Long Hole Film Cooling Dataset for CFD Development . Part 1; Infrared Thermography and Thermocouple Surveys (original) (raw)
Related papers
Volume 3: Turbo Expo 2004, 2004
The film-cooling performance of a flat plate in the presence of low and high freestream turbulence is investigated using liquid crystal thermography. This paper contributes high-resolution color images that clearly show how the freestream turbulence spreads the cooling air around a larger area of the film-cooled surface. Distributions of the adiabatic effectiveness are determined over the film-cooled surface of the flat plate using the hue method and image processing. Three blowing rates are investigated for a model with three straight holes spaced three diameters apart, with density ratio near unity. High freestream turbulence is shown to increase the area-averaged effectiveness at high blowing rates, but decrease it at low blowing rates. At low blowing ratio, freestream turbulence clearly reduces the coverage area of the cooling air due to increased mixing with the main flow. However, at high blowing ratio, when much of the jet has lifted off in the low turbulence case, high freestream turbulence turns its increased mixing into an asset, entraining some of the coolant that penetrates into the main flow and mixing it with the air near the surface.
Development of a novel film cooling hole geometry
2001
This thesis presents the design, development and testing of a new film cooling hole geometry, the converging slot-hole or console. Both the thermal and aerodynamic performance were measured, using the adiabatic effectiveness and heat transfer coefficient, and aerodynamic loss respectively, to quantify performance. Comparative measurements were made, by testing conventional film cooling hole shapes in parallel with the console experiments. The CFD code, Fluent, was used to predict the performance of the initial design concept before it was manufactured. Initial performance measurements in incompressible flow were performed in a low speed wind tunnel at an engine representative Reynolds number based on mainstream flow and hole diameter. For these experiments, the coolant to mainstream density ratio was approximately unity, and the cooling performance was measured over a flat plate. The console was tested in parallel with cylindrical holes, a slot and fan-shaped holes, all of which had...
Long Hole Film Cooling Dataset for CFD Development
2013
An experiment investigating flow and heat transfer of long (length to diameter ratio of 18) cylindrical film cooling holes has been completed. In this paper, the thermal field in the flow and on the surface of the film cooled flat plate is presented for nominal freestream turbulence intensities of 1.5 and 8 percent. The holes are inclined at 30° above the downstream direction, injecting chilled air of density ratio 1.0 onto the surface of a flat plate. The diameter of the hole is 0.75 in. (0.01905 m) with center to center spacing (pitch) of 3 hole diameters. Coolant was injected into the mainstream flow at nominal blowing ratios of 0.5, 1.0, 1.5, and 2.0. The Reynolds number of the freestream was approximately 11,000 based on hole diameter. Thermocouple surveys were used to characterize the thermal field. Infrared thermography was used to determine the adiabatic film effectiveness on the plate. Hotwire anemometry was used to provide flowfield physics and turbulence measurements. The results are compared to existing data in the literature. The aim of this work is to produce a benchmark dataset for Computational Fluid Dynamics (CFD) development to eliminate the effects of hole length to diameter ratio and to improve resolution in the near-hole region. In this report, a Time-Filtered Navier Stokes (TFNS), also known as Partially Resolved Navier Stokes (PRNS), method that was implemented in the Glenn-HT code is used to model coolant-mainstream interaction. This method is a high fidelity unsteady method that aims to represent large scale flow features and mixing more accurately.
2006
Detailed distributions of heat transfer coefficients downstream of a single film cooling hole were presented. The film cooling hole has an angle of inclination of 45° and a circular shape diameter of 10 mm. Tests were conducted in a purpose built heat transfer rig at the Department of Aerospace Engineering, UPM. The rig has been modified to conduct transient heat transfer testing using thermochromic liquid crystal technique. A single narrow-band liquid crystal was used to map the distribution of heat transfer coefficient downstream of a single film cooling hole at a blowing ratio ranging between 0.5-0.94. The detailed heat transfer coefficient distributions provide a clear understanding of free jet-mainstream interactions for different blowing ratio. Results shows that blowing ratio of 0.64 provides a better cooling protection compared to the other blowing ratios tested.
2014
Film cooling is used in gas turbine engines to cool turbine components. Cooler air is bled from the compressor, routed internally through turbine vanes and blades, and exits through discrete holes, creating a film of coolant on the parts' surfaces. Cooling the turbine components protects them from thermal damage and allows the engine to operate at higher combustion temperatures, which increases the engine efficiency. Shaped film cooling holes with diffuser exits have the advantage that they decelerate the coolant flow, enabling the coolant jets to remain attached to the surface at higher coolant flow rates. Furthermore, the expanded exits of the coolant holes provide a wider coolant distribution over the surface. The first part of this dissertation provides data for a new laidback, fan-shaped hole geometry designed at Pennsylvania State University's Experimental and Computational Convection Laboratory. The shaped hole geometry was tested on flat plate facilities at the
Mechanical Engineering Journal
The reliability of turbine blades and vanes of modern high temperature gas turbines is assured by turbine blade cooling technologies. Among the various cooling methods, film cooling has been a key technology to ensure the long-term operation of turbine blades and vanes that are exposed to hot gas-path flows. Therefore, many papers have been published aiming at the improvement of film cooling effectiveness by optimization of film cooling hole geometries. Although the turbulence intensity of the mainstream generated in the gas turbine combustor is very high and may reduce the film cooling effect on the turbine vane and blade, there are few papers investigating quantitatively the effect of the mainstream turbulence on the film cooling. For this reason, the influence of mainstream turbulence intensity on film cooling effectiveness was investigated with an active turbulence generator equipped with electric-motor driven propellers for circular and fan-shaped film cooling holes. Spatial distributions of the turbulent mixing field between turbulent mainstream and film coolant jet were measured with quantitative measurement methods, such as PIV and LIF. As a result, it was revealed that when the mainstream turbulence is high the counter-rotating vortex pair is weakened, the film cooling air spreads in the span-wise direction and the lateral-averaged film cooling effectiveness decreases about 10%.
Effect Of Hole Shapes, Orientation And Hole Arrangements On Film Cooling Effectiveness
In this present work, the effect of hole shapes, orientation and hole arrangements on film cooling effectiveness has been carried out. For this work a flat plate has been considered for the computational model. Computational analysis of film cooling effectiveness using different hole shapes with no streamwise inclination has been carried out. Initially, the model with an inclination of 30° has been verified with the experimental data. The validation results are well in agreement with the results taken from literature. Five different hole shapes viz. Cylindrical, Elliptic, Triangular, Semi-Cylindrical and Semi-Elliptic have been compared and validated over a wide range of blowing ratios. The blowing ratios ranged from 0.67 to 1.67. Later, orientation of holes have also been varied along with the number of rows and hole arrangements in rows. The performance of film cooling scheme has been given in terms of centerline and laterally averaged adiabatic effectiveness. Semi-elliptic hole utilizes half of the mass flow as in other hole shapes and gives nominal values of effectiveness. The triangular hole geometry shows higher values of effectiveness than other hole geometries. But when compared on the basis of effectiveness and coolant mass consumption, Semi-elliptic hole came out to give best results. ABSTRACT In this present work, the effect of hole shapes, orientation and hole arrangements on film cooling effectiveness has been carried out. For this work a flat plate has been considered for the computational model. Computational analysis of film cooling effectiveness using different hole shapes with no streamwise inclination has been carried out. Initially, the model with an inclination of 30 ° has been verified with the experimental data. The validation results are well in agreement with the results taken from literature. Five different hole shapes viz. Cylindrical, Elliptic, Triangular, Semi-Cylindrical and Semi-Elliptic have been compared and validated over a wide range of blowing ratios. The blowing ratios ranged from 0.67 to 1.67. Later, orientation of holes have also been varied along with the number of rows and hole arrangements in rows. The performance of film cooling scheme has been given in terms of centerline and laterally averaged adiabatic effectiveness. Semi-elliptic hole utilizes half of the mass flow as in other hole shapes and gives nominal values of effectiveness. The triangular hole geometry shows higher values of effectiveness than other hole geometries. But when compared on the basis of effectiveness and coolant mass consumption, Semi-elliptic hole came out to give best results. í µí±í µí±í µí±í µí± ∞ − í µí±í µí±í µí±í µí± í µí±¤í µí±¤í µí±¤í µí±¤ í µí±í µí±í µí±í µí± ∞ − í µí±í µí±í µí±í µí± í µí±í µí±í µí±í µí± M Mass flux ratio or blowing ratio (defined as ratio of mass flux of coolant to the mainstream) θ Non-dimensional Temperature, í µí±í µí±í µí±í µí± í µí°»í µí°»í µí°»í µí°» − í µí±í µí±í µí±í µí± í µí±¤í µí±¤í µí±¤í µí±¤ í µí±í µí±í µí±í µí± í µí°»í µí°»í µí°»í µí°» − í µí±í µí±í µí±í µí± í µí±í µí±í µí±í µí± INTRODUCTION The thermal management and protection of the components and surfaces in rocket engine combustion chambers presents one of the most challenging problems for designers. Film cooling is an active cooling strategy, which involves the continuous injection of a thin layer of protective fluid (coolant) near a wall or boundary to insulate it from rapidly flowing hot propellant gases. Its main advantages are that it allows for the use of much lighter-weight nozzle assemblies and it is relatively simple to implement from a fabrication standpoint. M Mass flux ratio or blowing ratio (defined as ratio of mass flux of coolant to the mainstream) ABSTRACT In this present work, the effect of hole shapes, orientation and hole arrangements on film cooling effectiveness has been carried out. For this work a flat plate has been considered for the computational model. Computational analysis of film cooling effectiveness using different hole shapes with no streamwise inclination has been carried out. Initially, the model with an inclination of 30 ° has been verified with the experimental data. The validation results are well in agreement with the results taken from literature. Five different hole shapes viz. Cylindrical, Elliptic, Triangular, Semi-Cylindrical and Semi-Elliptic have been compared and validated over a wide range of blowing ratios. The blowing ratios ranged from 0.67 to 1.67. Later, orientation of holes have also been varied along with the number of rows and hole arrangements in rows. The performance of film cooling scheme has been given in terms of centerline and laterally averaged adiabatic effectiveness. Semi-elliptic hole utilizes half of the mass flow as in other hole shapes and gives nominal values of effectiveness. The triangular hole geometry shows higher values of effectiveness than other hole geometries. But when compared on the basis of effectiveness and coolant mass consumption, Semi-elliptic hole came out to give best results. í µí±í µí±í µí±í µí± ∞ − í µí±í µí±í µí±í µí± í µí±¤í µí±¤í µí±¤í µí±¤ í µí±í µí±í µí±í µí± ∞ − í µí±í µí±í µí±í µí± í µí±í µí±í µí±í µí± M Mass flux ratio or blowing ratio (defined as ratio of mass flux of coolant to the mainstream) θ Non-dimensional Temperature, í µí±í µí±í µí±í µí± í µí°»í µí°»í µí°»í µí°» − í µí±í µí±í µí±í µí± í µí±¤í µí±¤í µí±¤í µí±¤ í µí±í µí±í µí±í µí± í µí°»í µí°»í µí°»í µí°» − í µí±í µí±í µí±í µí± í µí±í µí±í µí±í µí± INTRODUCTION The thermal management and protection of the components and surfaces in rocket engine combustion chambers presents one of the most challenging problems for designers. Film cooling is an active cooling strategy, which involves the continuous injection of a thin layer of protective fluid (coolant) near a wall or boundary to insulate it from rapidly flowing hot propellant gases. Its main advantages are that it allows for the use of much lighter-weight nozzle assemblies and it is relatively simple to implement from a fabrication standpoint.
Proceeding of 5th Thermal and Fluids Engineering Conference (TFEC)
The higher temperature of the combustion chamber of a gas turbine yield higher efficiencies for the turbines but can affect the blade's life. As a preventative method, Film-cooling is a useful technique to enhance the performance of it by injecting coolant jets that the metal surfaces can be protected against the hot main flow. To improve cooling efficiency and increase the life of these components, several cooling strategies have been introduced. In the present study, the effects of the laidback fan-shaped hole geometry, in particular, are examined against the conventional cylindrical hole geometry using Computational Fluid Dynamic simulations. Computations are carried out based on three-dimensional Large Eddy Simulation. The open-source software OpenFOAM was utilized to solve the filtered governing equations for mass, momentum, energy conservation, and heat transfer. The mixing mechanism between hot and coolant fluids, nondimensional adiabatic film cooling effectiveness, and dynamics of vortices are presented and discussed.