Film-cooling effectiveness was studied using a row of inclined holes that injected cryogenically cooled air across a flat, adiabatic test plate. The density ratio of the coolant to mainstream varied from 1.2 to 2.0. Surface temperatures were measured using a unique surface thermocouple arrangement free of conduction errors. Temperatures were obtained along the jet centerline and across a number of lateral locations. By independently varying density ratio and blowing rate, scaling of adiabatic effectiveness with mass flux ratio, velocity ratio, and momentum ratio was determined. Depending on the momentum flux ratio, the jet either remains attached to the surface, detaches and then reattaches, or is fully detached. For attached jets, the centerline effectiveness scaled with the mass flux ratio. However, for detached-reattached jets, a consistent scaling was not found although the general distribution of the centerline effectiveness scaled with momentum flux ratio. Laterally averaged effectiveness was found to be dependent on density ratio and momentum flux ratio. Decreases in density ratio and increases in momentum flux ratio were found to reduce the spreading of the film cooling jet significantly and thereby reduce laterally averaged effectiveness.

An evaluation of the effectiveness of the VITA, Quadrant, TPAV, U -level, Positive slope, and VITA with slope burst-detection algorithms has been done by making direct comparisons with flow visualization. Measurements were made in a water channel using an X-type hot-film probe located in the near-wall region. Individual ejections from bursts which contacted the probe were identified using dye flow visualization. The effectiveness of each of the detection algorithms was found to be highly dependent on the operational parameters, i.e. threshold levels and averaging or window times. These parameters were adjusted so that the number of events detected by each of the algorithms corresponded to the number of ejections identified by flow visualization, while the probability of a false detection was minimized. Comparing the detection algorithm using these optimum parameter settings, the Quadrant technique was found to have the greatest reliability with a high probability of detecting the ejections and a low probability of false detections. Furthermore, it was found that the ejections detected by the Quadrant technique could be grouped into bursts by analysing the probability distribution of the time between ejections.

The durability of gas turbine engines is strongly dependent on the component temperatures. For the combustor and turbine airfoils and endwalls, film cooling is used extensively to reduce component temperatures. Film cooling is a cooling method used in virtually all of today's aircraft turbine engines and in many power-generation turbine engines and yet has very difficult phenomena to predict. The interaction of jets-in-crossflow, which is representative of film cooling, results in a shear layer that leads to mixing and a decay in the cooling performance along a surface. This interaction is highly dependent on the jet-to-crossflow mass and momentum flux ratios. Film-cooling performance is difficult to predict because of the inherent complex flowfields along the airfoil component surfaces in turbine engines. Film cooling is applied to nearly all of the external surfaces associated with the airfoils that are exposed to the hot combustion gasses such as the leading edges, main bodies, blade tips, and endwalls. In a review of the literature, it was found that there are strong effects of freestream turbulence, surface curvature, and hole shape on the performance of film cooling. Film cooling is reviewed through a discussion of the analyses methodologies, a physical description, and the various influences on film-cooling performance. Dr. David Bogard is a Professor of Mechanical Engineering at the University of Texas at Austin, and holds the John E. Kasch Fellow in Engineering. He received his B.S. and M.S. degrees in mechanical engineering from Oklahoma State University, and his Ph.D. from Purdue University. He has served on the faculty at the University of Texas since 1982. Dr. Bogard has been active in gas turbine cooling research since 1986, and has published over 100 peer-reviewed papers. He was awarded the ASME Heat Transfer Committee Best Paper Award in 1990 and 2003, and is a fellow of the ASME. Dr. Karen Thole holds the William S. Cross Professorship of Mechanical Engineering at Virginia Polytechnic Institute and State University. She received her B.S. and M.S. degrees in mechanical engineering from the University of Illinois, and a Ph.D. from the University of Texas at Austin. She spent two years as a postdoctoral researcher at the Institute for Thermal Turbomachinery at the University of Karslruhe in Germany and in 1994 she accepted a faculty position at the University of Wisconsin-Madison. In 1999, she became a faculty member in the Mechanical Engineering Department at Virginia Polytechnic Institute and State University where she was promoted to professor in 2003. She received the National Science Foundation CAREER Award in 1996, which was directed at developing a better understanding of gas turbine heat transfer. Dr. Thole's areas of expertise are heat transfer and fluid mechanics specializing in turbulent boundary layers, convective heat transfer, and high freestream turbulence effects. She has published more than 80 peer-reviewed papers and has advised over 30 graduate theses.

The introduction of Lean Burn concept as basic Low-N O x scheme for future aero-engines is heavily affecting the aero-thermal design of combustors. A great amount of air is admitted through the injection system with relevant swirl components, producing very complex flow structures (recirculations, vortex breakdown) for flame stabilization. As a consequence a reduced quantity of air is available for liner cooling, pushing the adoption of high effectiveness cooling schemes. Effusion cooling represents one of the first choices due to its low weight and a relatively easy manufacturability. Liner metal temperature is kept low by the combined protective effect of coolant film, heat removal inside holes and an improved cold-side convection. In lean burn systems the evolution of film protection can be heavily influenced by the swirl flow interaction with combustor walls. The subject of this work is to investigate the effects of the realistic flow field of a lean burn injector on the adiabatic film cooling effectiveness on an effusion cooled combustor liner. A dedicated three-sector rig was designed with the aim of measuring film effectiveness with Pressure Sensitive Paint technique. Three effusion cooling geometries with different inclination angles were tested at various levels of pressure drops across the perforation, resulting in different blowing ratio values. It was also taken into consideration several flow rate levels of starter film realized by spent dome cooling air, injected through a dedicated plain slot. The analysis of film effectiveness measurements were supported by flow field investigation in the near wall region carried out by means of Particle Image Velocimetry. Results pointed out the relevant impact of combustor flow field on the adiabatic film cooling effectiveness as well as a significant role of the inclination angle, recommending a careful revision of standard design practices based on one dimensional flow assumption and suggesting possible holes arrangement optimization.