A numerical investigation of moment coefficient and flow structure in a rotor-stator cavity with rotor-mounted bolts

摘要

The torque associated with overcoming the losses on a rotating disc is of particular importance to the designers of gas turbine engines. Not only does this represent a reduction in useful work, but it also gives rise to unwanted heating of metal surfaces and the adjacent fluid. This paper presents a numerical study on the effect of rotor-mounted bolts on the moment coefficient and velocity distributions within a rotor-stator cavity under conditions representative of modern gas turbine engine design. Steady-state, 2D and 3D, CFD simulations are obtained using the FLUENT commercial code with a standard k- turbulence model. The model is validated against experimental data and then used to investigate the effects of varying the number of bolts and also a continuous ring. Two test cases are investigated: one corresponds to where the flow structure is dominated by the superimposed flow (T = 0.35); the other, where rotation is expected to govern the flow structure (T = 0.35). It is possible to separate out the contributions due to skin friction and pressure related (form drag and pumping loss) in the CFD results. This shows that the contribution of skin friction to the overall moment coefficient reduces as the number of bolts increases and the pressure related losses increase. There also appears to be a Covering Letter point where increasing the number of bolts does not bring about an increase in the overall moment coefficient. It is also interesting to report that the moment coefficient associated with a continuous ring is similar to that for a\udplain disc.