Details of Side Load Test Data and Analysis for a Truncated Ideal Contour Nozzle and a Parabolic Contour Nozzle

Ruf, Joseph H.; McDaniels, David; Brown, A.

doi:10.2514/6.2010-6813

Cited by 20 publications

(13 citation statements)

References 11 publications

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“…However, deviations are attributed to the differences in the TOP nozzle contours, NPR values and test environments; the sub-scale nozzles used in experimental campaigns exhaust in a diffuser and ejector pipe that have different designs. In particular, Ruf et al (2010a) [11] points out that the inlet of the ejector pipe can affect the location of flow separation and associated flow structures.…”

mentioning

confidence: 99%

Wall Pressure Unsteadiness and Side Loads in Overexpanded Rocket Nozzles

Baars

Tinney²,

Ruf³

et al. 2012

AIAA Journal

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Surveys of both the static and dynamic wall pressure signatures on the interior surface of a sub-scale, cold-flow and thrust optimized parabolic nozzle are conducted during fixed nozzle pressure ratios corresponding to FSS and RSS states. The motive is to develop a better understanding for the sources of off-axis loads during the transient start-up of overexpanded rocket nozzles. During FSS state, pressure spectra reveal frequency content resembling SWTBLI. Presumably, when the internal flow is in RSS state, separation bubbles are trapped by shocks and expansion waves; interactions between the separated flow regions and the waves produce asymmetric pressuredistributions. An analysis of the azimuthal modes reveals how the breathing mode encompasses most of the resolved energy and that the side load inducing mode is coherent with the response moment measured by strain gauges mounted upstream of the nozzle on a flexible tube. Finally, the unsteady pressure is locally more energetic during RSS, albeit direct measurements of the response moments indicate higher side load activity when in FSS state. It is postulated that these discrepancies are attributed to cancellation effects between annular separation bubbles.

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mentioning

confidence: 99%

Wall Pressure Unsteadiness and Side Loads in Overexpanded Rocket Nozzles

Baars

Tinney²,

Ruf³

et al. 2012

AIAA Journal

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“…3 NASA has embarked on a multi-year effort to American Institute of Aeronautics and Astronautics develop computational and test capabilities to characterize nozzle side loads in an effort to increase the experience and knowledge base needed to support liquid rocket nozzle development. [4][5][6][7][8][9][10][11][12] However, none of the computational studies incorporate nozzle flexibility coupled with CFD. Variations in the wall pressure may cause a significant distortion of the nozzle, which results in significant amplification of the initial load due to the fluid-structure coupling.…”

Section: B Nozzle Side Loadsmentioning

confidence: 99%

Fully Coupled Fluid-Structure Interaction Simulations of Rocket Engine Side Loads

Blades¹,

Luke²,

Ruf³

2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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The goal of this work is to simulate both the flow in a rocket engine nozzle and the resulting flow-induced transient loads on the nozzle. This unsteady nozzle flow results in structural dynamic excitation that contributes not only to nozzle stress and deformation but also to the dynamic loads transmitted to the rest of engine. This paper demonstrates the capability of a coupled fluid-structure interaction (FSI) simulation for predicting side loads on a rocket engine nozzle. The capability was demonstrated using the space shuttle main engine (SSME) during a portion of the engine startup sequence. A comparison to the rigid nozzle baseline solution is made, and the FSI solutions demonstrate the effect of nozzle flexibility on the structural and fluid dynamic response. Abaqus/Standard is used to compute the unsteady structural responses and the Loci/CHEM CFD program is used to simulate the unsteady, separated flow in the nozzle. The FSI simulations are performed using the Co-Simulation Engine (CSE) to couple the unsteady fluid and structural responses. Multiple fluid and structural cases were explored to achieve realistic and qualitatively correct flow and structural responses in preparation for the coupled solution attempts. These unsteady FSI results represent the first fully coupled, time-accurate, viscous FSI simulation for a rocket engine nozzle.

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“…The studies do have in common very low total and ambient densities (ρ 0 , ρ a ). Ruf et al [9] noted that a diffuser, mounted too close to the nozzle exit, shifted the flow separation downstream. Therefore, and based on experimental studies by the authors [10], the question arose whether the prediction of the dual bell transition NPR might provide inadequate results, as the influence of the ambient density is not taken into account.…”

Section: Introductionmentioning

confidence: 99%

Flow separation in rocket nozzles under high altitude condition

Stark

Génin

2016

Shock Waves

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The knowledge of flow separation in rocket nozzles is crucial for rocket engine design and optimum performance. Typically, flow separation is studied under sealevel conditions. However, this disregards the change of the ambient density during ascent of a launcher. The ambient flow properties are an important factor concerning the design of altitude-adaptive rocket nozzles like the dual bell nozzle. For this reason an experimental study was carried out to study the influence of the ambient density on flow separation within conventional nozzles.

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Details of Side Load Test Data and Analysis for a Truncated Ideal Contour Nozzle and a Parabolic Contour Nozzle

Abstract: Two cold flow subscale nozzles were tested for side load characteristics during simulated nozzle start transients. The two test article contours were a truncated ideal and a parabolic.

Cited by 20 publications

References 11 publications

Wall Pressure Unsteadiness and Side Loads in Overexpanded Rocket Nozzles

Wall Pressure Unsteadiness and Side Loads in Overexpanded Rocket Nozzles

Fully Coupled Fluid-Structure Interaction Simulations of Rocket Engine Side Loads

Flow separation in rocket nozzles under high altitude condition

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