Kevin Reid

The interaction of turbine inter-platform leakage flow with the mainstream flow

Individual nozzle guide vanes (NGV???s) in modern aeroengines are often cast as a single piece with integral hub and casing endwalls. When in operation, there is a leakage flow through the chord-wise interplatform gaps. An investigation into the effect of this leakage flow on turbine performance is presented. Efficiency measurements and NGV exit area traverse data from a low-speed research turbine are reported. Tests show that this leakage flow can have a significant impact on turbine performance, but that below a threshold leakage fraction this penalty does not rise with increasing leakage flow rate. The effect of various seal clearances are also investigated. Results from steady-state simulations using a three-dimensional multiblock Reynolds-averaged Navier-Stokes solver are presented with particular emphasis paid to the physics of the mainstream/leakage interaction and the loss generation.

The effect of stator-rotor hub sealing flow on the mainstream aerodynamics of a turbine

An investigation into the effect of stator-rotor hub gap sealing flow on turbine performance is presented. Efficiency measurements and rotor exit area traverse data from a low speed research turbine are reported. Tests carried out over a range of sealing flow conditions show that the turbine efficiency decreases with increasing sealant flow rate but that this penalty is reduced by swirling the sealant flow. Results from time-accurate and steady-state simulations using a three-dimensional multi-block RANS solver are presented with particular emphasis paid to the mechanisms of loss production. The contributions toward entropy generation of the mixing of the sealant fluid with the mainstream flow and of the perturbed rotor secondary flows are assessed. The importance of unsteady stator wake/sealant flow interactions is also highlighted.Copyright

Reducing the Perfomance Penalty Due to Turbine Inter-Platform Gaps

Individual nozzle guide vanes (NGV’s) in modern aero engines are often cast as a single unit with integral hub and casing endwalls. When in operation there is a leakage flow through the chord-wise inter-platform gaps. A previous paper [1] has shown that these gaps can result in a stage efficiency penalty of 0.5% – 1.5% depending upon how well they are sealed. In this paper, numerical calculations are used to re-design the inter-platform gaps with the aim of minimizing their effect on the mainstream aerodynamics and hence reduce the efficiency penalty. Experiments using a full scale, low speed model turbine and an improved gap-design show that significant performance improvements are possible regardless of how well the gap is sealed.Copyright

The Interaction of Turbine Inter-Platform Leakage Flow With the Mainstream Flow

Individual nozzle guide vanes (NGVs) in modern aero engines are often cast as a single piece with integral hub and casing endwalls. When in operation there is a leakage flow through the chord-wise inter-platform gaps. An investigation into the effect of this leakage flow on turbine performance is presented. Efficiency measurements and NGV exit area traverse data from a low speed research turbine are reported. Tests show that this leakage flow can have a significant impact on turbine performance, but that below a threshold leakage fraction this penalty does not rise with increasing leakage flow rate. The effect of various seal clearances are also investigated. Results from steady-state simulations using a three-dimensional multiblock RANS solver are presented with particular emphasis paid to the physics of the mainstream/leakage interaction and the loss generation.Copyright

Representation of a small-scale nozzle for gas–liquid injections into a fluidized bed on a large-scale grid

Abstract A novel method for efficient computations of a fluidized bed reactor with liquid injections is developed. It allows economical simulations for a reactor that contains multiple nozzles using a relatively coarse grid, while still accounting for the influence of particular features of individual nozzles. The method relies on patching variables in the near nozzle area obtained on the fine nozzle-scale grid onto the coarse reactor-scale grid followed by the solution of the flow equations elsewhere in the coarse grid domain. The procedure is tested for a small fluidized bed that permits both fine and coarse grid solutions. It was found that the developed procedure represents the flow adequately and allows for the distinction of different nozzle geometries.