Side Loads in Subscale Dual Bell Nozzles

Génin, Chloe; Stark, Ralf

doi:10.2514/1.b34170

Cited by 35 publications

(9 citation statements)

References 7 publications

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“…In comparison, during retransition, the rise in voltage signal from the strain gauge is seen to be much less. It would be very difficult to comment here on the reason for this, as the process of retransition is not very well understood to date [24]. Also, the focus of the present paper is on the flow unsteadiness experienced during sneak transition, which is absent during the dualbell retransition process.…”

Section: Power Spectramentioning

confidence: 95%

“…A rise in strain gauge signal is observed at a low NPR both during startup and shutdown operations. This is caused due to the transition of the boundary layer in the throat region from laminar to turbulent, which leads to partial flow reattachment [24]. As the NPR increases to 35 and the low-altitude mode is achieved, the shock front reaches the end of the base nozzle and separates in a controlled manner at the point of wall inflection.…”

Section: Power Spectramentioning

confidence: 99%

“…Also, the focus of the present paper is on the flow unsteadiness experienced during sneak transition, which is absent during the dualbell retransition process. Furthermore, it may be pointed out that the peak in strain gauge signal observed during retransition is not of much importance to real-flight application [24]. Figures 12a and 12b show the variation in the σ w ∕p w max value and the standard deviation of the strain gauge signal σ v in the two planes as a function of the NPR.…”

Section: Power Spectramentioning

confidence: 99%

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Unsteady Flow Conditions During Dual-Bell Sneak Transition

Verma

Hadjadj

Haidn

2015

Journal of Propulsion and Power

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A cold-gas test campaign was conducted on a subscale dual-bell nozzle operating under sea-level conditions to study the unsteady flow conditions encountered during sneak transition, which is a phenomenon prevalent just before final transition occurs. The study reveals that the flow during sneak transition is highly unsteady and is the major source of side-load generation in the dual-bell nozzle preceding the final transition. Statistical analysis suggests that, as the separation front moves into the region of wall inflection, the separated shear layer gradually comes in close proximity to the nozzle extension wall that alters the flow development process in the recirculation/backflow region considerably. This sets the entire backflow region into pressure fluctuations, making the flow conditions highly unsteady. It is further observed that the flow during sneak transition is associated with low frequencies in the vicinity of the separation location (0.8 kHz), which decreases as the sneak transition nozzle pressure ratio is approached (0.2 kHz).Nomenclature α e = wall angle at nozzle exit, deg _ m = mass flow rate of test gas, kg∕s P a = ambient pressure, bar P w = local wall pressure, bar P 0 = stagnation pressure of the test nozzle, bar r t = radius of nozzle throat, mm X = coordinate along the nozzle axis, mm α i = wall angle at the inflection point, deg α P = skewness coefficient; 1 n P n i0 P w i − P w 3 ∕σ 3 w β P = kurtosis coefficient; 1 n P n i0 P w i − P w 4 ∕σ 4 w ∈ = area ratio of the dual-bell nozzle ∈ b = area ratio of the base nozzle ∈ s = area ratio of the location of flow separation σ w = standard deviation of wall pressure fluctuations; P n i0 P w i −P w 2 n−1 r σ w ∕P w max = nondimensionalized peak value of standard deviation in the region of separation φ = angle in circumferential direction, dege

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Section: Power Spectramentioning

confidence: 95%

Section: Power Spectramentioning

confidence: 99%

Section: Power Spectramentioning

confidence: 99%

See 1 more Smart Citation

Unsteady Flow Conditions During Dual-Bell Sneak Transition

Verma

Hadjadj

Haidn

2015

Journal of Propulsion and Power

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“…The gap between transition and retransition NPR is called dual-bell hysteresis and is a well known effect from cold flow experiments. 28…”

Section: B Test Conditions and Instrumentation At Test Facility P61mentioning

confidence: 99%

A Numerical Model for Nozzle Flow Application under LOX/CH4 Hot Flow Conditions

Schneider¹,

Génin²,

Karl³

et al. 2016

52nd AIAA/SAE/ASEE Joint Propulsion Conference

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“…[39] In the following one and a half decades the work mainly focused on the dual bell flow behaviour itself. Experimentally, the performance [16][17][18], the transition/sneak transition [19][20][21][22][23][24], the hysteresis/buffeting effect [18,21,25], the side loads [26], and the heat loads [27] were studied. Numerically, the transition/sneak transition [24,[28][29][30][31][32][33][34], the hysteresis/buffeting effect [30,35], the side loads [30,33], the heat loads [24], and the jet oscillation [36] were studied as well.…”

Section: Introductionmentioning

confidence: 99%

Sea-level transitioning dual bell nozzles

Stark

Génin

2017

CEAS Space J

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To evaluate the impact of sea-level transitioning dual bell nozzles on the payload mass delivered into geostationary transfer orbit by Ariane 5 ECA, a detailed study was conducted. For this purpose, a multitude of Vulcain 2 and Vulcain 2.1 nozzle extension contours were designed. The two variation parameters were the position of the wall inflection and the constant wall pressure of the nozzle extension. Considering these parameters an approved analytical method was applied to predict the impact of the dual bell nozzles on the payload mass. The payload gain into geostationary transfer orbit was evaluated to be up to 219 kg.

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Side Loads in Subscale Dual Bell Nozzles

Cited by 35 publications

References 7 publications

Unsteady Flow Conditions During Dual-Bell Sneak Transition

Unsteady Flow Conditions During Dual-Bell Sneak Transition

A Numerical Model for Nozzle Flow Application under LOX/CH4 Hot Flow Conditions

Sea-level transitioning dual bell nozzles

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