SCALING PARAMETERS IN FILM-COOLING

1986 ◽  
Author(s):  
C.J.P. Forth ◽  
T. V. Jones
Keyword(s):  
Film Cooling ◽  
Scaling Parameters

Film Cooling Using Antikidney Vortex Pairs: Effect of Blowing Conditions and Yaw Angle on Cooling and Losses

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Lars Gräf ◽  
Leonhard Kleiser
Keyword(s):  
Film Cooling ◽  
Vortex Pair ◽  
Diffusion Region ◽  
Jet Interaction ◽  
Physical Mechanisms ◽  
Large Eddy ◽  
Scaling Parameters ◽  
Cooling Hole ◽  
Single Jet ◽  
Yaw Angle

A film-cooling configuration generating an antikidney vortex pair is studied. The configuration features cylindrical cooling holes inclined at an angle of α=35  deg and arranged in two spanwise rows with row-wise alternating yaw angles ±β. Results of several large-eddy simulations are presented with varying blowing conditions and yaw angles. The effects on the achieved cooling and the generated losses are studied. The film-cooling Reynolds number (based on the fully turbulent hot boundary layer along a flat plate and the cooling hole diameter) is 6570 and the Mach number is 0.2. The density as well as mass-flux ratios (DR and M) range from 1 to 2 and the yaw angles from β=±30  deg to ±60  deg. We identify scaling parameters and explain relevant mechanisms. Moreover, the flow field is subdivided into three regions featuring different physical mechanisms: the single-jet, the jet-interaction, and the diffusion region. A strong antikidney vortex pair occurs for high momentum ratios I. For the highest ratio, I = 2.3, our configuration may provide even better effectiveness than cooling with particular fan-shaped holes.

Conjugate Scaling in the Presence of Bore Cooling

2015 ◽  
Author(s):  
Thomas E. Dyson ◽  
James R. Winka ◽  
David B. Helmer
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Numerical Study ◽  
Additional Parameter ◽  
Scaling Parameters ◽  
Engine Components ◽  
The Heat Transfer Coefficient ◽  
Conductivity Models

Many analyses in the literature have assessed the appropriate manner in which to scale an experimental test rig to represent film-cooled engine components. For conventional testing using low conductivity models, the key parameters are the mainstream Reynolds number, scaled coolant flow rate, and the adiabatic film effectiveness. The few studies that have sought scaling parameters for conjugate testing have identified that one must additionally match the heat transfer coefficient ratio between the internal and external surfaces and external Biot number. However, these analyses have focused on blade or nozzle regions with single or sparse film rows. The validity of this scaling approach to regions or components with substantial bore cooling contributions is unclear — for example the showerhead and/or platform of a blade or nozzle, or a component like a shroud. The present analysis outlines the drivers for potential departure from the accepted scaling. A numerical study is performed to assess potential errors due to the traditional scaling. The results of the analysis demonstrate that the additional parameter, the ratio of bore cooling to external heat transfer coefficient, is more appropriate in the near hole region especially in cases where film cooling is not significant.

Experimental Investigation of Coolant-to-Mainstream Scaling Parameters With Cylindrical and Shaped Film Cooling Holes

2015 ◽  
Author(s):  
Joshua B. Anderson ◽  
Emily J. Boyd ◽  
David G. Bogard
Keyword(s):  
Film Cooling ◽  
Velocity Ratio ◽  
Density Ratio ◽  
Flux Ratio ◽  
Experimental Film ◽  
Single Row ◽  
Blowing Ratio ◽  
Scaling Parameters ◽  
Dimensional Parameters ◽  
Adiabatic Effectiveness

The performance of film cooling designs is typically quantified by the adiabatic effectiveness, with results presented in terms of non-dimensional parameters such as the blowing ratio, momentum flux ratio, or velocity ratio of the coolant to the overflowing mainstream gas. In order to appropriately model experimental film cooling designs, the correct coolant flow parameter should be selected. In this work, a single row of axial round holes and shaped holes were placed in a flat plate and tested within a recirculating wind tunnel at low speeds and temperatures. Mainstream turbulence intensity and boundary layer thickness were set similar to expected engine conditions. The density ratio of the coolant was varied from 1.2 to 1.6 in order to independently vary the parameters listed above, which were tested at six different conditions for each density ratio. High-resolution IR thermography was used to measure adiabatic effectiveness downstream of the single row of cooling holes. The results indicate that adiabatic effectiveness performance of cylindrical and shaped holes are scaled most effectively using velocity ratio, providing much more accurate results then when the blowing ratio is used.

IMPROVING ADIABATIC FILM-COOLING EFFECTIVENESS BY USING AN UPSTREAM PYRAMID

2016 ◽  
Vol 8 (2) ◽  
pp. 135-146 ◽  
Author(s):  
Zineb Hammami ◽  
Zineddine Ahmed Dellil ◽  
Fadela Nemdili ◽  
Abbes Azzi
Keyword(s):  
Film Cooling ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness

EFFECTIVENESS OF GASEOUS FILM COOLING IN ROCKET NOZZLES

2016 ◽  
Vol 7 (3-4) ◽  
pp. 235-249
Author(s):  
Shri Nidhi ◽  
Bhat K. Nishchith ◽  
S. R. Shine
Keyword(s):  
Film Cooling
Sign in / Sign up

Export Citation Format

Share Document