Mechanical & Manufacturing Eng (Scholarly Publications)
http://hdl.handle.net/2262/208
Mechanical & Manufacturing Eng (Scholarly Publications)2024-03-29T06:14:11ZInvestigating the Suitability of Multi-Scroll Volutes for Improving Spanwise Incidence of Mixed Flow Turbine Rotors With Varying Blade Cone Angles in Automotive Turbocharging Applications
http://hdl.handle.net/2262/105928
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
Stuart, Charles; Spence, Stephen
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.
PUBLISHED
2024-01-01T00:00:00ZBinder evaporation during powder sheet Additive Manufacturing
http://hdl.handle.net/2262/104429
Binder evaporation during powder sheet Additive Manufacturing
Lupoi, Rocco
Several Additive Manufacturing methods are well established and found access into regular production in
multiple sectors. For processing metals, typically wire or powder is used as feedstock. Wire processing is typically
used for comparably large structure building, while powder processes offer, in general, a more precise metal
application. For Powder Bed Fusion processes, very fine powder is used (typical 20 μm to 65 μm), while for
Directed Energy Deposition powders are in the range between 50 μm and 160 μm. Such fine powders can be a
health risk for humans (aspiration, skin integration). Avoiding contact with the powders in a production
environment can be a big effort or not avoidable. Therefore, an alternative process was developed that provides
the powder not as free powder particles but in form of powder sheets. For enabling the necessary bonding between
the particles, a binder is used. In order to understand the impact of the binder during laser processing of the powder
sheets, single pulse and line treatments were produced and recorded with high-speed imaging. Recordings show
the vaporization of the binder and the related ejections of powder particles. At lower energy input, the binder
evaporation led to less spattering, which indicates that a binder heating at low heating rates induces less pressure
on the powder particles.
2023-01-01T00:00:00ZEnergy Analysis of Fleet Operations using Green Liquid Hydrogen and Synthetic Sustainable Aviation Fuel
http://hdl.handle.net/2262/104423
Energy Analysis of Fleet Operations using Green Liquid Hydrogen and Synthetic Sustainable Aviation Fuel
Stuart, Charles; Gallagher, Conor; Spence, Stephen
Aircraft designs are changing more rapidly than ever, due to the disruptive technology revolution required to curb harmful emissions, and meet stringent climate targets. As a result, the role of conceptual design tools is evolving, shifting away from the tried-and-tested empirical models and theoretical design missions, to rapid, low-fidelity physics-based models that can accurately assess a range of unconventional, aircraft designs. This study presents an innovative conceptual design methodology, based on advanced conceptual design techniques observed in recent years, which enables the rapid assessment of novel technologies on a real-world airline operation schedule.
An automated simulation framework was developed to accurately model real-world flights, incorporating actual take-off weights and flight paths, followed by a validation and calibration of this simulation framework to ensure accuracy with respect to real flight data. Using the novel methodology, a comparative energy analysis was performed, measuring the ‘well-to-wake’ energy consumption of fleet operations, when powered using green liquid hydrogen (LH2) and synthetic sustainable aviation fuel (e-SAF), both which are produced using 100% renewable electricity.
Despite significant in-flight performance penalties, substantial ‘well-to-wake’ energy savings could be achieved for hydrogen aircraft, which may be desirable to reduce operating costs, and the significant strain placed on renewable electricity resources. Furthermore, it was found that a tank gravimetric efficiency of 50% was sufficient for superior energy performance of hydrogen aircraft against all e-SAF scenarios, highlighting the potential of green hydrogen to minimise the energy demand and operating cost of short-haul operations in the context of decarbonisation.
2023-01-01T00:00:00ZHow 110 Years of Turbocharging Changed the World
http://hdl.handle.net/2262/104352
How 110 Years of Turbocharging Changed the World
Stuart, Charles
PUBLISHED
2015-01-01T00:00:00Z