Showing papers by "Rolls-Royce Motor Cars published in 2004"

Fault tolerance in multiphase propulsion motors

Abstract: This paper reviews the current state of marine electric propulsion motors, considers the benefits to be achieved by using a high phase number for excitation and considers the specific increased fault tolerance available through the use of a multiphase configuration. The multiphase work uses a generalised machine model of arbitrary phase number.

Ideas and Methods of Turbomachinery Aerodynamics: A Historical View

Abstract: Most accounts of the history of turbomachinery look at the machines that were produced. This paper looks at the underlying ideas behind the designs and the methods that were used. It will be seen that in this history the inventiveness of engine designers far outstripped the capabilities of these methods and, further, that this gap spurred the advancement of new ideas. Thus, although analyses were unable to capture many features of the flows, this has not precluded aeroengine turbomachinery from being successfully developed using methods that were far from a complete description. The paper concludes with a look at two different ways in which engineers have dealt with some turbomachinery aerodynamic issues that seemed to offer major difficulties at the time.

Seakeeping Analysis of a High-Speed Monohull With a Motion-Control Bow Hydrofoil

Abstract: The seakeeping performance is studied of a foil-assisted high-speed monohull vessel using a state-of-the-art three-dimensional Rankine panel method. The vessel is equipped with a bow hydrofoil acting as a passive heave and pitch motion-control device in waves. The formulation of the seakeeping of ships equipped with lifting appendages is developed, and the mechanisms responsible for the reduction of the heave and pitch motions of high-speed vessels equipped with hydrofoils are studied. The sensitivity of the heave and pitch motions on the longitudinal position of the hydrofoil is studied. It is found that the most efficient location for the hydrofoil is at the ship bow leading to a 50% reduction of the root mean square values of the heave and pitch motions in a Joint North Sea Wave Project (JONSWAP) spectrum. Several extensions of the analysis of the present paper are discussed. They include the reduction of the roll motion of high-speed vessels, the design of optimal active motion-control mechanisms, and the coupling of the hull form and lifting appendage design for high-speed monohull vessels.

Solidification characteristics of advanced nickel-base single crystal superalloys

Abstract: Twenty-two Ni-base superalloy compositions were investigated to assess the influence of the constituent elements on their solidification characteristics. Increasing the amount of Cr and Mo in high refractory single crystal alloys appears to reduce the extent of microsegregation of the dense refractory elements, W and Re. This is likely to be advantageous for maintaining single crystal solidification since alloys containing elevated levels of W and Re are prone to the formation of macroscopic grain defects during single crystal solidification. These findings suggest that elemental interactions between Cr, Mo, W and Re need to be considered when optimising alloys for high temperature creep properties. Ru additions also appear beneficial not only through stabilisation of the microstructure with respect to topological-close-packed (TCP) phase formation but also by reducing the degree to which Re partitions to the dendrite core. Linear regression has been applied to predict the solid-liquid partition coefficients for the major constituent elements and therefore provide an indication of the susceptibility of a given composition to freckle formation during directional solidification.

The effect of an upstream turbine on a low-aspect ratio vane

Abstract: The interaction between a high-pressure rotor and a downstream vane is dominated by vortex-blade interaction. Each rotor blade passing period two co-rotating vortex pairs, the tip-leakage and upper passage vortex and the lower passage and trailing shed vortex, impinge on, and are cut by, the vane leading edge. In addition to the streamwise vortex the tipleakage flow also contains a large velocity deficit. This causes the interaction of the tip-leakage flow with a downstream vane to differ from typical vortex blade interaction. This paper investigates the effect these interaction mechanisms have on a downstream vane. The test geometry considered was a low aspect ratio second stage vane located within a S-shaped diffuser with large radius change mounted downstream of a shroudless high-pressure turbine stage. Experimental measurements were conducted at engine-representative Mach and Reynolds numbers, and data was acquired using a fastresponse aerodynamic probe upstream and downstream of the vane. Time-resolved numerical simulations were undertaken with and without a rotor tip gap in order to investigate the relative magnitude of the interaction mechanisms. The presence of the upstream stage is shown to significantly change the structure of the secondary flow in the vane and to cause a small drop in its performance.© 2004 ASME

Passive Control of Combustion Instability in a Low Emissions Aeroderivative Gas Turbine

Abstract: This paper describes the conceptual ideas, the theoretical validation, the laboratory testing and the field trials of a recently patented fuel-air mixing device for use in high-pressure ratio, low emissions, gaseous-fueled gas turbines. By making the fuel-air mixing process insensitive to pressure fluctuations in the combustion chamber, it is possible to avoid the common problem of positive feedback between mixture strength and the unsteady combustion process. More specifically, a mixing duct has been designed such that fuel-air ratio fluctuations over a wide range of frequencies can be damped out by passive design means. By scaling the design in such a way that the range of damped frequencies covers the frequency spectrum of the acoustic modes in the combustor, the instability mechanism can be removed. After systematic development, this design philosophy was successfully applied to a 35:1 pressure ratio aeroderivative gas turbine yielding very low noise levels and very competitive NOx and CO measurements. The development of the new premixer is described from conceptual origins through analytic and CFD evaluation to laboratory testing and final field trials. Also included in this paper are comments about the practical issues of mixing, flashback resistance and autoignition.Copyright © 2004 by ASME

Control of a waterjet propelled vessel

Abstract: A method for controlling a watercraft includes acquiring a desired heading of the watercraft, acquiring an actual heading of the watercraft at time T0, calculating a heading error by comparing the desired heading with the actual heading and determining a rate of change of the heading error. A P gain, I gain and D gain for use in maintaining the heading of the watercraft is determined and used to calculate factors related to heading error, cumulative heading error and rate of change of heading error. These factors are summed to form a control value for deflecting a nozzle of the watercraft to maintain a heading of the watercraft. Further embodiments include methods for calculating and correcting a heading of the watercraft, as well as methods for controlling roll out and sideways motion of the watercraft.

A contribution to the understanding and prediction of jet noise generation in forced mixers

Abstract: In recent work on coplanar, coaxial jet noise prediction, single stream noise methods have been successfully employed to predict the noise contribution of each region of the jet plume and the results summed to calculate the total far-field noise spectrum. The objective of the present work is to extend this approach to the ‘buried’ nozzle configurations, in which initial mixing is constrained within a short pipe before both flows exit through a common nozzle. Two basic configurations are considered, the unforced, annular or confluent mixer, in which the primary nozzle is of circular cross-section and the lobed or forced mixer, in which the primary nozzle is of lobed form designed to promote more rapid mixing between the primary and secondary flows prior to the final nozzle. For the annular configuration very little mixing takes place between the primary and final nozzle exit planes. The mixing takes place externally, and the noise is consistent with the acoustic modelling described previously. The lowest frequencies are controlled by the fully mixed flow, while the remainder of the spectrum is due to the ‘effective jet’, that is the free mixing of the primary and secondary flows. For the forced or lobed mixer, the noise reduction at low frequencies, relative to the annular, is due to the fact that the primary flow has almost ‘mixed out’ prior to the final nozzle; an observation confirmed by aerodynamic surveys. The low frequency decrease is therefore limited to the levels of noise anticipated for the fully mixed flow. The penalty paid for forced mixing is an increase in noise at higher frequencies, which increases with increased penetration. The spectrum of this forced mixer noise source appears to correlate with the mixed jet Strouhal number and velocity, except for the highest Mach number condition, where an additional source is identified, termed the ‘high Mach number lift’. An initial modelling of the forced mixer noise source is presented, based on a mixed jet with an enhanced turbulence level, which is in reasonable agreement with the measured data.

Method for carburizing steel components

Abstract: A carburizing process for increasing the hardness of a case region of a steel component. In one form the application includes plating the outer surface of a stainless steel component with nickel prior to carburizing. One component includes a stainless steel object having a hardened case substantially free of continuous phase grain boundary carbides.

Fuel cell module

Abstract: A solid oxide fuel cell module comprises a hollow support member and a plurality of fuel cells spaced apart longitudinally on one surface of the hollow support member. A plurality of interconnectors electrically connect the fuel cells in electrical series. Each fuel cell comprises a first electrode, an electrolyte and a second electrode. The first electrode of each of the fuel cells are electrically connected to the second electrode of adjacent fuel cells by a plurality of interconnectors spaced apart laterally with respect to the hollow support member. A laterally extending end of the first electrode of the said adjacent fuel cell has a plurality of recesses spaced apart laterally with respect to the hollow support member. Each of the interconnectors is positioned in a respective one of the plurality of recesses in the laterally extending end of the first electrode of the said adjacent fuel cell.

Design of gas turbine engines using cfd

Abstract: This paper describes a general purpose design system being developed at Rolls- Royce plc. The key elements of the system are a parametric design and rapid meshing capability; a state-of-the-art CFD solver with an adjoint capability; and, an advanced op- timisation system consisting of a library of optimisers. A description is given of each element in the design system. To illustrate its use and flexibility, five dierent applica- tions of the system to a gas turbine are described. These are: optimisation of the guide vanes in the bypass duct to minimise excitation of the fan rotor; the same bypass guide vane optimisation using sensitivity gradients from the adjoint solver; optimisation of a compressor stage to improve eciency whilst constraining flow rate, pressure ratio and outlet flow angle; minimisation of the forced excitation of a turbine rotor by modifying the wake of the upstream nozzle guide vane; and, optimisation of a fan rotor to reduce tone noise.

A tem study of the effect of platinum group metals in advanced single crystal nickel-base superalloys

Abstract: Several effects of platinum group metal (PGM) additions to Nibase alloys were investigated using a transmission electron microscope (TEM). An experimental Re-containing alloy, Cantab17 (C17), was designed to reflect current third generation single crystal superalloys. Various levels of Ru, Rh, Ir, Pd and Pt were then systematically added to investigate the effects of these alloying elements. In addition to this, ternary Ni-19at%Al3at%PGM alloys were investigated. J/J’ phase partitioning ratios determined through TEM-EDS showed that for the C17-based alloys, Ru was the only PGM to partition to J, while elevated levels of Rh, Ir, Pd and Pt were observed to reside within the J’ phase. Atomic site location (Al site or Ni site) of the PGMs in Ni3Al were found through ALCHEMI (atomic site location by channelling enhanced microanalysis) on the ternary Ni-Al-PGM alloys. Results showed that Ru preferentially partitions to Al sites with the other PGMs invariably showing some preference for Ni sites. Finally, a mechanism is proposed to explain the correlation between J/J’ phase partitioning and J’ atomic site location of the PGMs in advanced superalloys.

ROSAS Wind Tunnel Test Campaign Dedicated to Unconventional Aircraft Concepts Study

Abstract: An extensive acoustic wind tunnel test campaign was conducted between March and September 2003 in the frame of the European research project ROSAS to assess experimentally the noise shielding effectiveness of classic airframe components for unconventional aircraft configurations for the first time ever in Europe. A complete aircraft model (1/11th-scale) was installed in the ONERA CEPrA19 anechoic wind tunnel, successively with a fan and a jet noise simulator representing the noise sources of an advanced, high bypass ratio turbofan. Various positions of the engine with respect to the airframe were tested with noise measurements being performed in the far field. The ROSAS test campaign has allowed gathering a comprehensive database on noise installation effects for novel aircraft concepts, yet with the shortcomings of the first of its kind. Hence the effects of the noise source characteristics, of a number of geometrical parameters and of the external flow were analyzed to some extent. Significant noise attenuation was evidenced as expected, and other secondary installation effects were also studied. This paper presents the ROSAS experiment, results and preliminary analyses of the acoustic shielding phenomena.

Influence of Fuel Composition on Solid Oxide Fuel Cell Hybrid System Layout and Performance

Abstract: The design of Solid Oxide Fuel Cell (SOFC) Hybrid Systems (HS) is usually based on the use of natural gas as fuel. However, the possibility of using other fuels such as biomass gasification, pyrolysis, fermentation, and coal gasification could potentially increase the market for SOFC Hybrid Systems. In this paper, the influence of fuel composition on both HS layout and performance is investigated. The analysis is based on a layout and a detailed simulation model of a Hybrid System based on Rolls-Royce Integrated Planar SOFC (IP-SOFC) technology fed with natural gas, previously developed by the authors. Particular attention has been given to the thermal management of the stack, the anode flow recirculation design and the turbine-compressor redesign, including safe surge margin operation conditions.Copyright © 2004 by ASME

Stability and transient-behavioural assessment of power-electronics-based dc-distribution systems

Abstract: Power-electronic systems are becoming increasingly important in marine engineering applications. Power electronics is stimulating new concepts and developments in electrical machines and distribution systems.Concomitant with such developments is usually a need for new methods for analysis and design activities. An increasingly serious contender for a power distribution system is a dc one. Such systems are well-known in satellite engineering. Inevitably they will become more important as fuel-cells become common in marine use. One problem with dcbased systems is that they are susceptible to instability, particularly when a constantpower regime is operating. Work on examining this problem is described by Sudhoff et al11 using a method based on the Nyquist stability criterion.The purpose of this paper is to demonstrate that an approach to this problem, based on the root-locus technique, is well worth considering. Not only does this technique produce indications of when to expect instability, but it also indi...

Progress in the Development of a Low Cost 1MW SOFC Hybrid

Abstract: Rolls-Royce Fuel Cell Systems (RRFCS) is developing a low cost 1MW fuel cell hybrid system package, supported by a prototype demonstration of a 250kW module in 2006. This paper describes the detailed design process that has been carried out to produce the fuel cell stack, tailored turbo-machinery and other plant components for this hybrid. Progress in demonstrating components is described. Component interfacing, operability and control challenges have been assessed prior to assembly of the complete system and are reviewed. The baseline plant will be highly efficient compared to incumbent power generation technologies but is primarily optimised around cost-reduction. Evolution of the product will include opportunities for further increases in efficiency and power density. Opportunities for improvement are discussed.Copyright © 2004 by ASME

On the Development of Semi-Empirical Noise Models for the Prediction of the Noise from Jets with Forced Mixers

Abstract: In recent years there has been a significant interest in the development of jet noise prediction models due to increased restrictions on aircraft noise near airports. However, currently there are no industry tools that can be used to predict the noise from the complex flows of modern jet engines that include internal forced mixers. The four-source method is a noise prediction tool applicable to simple coplanar, coaxial jets. In this study the fundamental components of the four-source model are used as the building blocks for a noise prediction method which would be applicable to coaxial jets with internal forced mixers. First, the four-source model is applied to an internally mixed jet with a confluent or axisymmetric mixer. A two-source noise model is then proposed to predict the noise for cases with an internal forced mixer. Three variable parameters in this two-source model are optimized to match the forced mixer experimental noise data. It is shown that the twosource noise model is capable of accurately modeling the noise spectra of internally mixed jets with forced mixers.

Water Injection: Disruptive Technology1 to Reduce Airplane Emissions and Maintenance Costs

Abstract: Water injection is an old aviation technology that was previously used to generate increased engine power during takeoff. If water injection were now to be used without increasing thrust, it could result in large reductions in takeoff NOx emissions and would most likely enable longer engine life and reduced operator costs. Due to the cooling action of evaporating water, a large temperature reduction will be experienced at the point where the water is injected into the engine. This could improve combustion emissions, such as temperature-sensitive NOx, and help reduce temperatures throughout the turbine section of the engine. The two current preferred methods of water injection are: (1) direct injection into the combustor, and (2) misting of the conditioned water before the engine's compressor. Combustor injection could achieve up to 90% NOx reduction and offer few implementation challenges as it has been used in aero-derivative industrial engines for over 30 years. For compressor water misting, the rate of water flow is limited to about 3% of the core air flow iii , and so could only achieve slightly more than 50% NOx reduction level but would offer larger reductions in turbine inlet temperature. Newer high bypass ratio (i.e. low fan pressure ratio) engines experience a higher thrust lapse rate as airplane altitude increases. This results in a longer period of time that the engine is operating at high core temperatures. In order to reduce these temperatures and improve engine life, both water injection systems were evaluated for use all the way to top of climb. Although the water misting system showed better engine performance results, the best solution may be the combustor injection method when used for takeoff only. This configuration results in minimal airplane payload weight penalties because it uses less than half the water of the compressor water misting method. The combustor water injection method reduces the turbine inlet temperature just enough during takeoff that it would greatly improve engine hot section life which would reduce engine maintenance costs. Any airplane costs and inconvenience associated with water injection are anticipated to be more than offset by engine maintenance savings. These savings may generate enough market demand that water injection could be developed as an optional airplane emissions reduction technology.

Remote monitoring system

Abstract: A remote monitoring system including a sub-system, local to a nuclear power plant and a remote sub-system at an operations base. Process data is collected manually by a hand-held computer and automatically by instrumentation on the power plant. The data collected is stored on a storage device before being transmitted via a communication link to a remote computer. The remote computer runs data analysis and diagnostic simulations on the process data from the power plant to predict future events.

Wear Resistant Polymer Matrix Composites for Aerospace Applications

Abstract: Polymer matrix composites (PMCs) are attractive for use in propulsion engine components due to their high specific strength. The use of composites could be even more advantageous if the sand erosion life of the component were extended, thereby reducing maintenance costs. NASA Glenn Research Center (NASA GRC) and Rolls-Royce Corporation have developed erosion resistant coatings that can extend PMC component life and are applicable to current available and advanced high temperature PMCs. This paper describes the performance of SANPRES and SANRES, two similar erosion resistant coating systems that were subjected to engine test conditions on Rolls-Royce AE 3007 engine bypass vanes.Copyright © 2004 by ASME

Gas delivery substrate

Abstract: A gas delivery substrate and method of manufacture is disclosed. A thermoplastic extrusion compound is created comprising a ceramic material and a thermoplastic resin, a green body is formed by thermoplastic extrusion of the compound, and the green body is sintered to form the gas delivery substrate. Such gas delivery substrates may be thin walled, highly porous and have secondary operations such as crimping and machining done prior to sintering.

Hot Isostatic Pressing of Austenitic Stainless Steel Powders for Pressure Retaining Applications

Abstract: Hot Isostatic Pressing (HIP) has been used for many years to consolidate porosity in cast metal shapes to improve mechanical properties. When the technique is applied to fine metal powders, it becomes possible to produce Near Net Shape (NNS) items and more complex geometry components that are fully dense and offer an attractive set of properties and reduced cost. Manufacture of NNS items from powder delivers cost savings by reducing initial material usage and subsequent machining costs. Powder production and HIP processing are automated methods, which also provide protection against forging route obsolescence. Setup costs are lower and smaller batch sizes possible. HIPped powder microstructures are isotropic and equi-axed, with uniformly fine grain sizes not normally achieved in heavy section components. In austenitic stainless steel materials, this provides significant improvements in ultrasonic NDE (Non-Destructive Examination) in thick sections. Use of the technology has grown, particularly in the off-shore oil industry where it is already established in high integrity applications, but take-up in the more conservative nuclear industry has been slow. In a broad programme of testing, Rolls-Royce has established that HIPped powder 316L components, in items up to several tons in weight, have equivalent or slightly better strength, toughness and corrosion properties across a wide range of test environments. A methodology for developing robust safety justifications for use has been developed. Manufacture of pressure seal components is now in progress and the economics of other applications such as pump bowls are being considered. The quality of HIPped powder items can provide through life cost savings since there is greater assurance of structural integrity compared to welded or wrought components.Copyright © 2004 by ASME

The Application of Fluid Structure Interaction Techniques Within Finite Element Analyses Of Water-filled Transport Flasks

Abstract: Historically, finite-element (FE) analyses of water-filled transport flasks and their payloads have been carried out assuming a dry environment, mainly due to lack of robust fluid structure interaction (FSI) modelling techniques. Recent years have seen significant improvements in FSI techniques. These FSI techniques have been used to investigate the effects of assuming a wet environment for the regulatory drop test within a recent Rolls-Royce Naval Marine licence renewal application. This paper will present the FSI capabilities available within various FE codes. The required structural aspects of the FE codes will also be discussed, in particular material models, as these also influence the final code selection. Two explicit dynamic FE codes were finally identified, LS-DYNA, which was used in the extant dry analyses, and RADIOSS, which was used to provide additional confidence in the FSI calculations. Fluid flow and pressure vary significantly during an impact and the effects on the contents becom...

Utilization of gases from biomass gasification in a reforming reactor coupled to an integrated planar solid oxide fuel cell: Simulation analysis

Abstract: One of the high-efficiency options currently under study for a rational employment of hydrogen are fuel cells In this scenario, the integrated planar solid oxide fuel cell is a new concept recently proposed by Rolls-Royce The basic unit of a modular plant is the so called "strip", containing an electro-chemical reactor formed by a number of IP-SOFC modules, and a reforming reactor For a better under standing of the behavior of a system of this kind, a simulation model has been set up for both the electrochemical reactor and the reformer; both models follow the approach typically employed in the simulation of chemical reactors, based on the solution of mass and energy balances In the case of the IP-SOFC electro chemical reactor, the model includes the calculation of the electrical resistance of the stack (that is essentially due to ohmic losses, activation polar is action and mass transport limitations), the mass balances of the gaseous flows, the energy balances of gaseous flows (anodic and cathodic) and of the solid The strip is designed in such a way that the reaction in the reforming reactor is thermally sustained by the sensible heat of the hot air exiting the electrochemical section; this heat exchange is taken into account in the model of the reformer, which includes the energy balance of gaseous flows and of the solid structure Simulation results are reported and discussed for both the electrochemical reactor in stand-alone configuration (including comparison to experimental data in a narrow range of operating conditions) and for the complete strip

A reformer module

Abstract: A reformer module (10) comprises a hollow support member (12) having at least one passage (14) extending longitudinally therethrough. The hollow support member (14) has an external surface (20), a barrier layer (22) arranged on at least a portion of the external surface (20) of the hollow support member (12), a catalyst layer (24) arranged on the barrier layer (22) and a sealing layer (26) arranged on the catalyst layer (24) and the external surface (20) of the hollow support member (12) other than the at least a portion of the external surface of the hollow support member (12). By providing the barrier layer (22) and the catalyst layer (24) on the exterior surface (20) of the hollow support member (12), the distribution of the barrier layer (22) and/or the catalyst layer (24) may be more precisely controlled and thus a non-uniform distribution of barrier layer (22) and/or catalyst layer (24) may be achieved.

A service oriented architecture for integration of fault diagnostics

Abstract: Many model-based fault diagnosis approaches have been proposed so far and some of them have been put into industrial practices. But for modern complex processes, due to the variable nature of faults and model uncertainty, no single approach can diagnose all faults and meet different contradictory criteria. In this paper, the importance of integration of different fault diagnostic schemes in a common framework is emphasised. A service-oriented architecture for the integration is proposed based on Grid technologies. As an implementation, a decision support system for the gas turbine engine fault diagnosis is presented and some deployed services are discussed.

The influence of strain rate on the visibility of dislocations in transmission electron microscopy images of deformed Ti–6 wt% Al–4 wt% V and in Timet 550

Abstract: Samples of Ti–6 wt% Al–4 wt% V and Timet 550 (Ti–4 wt% Al–4 wt% Mo–2 wt% Sn–0.5 wt% Si) have been subjected to strain rates between 10−1 and 103 s−1and detailed examination of the dislocation structure in the α grains has been carried out using transmission electron microscopy (TEM). For samples deformed to a strain of 0.1 at 10−1 s−1, detailed analysis of the defects can be carried out using all diffracting vectors and the presence of (c + a) dislocations and a dislocations thus confirmed. In contrast, for samples strained to the same strain of 0.1 but at 5 s−1, it is not possible to obtain images of dislocations when using any diffracting vectors other than 0002. Thus the presence of dislocations which have a Burgers vector containing a c component can be confirmed in the samples strained at 5 s−1 but the presence of a-component dislocations can only be inferred from TEM of these samples because of the difficulty of obtaining images with diffracting vectors other than 0002. Limited observations on sampl...