Investigating the Suitability of Multi-Scroll Volutes for Improving Spanwise Incidence of Mixed Flow Turbine Rotors With Varying Blade Cone Angles in Automotive Turbocharging Applications
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Journal ArticleDate:
2024Access:
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Peter Martin, Stephen Spence, Charles Stuart, Thomas Leonard, Andre Starke, Marco Geron, Investigating the Suitability of Multi-Scroll Volutes for Improving Spanwise Incidence of Mixed Flow Turbine Rotors With Varying Blade Cone Angles in Automotive Turbocharging Applications, ASME Journal of Turbomachinery, 146, 6, 2024Download Item:
Abstract:
Targets to reduce fuel consumption and reduce CO2 emissions have been met using engine
downsizing and turbocharging. In automotive applications, it is important that the turbo charger responds well to transient events and operates efficiently at both the design and
off-design conditions. A mixed flow turbine (MFT) is not constrained to a radial inlet
blade angle, allowing the peak efficiency to be shifted to a lower U/C_is, providing addi tional freedom to the designer. As the MFT leading edge varies in radius, the spanwise inci dence angle also varies, leading to additional separation on the suction surface (SS) of the
blade near the hub because of increasingly positive incidence, which is most noticeable at
off-design conditions. A multi-scroll volute was previously paired with an MFT with a
45-deg blade cone angle (Λ), which generated a non-uniform spanwise flow that improved
efficiency at off-design at the cost of peak efficiency. The current study identified the range of
blade cone angles that benefitted from a multi-scroll volute to reduce incidence at the hub
region. A numerical investigation was conducted, which determined the influence a multi scroll volute can have on MFTs with varying levels of blade cone angle. When the MFT with
a large blade cone angle (Λ=60 deg) was paired with a multi-scroll volute, the efficiency
improved by 2.2%pts at design and 0.5%pts at off-design conditions. The incidence
improved, and the mass flowrate increased at the hub region. The MFT with a smaller
blade cone angle (Λ =30 deg) had performance losses at both operating conditions
because the multi-scroll volute increased incidence within the hub region, which reduced
the peak efficiency by 1.3%pts. The off-design condition had an excessively positive inci dence angle, which was further increased at the hub region by the multi-scroll volute.
This resulted in a 0.8%pts reduction in off-design efficiency. The multi-scroll volute
concept was shown to offer efficiency improvements for MFTs with larger blade cone
angles through better management of the non-uniform spanwise velocity distribution at
the rotor inlet.
Author's Homepage:
http://people.tcd.ie/stuartchhttp://people.tcd.ie/spences
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PUBLISHED
Author: Stuart, Charles; Spence, Stephen
Type of material:
Journal ArticleSeries/Report no:
ASME Journal of Turbomachinery;146;
6;
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Full text availableKeywords:
automotive, turbine, multi-scroll, mono-scroll, volute, MFT, computational fluid dynamics (CFD)Subject (TCD):
Smart & Sustainable PlanetDOI:
https://doi.org/10.1115/1.4064339Metadata
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