An Infrared Technique for Evaluating Turbine Airfoil Cooling Designs

1999 ◽  
Vol 122 (1) ◽  
pp. 170-177 ◽  
Author(s):  
P. C. Sweeney ◽  
J. F. Rhodes
Keyword(s):  
Surface Temperature ◽  
Flat Plate ◽  
Film Cooling ◽  
Large Scale ◽  
Imaging System ◽  
Cost Effective ◽  
Hole Injection ◽  
Internal Cooling ◽  
Turbine Engine ◽  
Injection Angle

An experimental approach is used to evaluate turbine airfoil cooling designs for advanced gas turbine engine applications by incorporating double-wall film-cooled design features into large-scale flat plate specimens. An infrared (IR) imaging system is used to make detailed, two-dimensional steady-state measurements of flat plate surface temperature with spatial resolution on the order of 0.4 mm. The technique employs a cooled zinc selenide window transparent to infrared radiation and calibrates the IR temperature readings to reference thermocouples embedded in each specimen, yielding a surface temperature measurement accuracy of ±4°C. With minimal thermocouple installation required, the flat plate/IR approach is cost effective, essentially nonintrusive, and produces abundant results quickly. Design concepts can proceed from art to part to data in a manner consistent with aggressive development schedules. The infrared technique is demonstrated here by considering the effect of film hole injection angle for a staggered array of film cooling holes integrated with a highly effective internal cooling pattern. Heated free stream air and room temperature cooling air are used to produce a nominal temperature ratio of 2 over a range of blowing ratios from 0.7 to 1.5. Results were obtained at hole angles of 90 and 30 deg for two different hole spacings and are presented in terms of overall cooling effectiveness. [S0889-504X(00)01901-2]

scholarly journals An Infrared Technique for Evaluating Turbine Airfoil Cooling Designs

1999 ◽  
Author(s):  
Patrick C. Sweeney ◽  
Jeffrey F. Rhodes
Keyword(s):  
Surface Temperature ◽  
Flat Plate ◽  
Film Cooling ◽  
Large Scale ◽  
Imaging System ◽  
Cost Effective ◽  
Hole Injection ◽  
Internal Cooling ◽  
Turbine Engine ◽  
Injection Angle

An experimental approach is used to evaluate turbine airfoil cooling designs for advanced gas turbine engine applications by incorporating double-wall film-cooled design features into large scale flat plate specimens. An infrared (IR) imaging system is used to make detailed, two-dimensional steady state measurements of flat plate surface temperature with spatial resolution on the order of 0.4 mm. The technique employs a cooled zinc selenide window transparent to infrared radiation and calibrates the IR temperature readings to reference thermocouples embedded in each specimen, yielding a surface temperature measurement accuracy of ±4 °C. With minimal thermocouple installation required, the flat plate/IR approach is cost effective, essentially non-intrusive, and produces abundant results quickly. Design concepts can proceed from art to part to data in a manner consistent with aggressive development schedules. The infrared technique is demonstrated here by considering the effect of film hole injection angle for a staggered array of film cooling holes integrated with a highly effective internal cooling pattern. Heated freestream air and room temperature cooling air are used to produce a nominal temperature ratio of 2 over a range of blowing ratios from 0.7 to 1.5. Results were obtained at hole angles of 90° and 30° for two different hole spacings and are presented in terms of overall cooling effectiveness.

Internal and Film Cooling of a Flat Plate With Conjugate Heat Transfer

2007 ◽  
Author(s):  
S. Na ◽  
B. Williams ◽  
R. A. Dennis ◽  
K. M. Bryden ◽  
T. I.-P. Shih
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Surface Temperature ◽  
Flat Plate ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Solid Phase ◽  
Computational Study ◽  
Internal Cooling ◽  
Cooling Hole

Computations were performed to study the internal and film cooling of a flat plate with and without thermal-barrier coating (TBC) that account for the heat transfer in the gas and in the solid. The goal is to understand the effects of the conjugate heat transfer on the temperature distribution in the region about the film-cooling hole and in the region further downstream of a row of film-cooling holes. Results obtained show that when there are no TBC, conduction heat transfer in the plate smears out the adverse effects of hot-gas entrainment by the film-cooling jet. When there is a TBC, the surface temperature and the temperature in the super alloy are greatly reduced because of the low thermal conductivity of the ceramic top coat (CTC), but the temperature gradient, which is nearly aligned with the X-axis further away from the film-cooling hole, turns towards the side of the flat plate with internal cooling, which alters the thermal stress distribution. Reducing the thermal conductivity of the CTC by a factor of 10 was found to increase slightly instead of decrease the surface temperature. This computational study is based on the ensemble average continuity, Navier-Stokes, and energy equations closed by the ideal gas equation of state and the two-equation realizeable k-ε turbulence model for the gas phase and the Fourier equations for conduction in the solid phase.

Computational Study of Parameters Affecting Turbulent Flat Plate Film Cooling

2004 ◽  
Author(s):  
Shadi Mahjoob ◽  
Mohammad Taeibi-Rahni
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Gas Turbines ◽  
Computational Study ◽  
Velocity Ratio ◽  
Hole Injection ◽  
Spanwise Direction ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Injection Angle

Blade film cooling is one of the best methods to improve efficiency of gas turbines. In this work, two different methods of film cooling, namely, slot injection and discrete hole injection have been numerically studied on a flat plate. Incompressible, stationary, viscous, turbulent flow has been simulated using the FLUENT CFD code with the standard k-ε model. The study of injection angle and velocity ratio show that the optimum film cooling in both methods, occurs at the jet angle of 30° but with the velocity ratio of 1.5 for slot case and 0.5 for discrete hole case. The study of jet aspect ratio in discrete hole method, shows that stretching the hole in spanwise direction increases the film cooling effectiveness. Because it not only cool a larger region in both spanwise and streamwise directions, but also can sustain the cooled flow closer to the blade’s wall. The study of jet spacing shows that increasing the jet spacing decreases the effectiveness but not as much as jet aspect ration does.

Numerical Investigation of Film Cooling over a Flat Plate with Varying Injection Angle

2017 ◽  
Vol 17 (17th International Conference) ◽  
pp. 1-16
Author(s):  
Abdelaziz Elareibi ◽  
Tarek Elnady ◽  
Ali Elmaihy ◽  
Salman Elshmarka
Keyword(s):  
Flat Plate ◽  
Numerical Investigation ◽  
Film Cooling ◽  
Injection Angle

Film cooling characteristics on a grooved surface with different injection orientation angles

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Peng Yang ◽  
Guangchao Li ◽  
Jianyong Zhu
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Orientation Angle ◽  
Hole Injection ◽  
Blowing Ratio ◽  
Reverse Trend ◽  
Grooved Surface ◽  
Shaped Hole

Abstract The film effectiveness was investigated on a grooved surface with the injection orientation angles of 30°, 90°, and 150° at the blowing ratios of 0.5, 0.8, 1.1, and 1.4. The injection orientation angle and the groove on the surface caused the effect of the various and irregular shaped hole injection due to the different orientation injection. The results showed that the new phenomenon of film effectiveness distributions was found on the grooved surface compared with the flat plate case. Film effectiveness distributions for the β = 30° were found to be the discontinuous strips. The surface averaged film effectiveness with the orientation angle of 30° was found to decrease with the increase of the blowing ratio. Additionally, the reverse trend was observed with the orientation angle of 150°. The film effectiveness with the orientation angle of 90° only slightly changed with the increase of the blowing ratio.

Film cooling characteristics on a grooved surface with different injection orientation angles

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Peng Yang ◽  
Guangchao Li ◽  
Jianyong Zhu
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Orientation Angle ◽  
Hole Injection ◽  
Blowing Ratio ◽  
Reverse Trend ◽  
Grooved Surface ◽  
Shaped Hole

AbstractThe film effectiveness was investigated on a grooved surface with the injection orientation angles of 30°, 90°, and 150° at the blowing ratios of 0.5, 0.8, 1.1, and 1.4. The injection orientation angle and the groove on the surface caused the effect of the various and irregular shaped hole injection due to the different orientation injection. The results showed that the new phenomenon of film effectiveness distributions was found on the grooved surface compared with the flat plate case. Film effectiveness distributions for the β = 30° were found to be the discontinuous strips. The surface averaged film effectiveness with the orientation angle of 30° was found to decrease with the increase of the blowing ratio. Additionally, the reverse trend was observed with the orientation angle of 150°. The film effectiveness with the orientation angle of 90° only slightly changed with the increase of the blowing ratio.

Influence of Anisotropic Thermal Conductivity on Overall Cooling Effectiveness on a Film Cooled Leading Edge

2021 ◽  
pp. 1-22
Author(s):  
Carol Bryant ◽  
James L. Rutledge
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Film Cooling ◽  
Leading Edge ◽  
Ceramic Matrix Composites ◽  
Internal Cooling ◽  
Matrix Composites ◽  
Edge Region ◽  
Turbine Engine ◽  
Anisotropic Thermal Conductivity

Abstract Increasing interest in the use of ceramic matrix composites (CMCs) for gas turbine engine hot gas path components requires a thorough examination of the thermal behavior one may expect of such components. Their highly anisotropic thermal conductivity is a substantial departure from traditional metallic components and can influence the temperature distribution in surprising ways. With the ultimate surface temperature dependent upon the internal cooling scheme, including cooling from within the film cooling holes themselves, as well as the external film cooling, the relative influence of these contributions to cooling can be affected by the directionality of the thermal conductivity. Conjugate heat transfer computational simulations were performed to evaluate the effect of anisotropy in the leading edge region of a turbine component. The leading edge region is modeled as a fully film-cooled half cylinder with a flat afterbody. The anisotropic directionality of the thermal conductivity is shown to have a significant effect on the temperature distribution over the surface of the leading edge. While structural considerations with CMC components are often paramount, designers should be aware of the thermal ramifications associated with the selection of the CMC layup.

The ultra-high efficiency gas turbine engine, UHEGT, Part II: A numerical study on reducing the stator blade surface temperature by indexing fuel injectors and using film cooling

2020 ◽  
pp. 095765092097353
Author(s):  
Seyed M Ghoreyshi ◽  
Meinhard T Schobeiri
Keyword(s):  
Surface Temperature ◽  
Gas Turbine ◽  
Film Cooling ◽  
Total Pressure ◽  
High Efficiency ◽  
Combustion Process ◽  
Blade Surface ◽  
Turbine Engine ◽  
Fuel Injectors ◽  
Stator Blade

In the Ultra-High Efficiency Gas Turbine Engine, UHEGT (introduced in our previous studies) the combustion process is no longer contained in isolation between the compressor and turbine, rather distributed within the axial gaps before each stator row. This technology substantially increases the thermal efficiency of the engine cycle to above 45%, increases power output, and reduces turbine inlet temperature. Since the combustion process is brought into the turbine stages in UHEGT, the stator blades are exposed to high-temperature gases and can be overheated. To address this issue and reduce the temperature on the stator blade surface, two different approaches are investigated in this paper. The first is indexing (clocking) of the fuel injectors (cylindrical tubes extended from hub to shroud), in which the positions of the injectors are adjusted relative to each other and the stator blades. The second is film cooling, in which cooling holes are placed on the blade surface to bring down the temperature via coolant injection. Four configurations are designed and studied via computational fluid dynamics (CFD) to evaluate the effectiveness of the two approaches. Stator blade surface temperature (as the main objective function) along with other performance parameters such as temperature non-uniformity at rotor inlet, total pressure loss over the injectors, and total power production by rotor are evaluated for all configurations. The results show that indexing presents the most promising approach in reducing the stator blade surface temperature while producing the least amount of total pressure loss.

scholarly journals Effects of Crossflow in an Internal-Cooling Channel on Film Cooling of a Flat Plate Through Compound-Angle Holes

2015 ◽  
Author(s):  
Zachary T. Stratton ◽  
Tom I-P. Shih ◽  
Gregory M. Laskowski ◽  
Brian Barr ◽  
Robert Briggs
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Gas Flow ◽  
Density Ratio ◽  
Internal Cooling ◽  
Cfd Simulations ◽  
Hot Gas ◽  
Adiabatic Effectiveness ◽  
Cooling Passage ◽  
Internal Cooling Passage

CFD simulations were performed to study the film cooling of a flat plate from one row of compound-angles holes fed by an internal-cooling passage that is perpendicular to the hot-gas flow. Parameters examined include direction of flow in the internal cooling passage and blowing ratios of 0.5, 1.0, and 1.5 with the coolant-to-hot-gas density ratio kept at 1.5. This CFD study is based on steady RANS with the shear-stress transport (SST) and realizable k-ε turbulence models. To understand the effects of unsteadiness in the flow, one case was studied by using large-eddy simulation (LES). Results obtained showed an unsteady vortical structure forms inside the hole, causing a side-to-side shedding of the coolant jet. Values of adiabatic effectiveness predicted by CFD simulations were compared with the experimentally measured values. Steady RANS was found to be inconsistent in its ability to predict adiabatic effectiveness with relative error ranging for 10% to over 100%. LES was able to predict adiabatic effectiveness with reasonable accuracy.

Analyzes of Film Cooling Effectiveness from Cylindrical and Staggered Compound Cooling Holes with Alignment Angle of 30 Degree at the End of Combustor

2014 ◽  
Vol 695 ◽  
pp. 389-392
Author(s):  
Shahin Salimi ◽  
Nor Azwadi Che Sidik ◽  
Leila Jahanshaloo ◽  
Kianpour Ehsan
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Internal Cooling ◽  
Ansys Fluent ◽  
Cooling Effectiveness ◽  
Turbine Engine ◽  
Film Cooling Effectiveness ◽  
Alignment Angle ◽  
Compound Angle

A numerical simulation has been performed for the investigation of flow and heat transfer characteristics of a film cooling injected through a hole with cylindrical and compound angle orientation. This paper presents the effects of coolant injector configuration of cylindrical and compound cooling holes with alignment angle of 30 degree at blowing ratio, BR = 3.18 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 ANSYS FLUENT 14.0. This study has been performed with Reynolds-averaged Navier-Stokes turbulence model (RANS) on internal cooling passages The results indicate that using compound angle cooling holes injection, give much better protection than that obtained when simple angle cooling holes were used.

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