Digital Commons Network^™

Cooled Liquid Rocket Thrust Chamber, Benjamin Gibson, Kealan Frederick Harris, Ryan Frank Schackel, Bjorn Thorsen

Mechanical Engineering

Cooling may affect the thrust output of a small-scale rocket. Little research is published about small-scale rocket performance. We hypothesize the thrust produced varies as the amount of cooling varies. To facilitate assessing this hypothesis, we have designed and built a liquid rocket engine rated for at approximately 25 lb_f of thrust. Our objective was to build in parallel with Cal Poly Space Systems, who built a rocket engine with similar specifications except without cooling. Our challenge is to integrate film cooling, so that the effects of cooling may be compared to Cal Poly Space System’s engine which has …

Effects Of High Freestream Turbulence And Conduction On Film Cooling Effectiveness Of Shaped Holes, Richard A. Macias Jr.

Theses and Dissertations

With technological advancements allowing higher turbine temperatures, film cooling continues to be an important research area. The Film Cooling Rig (FCR) was fitted with a turbulence generator to vary freestream turbulence intensity and length scale, enabling the effects of high freestream turbulence on overall effectiveness to be studied. A cylindrical hole and laidback fan-shaped hole were investigated over a range of Advective Capacity Ratio (ACR) for freestream turbulence intensities of 2%, 10%, and 15%. For a given ACR, increasing the turbulence intensity resulted in lower overall effectiveness values due to the larger heat transfer coefficient that comes from turbulent ow. …

Investigation Of Thermal Scaling Effects For A Turbine Blade Leading Edge And Pressure Side Model, Ryan A. Lynch

Theses and Dissertations

Recent experiments have attempted to quantify the overall cooling effectiveness at elevated temperature conditions. The Film Cooling Rig (FCR) at the Air Force Institute of Technology has been modified to better match the configuration of a similar large scale, low temperature rig at the Air Force Research Laboratory. This has enabled comparison and trend identification of how various properties scale from the low to high temperature condition. Various internal cooling and hole geometry configurations were investigated over a range of temperatures while utilizing the thermal scaling capability of Inconel 718. Film cooling trends and measures of overall effectiveness were matched, …

The Design, Fabrication, And Validation Of A Film Cooled Rotating Turbine Cascade With An Actively Cooled Shroud In A Closed Loop Wind Tunnel, Christopher Michael Drewes

LSU Master's Theses

To test shroud and blade cooling effectiveness, a closed loop, heated wind tunnel housing a film cooled rotating turbine cascade with prescribed blade and vane geometry surrounded by a fully cooled shroud with a leading edge gap were designed and assembled on Louisiana State University’s campus. Heat transfer coefficients and film cooling effectiveness results were computed using a 1-D semi-infinite solid conduction analysis of material temperatures obtained with liquid crystal thermography. Proper analysis required a step change in air temperature; so a bypass loop provided mainstream air heating while maintaining the shroud and blades at ambient temperature. Also, analysis required …

Experimental Study Of A Cascade Of Low Pressure Turbine Blades With Upstream Periodic Stator Wakes, Carlos Rene Gonzalez Rodriguez

LSU Master's Theses

The objective of this study is to experimentally study film cooling flows. A closed-loop wind tunnel with a four passage linear cascade of US Air Force Research Laboratory (AFRL) ultra-high-lift L1A low pressure turbine (LPT) blades and upstream wake generator is used in conjunction with Particle Image Velocimetry (PIV) flow visualization technique to study turbulent film cooling flows due to the interaction between vanes and blades. Further post-processing in the form of Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) modal analyses is performed to determine the relevant modes that characterize the coherent structures in the flow. An image …

A Full Coverage Film Cooling Study: The Effect Of An Alternating Compound Angle, Justin Hodges

Electronic Theses and Dissertations

This thesis is an experimental and numerical full-coverage film cooling study. The objective of this work is the quantification of local heat transfer augmentation and adiabatic film cooling effectiveness for two full-coverage film cooling geometries. Experimental data was acquired with a scientific grade CCD camera, where images are taken over the heat transfer surface, which is painted with a temperature sensitive paint. The CFD component of this study served to evaluate how well the v2-f turbulence model predicted film cooling effectiveness throughout the array, as compared with experimental data. The two staggered arrays tested are different from one another through …

Multi-Row Film Cooling Boundary Layers, Greg Natsui

Electronic Theses and Dissertations

High fidelity measurements are necessary to validate existing and future turbulence models for the purpose of producing the next generation of more efficient gas turbines. The objective of the present study is to conduct several different measurements of multi-row film cooling arrays in order to better understand the physics involved with injection of coolant through multiple rows of discrete holes into a flat plate turbulent boundary layer. Adiabatic effectiveness distributions are measured for several multi-row film cooling geometries. The geometries are designed with two different hole spacings and two different hole types to yield four total geometries. One of the …

Film Cooling In Fuel Rich Environments, Jacob J. Robertson

Theses and Dissertations

The ultra compact combustor is a high performance gas turbine design concept that portends reduced weight for future weapons platforms. A natural outcome of the design is the continual presence of fuel-rich air in the turbine component of the engine. Because modern cooling schemes for hot section turbine blades involve injecting cool, oxygen-rich air adjacent to the surface, the potential arises for reaction with the unconsumed radicals in the mainstream ow and augmented heat transfer to the blade. This outcome is contrary to the purpose of film cooling, and can lead to early life-cycle turbine failure. This study examined the …

Mechanistic Analysis And Reduced Order Modeling Of Forced Film Cooling Flows, Guillaume Francois Bidan

LSU Doctoral Dissertations

Abstract Unforced and forced film cooling jets are investigated in view to develop a reduced order model of the velocity and temperature fields. First, a vertical jet in cross-flow, a configuration well documented at high blowing ratios, is investigated at low blowing ratios using experimental visualizations and large eddy simulations. The unforced study reveals that dominant structures at low blowing ratio can be significantly different from the ones formed at high blowing ratio and describes their evolution and transition as the blowing ratio is changed. The forced jet investigations extend the results of past numerical studies in terms of starting …

Large Eddy Simulation And Analysis Of Shear Flows In Complex Geometries, Prasad Mohanrao Kalghatgi

LSU Doctoral Dissertations

In the present work, large eddy simulation is used to numerically investigate two types of shear flows in complex geometries, (i) a novel momentum driven countercurrent shear flow in dump geometry and (ii) a film cooling flow (inclined jet in crossflow). Verification of subgrid scale model is done through comparisons with measurements for a turbulent flow over back step, present cases of counter current shear and film cooling flow. In the first part, a three dimensional stability analysis is conducted for countercurrent shear flow using Dynamic mode decomposition and spectral analysis. Kelvin-Helmholtz is identified as primary instability mechanism and observed …

Analysis And Optimization Of Film Cooling Effectiveness, Hessam Babaee

LSU Doctoral Dissertations

In the first part, an optimization strategy is described that combines high-fidelity simu- lations with response surface construction, and is applied to pulsed film cooling for turbine blades. The response surface is constructed for the film cooling effectiveness as a function of duty cycle, in the range of DC between 0.05 and 1, and pulsation frequency St in the range of 0.2-2, using a pseudo-spectral projection method. The jet is fully modulated and the blowing ratio, when the jet is on, is 1.5 in all cases. Overall 73 direct numerical sim- ulations (DNS) using spectral element method were performed to …

An Investigation Of Mist/Air Film Cooling With Application To Gas Turbine Airfoils, Lei Zhao

University of New Orleans Theses and Dissertations

Film cooling is a cooling technique widely used in high-performance gas turbines

to protect turbine airfoils from being damaged by hot flue gases. Film injection holes are

placed in the body of the airfoil to allow coolant to pass from the internal cavity to the

external surface. The ejection of coolant gas results in a layer or “film” of coolant gas

flowing along the external surface of the airfoil.

In this study, a new cooling scheme, mist/air film cooling is proposed and

investigated through experiments. Small amount of tiny water droplets with an average

diameter about 7 μm (mist) is …

Coupled Usage Of Discrete Hole And Transpired Film For Better Cooling Performance, Michael Torrance

Electronic Theses and Dissertations

Electricity has become so ingrained in everyday life that the current generation has no knowledge of life without it. The majority of power generation in the United States is the result of turbines of some form. With such widespread utilization of these complex rotating machines, any increase in efficiency translates into improvements in the current cost of energy. These improvements manifest themselves as reductions in greenhouse emissions or possible savings to the consumer. The most important temperature regarding turbine performance is the temperature of the hot gas entering the turbine, denoted turbine inlet temperature. Increasing the turbine inlet temperature allows …

Design, Fabrication And Characterization Of A New Wind Tunnel Facility – Linear Cascade With A Wake Simulator, Jean-Philippe Junca-Laplace

LSU Master's Theses

A new wind tunnel has been designed and constructed at the LSU Mechanical Engineering Laboratories. The objective was to design a versatile test facility, suitable for a wide range of experimental measurements on turbine blades. The future study will investigate the impact of unsteady inflow conditions on film cooling performance. More specifically, it will study how the unsteady flow due to the upstream passing wakes coming from the front row vane affects the film cooling performances on the turbine blades. The test section consists of a four passage linear cascade composed of three full blades and two shaped wall blades. …

A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control, Olga V. Kartuzova

ETD Archive

Jets have been utilized in various turbomachinery applications in order to improve gas turbines performance. Jet pulsation is a promising technique because of the reduction in the amount of air removed from compressor, which helps to increase turbine efficiency. In this work two areas of pulsed jets applications were investigated, first one is film cooling of High Pressure Turbine (HPT) blades and second one is flow separation control over Low Pressure Turbine (LPT) airfoil using Vortex Generator Jets (VGJ) The inlet temperature to the HPT significantly affects the performance of the gas turbine. Film cooling is one of the most …

Study Of Film Cooling Effectiveness: Conical, Trenched And Asymmetrical Shaped Holes, Humberto Zuniga

Electronic Theses and Dissertations

Film cooling is a technique whereby air from the compressor stage of a gas turbine engine is diverted for cooling purposes to parts, such as the turbine stage, that operate at very high temperatures. Cooling arrangements include impingement jets, finned, ribbed and turbulated channels, and rows of film cooling holes, all of which over the years have become progressively more complex. This costly, but necessary complexity is a result of the industry's push to run engines at increasingly higher turbine inlet temperatures. Higher temperatures mean higher efficiency, but they also mean that the turbine first stage operates hundreds of degrees …

Dynamics Of Vortical Structures In A Low-Blowing-Ratio Pulsed Transverse Jet, Clementine Vezier

LSU Master's Theses

Large Eddy Simulation is used to study the interaction of a 35° inclined jet into a crossflow. Steady state cases, with a BR ranging from 0.150 to 1.2, are firstly examined to understand the dynamics of the flow field. Iso-surface of Laplacian of the pressure, vorticity contour and velocity fields highlight the presence of four main vortical structures: shear layer vortices, horse-shoes vortices, wake vortices and CRVP. Qualitative comparisons are performed between simulations and experiments. The dynamics of the flow field is next characterized by pulsing the jet. The studied pulsed cases have same low BR and duty cycle respectively …

Singular Superposition/Boundary Element Method For Reconstruction Of Multi-Dimensional Heat Flux Distributions With Application To Film Cooling Holes, Mahmood Silieti, Eduardo Divo, Alain J. Kassab

Publications

A hybrid singularity superposition/boundary element-based inverse problem method for the reconstruction of multi-dimensional heat flux distributions is developed. Cauchy conditions are imposed at exposed surfaces that are readily reached for measurements while convective boundary conditions are unknown at surfaces that are not amenable to measurements such as the walls of the cooling holes. The purpose of the inverse analysis is to determine the heat flux distribution along cooling hole surfaces. This is accomplished in an iterative process by distributing a set of singularities (sinks) inside the physical boundaries of the cooling hole (usually along cooling hole centerline) with a given …

Heat Transfer Due To Unsteady Effects As Investigated In A High-Speed, Full-Scale, Fully-Cooled Turbine Vane And Rotor Stage, Jonathan R. Mason

Theses and Dissertations

Experiments were conducted to examine the effects of film cooling on a gas turbine engine’s high‐pressure turbine section. The focus for this effort was in the tip/shroud region of a rotor stage and a high pressure turbine vane. A primary goal was to understand the unsteady flow effects. Attempts were also made to characterize the effects as caused by the fully‐cooled rotor stage. Data for this investigation was taken at the U.S. Air Force’s Turbine Research Facility (TRF), a transient blowdown facility with instrumentation fitted to a full‐scale, high‐speed, fully‐cooled vane and rotor stage of proprietary design. Measurements of pressure, …

The Impact Of Heat Release In Turbine Film Cooling, Dave S. Evans

Theses and Dissertations

The Ultra Compact Combustor is a design that integrates a turbine vane into the combustor flow path. Because of the high fuel-to-air ratio and short combustor flow path, a significant potential exists for unburned fuel to enter the turbine. Using contemporary turbine cooling vane designs, the injection of oxygen-rich turbine cooling air into a combustor flow containing unburned fuel could result in heat release in the turbine and a large decrease in cooling effectiveness. The current study explores the interaction of cooling flow from typical cooling holes with the exhaust of a fuel-rich well-stirred-reactor operating at high temperatures over a …

Effect Of Pressure Gradient And Wake On Endwall Film Cooling Effectiveness, Sylvette Rodriguez

Electronic Theses and Dissertations

Endwall film cooling is a necessity in modern gas turbines for safe and reliable operation. Performance of endwall film cooling is strongly influenced by the hot gas flow field, among other factors. For example, aerodynamic design determines secondary flow vortices such as passage vortices and corner vortices in the endwall region. Moreover blockage presented by the leading edge of the airfoil subjects the incoming flow to a stagnating pressure gradient leading to roll-up of the approaching boundary layer and horseshoe vortices. In addition, for a number of heavy frame power generation gas turbines that use cannular combustors, the hot and …

Turbulence Modeling For Film Cooling Flows, Asif Hoda

LSU Doctoral Dissertations

An improved two equation turbulence model has been developed in this dissertation to better predict the complex film cooling flow field that is formed from the interaction of a coolant jet and a crossflow over a modeled turbine blade surface. Film cooling of turbine blades is commonly employed to effectively protect turbine blades from thermal failure and thereby to allow higher inlet temperatures in order to increase the efficiency of gas turbine engines. Film cooling involves the injection of rows of coolant jets from slots on the surface of a turbine blade which is then bent over by the crossflow …

Film Cooling From A Row Of Holes Supplemented With Anti Vortex Holes, Alok Dhungel

LSU Master's Theses

Film cooling is a technique employed to protect the external surface of gas turbine blades from the hot mainstream gas by ejecting the internal coolant air through discrete holes or slots at several locations on the blade exterior surface. Passing the coolant through conventional cylindrical holes causes a pair of vortices to form which lifts off the coolant jet instead of letting it adhere to the surface. The present study aims at investigating the enhanced cooling performance caused by addition of anti-vortex holes to the main cylindrical film cooling holes. Both heat transfer coefficient and film cooling effectiveness are determined …

Pulsed Vertical Jet In Cross Flow At Mean Blowing Ratios 0.35 And 0.45, Pierre-Emmanuel Jacques Joseph Bouladoux

LSU Master's Theses

This thesis deals with a pulsed vertical jet transverse to a cross flow (U_∞=1.6m/s) at mean blowing ratios 0.35 and 0.45. First the reasons of this study are explained and the previous work in the field is described. Then the experimental setup, the experimental procedures and the data processing are detailed. The system (wind tunnel and jet) is characterized before studying the Jet in Cross Flow (JICF). The JICF is explored under unforced and forced conditions through LASER sheet visualizations and constant temperature anemometry (CTA) measurements using hot-wire sensors. Blowing ratios ranging from 0.150 to 0.600 are studied …

Preliminary Study On The Impact Of Impingement On The Effectiveness Of Film Cooling In The Presence Of Gas Path Pressure Gradient, Anil Peravali

Electronic Theses and Dissertations

Impingement is the most commonly used method of cooling in the hot stages of gas turbines. This is often combined with film cooling to further increase the cooling performance. The mainstream flow where in the coolant films discharge often has large stream wise pressure variations. All existing studies on coupled film and impingement cooling concentrated on the effect of the film depletion on the impingement heat transfer. This study investigates the impact of impingement on film cooling, where the jets impinging on a flat plate are depleted through arrays of film cooling holes in the presence of pressure gradient in …

Large Eddy Simulations Of Complex Turbulent Flows, Mayank Tyagi

LSU Doctoral Dissertations

In this dissertation a solution methodology for complex turbulent flows of industrial interests is developed using a combination of Large Eddy Simulation (LES) and Immersed Boundary Method (IBM) concepts. LES is an intermediate approach to turbulence simulation in which the onus of modeling of “universal” small scales is appropriately transferred to the resolution of “problem-dependent” large scales or eddies. IBM combines the efficiency inherent in using a fixed Cartesian grid to compute the fluid motion, along with the ease of tracking the immersed boundary at a set of moving Lagrangian points. Numerical code developed for this dissertation solves unsteady, filtered …

Toward Improved Film Cooling Prediction, G. Medic, Paul A. Durbin

Paul A. Durbin

Computations of flow and heat transfer for a film-cooled high pressure gas turbine rotor blade geometry are presented with an assessment of several turbulence models. Details of flow and temperature field predictions in the vicinity of cooling holes are examined. It is demonstrated that good predictions can be obtained when spurious turbulence energy production by the turbulence model is prevented.