Rolls-Royce Motor Cars

About: Rolls-Royce Motor Cars is a based out in . It is known for research contribution in the topics: Turbine & Gas compressor. The organization has 3845 authors who have published 4934 publications receiving 58973 citations. The organization is also known as: Rolls-Royce Motor Cars Limited.

The formation of columnar joints produced by cooling in basalt at Staffa, Scotland

Abstract: Columnar jointing in basaltic lava flows on the island of Staffa, NW Scotland, was studied using a combination of field mapping and measurement of column dimensions, sample petrology and measurements of plagioclase crystal size distributions (CSDs) interpreted using theoretical models of cooling. Four different lava flow units were measured, and column ordering was assessed using the hexagonality index and relative standard deviations of column side length, top area and internal angle. Upper and lower colonnades consist of dominantly 5-, 6- and 7-sided columns, with a hexagonality index value very similar to that of Giant’s Causeway and other basaltic columnar jointed localities. CSDs from samples at different heights within one colonnade were used to infer the propagation of the solidus isotherm, which was consistent with a convective cooling mechanism within the colonnade interior. Sample petrology and CSD measurements suggest that entablature can form both by the interaction of propagating joint sets and flooding of the flow surface by water, and the most widely exposed unit on Staffa shows evidence of both mechanisms operating on the same flow. Crystal size distribution measurements can provide a useful tool for field interpretation of lava flow cooling mechanisms.

A novel gate assisted circuit to reduce switching loss and eliminate shoot-through in SiC half bridge configuration

Abstract: The trend towards SiC-based high power density converter requires to drive SiC MOSFET with high-speed switching. However, it tends to aggravate dv/dt effect due to the impact of parasitic parameters, resulting in shoot-through and high device stress in the half bridge configuration. In this work, a novel gate assisted circuit is proposed to eliminate shoot-through issue without compromise on switching speed. The mathematical model for the gate assisted circuit is developed. Then the switching test experiment is set up to validate its performance with commercial SiC half bridge module, which shows a high dv/dt up to 20 and 31 V/ns at turn-on and turn-off respectively and a 34% reduction of switching loss without any shoot-through issue.

Blade track assembly with turbine tip clearance control

Abstract: A turbine shroud or blade track assembly adapted to extend around a turbine wheel assembly is disclosed. The turbine shroud includes a carrier and a blade track coupled to the carrier. The blade track is movable between a radially-inward position having a first inner diameter and a radially-outward position having a second inner diameter larger than the first inner diameter.

Effect of substrate surface condition on fatigue behavior of cold sprayed Ti6Al4V coatings

Abstract: Ti6Al4V coatings were deposited on Ti6Al4V substrates by using a high pressure cold spray system. Before deposition, the substrate surfaces were prepared with four different surface preparation methods, namely, grinding, milling, sand blasting and water-jet cutting. The fatigue behavior of the coated specimens was studied with three point-bending-fatigue test. The fracture characteristics of the specimens were observed by using scanning electron microscopy. The surface roughness and its effect on the crack initiation and propagation in the coatings were also investigated. The results indicated that the fracture mode of the coated samples was interface cracking. At two different stress levels such as 420 and 360 MPa, the samples with the coatings deposited on the ground surfaces survived the longest fatigue life before failure, while the samples with the coatings deposited on the water-jet cut surfaces survived the shortest fatigue life. It was clearly shown that the fatigue strength of the cold sprayed Ti6Al4V coatings was strongly affected by the both spraying and substrate surface preparation conditions.