A numerical method is employed to study effects of convergence angle and dimple shape on flow structure and heat transfer under a rotating frame. The investigated convergence angles are 0.0 , 6.3 , and 12.7. The dimple shapes are circular, streamwise-elliptical, and spanwise-elliptical. The rotation number ranges from 0.0 to 0.4. Computed flow structures and heat transfer are compared. Higher rotation number generates better heat transfer in the dimple-pin wedge duct. The rotation direction also affects the flow structure and heat transfer. The spanwise-elliptical dimple shape shows best heat transfer augmentation as it generates the strongest vortex structure and turbulent kinetic energy in the dimples. Larger convergence angles exhibit larger Nusselt numbers and better heat transfer enhancement. Effects of the Coriolis force are considered as this force has favorable effects on enhancing the heat transfer on the surface it acts on.

The effects of flow coefficient on the gas flow and loss characteristics inside the high-pressure turbine is investigated using a numerical simulation. In this paper, the midspan of the first stator of the “Lisa” 1.5 stage high-pressure turbine is used as a prototype to obtain different flow coefficients by changing the stagger angle and the exit angle. The boundary conditions of all cases are consistent with the experimental data of “Lisa”. The results show that the flow coefficient is decreased from 0.478 to 0.374 as the stagger angle is varied from 44.2° to 56.2° and from 0.630 to 0.341 as the exit angle is varied from 63° to 75°. Large stagger angle or large exit angle both cause an increase in turbine aerodynamic losses. The similarity between the two is that both cause enhanced effect of transverse secondary flow in the passage. The difference is that with large stagger angle, the adverse pressure gradient affects a large area, resulting in large boundary layer losses; with large exit angle, the passage vortex is weakened but with a large influence area.

The sealing capacity and heat transfer characteristics of the straight-through labyrinth seal with different geometric parameters are analyzed in this paper through numerical investigation. The geometric parameters studied include the gap width varying from 2 mm to 6 mm, the tooth tip thickness varying from 1 mm to 3 mm, and the front inclination angle varying from 75° to 100°. For each case, the Reynolds number is varied from 10,000 to 40,000. According to the results, the sealing performance is mainly influenced by the gap width, and less affected by the tooth tip thickness and the front inclination angle. As the gap width is increased, the discharge coefficient is increased by about 40%. With the tip thickness or the front inclination angle increased, the discharge coefficient is increased by less than 5%. For the heat transfer of the end wall, the gap width has significant effects, while the effects of the other two parameters are mainly in the first tooth cavity. For the stator, the increased flow rate at the tooth tip results in enhanced local heat transfer. For the rotor, the heat transfer is determined by the vortex intensity in the tooth cavity. The presence of small secondary vortices weakens the local heat transfer.