Numerical Simulation on Gas Turbine Film Cooling of Curved Surface With Backward Injection

Abstract

Due to the unique role of gas turbine engines in power generation and aircraft propulsion, significant effort has been made to improve the gas turbine performance. As a result, the turbine inlet temperature is usually elevated to be higher than the metal melting point. Therefore, effective cooling of gas turbines is a critical task for engines’ efficiency as well as safety and lifetime. Film cooling has been used to cool the turbine blades for many years. The main issues related to film cooling are its poor coverage, aerodynamic loss, and increase of heat transfer coefficient due to strong mixing. To overcome these problems, film cooling with backward injection has been found to produce a more uniform cooling coverage under low pressure and temperature conditions and with simple cylindrical holes. Therefore, the focus of this paper is on the performance of film cooling with backward injection at gas turbine operating conditions. By applying numerical simulation, it is observed that along the centerline on both concave and convex surfaces, the film cooling effectiveness decreases with backward injection. However, cooling along the span is improved, resulting in more uniform cooling.

Large Eddy Simulations for Film Cooling Assessment of Cylindrical and Laidback Fan-Shaped Holes With Reverse Injection

“…This deviation may be attributed to being the difference in density ratio (DR) and mainstream Reynolds number (Re) and length to diameter ratio (L/D). However, the coefficient of discharge for RC at 35 o injection angle and blowing ratio (M) =1 shows excellent agreement with reverse cylindrical hole, from literature findings [18,20]. The FS hole discharge coefficient at 35 o injection angle and blowing ratio (M) = 1 also shows good agreement with results of Liu et al…”

“…The results suggested that both at low blowing ratio (M = 0.5) and high blowing ratio (M = 2), the film cooling performance was improved. Shetty et al [18] carried out a numerical study of film cooling with backward injection over the aerofoil surface. They concluded that film cooling lateral effectiveness for backward injection was significantly higher than forward injection.…”

Numerical Evaluation on Effects of Upstream Sand-Dune-Shaped Ramp and Backward Coolant Injection on Heat Transfer

“…Over the past decades, film cooling with forward coolant injection was the main focus. Recently, a research group from Lamar University inspired the researches on film cooling with backward coolant injection [7][8][9][10]. These studies provided a clear understanding on the backward injection film cooling.…”