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  • Journal article
    Turner AB, Davies SJ, Childs PRN, Harvey CG, Millward JAet al., 2000,

    Development of a novel gas turbine driven centrifugal compressor

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY, Vol: 214, Pages: 423-437, ISSN: 0957-6509
  • Conference paper
    Jackson RA, Peyton Jones JC, Pan J, Roberts JB, Childs PRNet al., 1999,

    Chemical aspects of the dynamic performance of a three-way catalyst

    The gas components CO, CO2, HC, NOx and the AFR in the exhaust from a SI engine, both upstream and down-stream of a Pd/Rh catalytic converter, have been monitored using fast response analyzers. Regular sequential step changes in the upstream air/fuel ratio (AFR), between two pre-set levels, have been implemented with both long and short periods between the steps. For transitions from rich to lean conditions, and vice-versa, several distinct zones for the output emissions characteristics, corresponding to different states of the catalyst surface, have been identified. These results suggest that, under reducing conditions, hydrogen is stored on the catalyst surface whereas under oxidizing conditions oxygen is stored by two different processes. These chemical insights facilitate the development of realistic models for tailpipe emissions from engines which are perturbed from steady state running. Copyright © 1999 Society of Automotive Engineers, Inc.
  • Conference paper
    Nanayakkara T, Watanabe K, Izumi K, 1999,

    Evolving Runge-Kutta-Gill RBF networks to estimate the dynamics of a multi-link manipulator

    , ISSN: 0884-3627

    This paper proposes a method for identification of dynamics of a multi-link robot arm using Runge-Kutta-Gill Neural networks (RKGNN). Shape adaptive radial basis function (RBF) neural networks have been employed with an evolutionary algorithm to optimize the shape parameters and the weights of the RKGNN. Due to the fact that the RKGNN can accurately grasp the changing rates of the states, this method can effectively be used for long term prediction of the states of the robot arm dynamics. Unlike in conventional methods, the proposed method can even be used without input torque information because a torque network is part of the functional network. This method can be proposed as an effective option for dynamics identification for manipulators with high degrees of freedom, as opposed to the derivation of dynamic equations and making additional hardware changes in the case of statistical parameter identification such as linear least-squares method.
  • Journal article
    Childs PRN, Noronha MB, 1999,

    1997 John P. Davis Award - The impact of machining techniques on centrifugal compressor impeller performance

    , JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME, Vol: 121, Pages: 637-643, ISSN: 0889-504X
  • Journal article
    Childs PRN, Greenwood JR, Long CA, 1999,

    Heat flux measurement techniques

    , Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Vol: 213, Pages: 655-677, ISSN: 0954-4062

    <jats:p> Heat flux measurement is used in the field of fluid mechanics and heat transfer to quantify the transfer of heat within systems. Several techniques are in common use, including: differential temperature sensors such as thermopile, layered resistance temperature devices or thermocouples and Gardon gauges; calorimetric methods involving a heat balance analysis and transient monitoring of a representative temperature, using, for example, thin-film temperature sensors or temperature sensitive liquid crystals; energy supply or removal methods using, for example, a heater to generate a thermal balance; and, finally, by measurement of mass transfer which can be linked to heat transfer using the analogy between the two. No one method is suitable to all applications because of the differing considerations of accuracy, sensitivity, size, cost and robustness. </jats:p><jats:p> Recent developments including the widespread availability and application of thin-film deposition techniques for metals and ceramics, allied with advances in microtechnology, have expanded the range of devices available for heat flux measurement. This paper reviews the various types of heat flux sensors available, as well as unique designs for specific applications. Critical to the use of a heat flux measurement technique is accurate calibration. Use of unmatched materials disturbs the local heat flux and also the local convective boundary layer, producing a potential error that must be compensated for. The various techniques in common use for calibration are described. A guide to the appropriate selection of a heat flux measurement technique is provided according to the demands of response, sensitivity, temperature of operation, heat flux intensity, manufacturing constraints, commercial availability, cost, thermal disturbance and acceleration capability for vibrating, rotating and reciprocating applications. </jats:p>
  • Conference paper
    Jackson RA, Peyton-Jones JC, Pan J, ROberts JB, Childs PRNet al., 1999,

    Chemical aspects of the dynamic performance of a three-way catalyst. SAE 1999-01-0312

    , Society of Automotive Engineers International Congress 1999, Publisher: SAE
  • Journal article
    Greenwood JR, Childs PRN, Chaloner P, 1999,

    Gold leads to PRTs for monitoring high temperatures

    , GOLD BULLETIN, Vol: 32, Pages: 85-+, ISSN: 0017-1557
  • Conference paper
    Childs PRN, Nilsson K, 1999,

    Flow phenomena and functionality of the infant Flow system

    , 5th Annual Reason Conference
  • Journal article
    Childs PRN, Greenwood JR, Long CA, 1999,

    Heat flux measurement techniques

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, Vol: 213, Pages: 655-677, ISSN: 0954-4062
  • Book
    Childs PRN, 1998,

    Mechanical design

    , Publisher: Hodder Arnold, ISBN: 9780340692363

    Concentrating mainly on rotary machine elements such as bearings, shafts, gears, seals,chains, clutches and brakes, this book provides the methodology for ...
  • Conference paper
    Nanayakkara T, Nakamura M, Nanayakkara N, Furukawa K, Hatazaki Het al., 1998,

    Identification of system in a coal fired power plant to achieve desired compositions of fly-ash

    , 11th IFAC Symposium on System Identification (SYSID 97), Publisher: PERGAMON PRESS LTD, Pages: 1211-1216
  • Journal article
    PARTRIDGE M, CALVO R, 1998,

    Fast dimensionality reduction and simple PCA

    , Intelligent Data Analysis, Vol: 2, Pages: 203-214, ISSN: 1088-467X
  • Conference paper
    Turner AB, Long CA, Childs PRN, Hills NJ, Millward JAet al., 1997,

    Review of some current problems in gas turbine secondary systems

    , ISSN: 0402-1215

    This paper reviews the current position of five major problem areas in gas turbine secondary air system design. Although the problems are of primary interest to the designer of the coolant flow paths, since they directly affect the temperature, the stresses and thus the life of the major rotating components, three of the problems interact with the main gas path and are thus also the concern of the mainstream aerodynamicist. The five problems reviewed are: prediction of the flow distribution and heat transfer in the high pressure compressor drive cone cavity from the turbine to the rim of the HP compressor running underneath the combustion chamber; the flow penetration and heat transfer in the multiple rotating cavities formed by the multiple discs of the high pressure compressor with a rotating shaft running through the bores; the control of ingestion of hot turbine mainstream gas into the rotor-stator wheelspaces through the rim-seals; the problem of compressor and turbine stator-well heating, particularly compressor stator-wells in which excessive temperatures have been occasionally measured and finally, the pre-swirl coolant system which has to take the blade cooling air across from the stationary casing to the rotating turbine disc in the most advantageous manner.
  • Conference paper
    Childs PRN, Noronha MB, 1997,

    The Impact of Machining Techniques on Centrifugal Compressor Impeller Performance

    , ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition, Publisher: American Society of Mechanical Engineers

    <jats:p>A large proportion of modern centrifugal impellers are machined from solid forgings rather than made from cast metal. The CNC milling process offers options to manufacturers to minimise manufacturing costs whilst also enhancing performance of the impeller. Efficient manufacturing can result in cutter tool marks and paths and associated roughness remaining on the hub and blade surfaces of impellers as a result of minimising passes and maximising the cut. The goal of manufacturers is to allow these marks to be as deep as possible to minimise machining costs but without any negative effects in performance and possibly even enhancing it. There are existing modelling methods that predict the influence of roughness on compressor performance using the definition of an equivalent sand grain roughness. The purpose of this study is to relate the performance directly to the tool mark characteristics that are by-products of machining, namely cusp height, cutter path roughness and orientation of the cutter path relative to the local flow velocity, to review the current modelling techniques for predicting the influence of surface condition on compressor performance and to show the scope for optimisation of manufacturing and performance considerations.</jats:p>
  • Journal article
    Bayley FJ, Childs PRN, 1997,

    Prediction of ingress rates to turbine and compressor wheelspaces

    , INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW, Vol: 18, Pages: 218-228, ISSN: 0142-727X
  • Conference paper
    Turner AB, Long CA, Childs PRN, Hills NJ, Millward JAet al., 1997,

    A review of some current problems in gas turbine internal air systems. ASME Paper 97-GT-325

    , ASME Aeroengine Congress, Publisher: ASME
  • Conference paper
    Ozturk HK, Childs PRN, Turner AB, 1997,

    Numerical solution of flow and heat transfer in axial compressor stator wells

    , IChemE 5th UK National Heat Transfer Conference, Publisher: Institution of Chemical Engineers
  • Conference paper
    Bayley FJ, Childs PRN, 1997,

    Calculation of hot gas ingress and egress rates in turbo-machine wheelspaces

    , 2nd European Conference on Turbomachinery - Fluid Dynamics and Thermodynamics, Pages: 521-528
  • Conference paper
    Childs PRN, Noronha MB, 1997,

    The impact of machining techniques on centrifugal compressor impeller performance. ASME Paper 97-GT-456

    , ASME Turbo Expo 1997, Publisher: ASME
  • Conference paper
    Ozturk HK, Turner AB, Childs PRN, 1997,

    Numerical prediction of axial compressor stator well flows

    , International Centre for Heat and Mass Transfer, International Symposium on Advances in Computational Heat Transfer
  • Journal article
    Childs PRN, Long CA, 1996,

    A review of forced convective heat transfer in stationary and rotating annuli

    , PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, Vol: 210, Pages: 123-134, ISSN: 0954-4062
  • Journal article
    CALVO RA, CECCATTO HA, PIACENTINI RD, 1995,

    NEURAL-NETWORK PREDICTION OF SOLAR-ACTIVITY

    , ASTROPHYSICAL JOURNAL, Vol: 444, Pages: 916-921, ISSN: 0004-637X
  • Conference paper
    Childs PRN, Long CA, Turner AB, 1995,

    A review of convective heat transfer in open and closed rotating annular cavities

    , 4th UK National Conference on Heat Transfer, Publisher: MECHANICAL ENGINEERING PUBL, Pages: 67-71, ISSN: 1356-1448
  • Conference paper
    Basualdo MS, Calvo RA, Ceccatto HA, 1994,

    Neural control strategies of a binary distillation column

    , Pages: 77-81

    The ability of neural networks to model arbitrary nonlinear functions and their inverses is exploited for the adaptive control of nonlinear systems. Neural networks which model the plant and its inverse are directly incorporated within the internal model control structure. In addition, a test was made with the open loop control using only the neural model of the plant inverse. Finally, combined structures of conventional controllers (P, PD) with this inverse model were implemented in order to improve the performance of the controlled system. The potential of the proposed methods is demonstrated using the control of the top of a continuous Benzene-Toluene distillation column as an example. The dynamic behavior of that system is obtained by using a complex software simulation.
  • Conference paper
    Bayley FJ, Childs PRN, 1994,

    Air temperature rises in compressor and turbine stator wells

    , Pages: 1-10, ISSN: 0402-1215

    This paper considers the fluid dynamic principles determining the consequences of mainstream fluid ingressing to the comparatively shallow space between the rotor disc and the ring used in many designs of axial-flow turbo-machine, especially compressors, to support the stator blades at their inner ends. Windage power due to friction between this fluid and the bounding walls of this annular space, or 'stator well', can lead to substantial temperature rises in this region. The feasible range of flow regimes is first developed, especially as influenced by leakage through the internal seals beneath the stators separating adjacent wells. Using published data, on windage coefficients and the effects of geometry on the flow through the wells, very little of which has been obtained from truly representative flow conditions or geometries, calculations have been made to estimate the likely rises in temperature to be anticipated in realistic well designs. Leakage rates appear, not unexpectedly, to be crucial in determining these temperature rises, but the geometries of the system are little less critical, in particular the ratio of the outer to inner radiuses of the stator well and the outer peripheral clearances between rotor and stator surfaces. Leakage into a well from its adjacent neighbour is shown to lead to higher temperature rises downstream of the labyrinth seal and the possible effects of recirculation through stator wells from the mainstream boundary layer could be significant.
  • Conference paper
    Bayley FJ, Childs PRN, 1994,

    Air temperature rises in compressor and turbine stator wells. ASME Paper 94-GT-185

    , ASME Turbo Expo 1994, Publisher: ASME
  • Conference paper
    CHILDS PRN, TURNER AB, 1994,

    HEAT TRANSFER ON THE SURFACE OF A CYLINDER ROTATING IN AN ANNULUS AT HIGH AXIAL AND ROTATIONAL REYNOLDS NUMBERS

    , 10th International Heat Transfer Conference, Publisher: INST CHEMICAL ENGINEERS, Pages: 13-18
  • Conference paper
    Childs PRN, Turner AB, Vaughan CM, Rayner D, Bayley FJet al., 1992,

    Heat Transfer to a Rotating Drum in an Annulus With a Stator Blade Row and Axial Throughflow

    , ASME 1992 International Gas Turbine and Aeroengine Congress and Exposition, Publisher: American Society of Mechanical Engineers

    <jats:p>This paper describes an experimental and numerical investigation of heat transfer to a rotor drum rotating in an annulus with an axial throughflow of air. The application of the work is principally to the transient heating of axial compressor rotor drums, and the results obtained extend the range of previously published correlations by an order of magnitude. Rotational Reynolds numbers (Reω = ωri2/ν) up to 1.5 × 106 and axial Reynolds numbers (ReD = uaDh/ν, Dh = 2(ro – ri)) up to 3.7 × 105 have been achieved experimentally.</jats:p> <jats:p>A new experimental facility is described in which a 400mm diameter rotor drum, instrumented with miniature thermopile type heat flux meters and thermocouples, can be air turbine driven at up to 10000rpm. The drum rotates in an annulus with a gap of 30mm in which complete rows of stator vanes can be mounted to enable the effect of vane/rotor drum clearance to be examined. A correlation for the heat transfer between the rotor drum and a stator blade row is presented for varying axial and rotational Reynolds numbers and blade/rotor drum radial clearance.</jats:p>
  • Conference paper
    Rayner D, Vaughan CM, Childs PRN, Turner ABet al., 1992,

    Numerical simulation of the heat transfer in turbulent, swirling annular flows

    , Advanced Computational Methods in Heat Transfer II, Pages: 511-531
  • Conference paper
    Childs PRN, Rayner D, Turner AB, 1992,

    Heat transfer to a cylindrical drum rotating in an annulus under a single stator blade row

    , International Centre for Heat and Mass Transfer, International Symposium, Heat Transfer in Turbomachinery

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