Optimization of Trenched Film Cooling Using RSM Coupled CFD

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
V.G. Krishna Anand ◽  
K.M. Parammasivam
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Response Surfaces ◽  
Test Surface ◽  
Response Factor ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Flow Parameters ◽  
Considerable Impact ◽  
The Impact

AbstractThe 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.

Film Cooling From Novel Sister Shaped Single-Holes

2014 ◽  
Author(s):  
Siavash Khajehhasani ◽  
Bassam Jubran
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Lateral Spreading ◽  
Navier Stokes ◽  
The Novel ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Shaped Hole ◽  
Lift Off

A numerical investigation of the film cooling performance from novel sister shaped single-holes (SSSH) is presented in this paper and the obtained results are compared with a single cylindrical hole, a forward diffused shaped hole, as well as discrete sister holes. Three types of the novel sister shaped single-hole schemes namely downstream, upstream and up/downstream SSSH, are designed based on merging the discrete sister holes to the primary hole in order to reduce the jet lift-off effect and increase the lateral spreading of the coolant on the blade surface as well as a reduction in the amount of coolant in comparison with discrete sister holes. The simulations are performed using three-dimensional Reynolds-Averaged Navier Stokes analysis with the realizable k–ε model combined with the standard wall function. The upstream SSSH demonstrates similar film cooling performance to that of the forward diffused shaped hole for the low blowing ratio of 0.5. While it performs more efficiently at M = 1, where the centerline and laterally averaged effectiveness results improved by 70% and 17%, respectively. On the other hand, the downstream and up/downstream SSSH schemes show a considerable improvement in film cooling performance in terms of obtaining higher film cooling effectiveness and less jet lift-off effect as compared with the single cylindrical and forward diffused shaped holes for both blowing ratios of M = 0.5 and 1. For example, the laterally averaged effectiveness for the downstream SSSH configuration shows an improvement of approximately 57% and 110% on average as compared to the forward diffused shaped hole for blowing ratios of 0.5 and 1, respectively.

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.

Computational Investigation of Film Cooling from Cylindrical and Row Trenched Cooling Holes near the Combustor End Wall

2014 ◽  
Vol 554 ◽  
pp. 225-229 ◽  
Author(s):  
Nor Azwadi Che Sidik ◽  
Kianpour Ehsan
Keyword(s):  
Film Cooling ◽  
Surface Film ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Internal Cooling ◽  
Cooling Performance ◽  
Turbine Engine ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Three Dimensional Representation

This study was accomplished in order to investigate the effects of cylindrical and row trenched cooling holes with alignment angle of 0 degree and 90 degree at blowing ratio, BR = 3.18 on the film cooling performance adjacent to the endwall surface of a combustor simulator. In this research a three dimensional representation of Pratt and Whitney gas turbine engine was simulated and analyzed with a commercial finite volume package FLUENT 6.2. The current study has been performed with Reynolds-averaged Navier-Stokes turbulence model (RANS) on internal cooling passages. This combustor simulator combined the interaction of two rows of dilution jets, which were staggered in the stream wise direction and aligned in the span wise direction, with that of film cooling along the combustor liner walls. The findings of the study declared that with using the row trenched holes near the endwall surface, film cooling effectiveness is doubled compared to the cooling performance of baseline case.

Effect of Upstream Wake on Passage Flow and Tip Film Cooling Characteristics

2012 ◽  
Author(s):  
Jin Wang ◽  
Bengt Sundén ◽  
Min Zeng ◽  
Qiu-Wang Wang
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Tip Leakage Flow ◽  
Delta Wings ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Passage Vortex ◽  
Film Cooling Holes

Three-dimensional simulations of the squealer tip on the GE-E3 blade with eight film cooling holes were carried out. To form the wake by the trailing edges of the stator vanes, cylindrical rods and delta wings were placed upstream of the blades. The rods were placed according to three positions, and the influence on the film cooling effectiveness was calculated. Because delta wings were placed upstream of the blades to generate in the vane passage, the passage flow also was investigated. However, the passage vortex generated by the delta wings had a profound effect on the passage flow distribution. For the squealer tip, the cavity contributes to the improvement of the cooling effect in the tip zone. The passage flow and the tip leakage flow influenced by cylindrical rods and delta wings were analyzed using numerical simulations with the blowing ratio of M = 0.5. In addition, calculations with and without cylindrical rods and delta wings were performed and then comparisons were enabled. It was found that the vortex created by delta wings made the passage flow more turbulent and the result indicates a slight effect on the film cooling effectiveness in the tip gap.

Numerical Investigation of Scoop Effect on Film Cooling for Cylindrical Inclined Hole

2017 ◽  
Author(s):  
Yongbin Ji ◽  
Prashant Singh ◽  
Srinath V. Ekkad ◽  
Shusheng Zhang
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Diameter Ratio ◽  
Navier Stokes ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Sst Turbulence Model ◽  
Cooling Behavior ◽  
Length To Diameter Ratio

Film cooling behavior of a single cylindrical hole inclined at an angle of 35° with respect to a flat surface is numerically predicted in this study. Adiabatic film cooling effectiveness has been presented to evaluate the influence of the scoop placed on the coolant entry side. The effect of blowing ratio (0.65, 1, 1.5 and 2) and the length-to-diameter ratio (1.7 and 4.4) are examined. Three-dimensional Reynolds-averaged Navier-Stokes analysis with SST turbulence model is used for the computations. It has been found that both centerline and laterally averaged adiabatic film cooling effectiveness are enhanced by the scoop and the enhancement increases with the blowing ratio in the investigated range of variables. The scoop was more effective for the higher length-to-diameter ratio cases (L/D = 4.4) because of better velocity distribution at the film hole exit, which makes coolant reattach at a more upstream location after blowing off from the wall.

Numerical Study on the Influence of Hole Shape on Film Cooling Effectiveness

2013 ◽  
Vol 716 ◽  
pp. 699-704 ◽  
Author(s):  
Ping Dai ◽  
Nai Yun Yu
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Three Dimensional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Cylindrical Holes ◽  
Shaped Hole ◽  
Volume Method ◽  
Lateral Area

Effects of hole shapes on film cooling effectiveness downstream of one row of film holes at the blade were investigated using a three-dimensional finite volume method and multi-block technique. The present study also received velocity vectors about different hole shapes. The hole geometries studied include standard cylindrical hole and forward diffused shaped hole and converging slot-hole. It was found that the film cooling effectiveness of cylindrical holes obviously declined along with increasing the blowing ratio. Results of the shaped holes configuration present a marked improvement, with a high effectiveness at the lateral area between adjacent holes and effectiveness of the converging slot-hole was superior to other holes in various blowing ratios. The film cooling effectiveness realized by the slot-holes compared to the cylindrical and forward diffused shaped holes was more excelled at downstream of the intersection of the two slot-holes. The converging slot-hole and forward diffused shaped hole can reduce the vortex intensity, and then enhance the film cooling effectiveness.

Analyzes of Film Cooling from Cylindrical and Row Trenched Holes with Alignment Angle of 90 Degrees at Low Blowing Ratio

2014 ◽  
Vol 695 ◽  
pp. 376-379 ◽  
Author(s):  
Kianpour Ehsan ◽  
Nor Azwadi Che Sidik
Keyword(s):  
Film Cooling ◽  
Surface Film ◽  
Three Dimensional ◽  
Internal Cooling ◽  
Wall Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Alignment Angle ◽  
End Wall

The current study was conducted to analyze the effects of cylindrical and row trenched cooling holes with alignment angle of 90 degrees at blowing ratio, BR = 1.25 on the film cooling effectiveness near the end wall surface of a combustor simulator. In the current research a three dimensional representation of Pratt and Whitney gas turbine engine was simulated and analyzed with a commercial finite volume package FLUENT 6.2.26. This study has been performed with Reynolds-averaged Navier-Stokes turbulence model (RANS) on internal cooling passages. This combustor simulator combined the interaction of two rows of dilution jets, which were staggered in the stream wise direction and aligned in the span wise arrangement, with that of film cooling along the combustor liner walls. The findings of the study declared that with using the row trenched holes near the end wall surface, film cooling effectiveness is increased three times compared to the cooling performance of baseline case.

scholarly journals Improving the Film Cooling of a Rotor Blade Platform

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Giovanna Barigozzi ◽  
Antonio Perdichizzi ◽  
Roberto Abram
Keyword(s):  
Film Cooling ◽  
Rotor Blade ◽  
Thermal Protection ◽  
Secondary Flows ◽  
Thermal Tests ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Purge Flow ◽  
Cylindrical Holes ◽  
The Impact

This paper shows the results of an experimental activity developed in cooperation between Ansaldo Energia and the Department of Engineering and Applied Science of Bergamo University with the aim of assessing the impact of newly designed holes on the thermal protection of a rotor blade platform. The original rotor blade platform featured ten cylindrical holes located along the blade pressure side (PS). Moreover, the channel front side was cooled exploiting the seal purge flow exiting the stator to rotor interface gap. The front midchannel, and particularly the region around the interplatform gap, remained uncooled. To protect this region, two sets of cylindrical holes were designed and manufactured on a seven blade cascade model for experimental verification. Aerodynamic and thermal tests were carried out at low Mach number. To evaluate the interaction of injected flow with secondary flows a five hole probe was traversed downstream of the trailing edge plane. The thermal behavior was analyzed by using thermochromic liquid crystals technique, so to obtain film cooling effectiveness distributions. The seven-hole configuration coupled with a low blowing ratio of about 1.0 provided the best thermal protection without any impact on the aerodynamic performance.

Effect of Stagnation Regions on Film Cooling Effectiveness

2007 ◽  
Author(s):  
S. Rodri´guez ◽  
S. Kersten ◽  
H. A. Zuniga ◽  
J. C. Ling ◽  
J. S. Kapat
Keyword(s):  
Film Cooling ◽  
Diameter Ratio ◽  
Constant Density ◽  
Injection Point ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Blowing Ratio ◽  
Cylindrical Holes ◽  
The Impact

Over the last decades, researchers have investigated many aspects of film cooling. The present study investigates the impact of stagnation region created by a downstream airfoil on endwall film cooling effectiveness. Experimental measurements are presented for a single row of cylindrical holes inclined at 35° with hole length to diameter ratio, L/D = 7.5, pitch to diameter ratio, PI/D = 3 with a constant density ratio of 1.26 and with nitrogen as the coolant. Five different configurations were studied. Configuration 0 is the baseline, this configuration consist of a single row of cylindrical holes. Configuration I-III consisted of an airfoil positioned downstream of the injection point at x/D = 6.4, 12.7 and 25.4. The presence of wake is also investigated on configuration IV. This configuration in addition to the airfoil, also has a wake plate at x/D = −12.7, upstream of the injection location. The experimental data shows that slightly higher averaged effectiveness values are observed for configuration I for low blowing ratios. Configuration III average effectiveness is higher for mid and high blowing ratios. For all configurations, the average effectiveness increase with increasing blowing ratio at a x/D further downstream of the injection point where the jet has reattached. Higher blowing ratio increase lateral spreading of the jet promoting jet to jet interaction and mainstream interaction enhancing mixing.

scholarly journals Experimental investigation of geometrical effect on flow and heat transfer performance of lamilloy cooling structure

2020 ◽  
Vol 24 (3 Part A) ◽  
pp. 1835-1843 ◽  
Author(s):  
Bo Zhang ◽  
Libing Lin ◽  
Naru Zhang ◽  
Shuangsong Xue ◽  
Honghu Ji
Keyword(s):  
Film Cooling ◽  
Heat Transfer Performance ◽  
Test Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Discharge Coefficients ◽  
Flow And Heat Transfer ◽  
Geometrical Effect ◽  
Variation Tendency

Effect of film hole diameter to discharge coefficients and film cooling effectiveness of the lamilloy were experimentally investigated at the blowing ratios ranging from 0.6 to 2.5. Generally, the cooling effectiveness on the test surface is increased with the film hole diameters and blowing ratios increasing, and the variation tendency along the streamwise through the centerline of film holes also keeps consistent. In the upstream, all configurations have a relatively lower cooling effectiveness, however, with the flows to the downstream, cooling effectiveness grows gradually, and the peak values of effectiveness appeared periodically, the position matches the film hole positions. Besides, between the film holes, fluctuation exists simultaneously. By comparison, the cooling effectiveness and discharge coefficients are both increased with the blowing ratio with same film hole diameters, Moreover, under the same blowing ratios, the cooling effectiveness and discharge coefficients are getting higher when hole diameters increase.

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