Numerical investigation of fluid flow in protruded rotor- stator cavities

Roshani Moghaddam, Elham (2015) Numerical investigation of fluid flow in protruded rotor- stator cavities. Doctoral thesis (PhD), University of Sussex.

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Abstract

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.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Subjects: T Technology > TA Engineering (General). Civil engineering (General) > TA0349 Mechanics of engineering. Applied mechanics > TA0357 Applied fluid mechanics
T Technology > TJ Mechanical engineering and machinery > TJ1040 Machinery exclusive of prime movers > TJ1058 Rotors
Depositing User: Library Cataloguing
Date Deposited: 01 Jun 2015 05:27
Last Modified: 28 Sep 2015 14:15
URI: http://sro.sussex.ac.uk/id/eprint/53891

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