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Reynolds Number Influence on Dual-Bell Transition Phenomena

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TLDR
In this paper, an experimental investigation was conducted to study the Reynolds number influence on dual-bell transition behavior for tests inside a high-altitude simulation chamber, where the authors found that the width of the inflection region decreases with an increase in the nozzle Reynolds number.
Abstract
An experimental investigation was conducted to study the Reynolds number influence on dual-bell transition behavior for tests inside a high-altitude simulation chamber. For the range of nozzle supply pressures tested, the nozzle Reynolds number is seen to gradually decrease from a relatively high value (of the order of 107 for tests in sea-level atmospheric conditions) toward the transitional range (lower side of 106 for tests inside the high-altitude chamber). This influences the width of the inflection region, which is seen to decrease with an increase in nozzle Reynolds number. Because of the smaller negative pressure gradient experienced during sneak transition with a decrease in nozzle Reynolds number, the separation point is seen to move into the region of wall inflection much earlier and tends to stay in the region of wall inflection for a relatively longer time. Although the time duration of final transition remains more or less constant for different nozzle supply pressure values, the time durati...

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Citations
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Journal ArticleDOI

Parametric study of supersonic film cooling in dual bell nozzle for an experimental air–kerosene engine

TL;DR: In this paper, the authors performed numerical analysis on a dual-bell nozzle designed for an experimental semi-cryogenic rocket engine application to predict the effect of film injection on nozzle flow characteristics and transitional behavior.
Journal ArticleDOI

Effect of Ambient Pressure Fluctuations on Dual-Bell Transition Behavior

TL;DR: In this paper, the effect of ambient pressure fluctuations on the dual-bell transition behavior was studied and it was found that the dual bell transition behavior is very sensitive to backpressure fluctuations of magnitude >20%, which triggered a flip-flop phenomenon that was observed to continue as long as the fluctuations prevailed.
Journal ArticleDOI

Assessment of transition regimes in a dual-bell nozzle and possibility of active fluidic control

TL;DR: In this article, the dual-bell axisymmetric propulsive nozzle concept has been investigated for transition modes and effects for desired large envelope launcher stage trajectories, and experimental and numerical investigations show that dual-Bell nozzle can be very effective for desired larger envelope launcher stages trajectories.
Journal ArticleDOI

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

TL;DR: In this paper, a three-part numerical investigation has been conducted in order to identify the flow separation behavior of an annular conical aerospike nozzle, including the progression of the shock structure, flow separation pattern with an increase in the nozzle pressure ratio, and the prediction of the separation data on the nozzle wall.
Journal ArticleDOI

Unsteady Flow Conditions During Dual-Bell Sneak Transition

TL;DR: In this paper, 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.
References
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Book

Dynamics and thermodynamics of compressible fluid flow

TL;DR: In this paper, the Hodograph Method for Two-Dimensional, Subsonic Flow with Small Perturbations is used to describe the dynamics of two-dimensional and three-dimensional flow.
Journal ArticleDOI

Advanced Rocket Nozzles.

TL;DR: In this paper, the authors consider altitude-adaptive nozzles for the space industry and show that signie cant performance gains result from the adaptation of the exhaust flow to the ambient pressure.

Dual-bell altitude compensating nozzles

TL;DR: In this paper, the authors assess the performance characteristics of dual bell nozzles and obtain preliminary design criteria by testing a number of configurations, including low altitude performance, high altitude performance and flow transition process.

Experimental Study of Gas-Flow Separation in Overexpanded Exhaust Nozzles for Rocket Motors

TL;DR: In this article, a de Laval nozzle with a fixed expansion ratio was designed for a single-stage rocket motor, and the authors investigated four different types of overexpansion, including underexpansion, overexpansion and separation of the flow from the wall.
Journal ArticleDOI

Nozzle flow separation

TL;DR: In this article, the authors studied the basic structure of shock interactions with separation shock, which consists of incident shock, Mach reflections, reflected shock, triple point and sliplines.
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