The elliptic porous slider at low cross-flow reynolds number using a nonnewtonian second-order fluid

Wear ◽  
1981 ◽  
Vol 71 (2) ◽  
pp. 249-253 ◽  
Author(s):  
B.S. Bhatt
Keyword(s):  
Reynolds Number ◽  
Cross Flow ◽  
Second Order ◽  
Flow Reynolds Number

Turbulent Wake of a Stack and the Influence of Velocity Ratio

2006 ◽  
Author(s):  
M. S. Adaramola ◽  
D. Sumner ◽  
D. J. Bergstrom
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Reynolds Shear Stress ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Turbulent Wake ◽  
Mean Velocity ◽  
Distinct Structure ◽  
Flow Reynolds Number ◽  
Cross Flow Velocity

The effect of the jet-to-cross-flow velocity ratio, R, on the turbulent wake of a cylindrical stack of AR = 9 was investigated with two-component thermal anemometry. The cross-flow Reynolds number was ReD = 2.3×104, the jet Reynolds number ranged from Red = 7×103 to 4.6×104, and R was varied from 0 to 3. The stack was partially immersed in a flat-plate turbulent boundary layer, with a boundary layer thickness-to-height ratio of δ/H = 0.5 at the location of the stack. The flow around the stack was broadly classified into three flow regimes depending on the value of R, which were the downwash (R < 0.5), cross-wind dominated (0.5 < R < 1.5), and jet-dominated (R > 1.5) regimes. Each flow regime had a distinct structure to the mean velocity (streamwise and wall-normal directions), turbulence intensity (streamwise and wall-normal directions), and Reynolds shear stress fields.

VORTEX INTERFERENCE IN THE WAKE OF TWO TANDEM CIRCULAR CYLINDERS IN A CROSS FLOW

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1595-1598 ◽  
Author(s):  
KAZUO OHMI ◽  
SUXIA LI ◽  
SEUNGHEE JEON ◽  
LINGYUN CHEN
Keyword(s):  
Reynolds Number ◽  
Image Analysis ◽  
Cross Correlation ◽  
Laser Sheet ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Water Tank ◽  
Cylinder Wake ◽  
Flow Reynolds Number ◽  
Spacing Ratio

The wake of two circular cylinders in tandem arrangement is investigated by flow visualization and PIV experiments in a towing water tank. The two cylinders are spaced at L/d (spacing ratio) = 2.0 to 15.0 and the cross flow Reynolds number ranges from 60 to 120. The flow is seeded with fine Rilsan particles and illuminated by a 2 mm thick laser sheet. The PIV image analysis is done by a standard cross correlation scheme with a powerful validation algorithm followed by multi-pass adaptive cross correlation iterations. The main objective of the study is to investigate the characteristics of the downstream cylinder wake changing considerably with the spacing ratio of the two cylinders.

Unconditional Linear Stability of Plane Couette-Poiseuille Flow in Presence of Cross Flow

2010 ◽  
Author(s):  
Anirban Guha ◽  
Ian A. Frigaard
Keyword(s):  
Reynolds Number ◽  
Linear Stability ◽  
Poiseuille Flow ◽  
Energy Production ◽  
Energy Analysis ◽  
Cross Flow ◽  
Base Flow ◽  
Lower Range ◽  
Long Wavelength ◽  
Flow Reynolds Number

We have investigated the linear stability of plane Couette-Poiseuille flow in the presence of a cross-flow. The base flow is characterised by the cross flow Reynolds number, Ri and the dimensionless wall velocity, k. Corresponding to each k ∈ [0,1], we have observed two ranges of Ri for which the flow is unconditionally linearly stable. In the lower range, we have a stabilisation of long wavelengths leading to a cut-off Ri. In this range, cross-flow stabilisation and Couette stabilisation appear to act via very similar mechanisms in this range, leading to the potential for robust compensatory design of flow stabilisation using either mechanism. As Ri is increased, we see first destabilisation and then stabilisation at very large Ri. The instability is again a long wavelength mechanism. A linear energy analysis reveals that in this range the Reynolds stress becomes amplified, the critical layer is irrelevant and viscous dissipation is completely dominated by the energy production/negation, which approximately balances at criticality.

Investigation on Film Cooling Performance of the Compound Hole and Y-Shaped Hole Configurations With the Cross-Flow Coolant Channel

2018 ◽  
Author(s):  
Lin Li ◽  
Cun-liang Liu ◽  
Hai-yong Liu ◽  
Hui-ren Zhu ◽  
Jian-xia Luo
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Discharge Coefficient ◽  
Cross Flow ◽  
Flow Reynolds Number ◽  
Hole Configuration ◽  
Shaped Hole

Film cooling performance of the compound hole and the Y-shaped hole configurations with the cross-flow coolant channel is investigated experimentally and numerically in this paper. The Reynolds numbers of coolant flow are fixed as 50000 and 100000 respectively. The film cooling effectiveness and heat transfer coefficient were measured by the transient liquid crystal measurement technique under three blowing ratios of 0.5, 1.0 and 2.0 respectively. And flow resistance measurements were also performed to obtain the discharge coefficient of the two film hole configurations. Numerical simulations with Reynolds-averaged Navier-Stokes (RANS) method were performed to explain the experiment results. The results show that the distribution feature of film cooling effectiveness for the compound hole and Y-shaped hole configurations is different. The film cooling effectiveness of the Y-shaped hole configuration is higher than that of the compound hole, and the film spanwise coverage is larger than that of the compound hole under all cases. For two film hole configurations, the heat transfer coefficient increases with the increase of the cross-flow Reynolds number and the blowing ratio. The heat transfer coefficient of the compound hole and Y-shaped hole configurations is close to each other under small cross-flow Reynolds number. However, under large cross-flow Reynolds number, the compound hole configuration has much higher heat transfer coefficient. The discharge coefficient increases gradually with the rising blowing ratio, then tend to a fixed value. Under the condition of the small cross-flow Reynolds number, the discharge coefficient of two film hole configurations is high. The discharge coefficient of the Y-shaped hole configuration is a little higher than that of the compound hole configuration under the condition of the large blowing ratio.

Computational study of Staggered and Double Cross Flow Heat Exchanger

2017 ◽  
Vol 67 (4) ◽  
pp. 396
Author(s):  
Annur Srinivasan Krishnan ◽  
Palanivelu Gowtham
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Transfer Rate ◽  
Cross Flow ◽  
Flow Reynolds Number ◽  
Flow Heat ◽  
Shell And Tube ◽  
Double Cross

The preliminary findings of a comparative study of heat transfer rate and pressure drop between conventional staggered flow and double cross flow heat exchanger is reported. Excepting for the tube arrangements, the shell and tube dimensions, materials and inlet conditions are retained the same for the two configurations. While in the conventional arrangement, adjacent rows of tubes are normal only to the fluid flow in the shell, in the double cross-flow arrangement, they are normal to both fluid flow direction in the shell as well as to each other. Shell dimensions are 100 cm × 20 cm × 20 cm and tube outside and inside diameters are 1 cm and 0.8 cm. The shell and tube materials are steel and copper. Water and air were considered as tube and shell side fluids respectively, with an overall arrangement of parallel flow. The tube flow Reynolds number was fixed at 2200 and the shell flow Reynolds number was varied from 20 to 120 in the laminar regime and 360 to 600 in the turbulent zone. The study reveals that the proposed configuration gives a maximum increase of about 27 per cent in the heat transfer rate per unit pressure drop over the conventional one.

scholarly journals The effects of arbitrary injection angle and flow conditions on venturi-jet mixer

2012 ◽  
Vol 16 (1) ◽  
pp. 207-221
Author(s):  
S. Sundararaj ◽  
V. Selladurai
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Multivariate Linear Regression Analysis ◽  
Jet Injection ◽  
Injection Angle ◽  
Flow Reynolds Number ◽  
Jet Velocity ◽  
The Cross

This paper describes the effect of jet injection angle, cross flow Reynolds number and velocity ratio on entrainment and mixing of jet with incompressible cross flow in venturi-jet mixer. Five different jet injection angles 45o, 60o, 90o, 125o, 135o are tested to evaluate the entrainment of jet and mixing performances of the mixer. Tracer concentration along the downstream of the jet injection, cross flow velocity, jet velocity and pressure drop across the mixer are determined experimentally to characterize the mixing performance of the mixer. The experiments show that the performance of a venturi-jet-mixer substantially improves at high injection angle and can be augmented still by increasing velocity ratio. The jet deflects much and penetrates less in the cross flow as the cross flow Reynolds number is increased. The effect could contribute substantially to the better mixing index with moderate pressure drop. Normalized jet profile, concentration decay, jet velocity profile are computed from equations of conservation of mass, momentum and concentration written in natural co-ordinate systems. The comparison between the experimental and numerical results confirms the accuracy of the simulations. Correlations for jet trajectory and entrainment ratio of the mixer are obtained by multivariate-linear regression analysis using power law.

CFD Study of Combined Impingement and Film Cooling Flow on the Internal Surface Temperature Distribution of a Vane

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Arun Kumar Pujari
Keyword(s):  
Reynolds Number ◽  
Surface Temperature ◽  
Film Cooling ◽  
Guide Vane ◽  
Cross Flow ◽  
Internal Surface ◽  
Flow Reynolds Number ◽  
Nozzle Guide Vane ◽  
Lift Off ◽  
Nozzle Guide

Abstract Conjugate heat transfer analysis is carried out on the internal surface of the first-stage nozzle guide vane of a gas turbine, which has both impingement and film cooling holes. The mainstream flow Reynolds number and internal coolant flow Reynolds number systematically changed and its effect on internal local surface temperature variation is studied. It is found that an increase in the coolant mass flow rate causes a non-uniform decrease in the local internal surface temperature. The external film coolant jet-lift off and internal impingement cross-flow are significant contributors to the non-uniform variation in surface temperature. It is also observed that the leading edge regions are prone to jet lift-off, whereas the tip regions of the suction surface are prone to self-induced cross-flow, due to which hot patches are formed in these regions. Hot patches are observed near the hub regions of a pressure surface due to the reduced film thickness on the external surface. From these observations it is concluded that local values of internal surface temperature are differently affected in different regions of the vane surface for a given combination of mainstream and coolant flow rates. Therefore, the conventional method of obtaining the internal temperature distributions by considering generalized geometries may not yield accurate solutions, in predicting the life of the nozzle guide vane.

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