Influence of fillet shapes on secondary flow field in a transonic axial flow turbine stage

Ananthakrishnan, K.; Govardhan, M.

doi:10.1016/j.ast.2018.08.040

Cited by 46 publications

(20 citation statements)

References 27 publications

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“…The optimization was achieved using steady simulations; therefore, the computation domain was comprised of 1 stator and 1 rotor passage, as shown in Figure 2. It is worth mentioning that the secondary flows can be influenced by the presence of fillets and their shapes [21,22]. However, this study was focused on the mitigation of secondary flows due to non-axisymmetric endwalls; therefore, the presence of fillets was not accounted for.…”

Section: Grid Topologymentioning

confidence: 99%

Secondary Flow and Endwall Optimization of a Transonic Turbine

2019

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A detailed numerical analysis of secondary flows in a transonic turbine is presented in this paper. The turbine stage is optimized by mitigating secondary flow through the method of non-axisymmetric endwall design. An automated optimization platform of NUMECA/Design3D was coupled with Euranus as a flow solver for the numerical investigation. The contoured endwalls of the stator and the rotor hub were designed based on equidistant Bézier curves along the camber line in the blade channel. The initial design samples were ten times the number of the design variables, and were generated through the LHS method for database generation. The optimization of the endwalls was achieved by using a state-of-the-art multi-objective optimization algorithm, NSGA-II, connected with the BPNN to increase the isentropic efficiency and decrease the secondary kinetic energy, while the mass flow and the degree of reaction were constrained to remain on the datum value as in the original geometry. The individual optimization of the hub endwalls of the stator and the rotor produced an increase in the efficiency of 0.27% and 0.25%, respectively, resulting in a cumulative improvement of 0.46% in the efficiency. The increase in the performance was analyzed at part-load conditions, and it was further confirmed through unsteady simulations.

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Section: Grid Topologymentioning

confidence: 99%

Secondary Flow and Endwall Optimization of a Transonic Turbine

2019

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“…The mean span wise velocity field is observed to be much more related to cross flow turbine's wake recovery. Guide lines for the design optimization of efficient high supersonic passages were also derived [18][19][20].…”

Section: Numerical Analysis Of Axial Flow Turbinementioning

confidence: 99%

The Numerical Simulation and Evaluation of Aircraft Engine Axial Flow Turbine using Numerical Techniques

al.¹

2019

IJMPERD

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This research aims to improve the efficiency of an axial flow turbine by improving the boundary conditions. In the baseline paper, Sherwood number, Nusselts number for a given flow were determined. The pressure ratio was not considered in the paper. Research has been done to improve the values by considering the pressure difference which was neglected in the base line paper. Axial flow turbines expand the flow passing through it. Losses like tip losses, efficiency losses and loss on blades due to heat are high and needs to be looked after. A comprehensive literature study was carried out for the better understanding of axial flow turbines, recent developments and to analyze the control of loses.

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“…In summary, blade lean and sweep design are widely used in compressor and turbine blades [23,24]; however, these approaches are rarely applied to water pumps, in particular, the bowl diffuser. The present study aimed to address these limitations by applying the design ideas and methods used for pneumatic machinery to the bowl diffuser of a multistage submersible pump.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Sweep and Blade Lean for Diffuser to Suppress Hub Corner Vortex in Multistage Pump

et al. 2021

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The bowl diffuser is the main flow component in multistage submersible pumps; however, secondary flow fields can easily induce a separation vortex in the hub corner region of the bowl diffuser during normal operation. To explore the flow mechanism of the hub corner separation vortex and develop a method for suppressing hub corner separation vortices, the lean and sweep of the diffuser blade were optimized using computational fluid dynamics (CFD) simulations and central composite design. Diffuser efficiency, static pressure recovery coefficient, and non-uniformity were selected as the optimization objectives. Details of the internal flow were revealed and the collaborative response relationships between blade lean/sweep parameter equations and optimization objectives were established. The optimization results show that a greater pressure difference between the pressure surface and suction surface (PS–SS) at the inlet can offset transverse secondary flow, whereas a lower PS–SS pressure difference will cause a drop in low-energy fluid in the diffuser mid-section. The blade’s lean scheme suppresses the hub corner separation vortex, leading to an increase in pressure recovery and diffuser efficiency. Moreover, optimizing the sweep scheme can reduce the shroud–hub pressure difference at the inlet to offset spanwise secondary flow and enhance the hub–shroud pressure difference at the outlet, thus driving low-energy fluid further downstream. The sweep scheme suppresses the hub corner vortex, with a resulting drop in non-uniformity of 13.1%. Therefore, optimization of the diffuser blade’s lean and sweep can result in less low-energy fluid or drive it further away from hub, thereby suppressing the hub corner vortex and improving hydraulic performance. The outcomes of this work are relevant to the advanced design of bowl diffusers for multistage submersible pumps.

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Influence of fillet shapes on secondary flow field in a transonic axial flow turbine stage

Cited by 46 publications

References 27 publications

Secondary Flow and Endwall Optimization of a Transonic Turbine

Secondary Flow and Endwall Optimization of a Transonic Turbine

The Numerical Simulation and Evaluation of Aircraft Engine Axial Flow Turbine using Numerical Techniques

Optimization of Sweep and Blade Lean for Diffuser to Suppress Hub Corner Vortex in Multistage Pump

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