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.

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.

scholarly journals The Effect of Bulk Flow Pulsations on Film Cooling From Two Rows of Holes

1997 ◽  
Author(s):  
Dong Kee Sohn ◽  
Joon Sik Lee
Keyword(s):  
Boundary Layer ◽  
Film Cooling ◽  
Free Stream ◽  
Bulk Flow ◽  
Phase Lag ◽  
Cooling Effectiveness ◽  
Freestream Velocity ◽  
Film Cooling Effectiveness ◽  
Temperature Distributions ◽  
Flow Pulsations

Effect of bulk flow pulsations on film cooling from two rows of holes with inline and staggered arrangements is experimentally investigated. As a baseline study, a single row injection is also tested. Two-row injection is important because the phase lag between the two rows may cause changes in the film coolant coverage. Potential flow pulsations are generated by the rotating shutter mechanism attached downstream of the test section. Free-stream Strouhal number based on the boundary layer thickness is in the range of 0.033–0.33, and the amplitude of the phase-averaged freestream velocity due to static pressure variation about 10–20% Both the time-averaged and phase-averaged temperature distributions in the cross-sectional plane of the boundary layer are presented for four different pulsation frequencies of 0, 4, 20 and 40 Hz. Film cooling effectiveness is evaluated from the adiabatic wall temperature distributions, with time-averaged temperature measurements showing rapid diffusion of the injectant due to the free-stream pulsations. Effect of the phase lag between two rows is evidenced from the phase-averaged measurements, particularly in the case of staggered hole arrangement. All film cooling effectiveness distributions are reduced compared to no-pulsation case. Effect of pulsations appears dominantly in the case of the two-row staggered arrangement which shows more than 35% reduction in the film cooling effectiveness.

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.

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.

The Effect of High Free-Stream Turbulence on Film Cooling Effectiveness

1996 ◽  
Vol 118 (4) ◽  
pp. 814-825 ◽  
Author(s):  
J. P. Bons ◽  
C. D. MacArthur ◽  
R. B. Rivir
Keyword(s):  
Film Cooling ◽  
Free Stream ◽  
Density Ratio ◽  
Constant Density ◽  
Injection Hole ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Free Stream Turbulence

This study investigated the adiabatic wall cooling effectiveness of a single row of film cooling holes injecting into a turbulent flat plate boundary layer below a turbulent, zero pressure gradient free stream. Levels of free-stream turbulence (Tu) up to 17.4 percent were generated using a method that simulates conditions at a gas turbine combustor exit. Film cooling was injected from a single row of five 35 deg slant-hole injectors (length/diameter = 3.5, pitch/diameter = 3.0) at blowing ratios from 0.55 to 1.85 and at a nearly constant density ratio (coolant density/free-stream density) of 0.95. Film cooling effectiveness data are presented for Tu levels ranging from 0.9 to 17 percent at a constant free-stream Reynolds number based on injection hole diameter of 19,000. Results show that elevated levels of free-stream turbulence reduce film cooling effectiveness by up to 70 percent in the region directly downstream of the injection hole due to enhanced mixing. At the same time, high free-stream turbulence also produces a 50–100 percent increase in film cooling effectiveness in the region between injection holes. This is due to accelerated spanwise diffusion of the cooling fluid, which also produces an earlier merger of the coolant jets from adjacent holes.

Film Cooling Effectiveness on a Rotating Turbine Platform Using Pressure Sensitive Paint Technique

2007 ◽  
Author(s):  
A. Suryanarayanan ◽  
B. Ozturk ◽  
M. T. Schobeiri ◽  
J. C. Han
Keyword(s):  
Film Cooling ◽  
Gas Injection ◽  
Turbine Rotor ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Coolant Injection ◽  
Purge Flow ◽  
Effects Of Rotation

Film cooling effectiveness is measured on a rotating turbine blade platform for coolant injection through discrete holes using pressure sensitive paint technique (PSP). Most of the existing literatures provide information only for stationary end-walls. The effects of rotation on the platform film cooling effectiveness are not well documented. Hence, the existing 3-stage turbine research facility at TPFL, Texas A&M University was re-designed and installed to enable coolant gas injection on the 1st stage rotor platform. Two distinct coolant supply loops were incorporated into the rotor to facilitate separate feeds for upstream cooling using stator-rotor gap purge flow and downstream discrete-hole film cooling. As a continuation of the previously published work involving stator-rotor gap purge cooling, this study investigates film cooling effectiveness on the 1st stage rotor platform due to coolant gas injection through nine discrete holes located downstream within the passage region. Film cooling effectiveness is measured for turbine rotor frequencies of 2400rpm, 2550rpm and 3000rpm corresponding to rotation numbers of Ro = 0.18, 0.19 and 0.23 respectively. For each of the turbine rotational frequencies, film cooling effectiveness is determined for average film-hole blowing ratios of Mholes = 0.5, 0.75, 1.0, 1.25, 1.5 and 2.0. To provide a complete picture of hub cooling under rotating conditions, simultaneous injection of coolant gas through upstream stator-rotor purge gap and downstream discrete film-hole is also studied. The combined tests are conducted for gap purge flow corresponding to coolant to mainstream mass flow ratio of MFR = 1% with three downstream film-hole blowing ratios of Mholes = 0.75, 1.0 and 1.25 for each of the three turbine speeds. The results for combined upstream stator-rotor gap purge flow and downstream discrete holes provide information about the optimum purge flow coolant mass, average coolant hole blowing ratios for each rotational speed and coolant injection location along the passage to obtain efficient platform film cooling.

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.

Flow Dynamics and Film Cooling Effectiveness on a Non-Axisymmetric Contour Endwall in a Two-Dimensional Cascade Passage

2009 ◽  
Author(s):  
Gazi I. Mahmood ◽  
Ross Gustafson ◽  
Sumanta Acharya
Keyword(s):  
Temperature Field ◽  
Flow Field ◽  
Film Cooling ◽  
Free Stream ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Blowing Ratio

The measured flow field and temperature field near a three-dimensional asymmetric contour endwall employed in a linear blade cascade are presented with and without film-cooling flow on the endwall. Flow field temperature and Nusselt number distributions along the asymmetric endwall with wall heating and no film-cooling flow are also reported to show local high heat transfer region on the endwall and justify the locations of the coolant holes. Adiabatic film-cooling effectiveness along the endwall is then measured to indicate the local effects of the coolant jets. The near endwall flow field and temperature field provide the coolant flow behavior and the interaction of coolant jets with the boundary layer flow. Thus, the local film-cooling effectiveness can be explained with the coolant jet trajectories. The measurements are obtained at the Reynolds number of 2.30×105 based on blade actual chord and inlet velocity, coolant-to-free stream temperature ratio of 0.93, and coolant-to-free stream density ratio of 1.06. The cascade employs the hub side blade section and passage geometry of the first stage rotor of GE-E3 turbine engine. The contour endwall profile is employed on the bottom endwall only in the cascade. The blowing ratio of the film-cooling flow varies from 1.0 to 2.4 from 71 discrete cylindrical holes located in the contour endwall. The three-dimensional profile of the endwall varies in height in both the pitchwise and axial directions. The flow field is quantified with the streamwise vorticity and turbulent intensity, pitchwise static pressure difference, flow yaw angle, and pitchwise velocity. Both the flow field and temperature data indicate that the coolant jets cover more distance in the pitchwise and axial direction in the passage as the blowing ratio increases. Thus, the local and average film-cooling effectiveness increase with the blowing ratio.

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