scholarly journals Influence of Internal Flow on Film Cooling Effectiveness

1999 ◽  
Author(s):  
Günter Wilfert ◽  
Stefan Wolff
Keyword(s):  
Film Cooling ◽  
Cross Flow ◽  
Vortex Generator ◽  
Internal Flow ◽  
Main Stream ◽  
Thermochromic Liquid Crystal ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Inlet Conditions

Film cooling experiments were conducted to investigate the effects of internal flow conditions and plenum geometry on the film cooling effectiveness. The film cooling measurements show a strong influence of the coolant inlet conditions on film cooling performance. The present experiments were carried out on a flat plate with a row of cylindrical holes oriented at 30 degrees with respect to a constant-velocity external flow, systematically varying the plenum geometry and blowing rates (0.5≤M≤1.25). Adiabatic film cooling measurements using the multiple narrow-banded Thermochromic Liquid Crystal-technique (TLC) were carried out simulating a flow parallel to the main stream flow with and without cross flow at the coolant hole entry compared with a standard plenum configuration. An impingement in front of the cooling hole entry with and without cross flow was also investigated. For all parallel flow configurations ribs were installed at the top and bottom coolant channel wall. As the hole length-to-diameter ratio has an influence on the film cooling effectiveness, the wall thickness has also been varied. In order to optimise the benefit of the geometry effects with ribs, a vortex generator was designed and tested. Results from these experiments show in a region 5≤X/D≤80 downstream of the coolant injection location differences in adiabatic film cooling effectiveness between +5% and +65% compared with a standard plenum configuration.

Influence of Internal Flow on Film Cooling Effectiveness

1999 ◽  
Vol 122 (2) ◽  
pp. 327-333 ◽  
Author(s):  
Gu¨nter Wilfert ◽  
Stefan Wolff
Keyword(s):  
Film Cooling ◽  
Vortex Generator ◽  
Internal Flow ◽  
Thermochromic Liquid Crystal ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Cylindrical Holes ◽  
Flow Configurations ◽  
Inlet Conditions

Film cooling experiments were conducted to investigate the effects of internal flow conditions and plenum geometry on the film cooling effectiveness. The film cooling measurements show a strong influence of the coolant inlet conditions on film cooling performance. The present experiments were carried out on a flat plate with a row of cylindrical holes oriented at 30 deg with respect to a constant-velocity external flow, systematically varying the plenum geometry and blowing rates 0.5⩽M⩽1.25. Adiabatic film cooling measurements using the multiple narrow-banded thermochromic liquid crystal technique (TLC) were carried out, simulating a flow parallel to the mainstream flow with and without crossflow at the coolant hole entry compared with a standard plenum configuration. An impingement in front of the cooling hole entry with and without crossflow was also investigated. For all parallel flow configurations, ribs were installed at the top and bottom coolant channel wall. As the hole length-to-diameter ratio has an influence on the film cooling effectiveness, the wall thickness has also been varied. In order to optimize the benefit of the geometry effects with ribs, a vortex generator was designed and tested. Results from these experiments show in a region 5⩽X/D⩽80 downstream of the coolant injection location differences in adiabatic film cooling effectiveness between +5 percent and +65 percent compared with a standard plenum configuration. [S0889-504X(00)01102-8]

Large Eddy Simulations of Film-Cooling Flows With a Micro-Ramp Vortex Generator

2011 ◽  
Author(s):  
Aaron F. Shinn ◽  
S. Pratap Vanka
Keyword(s):  
Film Cooling ◽  
Cross Flow ◽  
Vortex Generator ◽  
Vortex Pair ◽  
Large Eddy Simulations ◽  
Wind Tunnel Experiments ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flows ◽  
Large Eddy

Large Eddy Simulations were performed to study the effect of a micro-ramp on an inclined turbulent jet interacting with a cross-flow in a film-cooling configuration. The micro-ramp vortex generator is placed downstream of the film-cooling jet. Changes in vortex structure and film-cooling effectiveness are evaluated and the genesis of the counter-rotating vortex pair in the jet is discussed. Results are reported with the jet modeled using a plenum/pipe configuration. This configuration was designed based on previous wind tunnel experiments at NASA Glenn Research Center, and the present results are meant to supplement those experiments. It is found that the micro-ramp improves film-cooling effectiveness by generating near-wall counter-rotating vortices which help entrain coolant from the jet and transport it to the surface. The pair of vortices generated by the micro-ramp are of opposite sense to the vortex pair embedded in the jet.

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.

Implementation of Vortex Generator and Ramp to Improve Film Cooling Effectiveness on Blade Endwall

2021 ◽  
Author(s):  
Sadam Hussain ◽  
Xin Yan
Keyword(s):  
Numerical Methods ◽  
Film Cooling ◽  
Vortex Generator ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Baseline Case ◽  
Cooling Hole ◽  
Cooling Effects ◽  
Endwall Film Cooling

Abstract With the arrangements of vortex generators (VG) and ramp, film cooling effects on endwall near leading edge were numerically investigated at two blowing ratios (i.e. M = 0.5 and M = 1). To determine suitable numerical methods, mesh independency analysis and turbulence model selection were carried out based on the existing experimental data and LES results. With the numerical methods, flow fields near the leading edge were visualized to illustrate the influence of VG and ramp on coolant coverage on blade endwall. Film cooling effectiveness distributions on endwall and coolant trajectories near leading edge were compared among five different configurations with VG and ramp. The results show that the attachment of coolant on blade endwall is improved with the implement of VG between shaped-hole and leading edge. With the implementation of ramp on endwall between cooling hole and leading edge, the coolant spreads wider on endwall along pitchwise direction than the baseline case. With the implementation of VG and ramp, film cooling effect on endwall near leading edge is significantly improved as compared with the only ramp and only VG cases. Compared with the baseline case, pitchwise-averaged film cooling effectiveness on blade endwall near leading edge is increased by about 9%, and the film cooling effectiveness distributions on endwall along pitchwise direction become much uniform, for the case with both ramp and VG at M = 1.

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

2016 ◽  
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 5,000–20,000, 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 non-dimensional 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 degrees 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 adiabatic film cooling effectiveness generally decrease and increase, respectively, with streamwise position, and generally decrease and increase, respectively, as blowing ratio becomes larger.

Cooling performance of vortex generator

2021 ◽  
pp. 095765092199396
Author(s):  
Nirmal Halder ◽  
PK Panigrahi
Keyword(s):  
Reynolds Number ◽  
Numerical Investigation ◽  
Film Cooling ◽  
Density Ratio ◽  
Cross Flow ◽  
Vortex Generator ◽  
Vortex Pair ◽  
Stream Velocity ◽  
Film Cooling Effectiveness ◽  
Cooling Hole

Present numerical investigation proposes to mitigate the effects of Counter rotating vortex pair (CRVP) by employing a pair of vortex generator. Numerical simulation has been carried out to investigate the effect of placement of vortex generator on the characteristics of film cooling effectiveness. Various configuration has been taken based on vortex generator location at upstream, downstream of circular film cooling hole. Along with these utilizing multiple vortex generator at different downstream location also has been detected. The jet to cross flow blowing ratios ( M =  ρ juj/ ρ cfucf) is maintained at unity while Reynolds number based on free stream velocity and film cooling hole dimension is kept at 17,000. The investigation of suitable turbulence model has been studied. The results are compared with baseline case. The numerical investigation is accomplished implementing FLUENT commercial code adopting the K-omega SST model. Among configuration E and all quantity (Density ratio ( DR), Blowing ratio ( M), Reynolds number (Re) and Turbulence intensity ( TI)) better CRVP distribution is depicted for TI and lowest for configuration E.

Large Eddy Simulations of Film-Cooling Flows With a Micro-Ramp Vortex Generator

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Aaron F. Shinn ◽  
S. Pratap Vanka
Keyword(s):  
Film Cooling ◽  
Cross Flow ◽  
Vortex Generator ◽  
Vortex Pair ◽  
Large Eddy Simulations ◽  
Wind Tunnel Experiments ◽  
Turbulent Structures ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Large Eddy

Large eddy simulations were performed to study the effect of a micro-ramp on an inclined turbulent jet interacting with a cross-flow in a film-cooling configuration. The micro-ramp vortex generator is placed downstream of the film-cooling jet. Changes in vortex structure and film-cooling effectiveness are evaluated. Coherent turbulent structures characteristic of a jet in a cross-flow are analyzed and the genesis of the counter-rotating vortex pair in the jet is discussed. Results are reported for two film-cooling configurations, where the primary difference is the way the jet inflow boundary conditions are prescribed. In the first configuration, the jet conditions are prescribed using a precursor simulation and in the second the jet is modeled using a plenum/pipe configuration. The latter configuration was designed based on previous wind tunnel experiments at NASA Glenn Research Center, and the present results are meant to supplement those experiments. It is found that the micro-ramp improves film-cooling effectiveness by generating near-wall counter-rotating vortices which help entrain coolant from the jet and transport it to the surface. The pair of vortices generated by the micro-ramp are of opposite sense to the vortex pair embedded in the jet.

Uncertainty Quantification Analysis of Back Facing Steps Film Cooling Configurations

2018 ◽  
Author(s):  
Eiji Sakai ◽  
Meng Bai ◽  
Richard Ahlfeld ◽  
Francesco Montomoli
Keyword(s):  
Uncertainty Quantification ◽  
Film Cooling ◽  
Lateral Spreading ◽  
Step Height ◽  
Stream Velocity ◽  
Main Stream ◽  
Stochastic Variation ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole

This paper compares two back step film-cooling configurations under an uncertainty quantification framework. An important limit of such configurations is their reliability under geometrical variations, which is taken into account in this study. For the back step configurations, a straight and a curved step is used. Detached eddy simulations with k-ω turbulence model are performed using OpenFOAM ver. 4.0. The Reynolds number is based on the main stream velocity and film cooling hole diameter, d, and is Re = 15,300. The investigated step heights are 0.5d and 0.75d, and the blowing ratios, BR, are 0.5 and 1.0. The straight and the curved steps are found to enhance lateral spreading of coolant flow, resulting in higher film cooling effectiveness compared to the baseline case without the step at comparatively higher BR conditions. The curved step shows better performance than the straight one in particular from BR = 1.0 upwards with the step height of 0.5d. At lower BR with lower H/d, and at higher BR with higher H/d, deterministic simulations are not able to identify the best performer. However when the performance of the two configurations is evaluated considering the stochastic variation of step height and the cooling condition, the benefit of the curved step becomes clear. In particular, the curved step shows better mean performance and has a higher probability to achieve a better performance than the other one. The uncertainty in the film cooling effectiveness caused by the uncertainty of the step height and the BR is investigated using Sparse Approximation of Moment-Based Arbitrary polynomial chaos (SAMBA).

Improved Trench Film Cooling With Shaped Trench Outlets

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Habeeb Idowu Oguntade ◽  
Gordon E. Andrews ◽  
A. D. Burns ◽  
Derek B. Ingham ◽  
Mohammed Pourkashanian
Keyword(s):  
Flat Plate ◽  
Mass Flow ◽  
Film Cooling ◽  
Cross Flow ◽  
Suction Side ◽  
Experimental Results ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Vertical Slot ◽  
Cooling Hole

The influence of the shape of the downstream edge of trench film cooling hole outlets on film cooling effectiveness was investigated using CFD for flat plate film cooling. A 90 deg trench outlet wall with impinging 30 deg film cooling jets results in improved transverse film cooling effectiveness but produces a vertical slot jet into the cross flow, which is not the best aerodynamics for optimum film cooling. It was considered that improvements in the cooling effectiveness would occur if the trailing edge of the trench outlet produced a flow that was inclined in the direction of the crossflow. Beveled and filleted trench outlet shapes were investigated. The CFD predictions were shown to predict well the conventional sharp edged trench outlet experimental results for a flat plate geometry. The flat plate CFD predictions were also shown to predict the experimental results for trench cooling on the suction side of a turbine vane, where the local curvature was small relative to the trench width. The beveled and filleted trench outlets were predicted to suppress the vertical jet momentum and give a Coanda effect that allowed the cooling air to attach to the downstream wall surface. This produced an improved transverse spread of the coolant. Also, it was predicted that reducing the coolant mass flow per hole and increasing the number of rows of holes gave, for the same total coolant mass flow and the same surface area, a superior surface averaged cooling effectiveness.

Sign in / Sign up

Export Citation Format

Share Document