Annular flow transition model in channels of various shapes.

This paper describes the modifications made to a successful attached flow transition model to produce a model capable of predicting both attached and separated flow transition. This transition model is used in combination with the Fluent CFD software, which is used to compute the flow around the blade assuming that it remains entirely laminar. The transition model then determines the start of transition location and the development of the intermittency. These intermittency values weight the laminar and turbulent boundary layer profiles to obtain the resulting transitional boundary layer parameters. The ERCOFTAC T3L test cases are used to validate the predictions. The T3L blade is a flat plate with a semi-circular leading edge, which results in the formation of a separation bubble the length of which is strongly dependent on the transition process. Predictions were performed for five T3L test cases for differing free-stream turbulence levels and Reynolds numbers. For the majority of these test cases the measurements were accurately predicted.

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Boundary Conditions of Flow Transition Model for Roughened Surface

AIAA Journal ◽

10.2514/1.j060641 ◽

2021 ◽

pp. 1-5

Author(s):

Chankyu Son ◽

Taeseong Kim

Keyword(s):

Boundary Conditions ◽

Transition Model ◽

Flow Transition ◽

Roughened Surface

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Predicting Transitional Separation Bubbles

Volume 4: Turbo Expo 2004 ◽

10.1115/gt2004-53353 ◽

2004 ◽

Cited By ~ 4

Author(s):

John A. Redford ◽

Mark W. Johnson

Keyword(s):

Boundary Layer ◽

Separation Bubble ◽

Separated Flow ◽

Leading Edge ◽

Transition Process ◽

Reynolds Numbers ◽

Test Cases ◽

Transition Model ◽

Flow Transition ◽

Attached Flow

This paper describes the modifications made to a successful attached flow transition model to produce a model capable of predicting both attached and separated flow transition. This transition model is used in combination with the Fluent CFD software, which is used to compute the flow around the blade assuming that it remains entirely laminar. The transition model then determines the start of transition location and the development of the intermittency. These intermittency values weight the laminar and turbulent boundary layer profiles to obtain the resulting transitional boundary layer parameters. The ERCOFTAC T3L test cases are used to validate the predictions. The T3L blade is a flat plate with a semi-circular leading edge, which results in the formation of a separation bubble the length of which is strongly dependent on the transition process. Predictions were performed for five T3L test cases for differing freestream turbulence levels and Reynolds numbers. For the majority of these test cases the measurements were accurately predicted.

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Cross-flow transition model predictions of hypersonic transition research vehicle

Aerospace Science and Technology ◽

10.1016/j.ast.2022.107327 ◽

2022 ◽

pp. 107327

Author(s):

Xing-hao Xiang ◽

Jian-qiang Chen ◽

Xian-xu Yuan ◽

Bing-bing Wan ◽

Yu Zhuang ◽

...

Keyword(s):

Cross Flow ◽

Transition Model ◽

Flow Transition ◽

Model Predictions ◽

Transition Research

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Experimental Study of Flow Patterns and Regimes of Condensation in Horizontal Three-Dimensional Micro-Fin Tubes

Heat Transfer: Volume 1 ◽

10.1115/ht2003-47026 ◽

2003 ◽

Cited By ~ 2

Author(s):

Qinghua Chen ◽

R. S. Amano ◽

Mingdao Xin

Keyword(s):

Flow Regime ◽

Annular Flow ◽

Plug Flow ◽

Three Dimensional ◽

Flow Patterns ◽

Smooth Tube ◽

Flow Transition ◽

Regime Map ◽

Fin Tubes ◽

Flow Regime Map

During condensation of R134a the flow patterns inside two three-dimensional (3-D) micro-fin tubes with different fin geometries were investigated. The flow patterns and their transitions were visibly observed and recorded. The experimental findings revealed the following results: a comparison of the condensation flow patterns in the 3-D microfin tubes with those in smooth tubes revealed no qualitative differences. The mist flow and the mist-annular flow that appeared in the smooth tube entrance region were not observed in 3-D micro-fin tubes. In the maps of the Mandhane flow regime and the Soliman flow regime, the area of annular flow region of the 3-D micro-fin tube extends towards lower Fr number range in the Soliman map and smaller vapor velocity range in the Mandhane map when compared with that of a smooth tube. The criterion of the flow regime transition between the annular flow and wavy flow decreases from Fr = 7 to Fr = 2 in the Soliman flow regime map. However, no significant effect on the criterion for the plug flow transition was observed. The experimental data points of plug flow in the 3-D micro-fin tubes were also obtained in the same regime of smooth tube in Mandhane flow regime map. The Soliman flow regime map indicates the criterion for plug flow transition to be Fr = 0.4.

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A Study of Flows Over Microgrooves for Different Flow Pattern

ASME 4th International Conference on Nanochannels, Microchannels, and Minichannels, Parts A and B ◽

10.1115/icnmm2006-96226 ◽

2006 ◽

Author(s):

Q. Chen ◽

R. S. Amano

Keyword(s):

Flow Regime ◽

Annular Flow ◽

Plug Flow ◽

Flow Patterns ◽

Smooth Tube ◽

Flow Transition ◽

Number Range ◽

Regime Map ◽

Fin Tubes ◽

Flow Regime Map

During condensation of R134a the flow patterns inside two three-dimensional (3-D) micro-fin tubes with different fin geometries were investigated. The flow patterns and their transitions were visibly observed and recorded. The experimental findings revealed the following results: a comparison of the condensation flow patterns in the 3-D micro-fin tubes with those in smooth tubes revealed no qualitative differences. The mist flow and the mist-annular flow that appeared in the smooth tube entrance region were not observed in 3-D micro-fin tubes. In the maps of the Mandhane flow regime and the Soliman flow regime, the area of annular flow region of the 3-D micro-fin tube extends towards lower Fr number range in the Soliman map and smaller vapor velocity range in the Mandhane map when compared with that of a smooth tube. The criterion of the flow regime transition between the annular flow and the wavy flow decreases from Fr = 7 to Fr = 2 in the Soliman flow regime map. However, no significant effect on the criterion for the plug flow transition was observed. The experimental data points of plug flow in the 3-D micro-fin tubes were also obtained in the same regime of smooth tube in Mandhane flow regime map. The Soliman flow regime map indicates the criterion for plug flow transition to be Fr = 0.4.

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