Understanding of the Interaction between Clearance Leakage Flow and Main Passage Flow in a VGT Turbine

Zhao, Ben; Yang, Ce; Hu, Liangjun; Sun, Harold; Yi, James; Eric, Curtis; Shi, Xiuyong; Engeda, Abraham

doi:10.1155/2014/652769

Cited by 17 publications

(13 citation statements)

References 11 publications

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“…In Figure 4(a), the predicted efficiency against mass flow is 2.5% higher than the experimental data from literature. 10 From Figure 4(b), it can be seen that the predicted expansion ratios show the same trend with the experimental results, but with a relative difference of 3.5% in mass flow. Those deviations are possibly due to the simplifications of the numerical model.…”

Section: Validation Of the Computational Fluid Dynamics Methodssupporting

confidence: 69%

“…In this study, the total clearance height, C shroud + C hub , is the same, about 3% of widths of nozzle passage ( h ). This value was selected according to the result reported by Zhao et al 10 that, with such clearance height, the intensity of the shock wave is very high.…”

Section: Vnt Model Illustrationmentioning

confidence: 99%

“…Similar result was also reported by Shi et al 8 and Zhao et al 9 Besides turbine performances, the effect of nozzle endwall clearances on unsteady flow has been analyzed as well. Zhao et al 10 investigated a variable geometry turbine with different sizes of the endwall clearance which was divided equally at two ends of nozzle vanes. It was reported that the shock wave from the nozzle exit varies with the changed nozzle endwall clearance height.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Variable nozzle turbocharger turbine performance improvement and shock wave alternation by distributing nozzle endwall clearances

Zhao

Sun

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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Effects of nozzle endwall clearances on variable nozzle turbocharger turbine performances have been widely studied, but improving the variable nozzle turbocharger efficiency utilizing an optimal distribution of nozzle endwall clearances between the hub and the shroud sides has not drawn wide attention. Meanwhile, with the various distributions, shock wave variations that are closely related to turbine reliability are rarely reported. To fill the gap, this research performed three-dimensional numerical simulations on a variable nozzle turbocharger turbine to analyze the effects of various nozzle endwall clearance distributions on both turbine performance and shock wave. The results showed that there is an optimal distribution of the nozzle endwall clearance that can improve turbine efficiency and shift nozzle trailing edge shock wave. Performed on a linear turbine nozzle and with detailed validations, both experimental measurements and numerical simulations provide evidence that supports the numerical analyses conducted on a variable nozzle turbocharger turbine.

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Section: Validation Of the Computational Fluid Dynamics Methodssupporting

confidence: 69%

Section: Vnt Model Illustrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Variable nozzle turbocharger turbine performance improvement and shock wave alternation by distributing nozzle endwall clearances

Zhao

Sun

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…Four grooves were clustered around the midspan of the nozzle vane, and each of them has the same distance to two ends of the nozzle vane, as shown in Figure 2, for the shock wave is mostly the strongest at midspan. 18 The grooves have different lengths that descend along the streamwise direction, the upstream groove being the longest one (about 6.8 mm) and the downstream one being the shortest one. The change in the groove length between the two adjacent grooves is about 1.0 mm.…”

Section: Investigated Modelsmentioning

confidence: 99%

Effects of grooved vanes on shock wave and forced response in a turbocharger turbine

Zhao

Shi

Sun

et al. 2019

International Journal of Engine Research

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In radial inflow turbine design, the optimization of turbine geometry for aerodynamic performance improvement is often constrained by the requirement of reliability, thus facing a trade-off. One of the vital challenges for a better trade-off is how to mitigate the forced response of turbine wheel, while maintaining high efficiency, so as to avoid high cycle fatigue failure. In this article, using a grooved surface on nozzle vanes for the forced response reduction was investigated. In light of the fact that the investigation on the high cycle fatigue issue involves both aerodynamic interactions and structural analyses, a customized computer code was developed using MATLAB software to couple computational fluid dynamics simulations with finite element analysis calculations. Partial results were compared against experimental results, respectively, to validate the numerical method. The coupled numerical method reveals that using the grooved surface on the nozzle vane alters the shock wave structure, decreases the peak stress of turbine wheel by 8%, and deteriorates turbine efficiency by 0.05 percentage points.

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“…Numerical computational fluid dynamics (CFD) simulations [13][14][15][16][17][18] have been widely used to investigate VGT performance and internal flow benefiting from the cost and time savings. In these investigations, VGT positions were controlled artificially and actively.…”

Section: Introductionmentioning

confidence: 99%

A novel variable geometry turbine achieved by elastically restrained nozzle guide vanes

Wang

Huang

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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Variable geometry turbocharging is one of the most significant matching methods between turbocharger and engine, and has been proven to provide air boost for entire engine speed range as well as to reduce turbo-lag. An elastically constrained device designed for a novel variable geometry turbocharger was presented in this paper. The design of the device is based on the nozzle vane’s self-adaptation under interactions of the elastic force by elastically restrained guide vane and the aerodynamic force from flowing gas. The vane rotation mechanism of the novel variable geometry turbocharger is different from regular commercial variable geometry turbocharger systems, which is achieved by an active control system (e.g. actuator). To predict the aerodynamic performance of the novel variable geometry turbocharger, the flow field of the turbine was simulated using transient computational fluid dynamics software combined with a fluid–structure interaction method. The results show that the function of elastically constrained device has similar effectiveness as the traditional variable geometry turbocharger. In addition, the efficiency of the novel variable geometry turbocharger is improved at most operating conditions. Furthermore, a turbocharged diesel engine was created using the AVL BOOST software to evaluate the benefits of the new variable geometry turbocharger. The proposed novel variable geometry turbocharger can effectively improve the engine performance at mid-high speeds, such that the maximum decrease of brake-specific fuel consumption reaches 17.91% under 100% load and 3600 r/min engine condition. However, the engine power and brake-specific fuel consumption decrease significantly at low engine speed conditions, and the decrease is more than 26% under 1000 r/min.

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Understanding of the Interaction between Clearance Leakage Flow and Main Passage Flow in a VGT Turbine

Cited by 17 publications

References 11 publications

Variable nozzle turbocharger turbine performance improvement and shock wave alternation by distributing nozzle endwall clearances

Variable nozzle turbocharger turbine performance improvement and shock wave alternation by distributing nozzle endwall clearances

Effects of grooved vanes on shock wave and forced response in a turbocharger turbine

A novel variable geometry turbine achieved by elastically restrained nozzle guide vanes

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