scholarly journals Anomalous intensification of separated flow and heat transfer in one and multiple row deep inclined oval trench dimples on the wall of a narrow channel and on the plate

2021 ◽  
Vol 2088 (1) ◽  
pp. 012018
Author(s):  
S A Isaev ◽  
A I Leontiev ◽  
E E Son ◽  
S V Guvernyuk ◽  
M A Zubin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Static Pressure ◽  
Separated Flow ◽  
Narrow Channel ◽  
Separation Flow ◽  
State University ◽  
Flow And Heat Transfer ◽  
Numerical Studies ◽  
Moscow State University ◽  
Good Agreement

Abstract At the stands of Research Institute of Mechanics at the Moscow State University, we experimentally confirmed the mechanism of anomalous intensification of the separation flow and heat exchange in inclined oval-trench dimples (OTD) on the plate, which was discovered during numerical studies. The measured static pressure differences in single OTD at Re=6.7×104 are in good agreement with the numerical forecasts within the framework of the RANS approach at Re=104.

scholarly journals Numerical and experimental study of abnormal enhancement of separated turbulent flow and heat transfer in inclined oval-trench dimples on the plate and on the narrow channel wall

2021 ◽  
Vol 2039 (1) ◽  
pp. 012009
Author(s):  
S A Isaev ◽  
S V Guvernyuk ◽  
N I Mikheev ◽  
I A Popov ◽  
D V Nikushchenko
Keyword(s):  
Heat Transfer ◽  
Channel Wall ◽  
Separated Flow ◽  
Narrow Channel ◽  
State University ◽  
Scientific Center ◽  
Pressure Drops ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Numerical Predictions

Abstract The numerically found abnormal enhancement of separated flow and heat transfer in inclined oval-trench dimples (OTDs) on the plate and on the wall of the narrow channel was experimentally confirmed at the stands of the Research Institute of Mechanics (Lomonosov Moscow State University), the Kazan Scientific Center RAS, and the Kazan State Research Technical University – the Kazan Aviation Institute. The measured static pressure drops in a single OTD at Re = 6.7 × 104 and 16.7 × 104, the velocity profiles of accelerating laminar (Re = = 1000) and turbulent (Re = 4300) flows in the narrow channel with two rows of 26 OTDs, the estimate of Nusselt numbers on the channel wall with single-row OTDs are in good agreement with the numerical predictions within the RANS approach.

LES of Turbulent Separated Flow and Heat Transfer in a Symmetric Expansion Plane Channel

2005 ◽  
Vol 127 (5) ◽  
pp. 865-871 ◽  
Author(s):  
Kazuaki Sugawara ◽  
Hiroyuki Yoshikawa ◽  
Terukazu Ota
Keyword(s):  
Heat Transfer ◽  
Finite Difference ◽  
Plane Channel ◽  
Separated Flow ◽  
Expansion Ratio ◽  
Vortical Flow ◽  
Flow And Heat Transfer ◽  
Finite Difference Equations ◽  
Separated And Reattached Flow ◽  
Fundamental Equations

The LES method was applied to analyze numerically an unsteady turbulent separated and reattached flow and heat transfer in a symmetric expansion plane channel of expansion ratio 2.0. The Smagorinsky model was used in the analysis and fundamental equations were discretized by means of the finite difference method, and their resulting finite difference equations were solved using the SMAC method. The calculations were conducted for Re=15,000. It is found that the present numerical results, in general, agree well with the previous experimental ones. The complicated vortical flow structures in the channel and their correlations with heat transfer characteristics are visualized through various fields of flow quantities.

Numerical Prediction of Combustor Heatshield Flow and Heat Transfer With Sub-Grid-Scale Modelling of Pedestals

2001 ◽  
Author(s):  
John K. Luff ◽  
James J. McGuirk
Keyword(s):  
Heat Transfer ◽  
Life Prediction ◽  
Conjugate Heat Transfer ◽  
Energy Equation ◽  
Flow And Heat Transfer ◽  
Extra Energy ◽  
Scale Modelling ◽  
Heat Transfer Calculation ◽  
Proper Account ◽  
Good Agreement

A goal for computational analysis of combustors is to produce a tool for life prediction. An important part of this will be the prediction of the temperature field in the combustor walls. The complex geometries of combustor components make this a formidable task. In this paper a 3D coupled numerical flow/conjugate heat transfer calculation procedure is presented for a combustor heatshield. Proper account must be taken of the blockage and heat transfer effects of pedestals. A scheme has been developed to account for these effects without resolving the pedestals in the computational grid. Extra sink terms are included in the momentum equations to account for pedestal pressure drop. An extra energy equation is solved to determine the local pedestal temperature and to account for heat transfer between pedestals and fluid. This treatment has been validated against empirical data for arrays of pedestals in ducts with good agreement for friction factor and Nusselt number. The methodology is then applied to a generic heatshield geometry to indicate that a viable computational route has been developed for combustor heatshield analysis.

Heat Transfer From a Cylinder in Crossflow With Transpiration Cooling

1963 ◽  
Vol 85 (2) ◽  
pp. 173-177 ◽  
Author(s):  
B. V. Johnson ◽  
J. P. Hartnett
Keyword(s):  
Heat Transfer ◽  
Stagnation Point ◽  
Heat Transfer Performance ◽  
Separated Flow ◽  
Local Heat Transfer ◽  
Flow Region ◽  
Local Heat ◽  
Stagnation Flow ◽  
Experimental Values ◽  
Good Agreement

Local heat-transfer measurements are reported for a transpiration-cooled cylinder in crossflow. The stagnation point measurements are found to be in good agreement with results from plane stagnation flow theory. In the laminar region beyond the stagnation point, the equivalent wedge method is found to predict heat-transfer performance within 10 percent of the experimental values. In the separated flow region the experimental results demonstrate that the transpiration process is still very effective in reducing the heat transfer.

LES of Turbulent Separated Flow and Heat Transfer in a Symmetric Expansion Plane Channel

2004 ◽  
Author(s):  
Kazuaki Sugawara ◽  
Hiroyuki Yoshikawa ◽  
Terukazu Ota
Keyword(s):  
Heat Transfer ◽  
Finite Difference ◽  
Plane Channel ◽  
Separated Flow ◽  
Expansion Ratio ◽  
Vortical Flow ◽  
Flow And Heat Transfer ◽  
Finite Difference Equations ◽  
Separated And Reattached Flow ◽  
Fundamental Equations

LES method is applied to simulate numerically a turbulent separated and reattached flow and heat transfer in a symmetric expansion plane channel of expansion ratio 2.0. Smagorinsky model is used in the analysis and fundamental equations are discretized by means of the finite difference method, and their resulting finite difference equations are solved using SMAC method. The calculations are conducted for Re = 15000. It is found that the present numerical results, in general, agree well with the previous experimental ones. The complicated vortical flow structures in the channel and their correlations with heat transfer characteristics are visualized through various fields of flow quantities.

Experimental and Numerical Studies of Heat Transfer in Human Uteri During Cryoablation

2002 ◽  
Author(s):  
Jim S. Chen ◽  
Kevin Agnissey ◽  
Marla Wolfson ◽  
Charles Philips ◽  
Thomas Shaffer
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Temperature History ◽  
Rubber Sheet ◽  
Numerical Studies ◽  
Numerical Predictions ◽  
Silicone Rubber Sheet ◽  
Nicolson Scheme ◽  
Sheet Good ◽  
Good Agreement

This paper presents experimental and numerical studies of transient heat transfer inside the uterus during application of a PFC (perfluorochemical) fluid into the endometrium cavity in order to achieve cryoablation. The numerical prediction is based on a 1-D finite difference method of the bio-heat equation using the Crank Nicolson scheme. The numerical method is first validated by a 1-D physical model by measuring temperature history at several locations within a silicone rubber sheet. Good agreement, thus positive predictability, was obtained by comparing numerical predictions with the experimental data obtained from eight intact, hysterectomized uteri during cryoablation.

DNS of Expansion Ratio Effects on Three-Dimensional Unsteady Separated Flow and Heat Transfer Around a Downward Step

2005 ◽  
Author(s):  
Aya Kito ◽  
Kazuaki Sugawara ◽  
Hiroyuki Yoshikawa ◽  
Terukazu Ota
Keyword(s):  
Heat Transfer ◽  
Rectangular Channel ◽  
Three Dimensional ◽  
Side Wall ◽  
Separated Flow ◽  
Flow Region ◽  
Expansion Ratio ◽  
Mean Velocity ◽  
Flow And Heat Transfer ◽  
Channel Expansion

The direct numerical simulation methodology was employed to analyze the unsteady features of a three-dimensional separated flow and heat transfer around a downward step in a rectangular channel, and to clarify systematically the channel expansion ratio effects upon them. Numerical calculations were carried out using the finite difference method. The Reynolds number Re based on the mean velocity at inlet and the step height was varied from 300 to 1000. The channel expansion ratio ER is 1.5, 2.0 and 3.0 under a step aspect ratio of 36.0. It is found that the flow is steady upto Re = 500 but becomes sensibly unsteady at Re = 700 for all the three expansion ratios. In the case of ER = 2.0, the separated shear layer is most unstable. In the case of ER = 1.5, the longitudinal vortices formed near the side walls of channel are strongest. Nusselt number reaches its maximum in the reattachment flow region and also in the neighborhood of the side wall, and their locations depend greatly upon ER and Re.

Sign in / Sign up

Export Citation Format

Share Document