الفهرس 
AbstractOnly 14 pages are availabe for public view
 |  | from | 112 |  |  |
| | | from | 112 | | |
Abstract
This study is a numerical investigation of the effect of injection holeinclination angle, number of holes and blowing ratio on film cooling effectiveness of elliptical fixed blade surface. The study is conducted on, gas turbine (I-R MT250) type data, with 0.7 mm hole diameter, hole injection angles from 30o to 90o with the horizontal and blowing ratio (from 0.3 to 1.3). Two and three holes configurations also investigated after finding the best inclination angle and blowing ratio. Commercial software Comsol multi physics, with use of finite element method, is used for solving a set of governing equations, K- & RANS equations turbulence model. The velocity of hot gases is remaining constant during the investigation, but the coolant velocity is varied depends on the blowing ratio variation. The hot gases flow is inclined by 300 with horizontal at coolant exit. During the study, the effect of film cooling layer and mixed coolant-hot gas on reducing the heat transfer between blade surface and main stream was studied. At low and moderate blowing ratios, an increasing effectiveness, when hole inclination angles increased (from 300 to 600) with the horizontal. At higher blowing ratio and an increase in inclination angle more than 600, leads to DROP in film cooling effectiveness down. Maximum film cooling effectiveness achieved at inclination angle of 60o with horizontal and blowing ratio of 1.3, while worst film cooling effectiveness occurs at 90o with the horizontal. The pressure DROP due to coolant injection is recorded for all inclination angles at different blowing ratios. The pressure DROP increases with the increasing of the inclination angles to reach its minimum at 90o. Also it is noticed that by increasing the blowing ratio the pressure DROP increase till Br= 0.8 after that pressure DROP decreases. At the end of the investigation two sets of multi holes configuration are used, the multi-holes configuration increases the average film cooling effectiveness and reduces the thermal instability. As the pitch distance between holes is decreased, the film cooling effectiveness increases.