bluuebunny/crossref_metadata_2025_split huggingface dataset:
Condensation in Jet Engine Intake Ducts During Stationary Operation
Authors: Young John B. 
Published: February 2015

The paper describes an analysis of the condensation of moist air in very long intake ducts of jet engines during stationary operation. Problems arising from such condensation include fan overspeed and increased stagnation pressure loss in the intake duct.
The analysis demonstrates that, for moderate values of relative humidity, homogeneous condensation will occur in an outer annulus adjacent to the intake cowling if the local flow Mach number attains values of about 1.0. In the central region of the intake duct, where design Mach numbers of 0.8 may be attained, homogeneous condensation is unlikely to occur except, possibly, when the relative humidity is close to 100% and the ambient temperature very high. However, if the intake duct is very long, significant heterogeneous condensation on foreign particles present in the atmosphere is possible. The concentration of foreign nuclei required for this type of condensation is comparable to the likely levels of contamination at many industrial test sites.
The effects of condensation on engine test results are twofold. Firstly, condensation is a thermodynamically irreversible process and results in an increase of entropy and hence loss of total pressure in the intake duct. Uncorrected measurements using Pitot probes may not record this loss correctly. Secondly, the mass and energy transfer between the phases during the condensation process has a tendency to accelerate the flow approaching the engine, an effect which may be counteracted by a reduction in mass flowrate in order to maintain the static pressure constant. These conclusions are in agreement with experimental results obtained on-site during the testing of a jet engine fitted with a very long intake duct.
Repairable Gas Turbine Electrical Cable Assemblies
Authors: DiCicco William 
Published: February 2015

Often electrical cable assemblies are required to operate under hostile environmental conditions which lead to the need for periodic maintenance. Several designs have been introduced, however many address repairability while sacrificing environmental suitability.
A repairable cable assembly has been designed which addresses both the environmental aspects of applications and ease of repair. The technique can be applied to the two basic types of shielded cable, the conduit type and the braided outer jacket type. The repairable design feature provides excellent shielding from EMI/RFI, is waterproof, and can be pushed back for easy access to the back of connectors to facilitate replacement of contacts.
The Modelling of Flow in the Volute and Vanes of a High Pressure Radial Inflow Turbine
Authors: Lobo M. , Elder R. L. 
Published: February 2015

The flow in a vaned volute of a radial inflow turbine is analysed using PHOENICS, a very general three-dimensional viscous CFD code based on finite-volume pressure-correction techniques for solving the Navier-Stokes equations. The study involves two physically complementary but mathematically very different problems — flow modelling in the vaneless section of the volute and flow modelling in the vanes. Each of these problems is considered in turn — and each presents characteristic hurdles. Particular attention is paid to grid-generation and the process is carried out alongside the flow computation, the grids being modified in such a way so as to facilitate convergence and accuracy.
Numerical results are presented in the form of vector plots for purposes of general description and tables for comparison with experiment. Agreement with experiment is good. However experimental results, for comparison are available only in the vanes. In the vaneless section of the volute, the converged solution depicts some interesting secondary flow features — in regions inaccesible to the current experimental measurements.
Investigation of Flow in a Radial Turbine Using Laser Anemometry
Authors: Zaidi Sohail Hamid , Elder Robin L. 
Published: February 2015

A lightweight, high pressure radial inflow turbine was tested and laser anemometry used to measure the flow at various positions within the nozzle guide vanes, immediately upstream of the rotor and at two axial stations downstream of the rotor.
The laser anemometry results indicated flow conditions within the nozzle vanes which were largely two dimensional (blade-to-blade with little hub to shroud variation) except at the vane outlet. Unsteadiness due to rotor blade passing effects were detected at the nozzle guide vane trailing edge but had almost entirely decayed at the vane throat. The results also indicate significant variations in flow conditions across the pitch of the nozzles suggesting incidence variations on the rotor of approaching 30 degrees. The laser anemometry results downstream of the turbine show a swirling flow characterised by a turbulent inner core region, a ‘centre annulus’ region of uniform velocity and flow direction and an outer flow region with a similar flow direction but velocity which increases rapidly towards the outer wall. The blade passing unsteadiness (blade-to-blade) is hardly noticeable some 50mm downstream of the rotor trailing edge.
The Turbine Components Development for the 100 kW Automotive Ceramic Gas Turbine
Authors: Nakazawa Norio , Inaba Shizuo , Izumi Takao , Munekiyo Masayuki , Sasaki Shoji , Fujimori Kokichi 
Published: February 2015

Based on the specifications of a 100 kW single shaft automotive CGT, the aerodynamic design and the basic structure design of the radial turbine components, and the detailed design of each part were carried out. When designing, attaching great importance to the problems (brittleness and difficulty in manufacturing) unique to ceramic materials is required. The life was estimated with a strength reliability designing tool.
The aerodynamic characteristics were evaluated by testing metallic models, and the level of the intermediate target efficiency was achieved. The turbine rotor and the stationary structure parts were manufactured, and the strength reliability was evaluated with single and combined parts respectively. A peripheral speed of 830 m/s (113% of the rated value) with a turbine inlet temperature of 1200°C was obtained for the rotor hot-spin burst test.
The aerodynamic characteristics and the strength reliability shall be improved by repeating trial manufacture and test evaluation of ceramic parts.
Measurement of Residual Stresses in Metal Matrix Composites
Authors: Wright P. K. 
Published: February 2015

Metal matrix composites (MMC) are expected to develop internal residual stresses on cooling from fabrication due to the large thermal expansion mismatch between reinforcing fibers and the matrix. This work was undertaken to experimentally measure these residual stresses and compare them with analytical calculations in order to clearly establish their levels and dependence on material parameters.
Two techniques for residual stress measurement were investigated: 1) Xray diffraction (sin2 psi method) and 2) neutron diffraction. Both techniques gave results in good agreement with analytical predictions for several systems (SCS-6/Ti-24Al-11Nb, W/NiAl, and Al2O3NiAl). The results obtained showed a dependence of residual stresses on thermal expansion coefficients, elastic moduli, volume fraction fibers, and matrix yield strengths. The fibers showed compressive stress states, and the matrix, tension. Average stresses were higher in the fiber direction than transverse to fibers.
Buoyancy-Affected Flow and Heat Transfer in Asymmetrically-Heated Rotating Cavities
Authors: Long C. A. , Morse A. P. , Zafiropoulos N. 
Published: February 2015

Finite-volume predictions are presented for the convective heat transfer rates in a rotating cavity, formed by two co-rotating plane discs and a peripheral shroud, and subjected to a radial outflow of cooling air. The heating of the discs is asymmetric, the air entering the cavity through a central hole in the cooler (upstream) disc. The predicted Nusselt number distributions for each disc are compared with unpublished data from the University of Sussex for dimensionless mass-flow rates in the range 2800 ≤ Cw ≤ 14000 and rotational Reynolds numbers, Reθ, up to 5.2 × 106. A single-grid elliptic procedure was used with turbulent transport represented via a low Reynolds number k-ε model and the turbulence Prandtl number concept. In comparing the predicted and measured convective heat fluxes, it is important to consider the radiative heat exchange between the discs. This is estimated using a conventional view-factor approach based on black-body emission.
Under conditions of asymmetric heating, rotationally-induced buoyancy forces can exert significant effect on the flow structure, the induced motion tending to oppose that imposed by the radial outflow. Indeed, flow visualisation studies have revealed that, as the rotational Reynolds number is increased (for a fixed value of Cw), the flow in the source region initially becomes oscillatory in nature, leading eventually to the onset of chaotic flow in which the usual Ekman layer structure does not persist in all angular planes. The extent to which the effects of such flow behaviour can be captured by the steady, axisymmetric calculation approach used here is questionable, but it is found that the turbulence model (used previously for the prediction of heat transfer in symmetrically-heated cavities) still leads to good (±10%) predictive accuracy for the heated (downstream) disc. However, the predicted Nusselt numbers for the cooler (upstream) disc generally show little accord with experimental data, often signifying heat flow into the disc instead of vice-versa. It is concluded that the modelling of the turbulent heat transport across the core region of the flow is erroneous, especially at high rotational Reynolds numbers: this is attributed to overestimated turbulence energy production in that region due to the action of the radial-circumferential component of shear stress (vw). Adoption of an algebraic-stress model for this shear stress is partly successful in removing the discrepancies between prediction and experiment.
Leading Edge Separation Bubbles on Turbomachine Blades
Authors: Walraevens R. E. , Cumpsty N. A. 
Published: February 2015

Results are presented for separation bubbles of the type which can form near the leading edges of thin compressor or turbine blades. These often occur when the incidence is such that the stagnation point is not on the nose of the aerofoil. Tests were carried out at low speed on a single aerofoil to simulate the range of conditions found on compressor blades. Both circular and elliptic shapes of leading edge were tested. Results are presented for a range of incidence, Reynolds number and turbulence intensity and scale.
The principal quantitative measurements presented are the pressure distributions in the leading edge and bubble region, as well as the boundary layer properties at a fixed distance downstream where most of the flows had reattached. Reynolds number was found to have a comparatively small influence, but a raised level of freestream turbulence has a striking effect, shortening or eliminating the bubble and increasing the magnitude of the suction spike. Increased freestream turbulence also reduces the boundary layer thickness and shape parameter after the bubble. Some explanations of the processes are outlined.
Comparison of Experimental and Theoretical Results for Unsteady Transonic Cascade Flow at Design and Off-Design Conditions
Authors: Carstens V. , Bölcs A. , Körbacher H. 
Published: February 2015

This paper presents experimental and theoretical results for turbine cascades performing harmonic oscillations in transonic flow at design and off-design conditions. The experimental investigations were performed in an annular test facility where unsteady blade pressures were measured in two different test cascades, one operating at the nominal inlet flow angle, the other at an incidence angle exceeding the normal value by more than 20 degrees. The corresponding theoretical results were computed with a 2D Euler code which makes use of flux vector splitting in combination with a time-dependent grid generation.
The present data were all obtained for tuned bending modes where the blades performed heaving oscillations with the same frequency and amplitude, but with a constant interblade phase angle. For the cascade operating at design conditions, the steady flow was purely subsonic. The other test cascade was run in transonic flow, and a normal shock appeared on the rear part of the blade’s suction surface.
It was found that measured unsteady pressure and damping coefficients are well reproduced by the computed results for the first test cascade. In the case of steady off-design flow (the second test cascade), significant differences between experimental and theoretical results are observed.
Inviscid-Viscous Interaction Method for 3D Inverse Design of Centrifugal Impellers
Authors: Zangeneh M. 
Published: February 2015

A 3D inverse design method for the design of the blade geometry of centrifugal compressor impellers is presented. In this method the blade shape is computed for a specified circulation distribution, normal (or tangential) thickness distribution and meridional geometry. As the blade shapes are computed by using an inviscid slip (or flow tangency) condition, the viscous effects are introduced indirectly by using a viscous/inviscid procedure. The 3D Navier-Stokes solver developed by Dawes is used as the viscous method. Two different approaches are described for incorporating the viscous effects into the inviscid design method. One method is based on the introduction of an aerodynamic blockage distribution throughout the meridional geometry. While in the other approach a vorticity term directly related to the entropy gradients in the machine is introduced.
The method is applied to redesign the blade geometry of Eckardt’s 30° backswept impeller as well as a generic high pressure ratio (transonic) impeller. The results indicate that the entropy gradient approach can fairly accurately represent the viscous effects in the machine.
Pressure and Temperature Distortion Testing of a Two-Stage Centrifugal Compressor
Authors: Cousins W. T. , Dalton K. K. , Andersen T. T. , Bobula G. A. 
Published: February 2015

Altitude pressure and temperature inlet distortion testing of the two-stage centrifugal compressor in the T800-LHT-800 engine is described. The test setup and the testing techniques are reviewed and the results of the test are presented.
The generation of classical 180 degree patterns of both pressure and temperature distortion is discussed. Temperature distortion was created using a hydrogen burner system while pressure distortion was created in the classical manner, using screens. Results of both individual and combined temperature and pressure distortions in both opposed and concurrent patterns are shown.
Numerical Analysis of the 3D Swirling Flow in Centrifugal Compressor Volutes
Authors: Ayder E. , Van den Braembussche R. 
Published: February 2015

The improvement of centrifugal compressor performance and the control of the radial forces acting on the impeller due to the circumferential variation of the static pressure caused by the volute require a good understanding of the flow mechanisms and an accurate prediction of the flow pattern inside the volute. A 3D volute calculation method has been developed for this purpose.
The volute is discretized by means of hexahedral elements. A cell vertex finite volume approach is used in combination with a time marching procedure. The numerical procedure makes use of a central space discretization and a four step Runge-Kutta time stepping scheme. The artificial dissipation used in the solver is based on the fourth order differences of the conservative variables. Implicit residual smoothing improves the convergence rate. The loss model implemented in the code accounts for the losses due to internal shear and friction losses on the walls.
A comparison of the calculated and measured results inside a volute with elliptical cross sectional shape reveals that the modified Euler solver accurately predicts the velocity and pressure distribution inside and upstream of the volute.
A New High-Efficiency Heavy-Duty Combustion Turbine 701F
Authors: Fukue I. , Aoki S. , Aoyama K. , Umemura S. , Merola A. , Noceto M. , Rosso M. 
Published: February 2015

The 701F is a high temperature 50Hz industrial grade 220 MW size engine based on a scaling of the 501F 150MW class 60Hz machine, and incorporates a higher compressor pressure ratio to increase the thermal efficiency. The prototype engine is under a two-year performance and reliability verification testing program at MHI’s Yokohama Plant and was initially fired in June of 1992.
This paper describes the 701F design features design changes made from 501F. The associated performance and reliability verification test program will also be presented.
A Method for the Calculation of the Tip Clearance Flow Effects in Axial Flow Compressors: Part II — Calculation Procedure
Authors: Nikolos I. K. , Douvikas D. I. , Papailiou K. D. 
Published: February 2015

An algorithm was set up for the implementation of the tip clearance models, described in Part I, in a secondary flow calculation method. A complete theoretical procedure was, thus, developed, which calculates the circumferentially averaged flow quantities and their radial variation due to the tip clearance effects.
The calculation takes place in successive planes, where a Poisson equation is solved in order to provide the kinematic field. The self induced velocity is used for the positioning of the leakage vortex and a diffusion model is adopted for the vorticity distribution.
The calculated pressure deficit due to the vortex presence is used, through an iterative procedure, in order to modify the pressure difference in the tip region. The method of implementation and the corresponding algorithm are described in this part of the paper and calculation results are compared to experimental ones for cascades and single rotors. The agreement between theory and experiment is good.
The Investigation of the Travelling Wave Resonance of Driven Helical Gear
Authors: Qiu Shijun , Xu Min 
Published: February 2015

The main vibration type gearing in modern aeroengine transmission is the travelling wave vibration which is divided into two kinds: the forward travelling wave vibration and the backward travelling wave vibration. If the frequency of vibration exciting force, which comes from the meshing of a set of helical gears, is the same as the frequency of travelling wave resonance, the dangerous resonant vibration will take place. However both of forward and backward travelling wave resonance can not be excited as easily. The results of an aeroengine transmission test indicate that forward travelling wave resonant vibrations are more easily excited to the driven helical gear and more dangerous.
The work done by the component force, which is generated because of the angle of travelling wave vibration, on the driven helical gear, work done on the forward travelling wave vibration is positive and the backward travelling wave vibration is negative. In other words, for backward travelling wave vibration the induced force acts as a damping force, but for forward travelling wave vibration the induced force acts as a self–exciting force. Therefore it is more dangerous to driven helical gear when forward travelling wave vibration appears.
Application of State-of-the-Art Power Plant (SOAPP) Workstation for Combustion Turbine Emissions Control
Authors: Perry Philip A. , Van Laar James A. , Touchton George , Pace Stanley E. 
Published: February 2015

The Electric Power Research Institute (EPRI) has been conducting a broad research and development effort over the last ten years to provide better designs and materials for fossil fuel power plants. To facilitate transferring this advanced design and technology knowledge to the power industry for the next generation of power plants, EPRI and Sargent & Lundy (S&L) are creating the State-of-the-Art Power Plant (SOAPP) Workstation. The SOAPP Workstation will be available to the industry as a powerful tool that can be used to screen advanced technologies for appropriateness to specific sites; obtain design guidelines for advanced technologies; and generate site-specific conceptual designs, including conceptual design drawings, heat balances, cost estimates, and schedules.
The technology transfer components of this project are a series of individual software modules that will be integrated into the SOAPP Workstation. This paper discusses two software modules that have recently been developed for combustion turbine power plant emission control. The Combustion Turbine Nitrogen Oxides (NOx) Combustor Control Strategies technology module presents state-of-the-art technologies that are commercially available to reduce NOx emissions during combustion, including water injection, steam injection, and dry low NOx combustors. The second technology module, Combustion Turbine Postcombustion NOx/CO Control Strategies, examines selective catalytic reduction (SCR) and carbon monoxide (CO) oxidation technologies for reducing postcombustion NOx and CO emissions. These two technology modules, operating within the SOAPP Workstation, will allow appropriate decisions to be made concerning combustion turbine emission control.
Experimental and Theoretical Investigations of Heat Transfer in Closed Gas-Filled Rotating Annuli
Authors: Bohn D. , Deuker E. , Emunds R. , Gorzelitz V. 
Published: February 2015

The prediction of the temperature distribution in a gas turbine rotor containing closed, gas-filled cavities, for example in between two discs, has to account for the heat transfer conditions encountered inside these cavities. In an entirely closed annulus forced convection is not present, but a strong natural convection flow exists, induced by a non-uniform density distribution in the centrifugal force field.
Experimental investigations have been made to analyze the convective heat transfer in closed, gas-filled annuli rotating around their horizontal axis. The experimental set-up is designed to establish a pure centripedal heat flux inside these annular cavities (hot outer, and cold inner cylindrical wall, thermally insulated side walls). The experimental investigations have been carried out for several geometries varying the Rayleigh number in a range usually encountered in cavities of turbine rotors (1007 < Ra < 1012). The convective heat flux induced for Ra = 1012 was found to be a hundred times larger compared to the only conductive heat flux. By inserting radial walls the annulus is divided into 45° sections and the heat transfer increases considerably.
A computer programme to simulate flow and heat transfer in closed rotating cavities has been developed and tested successfully for annuli with isotherm side walls with different temperatures giving an axial heat flux. For the centripedal heat flux configuration, three-dimensional steady state calculations of the sectored annulus were found to be consistent with the experimental results. Nevertheless, analysis of unsteady calculations show that the flow can become unstable. This is analogous to the Bénard problem in the gravitational field.