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 research presents a numerical study on the effect of rotor-mounted bolts on the moment coefficient and flow structure within a rotor–stator cavity under conditions representative of modern gas turbine engine design. Steady-state, two-dimensional and three-dimensional, computational fluid dynamics simulations are obtained using the FLUENT commercial code with a standard (k–ω) turbulence model. The model is firstly validated against experimental data and then used to study the effects of presence of rotormounted hexagonal bolts in the rotor-stator cavity under investigation using different dimensionless flow parameters. Also investigated were the effects of changing the number and size of rotor-mounted bolts on the flow structure and amount of losses for two test cases; one corresponding a throughflow dominated condition and the other corresponding a rotationally dominated one. The simulation results showed that decreasing the throughflow rate reduces the area of the wake region causing the wakes to become more circumferential in their path around the bolts. Also it was found that increasing the number and diameter of bolts respectively reduces and increases the area of the wake region. For N>18 a separation bubble forms above the bolt which its length increases with increasing the number of bolts. The total moment coefficient of all bolts in the system increases with increasing the number of bolts. However, the rate of this increase reduces by mounting more bolts. While increasing the diameter of the bolts consistently increases the moment and drag coefficients for the rotationally dominated condition, for the throughflow dominated case an increase and a reduction was observed for respectively the moment and drag coefficients.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:647934 |
| Date | January 2015 |
| Creators | Roshani Moghaddam, Elham |
| Publisher | University of Sussex |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://sro.sussex.ac.uk/id/eprint/53891/ |
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