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Three different kinds of coolant chamber configuration for film cooling are proposed to develop the swirling coolant flow at blowing ratios ranging from 0.5 to 2.0. The results show that the difference of film cooling effectiveness for three kinds of coolant chamber configuration is little at low blowing ratio, but the advantage of swirling film cooling becomes obviously with the increase of blowing ratio. When the blowing ratio is 2.0, the jet momentum of original coolant chamber configuration is large and uniform, which leads to the lowest cooling effectiveness due to the formation of a strong kidney vortex. The first coolant chamber configuration has a low jet momentum region at upstream of the film hole, the coolant in this region interacts with high temperature mainstream and bypasses the large jet momentum coolant to attach cooling surface at downstream. The second coolant chamber configuration is sprayed with the structure of unidirectional vortex, which forms a vortex pressing on other vortex, making the coolant in pressed vortex attach surface better, producing the best coverage and the higher film cooling effectiveness. [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]

• Accurate He-Xe properties calculation program is established. • Boundary layer is applied to explore the effect of fluids properties on flow loss. • A flow criteria set is specified for noble gas and air flow similarity. • Similarity criteria are verified by the flow field and efficiency of radial turbine. The performance of radial turbines with the He-Xe mixtures, helium, argon and air are examined in this paper. The published approach pertaining to Chapman-Enskog kinetic theory and corresponding states theory is adopted to calculate the transport properties of He-Xe mixtures with two different molecular weights of 15.9 g/mol and 40 g/mol. The independent or combined effects of the flow Euler number (Eu), Reynolds number (Re) and inflow velocity on flow similarity are discussed based on flat-plate flow. Under the consistent above conditions, the flows of these fluids are similar and the flow loss is merely a function of fluids properties. The established flow similarity conditions form a procedure to calculate the boundary conditions of similar turbines and its application makes the flow similar in radial turbines passages. It is reflected in the consistent topology skeleton of flow structures and the identical parameter distributions in the flow section. The turbines with He-Xe mixtures, Ar and air shares a pretty similar tendency of efficiency line and the values differ little. The differences between these turbines under the same working point have an upper limit of 0.3% before critical state. At the design point, a similar velocity triangle instead of an identical one can guarantee the flow similarity and an approximate efficiency compared with others. Once the working condition deviates from the design point, the efficiency error between the helium and other fluids widens as the working condition deviation increases. [ABSTRACT FROM AUTHOR]