Rolls-Royce Holdings

About: Rolls-Royce Holdings is a company organization based out in Derby, United Kingdom. It is known for research contribution in the topics: Turbine & Gas compressor. The organization has 4027 authors who have published 6305 publications receiving 80517 citations. The organization is also known as: Rolls-Royce Holdings plc.

Factors affecting influenza vaccine uptake among health care workers

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Permanent magnet generator options for the More Electric Aircraft

Abstract: This study has shown that a permanent magnet generator coupled with a PWM voltage source converter will adequately meet the LP shaft generator requirements for a future More Electric Aircraft. It also adequately satisfies the requirements for wide speed range control and fault tolerance, although it should be noted that full fault tolerance only seems achievable with a direct drive (nongeared) generator. The direct drive machine is suitable for either oil or air cooling, the oil-cooled option being smaller and lighter, even after taking into account the additional converter and cable weight arising from its increased reactance. The geared machine offers a net weight saving of 16% (compared with oil-cooled direct drive) but its fault tolerance is limited to open circuit faults and loss of drive in the power converter only. The study has firmly established the feasibility of permanent magnet generators for the More Electric Aircraft; however further work is required, most notably the estimation of rotor stray loss and the study of power system stability and protection.

Thermally sprayed coating systems for surface protection and clearance control applications in aero engines

Abstract: The principal current and new thermal spray coating processes used for compressor, combustion chamber and turbine applications in aero engines are described with particular reference to high velocity combustion and plasma spraying techniques. The uses of coatings for wear and erosion resistance, oxidation and corrosion control, thermal barrier applications and gas path sealing (clearance control) are discussed.

Experiments in active control of stall on an aeroengine gas turbine

Abstract: This paper describes work carried out between 1989 and 1994 to investigate the application of Active Stall Control to a Rolls-Royce Viper turbojet. The results demonstrate that stall control is feasible and can increase the stable operating range by up to 25 percent of pressure rise. Stall disturbances were detected using rings of high response pressure transducers positioned at different axial planes along the compressor, and processed using a PC-based data acquisition and control system. Actuation was provided by six hydraulically operated sleeve valves positioned to recirculate air over all or part of the compressor. Stall was artificially induced using combinations of in-bleed into the combustor outer casing, fuel spiking, hot gas ingestion, and inlet pressure spoiling, thus replicating many of the transient conditions commonly observed to make a compressor prone to stall. Results are compared from a number of stall control strategies including those demonstrated at low speed by Paduano et al. (1993) and Day (1993). Best results were obtained with detection of nonaxisymmetric disturbances coupled with axisymmetric control action. A control system of this type is demonstrated to be capable of extending the stable engine operating range at all speeds and with each method of inducing stall.

Design of a nickel-base superalloy using a neural network

Abstract: A new computational tool has been developed to model, discover, and optimize new alloys that simultaneously satisfy up to eleven physical criteria. An artificial neural network is trained from pre-existing materials data that enables the prediction of individual material properties both as a function of composition and heat treatment routine, which allows it to optimize the material properties to search for the material with properties most likely to exceed a target criteria. We design a new polycrystalline nickel-base superalloy with the optimal combination of cost, density, gamma' phase content and solvus, phase stability, fatigue life, yield stress, ultimate tensile strength, stress rupture, oxidation resistance, and tensile elongation. Experimental data demonstrates that the proposed alloy fulfills the computational predictions, possessing multiple physical properties, particularly oxidation resistance and yield stress, that exceed existing commercially available alloys.