The Influence of cooling configuration and tip geometry on gas turbine blade tip leakage flow and heat transfer

Download
2019
Sakaoğlu, Sergen
In gas turbine engines, an increase in the thermal efficiency and power output can be ensured by increasing the turbine inlet temperature. This causes the high-pressure turbine (HPT) blades to be exposed to extremely high temperatures that requires the introduction of cooling flow in order to keep the temperatures within the allowable material limits and to reduce the high thermal loads on the blade. However, cooling flow introduced around the blade tip region affects the blade tip leakage flow and blade tip heat transfer. This work explores the effects of various combinations of location, size, and number of cooling holes used for blade tip cooling and different tip types with varying geometry on pressure loss and thermal performance. These combinations are analyzed either in the stationary or the rotating domain using computational fluid dynamics (CFD). The first-stage high-pressure turbine blade profile of the well-known General Electric Energy Efficient Engine (GE-E3) is used in the research. Findings suggest that squealer tips are superior to flat tips in terms of both aero and thermal performances and they give the best cooling performance when a larger number of cooling holes is located closer to the blade pressure side. v For squealer tips, rotation and addition of cooling at the tip are observed to alter the tip gap flow. Heat transfer coefficient on the squealer blade tip is found to increase with the addition of cooling, while higher film-cooling effectiveness is obtained with increasing the rim height

Suggestions

Experimental investigation of the effects of tip geometry on the flow and loss characteristics in a linear turbine cascade
Alican, Ozan; Uzol, Oğuz; Department of Aerospace Engineering (2017)
In gas turbines, there are a number of factors causing efficiency decrease. When internal flow in turbomachines is considered, flow vortices are one of those factors. This study aims to investigate the main mechanisms behind the efficiency losses occurring due to Tip Leakage Vortex (TLV) in gas turbine rotor blades. Additionally, according to these mechanisms, two squealer tip geometries were applied to the turbine blades and the improvements were reported. This work is the experimental branch of an optimum...
Effects of heat input on metallurgical behavior in HAZ of multi-pass and multi-layer welded IN-939 superalloy
Mashhuriazar, Amirhossein; Gür, Cemil Hakan; Sajuri, Zainuddin; Omidvar, Hamid (2021-11-01)
The hot components of a gas turbine are susceptible to damage in the high-temperature environment of turbine engine operation. Given that these components are relatively costly to manufacture, they are often repaired than replaced when damaged. Fusion welding is an economical method for repairing the damaged components of a gas turbine. This research examines the roles of heat input, pass number and layer number on the intergranular liquation cracking of the Inconel-939 (IN-939) precipitate nickel base supe...
Aerothermodynamics of turbine blade trailing edge cooling
Tunçel, Tuğba; Kahveci, Harika Senem; Department of Aerospace Engineering (2018)
It is known that the thermal efficiency of gas turbines strongly depends on the turbine entry temperature of the working fluid. This has resulted in increased turbine working temperatures, and peak temperatures in advanced gas turbines have been well above maximum allowable metal temperatures for quite some time. For turbine blades to survive while operating beyond these material temperature limits, internal and external cooling techniques have been developed. Due to structural and aerodynamic restrictions,...
Cooling performance investigation of a two-pass rib-roughened channel
Kavas, İsa; Kurtuluş, Dilek Funda; Yasa, Tolga; Department of Aerospace Engineering (2015)
The performance of the modern aero-engines is highly dependent on the turbine inlet gas temperature. The higher temperature leads to more compact and efficient machines. Additionally, specific fuel consumption of the engine is decreased for the same thrust rating. However, the turbine inlet temperatures of the today’s engines are already beyond the material structural limits. Hence, the turbine section must be cooled down to acceptable levels. Various types of cooling methods are typically applied to the ga...
Effect of Turbine Blade Tip Cooling Configuration on Tip Leakage Flow and Heat Transfer
Sakaoğlu, Sergen; Kahveci, Harika Senem (2019-06-21)
The pressure difference between suction and pressure sides of a turbine blade leads to the so-called phenomenon, the tip leakage flow, which most adversely affects the first-stage high-pressure (HP) turbine blade tip aerodynamics. In modern gas turbines, HP turbine blade tips are also exposed to extreme thermal conditions requiring the use of tip cooling. If the coolant jet directed into the blade tip gap cannot counter the leakage flow, it will simply add up to the pressure losses due to this leakage flow....
Citation Formats
S. Sakaoğlu, “The Influence of cooling configuration and tip geometry on gas turbine blade tip leakage flow and heat transfer,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Aerospace Engineering., Middle East Technical University, 2019.