Convex and concave surface curvature effects in wall-bounded turbulent flows

AIAA Journal ◽  
1991 ◽  
Vol 29 (6) ◽  
pp. 895-902 ◽  
Author(s):  
Marshall C. Richmond ◽  
Virendra C. Patel
Keyword(s):  
Turbulent Flows ◽  
Surface Curvature ◽  
Concave Surface ◽  
Curvature Effects

Convex Curvature Effects on Film Cooling Adiabatic Effectiveness

2013 ◽  
Author(s):  
James R. Winka ◽  
Joshua B. Anderson ◽  
David G. Bogard ◽  
Michael E. Crawford ◽  
Emily J. Boyd
Keyword(s):  
Film Cooling ◽  
Suction Side ◽  
Surface Curvature ◽  
Radius Of Curvature ◽  
Exact Matching ◽  
Curvature Effects ◽  
Cooling Hole ◽  
Cylindrical Holes ◽  
Series Of Experiments ◽  
Convex Curvature

Surface curvature is known to have significant effects on film cooling performance, with convex curvature inducing increased film effectiveness and concave curvature causing decreased film effectiveness. Generally, these curvature effects have been presumed to scale with 2r/d at the film cooling hole location, where r is the radius of curvature and d is coolant hole diameter. In this study, the validity of this scaling of curvature effects are examined by performing experiments in regions of large and low curvature on a model vane. Single rows of cylindrical holes were placed at various locations along the high curvature section of the suction side of the vane. For the first series of experiments, a single row of holes was placed at two locations with different local surface curvature. The coolant hole diameters were then adjusted to match 2r/d values. Results from these experiments showed that there was better correspondence of film performance when using the 2r/d scaling, but there was not an exact matching of performance. A second series of experiments focused on evaluating the effects of curvature downstream of the coolant holes. One row of holes was placed at a position upstream of the highest curvature, while another row was placed at a downstream position such that the radius of curvature was equivalent for the two rows of holes. Results indicated that the local radius of curvature is not sufficient in understanding the performance of film cooling. Instead, the curvature envelope downstream of the coolant holes plays a significant role on the performance of film cooling for cylindrical holes.

Surface Curvature Effects on Three-Dimensional Blunt-Body Boundary Layers

AIAA Journal ◽  
1979 ◽  
Vol 17 (2) ◽  
pp. 133-134 ◽  
Author(s):  
D. L. Dwoyer ◽  
Clark H. Lewis ◽  
P. R. Gogineni
Keyword(s):  
Boundary Layers ◽  
Blunt Body ◽  
Three Dimensional ◽  
Surface Curvature ◽  
Curvature Effects ◽  
Body Boundary

Surface Curvature Effects on Film Cooling Performance for Shaped Holes on a Model Turbine Blade

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Jacob D. Moore ◽  
Christopher Yoon ◽  
David G. Bogard
Keyword(s):  
Flat Plate ◽  
Turbine Blade ◽  
Film Cooling ◽  
Gas Turbines ◽  
Convex Surface ◽  
Adverse Pressure Gradient ◽  
Suction Side ◽  
Surface Curvature ◽  
Cooling Performance ◽  
Curvature Effects

Abstract Surface curvature has been shown to have significant effects on the film cooling performance of round holes, but the literature include few studies of its effects on shaped holes despite their prevalence in gas turbines. Experiments were performed using two rows of holes placed on the suction side of a scaled-up turbine blade in a low Mach number linear cascade wind tunnel with low freestream turbulence. The rows were placed in regions of high and low convex surface curvature. Geometries and flow conditions for the rows were matched to those from previous flat plate studies. Comparison of the adiabatic effectiveness results from the high curvature and flat plate rows revealed the same trends as those in the literature using round holes, with increased performance for the high curvature row at lower blowing ratios and the opposite at higher ones. The low curvature row had similar performance to the flat plate row at lower blowing ratios, suggesting the mild convex curvature had little beneficial effect. At higher blowing ratios, the low curvature row had inferior performance, which was attributed to the local freestream adverse pressure gradient that generated additional turbulence, promoting jet-to-mainstream mixing and decreasing performance.

Analysis of heat transfer and fluid flow of a slot jet impinging on a confined concave surface with various curvature and small jet to target spacing

2019 ◽  
Vol 29 (8) ◽  
pp. 2885-2910 ◽  
Author(s):  
Dandan Qiu ◽  
Lei Luo ◽  
Songtao Wang ◽  
Bengt Ake Sunden ◽  
Xinhong Zhang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Thermal Performance ◽  
Flow Characteristics ◽  
Target Surface ◽  
Surface Curvature ◽  
Content Type ◽  
Curvature Effects ◽  
Target Spacing

Purpose This study aims to focus on the surface curvature, jet to target spacing and jet Reynolds number effects on the heat transfer and fluid flow characteristics of a slot jet impinging on a confined concave target surface at constant jet to target spacing. Design/methodology/approach Numerical simulations are used in this research. Jet to target spacing, H/B is varying from 1.0 to 2.2, B is the slot width. The jet Reynolds number, Rej, varies from 8,000 to 40,000, and the surface curvature, R2/B, varies from 4 to 20. Results of the target surface heat transfer, flow parameters and fluid flow in the concave channel are performed. Findings It is found that an obvious backflow occurs near the upper wall. Both the local and averaged Nusselt numbers considered in the defined region respond positively to the Rej. The surface curvature plays a positive role in increasing the averaged Nusselt number for smaller surface curvature (4-15) but affects little as the surface curvature is large enough (> 15). The thermal performance is larger for smaller surface curvature and changes little as the surface curvature is larger than 15. The jet to target spacing shows a negative effect in heat transfer enhancement and thermal performance. Originality/value The surface curvature effects are conducted by verifying the concave surface with constant jet size. The flow characteristics are first obtained for the confined impingement cases. Then confined and unconfined slot jet impingements are compared. An ineffective point for surface curvature effects on heat transfer and thermal performance is obtained.

scholarly journals Isolating curvature effects in computing wall-bounded turbulent flows

2001 ◽  
Vol 22 (6) ◽  
pp. 573-582 ◽  
Author(s):  
Christopher L. Rumsey ◽  
Thomas B. Gatski ◽  
W. Kyle Anderson ◽  
Eric J. Nielsen
Keyword(s):  
Turbulent Flows ◽  
Curvature Effects

Numerical Investigation of Surface Curvature Effects on Aerofoil Aerodynamic Performance

2015 ◽  
Vol 798 ◽  
pp. 589-595 ◽  
Author(s):  
Xiang Shen ◽  
Theodosios Korakianitis ◽  
Eldad Avital
Keyword(s):  
Separation Bubble ◽  
Circle Method ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Aerodynamic Performance ◽  
Surface Curvature ◽  
Operating Conditions ◽  
Curvature Effects ◽  
Curvature Continuity ◽  
Curvature Distribution

The prescribed surface curvature distribution blade design (CIRCLE) method optimises aerofoils and blades by controlling curvature continuity and slope of curvature distribution along their surfaces. The symmetrical NACA0012 exhibits a surface curvature discontinuity at the leading edge point, and the non-symmetrical E387 exhibits slope-of-curvature discontinuities in the surface. The CIRCLE method is applied to both aerofoils to remove both surface curvature and slope-of-curvature discontinuities. Computational fluid dynamics analyses are used to investigate the curvature effects on aerodynamic performance of the original and modified aerofoils. These results are compared with experimental data obtained from tests on the original aerofoil geometry. The computed aerodynamic advantages of the modified aerofoil are analysed in different operating conditions. The leading edge singularity of NACA0012 is removed and it is shown that the surface curvature discontinuity affects the aerodynamic performance near the stalling angle of attack. The discontinuous slope-of-curvature distribution of E387 influences the size of the laminar separation bubble at lower Reynolds numbers, and it affects the inherent profile of the aerofoil at higher Reynolds numbers. It is concluded that the surface curvature distribution of aerofoils has a significant effect on aerofoil aerodynamic performance, which can be improved by redesigning the surface curvature distribution of the original aerofoil geometry.

CFD Analysis of the Twin Inclined Injection Flows in an Axi-Symmetric Duct along with Main Turbulent Flow

2014 ◽  
Vol 592-594 ◽  
pp. 1897-1902
Author(s):  
Debajit Saha ◽  
Snehamoy Majumder
Keyword(s):  
Turbulent Flows ◽  
Velocity Variation ◽  
Angle Variation ◽  
Bulk Fluid ◽  
Circular Duct ◽  
Injection Angle ◽  
Curvature Effects ◽  
Mass Injection ◽  
Secondary Injection ◽  
The Impact

A numerical simulation has been carried out to study the effects of twin inclined side mass injection with cross flow through a circular duct using modified model, considering streamline curvature effects by modifying the model constants. 1/7th turbulent velocity profile has been taken at the inlet. The effects of side mass injection on the flow pattern of the main bulk fluid and the mixing of two mutually cross turbulent flows have been studied in details. The formation of recirculatory flow has been visualized by varying the primary as well as secondary injection angle. With the variation of the injection angle axial velocity profiles at various locations and the centerline velocity variation along the duct have been studied. It has been observed that the impact of primary injection angle variation on the recirculation size is more than the secondary injection angle variation.

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