on the DBN to understand the transition and side loads generation numerically [14,15,16,17,18] and experimentally [9,19,20,21].…”

Section: Introductionmentioning

confidence: 99%

Numerical Assessment of the Backward Facing Steps Nozzle

.¹

2015

IJRET

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The backward facing steps nozzle (BFSN) is a flow adjustable exit area nozzle for large rocket engines. It consists of two parts, the first is a base nozzle with small area ratio and the second part is a nozzle extension with surface consists of backward facing steps. The number of steps and their heights are carefully chosen to produce controlled flow separation at steps edges that adjust the nozzle exit area at all altitudes (pressure ratios). The BFSN performance parameters are assessed in terms of thrust and side loads against the dual-bell nozzle (DBN) with the same pressure ratios and cross sectional areas. The DBN is a two-mode flow adjustable exit area nozzle for low and high altitude. Three-dimensional turbulent flow solutions are obtained for the BFSN indicating that the flow is axi-symmetric and does not generate significant side loads. Further confirmation of the axi-symmetric flow is obtained by comparing the three-dimensional flow with the two-dimensional axi-symmetric solutions. The comparison of the thrust generated over the PR range from 50 to 1500 shows that BFSN generates more uniform and higher thrust than the DBN in the intermediate pressure ratios. At PR 1500 (high altitude), the BFSN thrust is 0.28% less than the DBN. All numerical solutions are obtained using the Fluent code.

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“…In low altitudes, 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. Experimental tests [1] on a subscale dual-bell nozzle were carried out to investigate the value of the side loads generated during transition from low to high altitude. It has been found in ref [1] that, although the transition duration is very short, typically in order of milliseconds, the separation point showed a significant asymmetry with an order of magnitude of the nozzle throat radius.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental tests [1] on a subscale dual-bell nozzle were carried out to investigate the value of the side loads generated during transition from low to high altitude. It has been found in ref [1] that, although the transition duration is very short, typically in order of milliseconds, the separation point showed a significant asymmetry with an order of magnitude of the nozzle throat radius. A hot full-scale dual-bell nozzle test was carried out [2] to clarify why attention has to be paid to the onset of side loads during transition.…”

Section: Introductionmentioning

confidence: 99%

Development and Assessment of a Backward Facing Steps Planar Rocket Nozzle

our²,

Abdallah

2014

Glob J Tech Opt

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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.

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Side Loads in Subscale Dual Bell Nozzles

Cited by 7 publications

References 6 publications

Experimental investigation of the inflection geometry on dual bell nozzle flow behavior

Experimental investigation of the inflection geometry on dual bell nozzle flow behavior

Numerical Assessment of the Backward Facing Steps Nozzle

Development and Assessment of a Backward Facing Steps Planar Rocket Nozzle

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