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In this paper, a hexagonal prism inlet chamber is used to form a swirling flow for the film cooling, and three kinds of compound angle of film hole (γ = 10°, 20°, 30°) with clockwise swirling or counterclockwise swirling are used for numerical simulation studies. The influence of different compound angles of film hole and the swirling directions for the film cooling effectiveness are obtained. The results show that the film cooling effectiveness and spanwise cooling coverage range of the clockwise swirling or counterclockwise swirling flow both are low when the compound angle of film hole is 10°. With the increasing compound angle of film hole, the kidney shaped vortex of film hole exit gradually weakens until it disappears, which reduces the entrainment effect by the coolant jet. So that the spanwise coverage range of two swirling modes is obviously improved. When the compound angle of film hole is 30° compared to 10°, the average spanwise film cooling effectiveness of clockwise swirling and counterclockwise swirling are increased by about 133.75 and 212.6%, respectively. The average spanwise film cooling effectiveness on the downstream of film hole for counterclockwise swirling is increased by about 140% compared with clockwise swirling. [ABSTRACT FROM AUTHOR]

A comparative study of the flow field and heat transfer characteristics between swirl and impingement of mist/air cooling on blade leading edge is carried out to find a better cooling configuration for phase transition cooling. The Eulerian–Lagrangian particle tracking technique is used to investigate mist/air cooling. Comparisons are made between these two cooling forms in such aspects as vortex structure, heat transfer enhancement, pressure loss, and thermal uniformity with and without mist injection. The influences of mist ratio and Reynolds numbers on these parameters are studied in this paper. Results show that heat transfer is enhanced while pressure loss and thermal uniformity are improved by the swirl flow created by vortex impingement. The heat transfer performance increases by about 46.2 and 51.9%, respectively, for impingement and swirl cooling with 8% mist injection, and the pressure loss coefficient increases by 19%. The difference of heat transfer coefficient between swirl and impingement cooling with and without mist injection at high Reynolds number is larger than that at low Reynolds number. In addition, the heat transfer nonuniform coefficient of swirl cooling is about 15% lower than for impingement cooling. [ABSTRACT FROM PUBLISHER]

The idea of utilizing a finely dispersed water-in-air mixture has been proven to be a feasible technique to produce very high cooling rates. The accuracy of numerical simulation program for conjugate heat transfer methodology is verified with the Mark II transonic high pressure turbine stator which is cooled by internal convection through radial round pipes, and different turbulence models and transition models are employed to analyze the influence on results. On the basis of it, the mist cooling is simulated under typical gas turbine operating conditions for internal convective cooling to discuss the improvement of cooling performance. Though the results indicate that mist cooling can decrease the temperature of boundary layer without impact on the temperature of the mainstream and the thickness of boundary layer, the cooling capacity is limited by inadequate evaporation of mist. Considering the distribution of thermal stress and mist evaporation, a compound cooling blade of film cooling with trailing edge ejection is acquired which is modified from the blade of Mark II internal convective cooling; the effects of various parameters including mist concentration and mist diameter on the improvement of cooling performance are investigated, meanwhile the impact of curvature on cooling efficiency and mist trajectory is analyzed finally. [ABSTRACT FROM AUTHOR]

Jet impingement cooling is usually used in zones with extremely high thermal loads. The major factor that limits impingement heat transfer uniformity is the crossflow. The impingement cooling with return hole is applied to reduce the negative effect of crossflow on the target surface heat transfer in present paper. The influences of jet-to-plate spacing (H / D), impingement target surface curvature (α), temperature ratio (TR) and Reynolds number on flow field and heat transfer performance are investigated in detail. The results indicate that the correlation between the overall area average Nusselt number of target surface and H / D , the overall area average Nusselt number decreases by approximately 5.76% with H / D increases by one unit. Increasing the impingement target surface curvature is beneficial to expand the spanwise heat transfer. The overall area average Nusselt number increases by 295.5% for Reynolds number varying from 10,000 to 50,000 at TR = 0.910, and the overall area average Nusselt number increases by 8.68% for the TR varying from 0.668 to 0.910 at Re = 30,000. The results indicate that impingement cooling with return hole can achieve high heat transfer coefficient and uniform heat transfer distribution. [ABSTRACT FROM AUTHOR]

The aerodynamic, heat transfer and film cooling characteristics of three tip configurations (including pressure-side partial squealer tip, suction-side partial squealer tip and cavity squealers tip) with cooling are evaluated on transonic turbine, and the effect of the jet and shroud motion are talked. The flow and heat transfer mechanisms of three cooled tip configurations are analyzed. Results show that both the jet and shroud motion alter the tip gap flow, which is found to have a different impact on the aerothermal and film cooling performances of three tip configurations. The addition of cooling significantly increases the overall heat transfer coefficient of the SS tip, but has a relatively small impact on that of the PS tip and Squealers tip. As a result, the total h ¯ of SS cooled tip is even increased by 9.0% compared to Squealers cooled tip. The shroud motion increases the film cooling effectiveness of PS cooled tip and Squealers cooled tip, but reduces that of SS cooled tip. Under the moving shroud condition, Squealers cooled tip have significant advantages in aerodynamic, heat transfer and film cooling performances compared to the other two cooled tip structures. [ABSTRACT FROM AUTHOR]

In the turbine passage, the secondary flow makes the film cooling jets driven from the pressure side to the suction side, resulting in the corner region of the pressure surface is difficult to cool. In this paper, end-wall film cooling performance and aerothermal performance with the three cases, which include the cylindrical cooling scheme, the swirling cooling scheme and the compound cooling scheme, at different axial positions of the turbine passage are studied respectively. Results show that significant improving the cooling performance for the swirling case at corner region of pressure surface is found. Furthermore, its overall adiabatic averaged cooling effectiveness at different axial positions are all increased. Compared with the compound and cylindrical cases, the swirling cooling effectiveness of the first row is increased by 77.4% and 63%, respectively, at M = 2.2. The physical mechanism of the improvement end-wall cooling performance is that the pair anti-vortex produced by the swirling coolant are twisted and squeezed each other, which makes the coolant injections attached to the wall and achieves a larger coolant coverage in lateral direction. Although the swirling cooling scheme increases the heat transfer of the endwall, it still has the best overall endwall cooling performance. • The interaction between the swirling coolant and the mainstream restructures the vortex structure and restrains the passage vortex. • The swirling coolant has better ability to adhere to the wall and stability, making it difficult for swirling coolant lifted off the wall. • Swirling cooling scheme enhances endwall overall cooling performance. • The pressure surface corner region where is difficult to cool obtains good coolant coverage effect. [ABSTRACT FROM AUTHOR]