An investigation of the flowfield through a variable geometry turbine stator with vane endwall clearance

Spence, Stephen; O'Neill, J.W.; Cunningham, Geoffrey

doi:10.1243/09576509jpe171

Cited by 16 publications

(7 citation statements)

References 9 publications

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“…A hub endwall clearance of 0.215mm was introduced and an H/J/C/L grid type in conjunction with an O-Grid of width factor 0.2 was used as it was found to yield the best results in terms of mesh skewness. The number of elements was set to 280,000, and the tip clearance was modelled with 10 equispaced node points, which are similar values to those employed by Spence et al, 2006 [9]. Furthermore, as the SST turbulence model was employed, a y + value close to unity was required in order to resolve the details in the boundary layer.…”

Section: Computational Methodologymentioning

confidence: 99%

A Comparison of flow control devices for variable geometry turbocharger application

Pesiridis¹,

Vassil²,

Padzillah³

et al. 2014

IJAET

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In this paper the aerodynamic performance of two common variable geometry inlet flow control devices for use in turbocharger turbines is investigated, namely: the pivoting vane and sliding wall flow restrictors, as well as a combination of the two mechanisms at the inlet to the turbine rotor, acting as coupled Active Control Turbocharger (ACT)/ Variable Geometry Turbine (VGT) mechanisms in series (one mechanism providing instantaneous area flow control for ACT -an instantaneous exhaust energy recovery capability; the other providing optimum mean nozzle position in conventional VGT mode), using computational fluid dynamics (CFD) techniques. The latter coupled study was carried out with the purpose to explore a more optimal application of turbine inlet flow control to an advanced ACT system. Numerical models of the stator passages for the different mechanisms were developed and a study of the flow unsteadiness based on the Strouhal number was performed. The latter found that the flow was quasi-steady allowing transient conditions to be modelled by superposition of steady state scenarios. The numerical models were subsequently validated using experimental data. An investigation of the NACA profile thickness of the pivoting vanes was also undertaken, the findings of which indicated that a NACA thickness of 0018 constituted the optimum compromise between increased velocity and incurred losses. The results for the pivoting vane simulations demonstrated the effect of loss mechanisms such as leakage and flow separation. It was established that the 65° vane angle delivered the highest velocity to the rotor, corroborating the earlier research findings. In the case of the coupled mechanisms, the main loss generating flow structure was found to be the large wake produced by the sliding wall, which significantly increased the inefficiencies through the stator. In comparison, the pivoting vane mechanism exhibited substantially lower levels of pressure losses and delivered higher velocities to the rotor.

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Section: Computational Methodologymentioning

confidence: 99%

A Comparison of flow control devices for variable geometry turbocharger application

Pesiridis¹,

Vassil²,

Padzillah³

et al. 2014

IJAET

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“…Several early studies have shown that at small nozzle openings, turbine stage performance is seriously affected by nozzle endwall leakage flow. 9–14 In case the length of the nozzle endwall clearance can be reduced effectively, there will be a great mitigation in nozzle leakage flow rate. Based on this idea, the FRGV design is carried out.…”

Section: Research Modelmentioning

confidence: 99%

“…Some studies highlighted the characteristics of nozzle leakage flow by CFD methods. Research works of Spence et al 11 and Walkingshaw et al 12 indicated that the nozzle leakage flow interacted with the main flow to produce continuous dissipating leakage vortex, which then causes flow losses. Besides that, the characteristics of leakage vortex also varied considerably with guide vane position.…”

Section: Introductionmentioning

confidence: 99%

A detailed investigation of a variable nozzle turbine with novel forepart rotation guide vane

Yang

Lao

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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One of the disadvantages of a variable nozzle turbine in practical application is the stage performance degradation due to nozzle endwall leakage flow at small nozzle openings. Aiming at restricting the nozzle leakage flow rate to improve turbine stage performance, a novel forepart rotation guide vane has been proposed and numerically studied in present work. First, the numerical results of baseline turbine were validated by experimental data to ensure the accuracy of numerical methods. Then steady and unsteady simulations were performed on both baseline and forepart rotation guide vane turbines to demonstrate the effectiveness of the novel vane and to study the characteristics of nozzle leakage flow, respectively. Results indicate that there is up to 13.5% peak efficiency improvement that has been achieved at 10% nozzle opening with the forepart rotation guide vane design; besides, rotor–stator interaction for forepart rotation guide vane is also mitigated due to the reduced nozzle leakage flow rate, thus the intensity of loading fluctuation on rotor blades is weakened significantly, which is beneficial to improve rotor blade forced response.

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“…Figure 5 shows the three vane angle settings used in the testing and the measured surfaces. The suction and pressure surfaces are indicated similar to the reference [13].…”

Section: Vane Surface Static Pressure Surveymentioning

confidence: 99%

Variable Geometry Mixed Flow Turbine for Turbochargers: An Experimental Study

Rajoo

Martinez-Botas

2008

International Journal of Fluid Machinery and Systems

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This paper investigates a variable geometry (VG) mixed flow turbine with a novel, purposely designed pivoting nozzle vane ring. The nozzle vane ring was matched to the 3-dimensional aspect of the mixed flow rotor leading edge with lean stacking. It was found that for a nozzle vane ring in a volute, the vane surface pressure is highly affected by the flow in the volute rather than the adjacent vane surface interactions, especially at closer nozzle positions. The performance of the VG mixed flow turbine has been evaluated experimentally in steady and unsteady flow conditions. The VG mixed flow turbine shows higher peak efficiency and swallowing capacity at various vane angle settings compared to an equivalent nozzleless turbine. Comparison with an equivalent straight vane arrangement shows a higher swallowing capacity but similar efficiencies. The VG turbine unsteady performance was found to deviate substantially from the quasi-steady assumption compared to a nozzleless turbine. This is more evident in the higher vane angle settings (smaller nozzle passage), where there are high possibility of choking during a pulse cycle. The presented steady and unsteady results are expected to be beneficial in the design of variable geometry turbochargers, especially the ones with a mixed flow turbine.

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An investigation of the flowfield through a variable geometry turbine stator with vane endwall clearance

Cited by 16 publications

References 9 publications

A Comparison of flow control devices for variable geometry turbocharger application

A Comparison of flow control devices for variable geometry turbocharger application

A detailed investigation of a variable nozzle turbine with novel forepart rotation guide vane

Variable Geometry Mixed Flow Turbine for Turbochargers: An Experimental Study

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