Cross-term events of scale-decomposed skewness factor in turbulent boundary layer at moderate Reynolds number

2021 ◽  
Vol 33 (5) ◽  
pp. 055124
Author(s):  
Zhanqi Tang ◽  
Letian Chen ◽  
Ziye Fan ◽  
Xingyu Ma ◽  
Nan Jiang
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Cross Term ◽  
Moderate Reynolds Number ◽  
Skewness Factor

Effect of small roughness elements on thermal statistics of a turbulent boundary layer at moderate Reynolds number

2015 ◽  
Vol 787 ◽  
pp. 84-115 ◽  
Author(s):  
Ali Doosttalab ◽  
Guillermo Araya ◽  
Jensen Newman ◽  
Ronald J. Adrian ◽  
Kenneth Jansen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Prandtl Number ◽  
Rough Surface ◽  
Surface Flow ◽  
Unit Mass ◽  
Turbulent Prandtl Number ◽  
Reynolds Analogy ◽  
Moderate Reynolds Number

A zero-pressure-gradient turbulent boundary layer flowing over a transitionally rough surface (24-grit sandpaper) with$k^{+}\approx 11$and a momentum-thickness Reynolds number of approximately 2400 is studied using direct numerical simulation (DNS). Heat transfer between the isothermal rough surface and the turbulent flow with molecular Prandtl number$Pr=0.71$is simulated. The dynamic multiscale approach developed by Arayaet al.(J. Fluid Mech., vol. 670, 2011, pp. 581–605) is employed to prescribe realistic time-dependent thermal inflow boundary conditions. In general, the rough surface reduces mean and fluctuating temperature profiles with respect to the smooth surface flow when normalized by Wang & Castillo (J. Turbul., vol. 4, 2003, 006) inner/outer scaling. It is shown that the Reynolds analogy does not hold for$y^{+}<9$. In this region the value of the turbulent Prandtl number departs substantially from unity. Above this region the Reynolds analogy is only approximately valid, with the turbulent Prandtl number decreasing from 1 to 0.7 across the boundary layer for rough and smooth walls. In comparison with the smooth-wall case, the turbulent transport of heat per unit mass,$\overline{v^{\prime }v^{\prime }{\it\theta}^{\prime }}$, towards the wall is enhanced in the buffer layer, but the transport of$\overline{v^{\prime }v^{\prime }{\it\theta}^{\prime }}$away from the wall is reduced in the outer layer for the rough case; similar behaviour is found for the vertical transport of turbulent momentum per unit mass,$\overline{v^{\prime }u^{\prime }v^{\prime }}$. Above the roughness sublayer (3$k$–5$k$) it is found that most of the temperature field statistics, including higher-order moments and conditional averages, are highly similar for the smooth and rough surface flow, showing that the Townsend’s Reynolds number similarity hypothesis applies for the thermal field as well as the velocity field for the Reynolds number and$k^{+}$considered in this study.

scholarly journals Simulation of a Large-Eddy-Break-up Device (LEBU) in a Moderate Reynolds Number Turbulent Boundary Layer

2016 ◽  
Vol 98 (2) ◽  
pp. 445-460 ◽  
Author(s):  
Cheng Chin ◽  
Ramis Örlü ◽  
Jason Monty ◽  
Nicholas Hutchins ◽  
Andrew Ooi ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Moderate Reynolds Number ◽  
Large Eddy ◽  
Break Up

The Turbulent Boundary Layer on an Axial Compressor Blade

1982 ◽  
Author(s):  
G. J. Walker
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Convex Surface ◽  
Axial Compressor ◽  
Reynolds Numbers ◽  
Positive Pressure ◽  
Mean Flow ◽  
Flow Measurements ◽  
Moderate Reynolds Number

Time-mean flow measurements of turbulent boundary layer development on the convex surface of an outlet stator blade in a single-stage axial compressor are presented. There is no evidence of logarithmic wall similarity at blade chord Reynolds numbers from 3 × 104 to 2 × 105, and its absence appears due to the combined effects of low Reynolds number, large positive pressure gradient and rapidly changing boundary conditions. Conventional skin friction laws compare very poorly with experiment. The performance of local equilibrium and entrainment-type calculation methods is examined and serious errors are found to develop at blade Reynolds numbers below 105. The best results are obtained from a lag-entrainment method of Green, Weeks and Brooman, which can be recommended for predicting axial turbomachine blade boundary layers at moderate Reynolds number.

Effect of Reynolds number on drag reduction in turbulent boundary layer flow over liquid–gas interface

2020 ◽  
Vol 32 (12) ◽  
pp. 122111
Author(s):  
Hongyuan Li ◽  
SongSong Ji ◽  
Xiangkui Tan ◽  
Zexiang Li ◽  
Yaolei Xiang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Drag Reduction ◽  
Boundary Layer Flow ◽  
Turbulent Boundary Layer Flow ◽  
Layer Flow

Reynolds Number Effects on Shock-Wave Turbulent Boundary-Layer Interactions

AIAA Journal ◽  
1977 ◽  
Vol 15 (8) ◽  
pp. 1152-1158 ◽  
Author(s):  
C. C. Horstman ◽  
G. S. Settles ◽  
I. E. Vas ◽  
S. M. Bogdonoff ◽  
C.M. Hung
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Reynolds Number Effects

An Experimental Study of Heat Transfer on an Outlet Guide Vane

2014 ◽  
Author(s):  
Chenglong Wang ◽  
Lei Wang ◽  
Bengt Sundén ◽  
Valery Chernoray ◽  
Hans Abrahamsson
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Guide Vane ◽  
Incidence Angle ◽  
Boundary Layer Transition ◽  
Transfer Coefficients ◽  
Suction Surface ◽  
Layer Transition

In the present study, the heat transfer characteristics on the suction and pressure sides of an outlet guide vane (OGV) are investigated by using liquid crystal thermography (LCT) method in a linear cascade. Because the OGV has a complex curved surface, it is necessary to calibrate the LCT by taking into account the effect of viewing angles of the camera. Based on the calibration results, heat transfer measurements of the OGV were conducted. Both on- and off-design conditions were tested, where the incidence angles of the OGV were 25 degrees and −25 degrees, respectively. The Reynolds numbers, based on the axial flow velocity and the chord length, were 300,000 and 450,000. In addition, heat transfer on suction side of the OGV with +40 degrees incidence angle was measured. The results indicate that the Reynolds number and incidence angle have considerable influences upon the heat transfer on both pressure and suction surfaces. For on-design conditions, laminar-turbulent boundary layer transitions are on both sides, but no flow separation occurs; on the contrary, for off-design conditions, the position of laminar-turbulent boundary layer transition is significantly displaced downstream on the suction surface, and a separation occurs from the leading edge on the pressure surface. As expected, larger Reynolds number gives higher heat transfer coefficients on both sides of the OGV.

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