Experimental study of boundary layer separation in truncated ideal contour nozzles

Stark, Ralf; Wagner, B.

doi:10.1007/s00193-008-0174-6

Cited by 59 publications

(26 citation statements)

References 8 publications

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“…The geometrical parameters are summarized in Fig. 2 Using the geometrical parameters, the Prandtl-Meyer relation and an empirical flow separation criterion (identified by Stark 4) as P sep /P a = 1/Ma), the nozzle pressure ratio (NPR = P 0 /P a ) leading to the transition can be defined as:…”

Section: Transition Predictionmentioning

confidence: 99%

Influence of the Test Environment on the Transition of Dual-Bell Nozzles

Génin

Stark

2012

AEROSPACE TECHNOLOGY JAPAN

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The dual bell nozzle offers a simple and efficient altitude adaption through its contour inflection, which insures symmetrical and controlled separation at sea level and a large area ratio at high altitude. The understanding of the transition from one operating mode to the other is the key to its prediction. Intensive cold flow investigation has led to an empirical criterion for a precise transition prediction. However, the testing conditions may have a great influence on the actual transition. The temperature of the flow and the nozzle wall, especially when driving test series, can shift the nozzle pressure ratio leading to the transition. A test campaign in a high altitude chamber has also shown the dependence of the transition condition with the chamber pressure, i.e. with the density of the separated backflow. For a reliable prediction of the dual-bell nozzle flow behavior, both on test facility and in real flight conditions, all these influences have to be identified and taken into account.

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Section: Transition Predictionmentioning

confidence: 99%

Influence of the Test Environment on the Transition of Dual-Bell Nozzles

Génin

Stark

2012

AEROSPACE TECHNOLOGY JAPAN

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“…The separation positions are normalized over the nozzle throat radius R th . Configurations 1 to 3 depict a linear correlation between separation position and NPR, as known for TIC nozzles under sea-level operation [3,4]. Within the back section of the nozzle (X sep /R th > 6), for configuration 4 and 5 the separation locations are only attainable with increased NPRs.…”

Section: Resultsmentioning

confidence: 99%

“…Here, the deviation from the turbulent separation trend appears for wall Mach numbers below 2.4. This is caused [3,4], as for low total pressures p 0 , the boundary layer relaminarizes in the nozzle throat.…”

Section: Resultsmentioning

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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“…14 plots the separation data (p sep /p a or p sep /p ON ) as a function of the corresponding wall separation Mach number, Ma sep , or the NPR, on the spike surface as well as the cowl wall, where the wall separation Mach number is based on the isentropic ratio of p ON /p sep . Three separation criteria are plotted for comparison: the well-known Schmucker criterion 50 (1), the separation criterion (2) for turbulent nozzle flows suggested by Stark et al 51,52 , and the separation criterion (3) suggested by Ge et al 53 recently based on flow separation data in asymmetric ramp nozzles. p sep p a ¼ 1:88Ma sep À 1 À Á À0:64 ð1Þ…”

Section: Prediction Of the Flow Separation Behaviormentioning

confidence: 99%

Numerical investigation of flow separation behavior in an over-expanded annular conical aerospike nozzle

Miaosheng

Li-zi

Liu

2015

Chinese Journal of Aeronautics

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A three-part numerical investigation has been conducted in order to identify the flow separation behavior--the progression of the shock structure, the flow separation pattern with an increase in the nozzle pressure ratio (NPR), the prediction of the separation data on the nozzle wall, and the influence of the gas density effect on the flow separation behavior are included. The computational results reveal that the annular conical aerospike nozzle is dominated by shock/shock and shock/boundary layer interactions at all calculated NPRs, and the shock physics and associated flow separation behavior are quite complex. An abnormal flow separation behavior as well as a transition process from no flow separation at highly over-expanded conditions to a restricted shock separation and finally to a free shock separation even at the deign condition can be observed. The complex shock physics has further influence on the separation data on both the spike and cowl walls, and separation criteria suggested by literatures developed from separation data in conical or bell-type rocket nozzles fail at the prediction of flow separation behavior in the present asymmetric supersonic nozzle. Correlation of flow separation with the gas density is distinct for highly overexpanded conditions. Decreasing the gas density or reducing mass flow results in a smaller adverse pressure gradient across the separation shock or a weaker shock system, and this is strongly coupled with the flow separation behavior. The computational results agree well with the experimental data in both shock physics and static wall pressure distribution at the specific NPRs, indicating that the computational methodology here is advisable to accurately predict the flow physics.

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Experimental study of boundary layer separation in truncated ideal contour nozzles

Cited by 59 publications

References 8 publications

Influence of the Test Environment on the Transition of Dual-Bell Nozzles

Influence of the Test Environment on the Transition of Dual-Bell Nozzles

Flow separation in rocket nozzles under high altitude condition

Numerical investigation of flow separation behavior in an over-expanded annular conical aerospike nozzle

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