Experimental and Numerical Investigations of Effects of Flow Control Devices Upon Flat-Plate Film Cooling Performance

2013 ◽  
Author(s):  
Hirokazu Kawabata ◽  
Ken-ichi Funazaki ◽  
Ryota Nakata ◽  
Daichi Takahashi
Keyword(s):  
Flow Field ◽  
Flow Control ◽  
Flat Plate ◽  
Vortex Structure ◽  
Film Cooling ◽  
Pressure Probe ◽  
Cooling Performance ◽  
Flow Control Devices ◽  
Cooling Hole ◽  
Control Devices

This study deals with the experimental and numerical studies of the effect of flow control devices (FCDs) on the film cooling performance of a circular cooling hole on a flat plate. Two types of FCDs with different heights are examined in this study, where each of them is mounted to the flat plate upstream of the cooling hole by changing its lateral position with respect to the hole centerline. In order to measure the film effectiveness as well as heat transfer downstream of the cooling hole with upstream FCD, a transient method using a high-resolution infrared camera is adopted. The velocity field downstream of the cooling hole is captured by 3D Laser Doppler Velocimeter (LDV). Furthermore, the aerodynamic loss associated with the cooling hole with/without FCD is measured by a total pressure probe rake. The experiments are carried out at blowing ratios ranging from 0.5 to 1.0. In addition, numerical simulations are also made to have a better understanding of the flow field. LES approach is employed to solve the flow field and visualize the vortex structure around the cooling hole with FCD. When a higher FCD is mounted to the plate, the film effectiveness tends to increase due to the vortex structure generated by the FCD. As FCD is laterally shifted from the centerline, the film effectiveness increases, while the lift-off of cooling air is also promoted when FCD is put on the center line.

Experimental and Numerical Investigations of Effects of Flow Control Devices Upon Flat-Plate Film Cooling Performance

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Hirokazu Kawabata ◽  
Ken-ichi Funazaki ◽  
Ryota Nakata ◽  
Daichi Takahashi
Keyword(s):  
Flow Field ◽  
Flow Control ◽  
Flat Plate ◽  
Vortex Structure ◽  
Film Cooling ◽  
Pressure Probe ◽  
Cooling Performance ◽  
Flow Control Devices ◽  
Cooling Hole ◽  
Control Devices

This study deals with the experimental and numerical studies of the effect of flow control devices (FCDs) on the film cooling performance of a circular cooling hole on a flat plate. Two types of FCDs with different heights are examined in this study, where each of them is mounted to the flat plate upstream of the cooling hole by changing its lateral position with respect to the hole centerline. In order to measure the film effectiveness as well as heat transfer downstream of the cooling hole with upstream FCD, a transient method using a high-resolution infrared camera is adopted. The velocity field downstream of the cooling hole is captured by 3D laser Doppler velocimeter (LDV). Furthermore, the aerodynamic loss associated with the cooling hole with/without FCD is measured by a total pressure probe rake. The experiments are carried out at blowing ratios ranging from 0.5 to 1.0. In addition, numerical simulations are also made to have a better understanding of the flow field. LES approach is employed to solve the flow field and visualize the vortex structure around the cooling hole with FCD. When a taller FCD is mounted to the plate, the film effectiveness tends to increase due to the vortex structure generated by the FCD. As FCD is laterally shifted from the centerline, the film effectiveness increases, while the lift-off of cooling air is also promoted when FCD is put on the center line.

Improvement of Flat-Plate Film Cooling Performance by Double Flow Control Devices: Part I — Investigations on Capability of a Base-Type Device

2014 ◽  
Author(s):  
Ken-ichi Funazaki ◽  
Ryota Nakata ◽  
Hirokazu Kawabata ◽  
Hisato Tagawa ◽  
Yasuhiro Horiuchi
Keyword(s):  
Flow Control ◽  
Flat Plate ◽  
Film Cooling ◽  
Laser Doppler Velocimeter ◽  
Pressure Probe ◽  
Cooling Performance ◽  
Flow Control Devices ◽  
Type Device ◽  
Cooling Hole ◽  
Control Devices

This paper deals with effects of double flow control devices (DFCDs) on flat plate film cooling performance. Aiming for further improvement of film effectiveness of discrete cooling holes, this new type of controlling method is invented and recently patented by the authors. The performance of base-type DFCDs, installed just upstream of cooling holes with conventional round or fan-shaped exits, is thoroughly investigated and reported in this study. Effects of the hole pitch are examined. Three hole-pitch cases, 3.0d, 4.5 d and 6.0 d are examined in this study to explore a possibility of reducing the cooling air by the application of DFCDs, where d is a hole diameter. In order to investigate the film effectiveness, a transient method using a high-resolution infrared camera is adopted. At the downstream of the cooling hole, the time-averaged temperature field is captured by a thermocouple rake and the time-averaged velocity field is captured by 3D Laser Doppler Velocimeter (LDV), respectively. Furthermore, the aerodynamic loss characteristics of the cooling hole with and without DFCDs are measured by a total pressure probe rake. The experiments are carried out for two blowing ratios, 0.5 and 1.0. It is found that DFCDs are quite effective in increasing the film effectiveness not only for round but also the fan-shaped holes. Starting from the base-type device, a robust optimization using Taguchi Method has been made by the present authors and will be reported as Part II.

Enhancement of Film Effectiveness of Cooling Holes With Fan-Shaped Exit Geometry by the Application of Double Flow-Control Devices: Optimization in Consideration of Device Offset

2017 ◽  
Author(s):  
Ken-ichi Funazaki
Keyword(s):  
Taguchi Method ◽  
Flow Control ◽  
State University ◽  
Ir Camera ◽  
Cooling Performance ◽  
Flow Control Devices ◽  
Penn State ◽  
Cooling Hole ◽  
Shaped Hole ◽  
Control Devices

This study deals with CFD-based optimization of Double Flow Control Devices (DFCDs); a patented technology for enhancing film effectiveness using Taguchi method as a robust optimizing technique. This study adopts offset of the devices with respect to the centerline of the hole, which may happen in the manufacturing process, as a noise factor in the optimizing process. The aim of this study is to explore a possibility of DFCDs to improve the cooling performance of a sophisticated fan-shaped cooling hole called 7-7-7 shaped hole developed by Penn State University [9]. Aerodynamic and thermal performances of the optimized DFCD model were evaluated through the detailed experiments using IR camera and temperature rake.

Improvement of film cooling performance by flow control devices

2018 ◽  
Vol 2018 (0) ◽  
pp. OS8-10
Author(s):  
Tomohiro KAWAMURA ◽  
Ken-ichi FUNAZAKI ◽  
Suzuna SAITO
Keyword(s):  
Flow Control ◽  
Film Cooling ◽  
Cooling Performance ◽  
Flow Control Devices ◽  
Control Devices

Improvement of Turbine Vane Film Cooling Performance by Double Flow-Control Devices

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Hirokazu Kawabata ◽  
Ken-ichi Funazaki ◽  
Yuya Suzuki ◽  
Hisato Tagawa ◽  
Yasuhiro Horiuchi
Keyword(s):  
Flow Control ◽  
Film Cooling ◽  
Test Facility ◽  
Rans Simulation ◽  
Flow Control Devices ◽  
Turbine Vane ◽  
Cooling Hole ◽  
Control Devices ◽  
Secondary Air ◽  
Lift Off

This study deals with the studies of the effect of double flow-control devices (DFCDs) on turbine vane film cooling. Aiming for improving film effectiveness, two semispheroid DFCDs per pitch were attached to the vane surface upstream of the cooling hole. Although the DFCDs were successfully applied to the flat-plate film cooling in the previous study, the applicability to the turbine vane was to be investigated. In order to observe the flow field in detail, Reynolds-averaged Navier–Stokes (RANS) simulation was conducted first. The DFCDs were installed upstream of each cooling hole of the pressure and suction sides of the vane to investigate the effect of the device position. In this paper, the effects of blowing ratio and cooling hole pitch were also investigated. The results obtained by CFD showed that the vortex generated from DFCD suppressed lift-off of the secondary air. As a result, the film effectiveness became significantly higher than that without DFCD condition. Moreover, the improvement in the film effectiveness by DFCD was observed by both of the pressure and suction sides of the turbine vane. Based on the findings through RANS simulation, adiabatic effectiveness and total pressure loss coefficient measurement were performed in a linear cascade test facility. The experiment confirmed that the film effectiveness was improved when DFCDs existed.

An Experimental Investigation of an Anti-Vortex Film Cooling Geometry Under Low and High Turbulence Conditions

2012 ◽  
Author(s):  
Sebastian Schulz ◽  
Simon Maier ◽  
Jeffrey P. Bons
Keyword(s):  
Flat Plate ◽  
Secondary Flow ◽  
Infrared Thermography ◽  
Film Cooling ◽  
Streamwise Direction ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
High Turbulence

In an attempt to abate the detrimental jet vorticity and lift-off effects at high blowing ratios, the objective of the present study is to investigate the impact of an anti-vortex film cooling hole design on the film cooling effectiveness and the secondary flow field. Furthermore, the influence of low and high turbulence levels is studied with Tu ≈ .0.7% and ≈ 10%, respectively. For the experiments infrared thermography and particle image velocimetry (PIV) are employed. The experiments are conducted in a subsonic wind tunnel at a Reynolds number of 11000 based on the film cooling hole diameter. A flat plate model with an array of three cylindrical primary holes with secondary offshoots to each side represents the anti-vortex geometry. The cylindrical hole arrangement with a diameter of 17.5 mm is inclined at 30° in streamwise direction, with the anti-vortex holes branching off from the primary hole base in a 21° angle. Information from a flat plate with six cylindrical holes of 17.5 mm in diameter inclined at 30 in streamwise direction is used as baseline for comparison. The primary hole spacing was 4.75 and 3 hole diameters, respectively. Results are presented for blowing ratios of 1 and 2 with a constant density ratio of 1.1. The PIV measurements are taken in two planes perpendicular to the flow direction to record the secondary flow structures. The results of the infrared thermography show a strong decrease in film cooling effectiveness as high turbulence levels occur, especially for low blowing ratios. For higher blowing ratios low and high turbulence levels have similar effects on film cooling effectiveness. A significant improvement in film cooling performance is displayed by the anti-vortex design over the standard circular hole arrangement for every blowing ratio. The effectiveness results reveal an improved lateral spreading of the coolant with coolant jets staying attached throughout the series of experiments. By remaining inside the boundary layer, the effects of a high turbulent freestream on film cooling performance is less. The PIV results unveil information of a new vortex pair on either side of the primary hole kidney vortex. Especially at high blowing ratios the results indicate, that the anti-vortex hole design promotes the interaction between the vortical structures, explaining the increased lateral film effectiveness results. The factor which lends to the superior performance and credibility of the studied anti-vortex design is that the results are obtained for 35% less mass flow than the baseline.

Experimental and Numerical Study on Effects of Turbulence Promoters on Flat Plate Film Cooling

2011 ◽  
Author(s):  
Eiji Sakai ◽  
Toshihiko Takahashi
Keyword(s):  
Flat Plate ◽  
Secondary Flow ◽  
Film Cooling ◽  
Numerical Study ◽  
Secondary Flows ◽  
Temperature Fields ◽  
Main Stream ◽  
Cooling Performance ◽  
Cooling Hole ◽  
Stream Lines

Turbulence promoters such as ribs inside turbine blade coolant channels are used to improve convective cooling but at the same time could influence external film cooling performance. The effects of rib orientation and rib position on film cooling performance are experimentally and numerically studied with a flat plate configuration in which external (main) flow and internal (secondary) flow are oriented perpendicular to each other. In the experiment, temperature fields are measured by thermo-couples varying blowing ratio at constant Reynolds number of main and secondary flows. To obtain detailed information about flow fields, Reynolds Averaged Navier Stokes (RANS) simulation and Detached Eddy Simulation (DES) are also performed using a commercial code Fluent. Temperature measured shows that rib orientation has a strong influence on film effectiveness. With forward-oriented ribs, higher film effectiveness is observed compared to the reference case without ribs. On the contrary with inverse-oriented ribs, lower film effectiveness is observed. The difference comes from the flow structure in the film cooling hole. With the forward-oriented ribs, straight stream lines are observed in the cooling hole, while with the inverse-oriented ribs, helical stream lines are observed. Due to the helical stream lines in the hole, ejection angle of the secondary flow to the main stream becomes large, resulting in so called lift-off and lower film effectiveness.

Numerical Evaluation of Surface Roughness Effects on Film-Cooling Performance in a Laidback Fan-Shaped Hole

2020 ◽  
Author(s):  
Ali Zamiri ◽  
Sung Jin You ◽  
Jin Taek Chung
Keyword(s):  
Surface Roughness ◽  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Roughness Height ◽  
Constant Density ◽  
Cooling Performance ◽  
Cooling Hole ◽  
Shaped Hole ◽  
Grain Roughness

Abstract This study numerically investigates the influences of cooling hole surface roughness in a laidback fan-shaped hole on the flow structure and film-cooling effectiveness. The three-dimensional compressible LES approach (large eddy simulation) is conducted in a baseline 7-7-7 laidback fan-shaped hole. The cooling hole is located on a flat plate surface with a 30-degree injection angle at a constant density ratio DR = 1.5 and two blowing ratios M = 1.5 and 3. The computational results were validated by the measurements in terms of velocity and thermal fields for both the smooth and rough holes. In order to numerically consider the influences of the surface roughness on cooling hole side, the equivalent sand grain roughness method was utilized. Different correlations between the equivalent sand grain roughness height and arithmetic average roughness height were numerically tested to find an accurate correlation in comparison to the measurements. The computational data revealed that the surface roughness of the hole interior walls increases the thickness of the boundary layers within the hole. This leads to a higher jet core flow at the hole exit and lower film-cooling performance at the surface of flat plate compared to those of the smooth cooling hole. The minimum area-averaged film-cooling performance was observed in the case of the highest blowing ratio and the largest surface roughness height. The present work reveals that the current LES approach by considering the proper equivalent sand grain roughness height is a powerful tool to obtain the accurate solution in the prediction of the heat transfer characteristics and the flow structures in the fan-shaped cooling holes.

Columnar vortex generator for flow control over a ski-jump ramp

2018 ◽  
Vol 28 (5) ◽  
pp. 1156-1168 ◽  
Author(s):  
Rafael Bardera ◽  
Marina León-Calero ◽  
Joaquín de Nova-Trigueros
Keyword(s):  
Flow Field ◽  
Flow Control ◽  
Vortex Generator ◽  
Geometrical Parameters ◽  
Recirculation Bubble ◽  
Content Type ◽  
Flow Configuration ◽  
Columnar Vortex ◽  
Flow Control Devices ◽  
Control Devices

Purpose Aircraft carriers are essential for modern naval operations. Takeoff maneuver is critical because of the short runway distance. The ski-jump ramp is a system which increases the angle of attack of the aircraft, so an extra lift is obtained. Regarding the flow configuration over the ski-jump ramp at ahead wind conditions, the complex aerodynamic environment generated by the ramp configuration influences aircraft operations. This flow field is mainly characterized by a low velocity recirculation bubble that reduces aircraft performances. The purpose of this paper is to find a solution to reduce these adverse effects, by means of flow control devices, which opens a wide field of research. Design/methodology/approach This paper presents wind tunnel tests performed to study the flow configuration in the vicinity of the ski-jump ramp and the flow control devices effects. A 1:100 scaled ship model was built to develop experimental tests by using flow control devices fabricated by means of additive manufacturing. Particle image velocimetry technique was used to measure the velocity flow field and the turbulence intensity maps. Findings Interesting results were obtained when the angle between the intersection of the ski-jump ramp and the columnar vortex generator (CVG) is modified. The results showed a high reduction of the recirculation bubble generated over the flight deck. Originality/value CVG has presented encouraging results as a passive flow control device. A study of the variation of CVG geometrical parameters has been developed.

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