Abstract
The trench film cooling employs film holes embedded in a slot created on the surface that requires protection from the impact of hot mainstream flow. The present investigation employs Response Surface Methodology (RSM) approach coupled with CFD analysis to develop a regression predictive model and to optimize the trench geometric and flow parameters viz., trench width (w), trench depth (d), film hole compound angle (β) and blowing ratio (M). The Area-averaged film cooling effectiveness (ȠAA) were chosen as a response factor for RSM and with trench design and flow parameters used as input factors for regression analysis. Analysis of variance (ANOVA) analysis was carried out on the regression model to identify the influence of individual parameters. Three dimensional response surfaces that relate the effect of input parameters on the response factor were analyzed. Experimental results of a case identified from the RSM matrix was found to correlate well with computational investigations. Results from the study indicate that the parameters d, β and M have considerable impact on film cooling performance of test surface with trenches.
Nomenclature
- d
-
depth of trench,mm
- w
-
Width of trench, mm
- M
-
Blowing ratio
- D
-
Diameter of film hole, mm
- X/D
-
Non dimensional distance along mainstream direction
- Y/D
-
Non dimensional vertical distance from wall surface
- Z/D
-
Non dimensional lateral distance of test surface
- L
-
Length of film hole, mm
- T
-
Temperature of fluid/wall surface, k
- P
-
Film hole pitch distance, mm
- u
-
Velocity of air, m/sec
- SIMPLE
-
Semi implicit method for pressure linked equations
- FHCA
-
Film hole compound angle
- ANOVA
-
Analysis of variance
- PLC
-
Programmable logic controller
- Cp
-
Pressure coefficient
- RANS
-
Reynolds averaged navier stokes
- Greek symbols
- α
-
Inclination angle of film hole,°
- β
-
Orientation angle of film hole,°
- ρ
-
Density of air, kg/m3
- Ƞ
-
Film cooling effectiveness
-
-
Uncertainty in film cooling effectiveness
- Subscripts
- AA
-
Area averaged
- CL
-
Centerline
- c
-
coolant
- ∞
-
mainstream
- aw
-
Adiabatic wall
- Superscript
- _
-
Averaged film cooling effectiveness
Acknowledgements
The first author gratefully acknowledges Department of Science and Technology, Government of India for awarding DST INSPIRE Fellowship.
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