Film Cooling With Injection Through Holes: Adiabatic Wall Temperatures Downstream of a Circular Hole

1968 ◽  
Vol 90 (4) ◽  
pp. 384-393 ◽  
Author(s):  
R. J. Goldstein ◽  
E. R. G. Eckert ◽  
J. W. Ramsey
Keyword(s):  
Boundary Layer ◽  
Experimental Investigation ◽  
Turbulent Boundary Layer ◽  
Film Cooling ◽  
Main Flow ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Secondary Air ◽  
Secondary Fluid

An experimental investigation has been conducted to determine the film cooling effectiveness with injection of air through a discrete hole into a turbulent boundary layer of air on a flat plate. The secondary air enters at either an angle of 35 deg or an angle of 90 deg to the main flow. The film cooling effectiveness is found to be considerably different from that obtained in previous studies in which the secondary fluid was introduced through a continuous slot.

Effect of Streamline Curvature on Film Cooling

1977 ◽  
Vol 99 (1) ◽  
pp. 77-82 ◽  
Author(s):  
R. E. Mayle ◽  
F. C. Kopper ◽  
M. F. Blair ◽  
D. A. Bailey
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Film Cooling ◽  
Flat Surface ◽  
Temperature Measurements ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Streamline Curvature ◽  
Layer Velocity

The effects of streamline curvature on film cooling effectiveness are discussed. Experiments for air discharged through a slot and into a turbulent boundary layer along a flat, convex, and concave surface are described. Adiabatic wall effectiveness measurements on each surface for several blowing rates are presented. Boundary-layer velocity and temperature measurements are also presented for one of the blowing rates. Compared to the results for the flat surface, convex curvature is found to increase the adiabatic wall effectiveness whereas concave curvature is found to be detrimental.

Large Eddy Simulations on Fan Shaped Film Cooling Hole with Upstream Boundary Layer Turbulence Effect Generated by Trip Strip

2021 ◽  
pp. 1-37
Author(s):  
Young Seok Kang ◽  
Sangook Jun ◽  
Dong-Ho Rhee
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Film Cooling ◽  
Main Flow ◽  
Large Eddy Simulations ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Large Eddy ◽  
Cooling Hole

Abstract Large eddy simulations on the well-known 7-7-7 fan shaped cooling hole were carried out. Like using a trip strip to create turbulent boundary layer in practical experiments, trip strips with different configurations were placed upstream of the cooling hole to investigate incoming turbulent boundary layer effect on the film cooling flow behavior. Without the trip, horseshoe vortex generated by laminar boundary layer induced laterally discharging cooling flow in the lateral direction. Meanwhile, the induced cooling flow formed high film cooling effectiveness region around the film cooling hole. When the incoming boundary flow was turbulent, laterally discharged cooling flow was influenced by the turbulent boundary layer to dissipate to the main flow and resultant high effectiveness region disappeared. Depending on the trip configuration, quantitative characteristics of boundary layer such as turbulent intensity, momentum thickness and shape factor were strongly affected. Some trip configurations resulted in fully developed turbulent boundary layer just before leading edge of the film cooling hole. In such cases, distribution of the film cooling effectiveness showed a reasonable agreement with available experimental data where the quantitative properties of the turbulent boundary layer were similar. However, when the trip was located too close to the film cooling hole, the separated and reattached flow did not develop into the stabilized turbulent boundary layer. Then strong turbulence intensity in the main flow boundary layer stimulated break down of the cooling flow vortex structure and early dissipation to the main flow. It resulted in restricted film cooling flow coverage.

Adiabatic Wall Temperature and Heat Transfer Downstream of Injection Through Two Rows of Holes

1978 ◽  
Vol 100 (2) ◽  
pp. 303-307 ◽  
Author(s):  
M. Y. Jabbari ◽  
R. J. Goldstein
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Wall Temperature ◽  
Film Cooling ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
The Heat Transfer Coefficient

Results of an experimental investigation of film cooling and heat transfer following injection through two staggered rows of holes are reported. The two staggered rows are considerably more effective in protecting the wall than a single row. The film cooling effectiveness at locations beyond about 30-hole dia downstream of injection is laterally uniform. The heat transfer coefficient is within a few percent of that without injection at low blowing rates, but it increases rapidly as the blowing rate increases above unity.

Film-Cooling Effectiveness With Injection Through a Porous Section

1965 ◽  
Vol 87 (3) ◽  
pp. 353-359 ◽  
Author(s):  
R. J. Goldstein ◽  
G. Shavit ◽  
T. S. Chen
Keyword(s):  
Film Cooling ◽  
Free Stream ◽  
Stream Velocity ◽  
Temperature Profiles ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Secondary Air Injection ◽  
Layer Velocity ◽  
Secondary Air

An experimental study of the effectiveness of film cooling following secondary air injection through a porous section into a turbulent free stream is presented. Boundary-layer velocity and temperature profiles are described. The adiabatic wall temperatures are presented in terms of the film-cooling effectiveness. The effects of varying the secondary air temperature, the blowing rate, and the free-stream velocity are studied. It is found that the protection given to a surface downstream of a porous section through which air is injected compares favorably to earlier studies where the secondary air was injected nearly tangential to the surface.

scholarly journals Numerical investigation of heat transfer in film layer under supersonic condition of convergent-divergent transition

2020 ◽  
Vol 24 (3 Part B) ◽  
pp. 2279-2288
Author(s):  
Bo Zhang ◽  
Quan Hong ◽  
Yun Bai ◽  
Jiquan Li ◽  
Honghu Ji
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Main Flow ◽  
Oblique Shock Wave ◽  
Incline Angle ◽  
Local Cooling ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness

The distribution of film cooling effectiveness in supersonic mainstream of circle-rectangular Convergent-Divergent transition has been numerically investigated under different pressure ratios. The shock wave exerted superior influence on film cooling. In supersonic main flow, extra compression waves formed in upstream of the film holes, resulted by the obstruction of the multiple cooling jets. This exerted extra pressure to the boundary-layer, induced adverse pressure gradient, and led to weakening of the film flow attachment ability and decreasing of local cooling effectiveness. Bow oblique shock wave occurred in front of holes, the two oblique bow shaped low pressure zones formed on both sides of the hole, and low cooling effectiveness zones appeared accordingly. The inefficient region at the leading edge of the hole destroyed the film developing between holes, decreased the cooling effectiveness accumulation in the rear part. The decrease of hole incline angle caused an increase of cooling effectiveness, which reduced reverse velocity gradient caused by shock wave in the boundary-layer and improved film attachment. The influence of main flow pressure ratio to film cooling was also investigated, and found with increasing of the ratio, the influence will became even significant.

scholarly journals Large Eddy Simulations on Film Cooling Flow Behaviors with Upstream Turbulent Boundary Layer Generated by Circular Cylinder

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7227
Author(s):  
Young Seok Kang ◽  
Dong-Ho Rhee ◽  
Yu Jin Song ◽  
Jae Su Kwak
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Film Cooling ◽  
Measured Data ◽  
Large Eddy Simulations ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Large Eddy ◽  
Cooling Hole

Large eddy simulations on film cooling hole array on a flat plate was carried out to investigate upstream turbulence effect. Circular cylinders were configured to create a turbulent boundary layer and its diameter has been adjusted to generate 13% upstream turbulence intensity in the main flow. Due to the small pitch to diameter configuration of the cylinder, two-dimensional LES analysis was carried out in advance and the results showed that LES was an essential method to resolve flow field around and downstream circular cylinder, which was not available in RANS simulations. The three-dimensional LES results showed reasonable agreement in turbulence intensity and normalized velocity distributions along the vertical with measured data. According to the blowing ratio, the cooling flow coverage on the surface along the stream-wise direction was varied and well agreed with measured data. Additionally, upstream boundary flows were partially ingested inside the cooling hole and discharged again near along the centerline of the cooling hole. This accounted for film cooling effectiveness distribution inside the cooling hole surface and along the centerline. The current study revealed that the LES for predicting turbulent boundary layer behaviors due to upstream turbulence generation source was an effective and feasible method. Moreover, the LES effectively resolved flow fields such as film cooling flow behaviors and corresponding film cooling effectiveness distributions.

Film Cooling With Normal Injection Into a Supersonic Flow

1968 ◽  
Vol 90 (4) ◽  
pp. 584-588 ◽  
Author(s):  
R. J. Goldstein ◽  
E. R. G. Eckert ◽  
D. J. Wilson
Keyword(s):  
Boundary Layer ◽  
Film Cooling ◽  
High Speed ◽  
Incompressible Flows ◽  
Free Stream ◽  
Gas Injection ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Good Agreement

An experimental study of film cooling with subsonic gas injection into a mainstream with a Mach number of 2.90 is reported. Air, used as both the mainstream and secondary fluids, is injected normal to the surface of a flat plate through a short porous section into a two-dimensional turbulent boundary layer. The secondary fluid enters the boundary layer with a mass velocity which ranges from 0.0085 to 0.0223 of the free-stream value. The adiabatic wall temperatures are presented as the film-cooling effectiveness. The results of the present study, when the proper choice is made for the reference state used to account for fluid property variations across the high-speed boundary layer, are in good agreement with previous investigations in incompressible flows.

scholarly journals The Application of Adiabatic Film Cooling Effectiveness to Non-Adiabatic Blade Cooling Design

1983 ◽  
Author(s):  
C. P. Lee ◽  
J. C. Han
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Heat Transfer Analysis ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Transfer Parameter ◽  
Adiabatic Effectiveness ◽  
C 32 ◽  
Heat Transfer Parameter

The effect of heat transfer on film cooling has been studied analytically. The proposed model shows that the non-adiabatic film cooling effectiveness will increase with increasing of the heat transfer parameter, Ū / (ρVCp)2, on the convex, the flat and the concave walls over the entire range of film cooling parameter, X/MS. On the convex wall with a blowing rate, M, of 0.51 and a heat transfer parameter of 10−3 at the typical engine conditions, the non-adiabatic effectiveness can be higher than the adiabatic effectiveness by 45% at a film cooling parameter of 103; while the film temperature can be lower than the adiabatic wall by 18°C (32°F) at a dimensionless distance of 500. The model can be extended and applied to the heat transfer analysis for any kind of turbine blade with film cooling.

scholarly journals Adiabatic Wall Effectiveness Measurements of Film-Cooling Holes With Expanded Exits

1997 ◽  
Author(s):  
M. Gritsch ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Mach Number ◽  
Film Cooling ◽  
Thermal Protection ◽  
Lateral Spreading ◽  
Cylindrical Hole ◽  
Adiabatic Wall ◽  
Camera System ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole

This paper presents detailed measurements of the film-cooling effectiveness for three single, scaled-up film-cooling hole geometries. The hole geometries investigated include a cylindrical hole and two holes with a diffuser shaped exit portion (i.e. a fanshaped and a laidback fanshaped hole). The flow conditions considered are the crossflow Mach number at the hole entrance side (up to 0.6), the crossflow Mach number at the hole exit side (up to 1.2), and the blowing ratio (up to 2). The coolant-to-mainflow temperature ratio is kept constant at 0.54. The measurements are performed by means of an infrared camera system which provides a two-dimensional distribution of the film-cooling effectiveness in the nearfield of the cooling hole down to x/D = 10. As compared to the cylindrical hole, both expanded holes show significantly improved thermal protection of the surface downstream of the ejection location, particularly at high blowing ratios. The laidback fanshaped hole provides a better lateral spreading of the ejected coolant than the fanshaped hole which leads to higher laterally averaged film-cooling effectiveness. Coolant passage crossflow Mach number and orientation strongly affect the flowfield of the jet being ejected from the hole and, therefore, have an important impact on film-cooling performance.

Effects of Double Wall Cooling Configuration and Conditions on Performance of Full-Coverage Effusion Cooling

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Nathan Rogers ◽  
Zhong Ren ◽  
Warren Buzzard ◽  
Brian Sweeney ◽  
Nathan Tinker ◽  
...  
Keyword(s):  
Film Cooling ◽  
Cross Flow ◽  
Hole Array ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Full Coverage ◽  
Cooling Hole ◽  
Double Wall

Experimental results are presented for a double wall cooling arrangement which simulates a portion of a combustor liner of a gas turbine engine. The results are collected using a new experimental facility designed to test full-coverage film cooling and impingement cooling effectiveness using either cross flow, impingement, or a combination of both to supply the film cooling flow. The present experiment primarily deals with cross flow supplied full-coverage film cooling for a sparse film cooling hole array that has not been previously tested. Data are provided for turbulent film cooling, contraction ratio of 1, blowing ratios ranging from 2.7 to 7.5, coolant Reynolds numbers based on film cooling hole diameter of about 5000–20,000, and mainstream temperature step during transient tests of 14 °C. The film cooling hole array consists of a film cooling hole diameter of 6.4 mm with nondimensional streamwise (X/de) and spanwise (Y/de) film cooling hole spacing of 15 and 4, respectively. The film cooling holes are streamwise inclined at an angle of 25 deg with respect to the test plate surface and have adjacent streamwise rows staggered with respect to each other. Data illustrating the effects of blowing ratio on adiabatic film cooling effectiveness and heat transfer coefficient are presented. For the arrangement and conditions considered, heat transfer coefficients generally increase with streamwise development and increase with increasing blowing ratio. The adiabatic film cooling effectiveness is determined from measurements of adiabatic wall temperature, coolant stagnation temperature, and mainstream recovery temperature. The adiabatic wall temperature and the adiabatic film cooling effectiveness generally decrease and increase, respectively, with streamwise position, and generally decrease and increase, respectively, as blowing ratio becomes larger.

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