Numerical Investigation of Dual Bell Nozzle Flow Field

Génin, Chloe; Stark, Ralf; Karl, Sebastian; Schneider, Dirk

doi:10.2514/6.2012-4164

Cited by 11 publications

(7 citation statements)

References 2 publications

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“…For both approaches, transition takes place between NPR 47 and 48. This transition NPR Article in Advance / SCHNEIDER AND GÉNIN prediction accuracy was also shown in Génin et al [16] for a dual-bell nozzle with constant pressure extension. Figure 13 illustrates the wall pressure distribution for the conducted URANS simulations.…”

Section: Transient Transition Behaviorsupporting

confidence: 55%

“…A more progressive movement of the flow separation position inside the nozzle extension is observed. To determine the transition NPR of the numerical results and compare it with experimental data, a definition as described in Génin et al [16] was made. Thus, the inflection point of the flow separation position evolution curve was defined as transition NPR of the numerical simulations.…”

Section: Transient Transition Behaviormentioning

confidence: 99%

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Numerical Investigation of Flow Transition Behavior in Cold Flow Dual-Bell Rocket Nozzles

Schneider

Génin

2016

Journal of Propulsion and Power

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The dual-bell nozzle is an altitude-adaptive nozzle concept. It combines the advantages of a nozzle with small area ratio under sea-level conditions and a large area ratio nozzle under high-altitude conditions. Reynolds-averaged Navier-Stokes and unsteady Reynolds-averaged Navier-Stokes simulations on two-dimensional axisymmetric grids were conducted at DLR, German Aerospace Center in Lampoldshausen to investigate the transition from one mode to the other of a dual-bell nozzle model with positive pressure gradient extension. A cold flow test campaign conducted at DLR's cold flow test facility P6.2 provided validation data for the numerical approach. The present study investigates the influence of different turbulence models and feeding pressure gradients on the dual-bell flow transition behavior. Better results were achieved for the Spalart-Allmaras and Reynolds stress turbulence model. A clear impact of the feeding pressure ramp on the dual-bell transition pressure ratio and the flow separation position velocity was shown. The transition nozzle pressure ratio was predicted with an accuracy of 1%. For the hysteresis between transition and retransition nozzle pressure ratio, an accuracy of approximately 10% was reached. The calculated values of the experimental and numerical transition duration were on the same order of magnitude. Nomenclature A = area, m 2 H = hysteresis gap, % L = length, m R = radius, m y = dimensionless wall spacing α = angle, deg ϵ = expansion ratio Subscripts b = base nozzle e = nozzle extension i = inflection retr = retransition t = total th = nozzle throat tr = transition

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Section: Transient Transition Behaviorsupporting

confidence: 55%

Section: Transient Transition Behaviormentioning

confidence: 99%

Numerical Investigation of Flow Transition Behavior in Cold Flow Dual-Bell Rocket Nozzles

Schneider

Génin

2016

Journal of Propulsion and Power

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“…The thrust value is found to be highest for the BFSN with two backward facing steps at pressure ratio 1500 as shown in table 3, there for, the thrust curves for the BFSN with two backward facing steps and the DBN are shown in Figure (21). It is important to note here that the thrust curve for the DBN calculated from the 2-D axi-symmetric solutions following many studies have been done using the 2-D axi-symmetric solutions [11], [14], [18], [23], and [24]. The thrust curve is calculated from the flow parameters (pressure and axial velocity) based on the base nozzle exit area before the flow separation point leaves the end of the base nozzle following Refs [8] and [25].…”

Section: Thrust Calculation and Parametric Studymentioning

confidence: 99%

“…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]. From the literature survey about the nozzle flow separation and side loads, it can be concluded that the key to decrease the side loads is to control the flow separation at all operating conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Wall pressure distribution at different azimuth angels for PR=400 Wall pressure distribution at different azimuth angels for PR=400 zoomed at 2nd step Wall pressure distribution at different azimuth angels for PR=600 Wall pressure distribution at different azimuth angels for PR=600 zoomed at 2nd step Wall pressure distribution at different azimuth angels for PR=400 Wall pressure distribution at different azimuth angels for PR=400 zoomed at separation location Wall pressure distribution at different azimuth angels for PR=600 Wall pressure distribution at different azimuth angels for PR=600 zoomed at separation location Mach contours in the plane of symmetry for PR 400 and 600 are plotted for both the BFSN and the DBN as shown fromFigures (13)to(17). The symmetrical nature of the flow inside the BFSN can be noticed from the Mach contours for both PRs ofFigures (13)and(14). The BFSN Mach contours show that the flow separation occurred at the eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 04 Issue: 07 | July-2015, Available @ http://www.ijret.org second step for PR 400 and 600.…”

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confidence: 96%

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Numerical Assessment of the Backward Facing Steps Nozzle

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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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Rocket nozzles: 75 years of research and development

Khare

Saha

2021

Sādhanā

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Numerical Investigation of Dual Bell Nozzle Flow Field

Cited by 11 publications

References 2 publications

Numerical Investigation of Flow Transition Behavior in Cold Flow Dual-Bell Rocket Nozzles

Numerical Investigation of Flow Transition Behavior in Cold Flow Dual-Bell Rocket Nozzles

Numerical Assessment of the Backward Facing Steps Nozzle

Rocket nozzles: 75 years of research and development

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