We have used variable cooling rate ellipsometric measurements to probe the slow dynamics in thin supported polystyrene films. For the slowest cooling rates (approximately 1 K/min) the measured Tg values are reduced below the bulk value with the measured Tg of 341 K for a 6 nm film. As the cooling rate is increased the Tg reductions become smaller until at cooling rates >90 K/min there is only s...

This work presents a comparison of thin film gauge (TFG) and infrared (IR) thermography measurement techniques to simultaneously determine heat transfer coefficient and film cooling effectiveness. The first comparison was with an uncooled vane where heat transfer coefficient was measured at Mex=0.77 and Tu=16%. Relatively good agreement was found between the results of the two methods and the e...

In this study, the effect of randomness of blowing ratio on film cooling performance is investigated by combining direct numerical simulations with a stochastic collocation approach. The geometry includes a 35-deg inclined jet with a plenum attached to it. The blowing ratio variations are assumed to have a truncated Gaussian distribution with mean of 0.3 and the standard variation of approximat...

We report results from a computational study of film cooling from cylindrical holes inclined at 35 degrees with respect to a flat surface using Large Eddy Simulations (LES). The hole length is L/d = 3.5, distance between the holes is P/d = 3, boundary layer above the flat surface is turbulent with Reθ = 938, density ratio = 0.95, velocity ratio = 0.5. All pertinent components of geometry, namel...

In order to cool the gas turbine vane or blade and raise operating temperature, two standard convective cooling methods are used: jet impingement film cooling. The current study uses computational analysis analyze compare effectiveness with without multi-jet on a flat plate. Ansys Fluent software is used perform results were compared experimental result using K-ω SST turbulence model validated ...

Film-cooling technology is used in high-temperature components of gas turbines to extend their service lives. Hot-gas path are susceptible damage or failure the absence film cooling. Much optimization research efforts have been focused on hole shapes, heat/mass transfer measurement techniques, and cooling performance under various mainstream coolant side operating conditions. Due recent rapid a...

SUMMARY Experiments are reported in which film cooling tests are carried out using coolent injection through rows of discrete holes. A shock tunnel is used to provide a transient mainstream flow at stagnation temperatures of 5m°K, 1000°K and 2COO'K. Wall heat transfer rates are measured with and without coolant injection using thin film gauges. Mainstream Mach numbers of 0.2, 0.5 and 0.7 are em...