Showing papers by "Rolls-Royce Holdings published in 2010"

Distributed power generation

Abstract: Distributed power generation systems generally comprise a number of power sources and electrical power loads interconnected by a distribution network. Electrical switches and fuses are provided such that local groups of power sources and power loads can be established. Should there be a degradation in the distribution network in terms of a set of criteria such as electrical frequency, current or voltage then the switch or fuse may be thrown to establish each local group as an island. By monitoring divergence from a set of criteria a method and controller may be utilised whereby the distribution network as a whole is considered and configured to establish virtual islands which operate prior to the establishment whether inadvertently or deliberately of actual islands within the distribution network. In such circumstances the transition from normal operation for the distribution network to islanded operation for the distribution network is less severe.

Architecture of a Network-in-the-Loop Environment for Characterizing AC Power-System Behavior

Abstract: This paper describes the method by which a large hardware-in-the-loop environment has been realized for three-phase ac power systems. The environment allows an entire laboratory power-network topology (generators, loads, controls, protection devices, and switches) to be placed in the loop of a large power-network simulation. The system is realized by using a real-time power-network simulator, which interacts with the hardware via the indirect control of a large synchronous generator and by measuring currents flowing from its terminals. These measured currents are injected into the simulation via current sources to close the loop. This paper describes the system architecture and, most importantly, the calibration methodologies which have been developed to overcome measurement and loop latencies. In particular, a new ?phase advance? calibration removes the requirement to add unwanted components into the simulated network to compensate for loop delay. The results of early commissioning experiments are demonstrated. The present system performance limits under transient conditions (approximately 0.25 Hz/s and 30 V/s to contain peak phase- and voltage-tracking errors within 5° and 1%) are defined mainly by the controllability of the synchronous generator.

Variable drive gas turbine engine

Abstract: A system and method for variable drive of a propeller or fan of a gas turbine engine. The gas turbine engine has a combustor and a turbine arranged to be driven by a combustion product from the combustor. The variable drive system comprises a primary shaft arranged for transmission of torque from said turbine to the propeller; an electric generator arranged to be driven by said turbine; and an electric motor arranged to be driven by the output of said generator. A clutch is mounted between the propeller and the primary rotor and is operable to mechanically disconnect the shaft from the propeller so that the propeller can be driven by any or any combination of the turbine and/or electric motor. The invention may be applied to a turboprop or turbofan engine having a gearing between the shaft and propeller or fan and may be particularly suited to unmanned aerial vehicle proulsion.

The importance of human skills in project management professional development

Abstract: Purpose – The purpose of this paper is to provide insights into the importance of human skills in project management success and the apparent emphasis placed on this within the context of university education.Design/methodology/approach – An investigation into the effectiveness of a British Project Management Professional Development Programme (PMPDP) case study is reported. Using as a benchmark, the core behavioural competencies outlined in the International Project Management Association (IPMA) International Competence Baseline version 3, the paper investigates the extent to which the knowledge gained from the PMPDP effects the behaviours of delegates and graduates. The soft skills of a control group are also explored.Findings – The results deal with certain improvements in most of the behavioural competencies of delegates and graduates which the control group could not develop in the same way.Research limitations/implications – The sample is drawn from the PMPDP consortium comprising companies from the...

Big Ears (The Return of "Easy Approach to Requirements Engineering")

Abstract: During a previous study, five simple templates were proposed to improve the quality of Natural Language requirements. That study applied the Easy Approach to Requirements Syntax (EARS) templates to the requirements for the certification of an aero engine control system contained in an airworthiness regulatory document. This paper reports on a wider series of experiments, which applied the templates to several different sets of requirement documents. Back-to-back comparisons were undertaken for documents before and after the application of the EARS templates. During these studies the templates were refined, known limitations of EARS were addressed and metrics were collected. The results strongly support the hypothesis that a small set of simple requirement structures would be an efficient way to enhance the writing of high-level stakeholder requirements. The implications of the results are discussed and additional guidance is provided through Lessons Learned, with the aim of making the templates easier to apply.

Aeromechanical Optimization of a Winglet-Squealer Tip for an Axial Turbine

Abstract: The possibility of reducing the over tip leakage loss of unshrouded axial turbine rotors has been investigated in an experiment using a linear cascade of turbine blades and by using CFD. A numerical optimisation of a winglet-squealer geometry was performed. The optimisation involved the structural analysis alongside the CFD. Significant effects of the tip design on the tip gap flow pattern, loss generation and mechanical deformation under centrifugal loads were found. The results of the optimisation process were verified by low speed cascade testing. The measurements showed that the optimised winglet-squealer design had a lower loss than the flat tip at all of the tested tip gaps. At the same time, it offered a 37% reduction in the rate of change of the aerodynamic loss with the tip gap size. The optimised tip geometry was used to experimentally assess the effects of the opening of the tip cavity in the leading edge part of the blade and the inclination of the pressure side squealer from the radial direction. The opening of the cavity had a negligible effect on the aerodynamic performance of the cascade. The squealer lean resulted in a small reduction of the aerodynamic loss at all the tested tip gaps. It was shown that a careful consideration of the mechanical aspects of the winglet is required during the design process. Mechanically unconstrained designs could result in unacceptable deformation of the winglet due to centrifugal loads. An example winglet geometry is presented that produced a similar aerodynamic loss to that of the optimised tip but had a much worse mechanical performance. The mechanisms leading to the reduction of the tip leakage loss were identified. Using this knowledge, a simple method for designing the tip geometry of a shroudless turbine rotor is proposed. Numerical calculations indicated that the optimised low-speed winglet-squealer geometry maintained its aerodynamic superiority over the flat tip blade with the exit Mach number increased from 0.1 to 0.8.Copyright © 2010 by ASME and Rolls-Royce plc

Efficient Finite Element Analysis/Computational Fluid Dynamics Thermal Coupling for Engineering Applications

Abstract: An efficient finite element analysis/computational fluid dynamics (FEA/CFD) thermal coupling technique has been developed and demonstrated. The thermal coupling is achieved by an iterative procedure between FEA and CFD calculations. Communication between FEA and CFD calculations ensures continuity of temperature and heat flux. In the procedure, the FEA simulation is treated as unsteady for a given transient cycle. To speed up the thermal coupling, steady CFD calculations are employed, considering that fluid flow time scales are much shorter than those for the solid heat conduction and therefore the influence of unsteadiness in fluid regions is negligible. To facilitate the thermal coupling, the procedure is designed to allow a set of CFD models to be defined at key time points/intervals in the transient cycle and to be invoked during the coupling process at specified time points. To further enhance computational efficiency, a “frozen flow” or “energy equation only” coupling option was also developed, where only the energy equation is solved, while the flow is frozen in CFD simulation during the thermal coupling process for specified time intervals. This option has proven very useful in practice, as the flow is found to be unaffected by the thermal boundary conditions over certain time intervals. The FEA solver employed is an in-house code, and the coupling has been implemented for two different CFD solvers: a commercial code and an in-house code. Test cases include an industrial low pressure (LP) turbine and a high pressure (HP) compressor, with CFD modeling of the LP turbine disk cavity and the HP compressor drive cone cavity flows, respectively. Good agreement of wall temperatures with the industrial rig test data was observed. It is shown that the coupled solutions can be obtained in sufficiently short turn-around times (typically within a week) for use in design.

Combustor tile mounting arrangement

Abstract: A tile is provided for lining the hot side of a wall of a combustor. The tile has a tile body with one or more bosses protruding from the cold side thereof. The or each boss extends, in use, through the wall of the combustor and has a threaded recess formed therein for threadingly connecting with a bolt which is inserted into the recess from the cold side of the combustor wall. The bolt fastens the tile to the combustor wall.

Effect of Temperature Nonuniformity on Heat Transfer in an Unshrouded Transonic HP Turbine: An Experimental and Computational Investigation

Abstract: Detailed experimental measurements have been performed to understand the effects of turbine inlet temperature distortion (hot-streaks) on the heat transfer and aerodynamic characteristics of a full-scale unshrouded high pressure turbine stage at flow conditions that are representative of those found in a modern gas turbine engine. To investigate hot-streak migration, the experimental measurements are complemented by three-dimensional steady and unsteady CFD simulations of the turbine stage. This paper presents the time-averaged measurements and computational predictions of rotor blade surface and rotor casing heat transfer. Experimental measurements obtained with and without inlet temperature distortion are compared. Time-mean experimental measurements of rotor casing static pressure are also presented. CFD simulations have been conducted using the Rolls-Royce code Hydra, and are compared to the experimental results. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough UK. This is a short duration transonic facility, which simulates engine representative M, Re, Tu, N/T and Tg /Tw at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation temperature distortion generator, capable of simulating well-defined, aggressive temperature distortion both in the radial and circumferential directions, at the turbine inlet.Copyright © 2010 by Rolls-Royce plc

Cooled aerofoil for a gas turbine engine

Abstract: A cooled aerofoil for a gas turbine engine has an aerofoil section with pressure and suction surfaces extending between inboard and outboard ends thereof. The aerofoil section includes first and second internal passages for carrying cooling air. The aerofoil section further includes a plurality of holes in the external surface of the aerofoil section which receive cooling air from the internal passages. The external holes are arranged such that cooling air exiting a first portion of the external holes participates in a cooling film extending from the leading edge of the aerofoil section over said pressure surface and cooling air exiting from a second portion of the external holes participates in a cooling film extending from the leading edge over said suction surface. The first portion of external holes receives cooling air from the first internal passage, and the second portion of external holes receives cooling air from the second internal passage. The first and second internal passages are supplied with cooling air from respective and separate passage entrances. Each entrance is located at either the inboard end or the outboard end of the aerofoil section.

Back-up featherer

Abstract: A back-up featherer is provided for an engine arrangement having a main hydraulic actuator which angularly displaces propellers of a propeller assembly of the engine arrangement. The back-up featherer has a back-up hydraulic actuator for angular displacement of the propellers, the back-up hydraulic actuator rotating with the propeller assembly. The back-up featherer further has one or more back-up fluid supply lines for transferring hydraulic fluid between a hydraulic pressure power source located on a static structure of the engine arrangement and the back-up hydraulic actuator. The back-up featherer further has a back-up hydraulic rotating coupling, the back-up fluid supply lines fluidly communicating with the back-up hydraulic actuator via the back-up rotating coupling. A static side of the back-up hydraulic rotating coupling is mounted to the static structure of the engine arrangement, and a rotating side of the back-up hydraulic rotating coupling rotates with the propeller assembly.

Effect of Simulated Combustor Temperature Nonuniformity on HP Vane and End Wall Heat Transfer: An Experimental and Computational Investigation

Abstract: This paper presents experimental measurements and computational predictions of surface and end wall heat transfer for a high-pressure (HP) nozzle guide vane operating as part of a full HP turbine stage in an annular rotating turbine facility, with and without inlet temperature distortion (hot streaks). A detailed aerodynamic survey of the vane surface is also presented. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough, UK. This is a short-duration facility, which simulates engine-representative M, Re, nondimensional speed, and gas-to-wall temperature ratio at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation combustor simulator, capable of simulating well-defined, aggressive temperature profiles in both the radial and circumferential directions. This work forms part of the pan-European research program, TATEF II. Measurements of HP vane and end wall heat transfer obtained with inlet temperature distortion are compared with results for uniform inlet conditions. Steady and unsteady computational fluid dynamics (CFD) predictions have also been conducted on vane and end wall surfaces using the Rolls-Royce CFD code HYDRA to complement the analysis of experimental results. The heat transfer measurements presented in this paper are the first of their kind in that the temperature distortion is representative of an extreme cycle point, and was simulated with good periodicity and with well-defined boundary conditions in the test turbine.

Design of Electromagnetic Dampers for Aero-Engine Applications

Abstract: The vibration control of rotors for gas or steam turbines is usually performed using passive dampers when hydrodynamic bearings are not used. In layouts where the rotating parts are supported by rolling bearings, the damping is usually provided by squeeze film dampers. Their passive nature and the variability of their performances with temperature and frequency represent the main disadvantages. Dampers with magnetorheological and electrorheological fluid allow solving only a part of the abovementioned drawbacks. Active magnetic bearings (AMBs) are promising since they are very effective in controlling the vibration of the rotor and offering the possibility of monitoring the rotor’s behavior using their displacement sensors. However they show serious drawbacks related to their stiffness. Electromagnetic dampers seem to be a valid alternative to visco-elastic, hydraulic dampers due to, among the others, the absence of all fatigue and tribology issues resulting from the absence of contact, the small sensitivity to the working environment, the wide possibility of tuning even during operation, the predictability of the behavior, the smaller mass compared with AMBs, and the failsafe capability. The aim of the present paper is to describe a design methodology adopted to develop electromagnetic dampers to be installed in aero-engines. The procedure has been validated using a reduced scale laboratory test rig. The same approach has then been adopted to design the electromagnetic dampers for real civil aircraft engines. The results in terms of achievable vibration reductions, mass, and overall dimensions are hence presented. A trade-off between the various proposed solutions has been carried out evaluating quantitative performance parameters together with qualitative aspects that this “more electric” technology implies.

Effect of Roughness and Unsteadiness on the Performance of a New Low Pressure Turbine Blade at Low Reynolds Numbers

Abstract: This paper presents a study of the performance of a high-lift profile for low pressure turbines at Reynolds numbers lower than in previous investigations. By following the results of Coull et al. (2008, "Velocity Distributions for Low Pressure Turbines," ASME Paper No. GT2008-50589) on the design of high-lift airfoils, the profile is forward loaded. The separate and combined effects of roughness and wake passing are compared. On a front loaded blade, the effect of incidence becomes more important and the consequences in terms of cascade losses, is evaluated. The experimental investigation was carried out in the high speed wind tunnel of Whittle Laboratory, University of Cambridge. This is a closed-circuit continuous wind tunnel where the Reynolds number and Mach number can be fixed independently. The unsteadiness caused by wake passing in front of the blades is reproduced using a wake generator with rotating bars. The results confirm that the beneficial effect of unsteadiness on losses is present even at the lowest Reynolds number examined (Re 3 = 20,000). This beneficial effect is reduced at positive incidence. With a front loaded airfoil and positive incidence, the transition occurs on the suction side close to the leading edge and this results in higher losses. This has been found valid for the entire Reynolds range investigated (20,000 ≤ Re 3 140,000). Roughening the surface also had a beneficial effect on the losses but this effect vanishes at the lower Reynolds numbers, i.e., (Re 3 ≤ 30,000), where the surface becomes hydraulically smooth. The present study suggests that a blade with as-cast surface roughness has a lower loss than a polished one.

Technology management at Rolls-Royce

Abstract: Technology management tools, such as technology roadmapping, have received significant attention in Rolls-Royce and other manufacturing organizations. Yet, these tools have often been treated and u...

Variable shape rotor blade

Abstract: A rotor blade comprising a core blade section; and a trailing edge section, the trailing edge section being attached to the core blade section along a join interface. The trailing edge section comprises a shape memory material which is actuable so as to cause selective deformation of the trailing edge section between a first condition in which a trailing edge of the trailing edge section follows a substantially smooth profile and a second condition in which the trailing edge is perturbed. The direction of the perturbation may be oblique or perpendicular to the direction of flow over the blade in use. The rotor blade may be a fan or propeller for a gas turbine engine.

An aircraft having a lift/propulsion unit

Abstract: An aircraft having a lift/propulsion unit which includes a power unit such as a turboshaft engine which drives a fan through a transmission mechanism. The fan discharges to vectoring nozzles which can be independently swivelled to provide lift or propulsion thrust. An output shaft of the transmission mechanism serves as the main shaft of a motor/generator of modular form. The motor/generator can act as a generator to charge an electrical storage device such as a battery, or as a motor to drive the fan, either alone or to supplement the output of engine. Reaction control nozzles are provided at extremities of the aircraft to provide stabilizing thrust. The aircraft is capable of vertical take off and hovering, with the vectoring nozzles swivelled to a lift position, and forward thrust with the vectoring nozzles swivelled to a propulsion position.

Aerofoil with erosion resistant leading edge

Abstract: The present invention relates to an aerofoil having an erosion resistant leading edge. The aerofoil comprises an aerofoil main body portion and a leading edge portion. The leading edge portion comprises a plurality of functionally distinct parts, including at least; a first part for resisting abrasion of the leading edge portion, and a second part for resisting a bending force applied to the leading edge portion, and located behind the first part.

Modelling the behaviour of titanium alloys at high temperature for gas turbine applications

Abstract: Increased efficiency within the aero engine can be achieved through higher operating temperatures. In order to meet this requirement designers seek either to implement new alloys or show that existing alloys are capable of operating under more extreme conditions. At higher temperatures fatigue is no longer the sole damage mechanism and contributions from creep and environmental interactions must also be considered. This paper seeks to address some of these issues within titanium alloys, and in particular how these high temperature interactions may affect stress concentrations which are often the source of potentially catastrophic fatigue cracks. The requirement to consider both the crack initiation and propagation phase under these conditions is addressed and a modelling capability is presented which shows the ability to predict some of these effects at high temperature.

Microstructural Characterization of a Polycrystalline Nickel-Based Superalloy Processed via Tungsten-Intert-Gas-Shaped Metal Deposition

Abstract: Recent trials have produced tungsten-inert-gas (TIG)-welded structures of a suitable scale to allow an evaluation of the technique as an economic and commercial process for the manufacture of complex aeroengine components. The employment of TIG welding is shown to have specific advantages over alternative techniques based on metal inert gas (MIG) systems. Investigations using the nickel-based superalloy 718 have shown that TIG induces a smaller weld pool with less compositional segregation. In addition, because the TIG process involves a pulsed power source, a faster cooling rate is achieved, although this rate, in turn, compromises the deposition rate. The microstructures produced by the two techniques differ significantly, with TIG showing an absence of the detrimental delta and Laves phases typically produced by extended periods at a high temperature using MIG. Instead, an anisotropic dendritic microstructure was evident with a preferred orientation relative to the axis of epitaxy. Niobium was segregated to the interdendritic regions. A fine-scale porosity was evident within the microstructure with a maximum diameter of approximately 5 μm. This porosity often was found in clusters and usually was associated with the interdendritic regions. Subsequent postdeposition heat treatment was shown to have no effect on preexisting porosity and to have a minimal effect on the microstructure.

Containment casing for an aero engine

Abstract: A containment assembly for a turbo fan engine, has a casing arranged in use around a rotatable fan, to form a duct for the fan and a liner element disposed on an interior surface between the casing and blades of a rotatable fan The liner element includes a body portion mounted in a recess in the casing and a wall portion arranged to form part of an inner wall of the duct The wall portion and the body portion being attached and defining a containment cavity therebetween for containment of a detached fan blade fragment in use, wherein the wall portion has a moveable portion movable between a first configuration in which it lies substantially flush with the inner wall of the duct, and a second configuration in which it provides an opening through which a fan blade fragment can enter the containment cavity

Apparatus and method of operating a gas turbine engine

Abstract: A gas turbine engine and an apparatus for operating the gas turbine engine includes at least one microphone to detect the sound of impacts of particles, recorder to record the sound of the impacts, an analyser to analyse the sound of the impacts of the particles, and a store of sounds of impacts, the stored sounds of impacts correspond to unfavourable weather conditions. A comparator compares the sound of the impacts of particles with one or more sounds of impacts stored in the store 68 sounds of impacts and if the comparator determines that the sound of the impacts of particles matches one or more stored sounds of impacts, a signal is sent to a control system for the gas turbine engine to adjust the operation of the gas turbine engine such that it operates in a safe mode of operation.

Adjustable fan case liner and mounting method

Abstract: A liner for an interior surface of an engine casing, comprises a number of liner panels disposed radially outwardly of a rotatable component of the engine, such as a fan blade, and the panels are mounted on the interior surface of the casing, wherein each panel is individually adjustable, such that the clearance between the panel and the rotatable component of the engine may be varied individually for each panel.

Application of value-driven design to commercial aero-engine systems

Abstract: Value-Driven Design provides a framework to enhance the systems engineering processes for the design of large systems. By employing economics in decision making, Value-Driven Design enables rational decision making in terms of the optimum business and technical solution at every level of engineering design. This paper explains the application of ValueDriven Design to the aero-engine system through two case studies, which were conducted through workshops under the Rolls-Royce plc Advanced Cost Modeling Methodologies project. The Surplus Value Theory was utilized to provide a metric that can trade-off component designs with changes in continuous and discrete design variables. Illustrative results are presented to demonstrate how the methodology and modeling approach can be used to evaluate designs and select the value-enhancing solution.

Development of a Reconfigurable Fixture for the Automated Assembly and Disassembly of High Pressure Rotors for Rolls-Royce Aero Engines

Abstract: This paper describes a novel fixturing system for the automated assembly and disassembly of aero engine components. The proposed system has the ability to automatically reconfigure for a number of different parts and allows the precise control and monitoring of its clamping positions and exerted clamping forces. Aspects of the control software of this system, like the graphical user interface (GUI) and the relational data base system containing post-process and configuration data, are described.