bluuebunny/crossref_metadata_2025 huggingface dataset:
A Fully Compressible Three Dimensional Inverse Design Method Applicable to Radial and Mixed Flow Turbomachines
Authors: Zangeneh M. , Hawthrone W. R.
Published: March 2015

A fully three dimensional compressible inverse design method for the design of radial and mixed flow machines is described. In this method the distribution of the circumferentially averaged swirl velocity, or rV¯θ on the meridional geometry of the impeller is prescribed and the corresponding blade shape is computed iteratively. Two approaches are presented for solving the compressible flow problem. In the approximate approach, the pitchwise variation in density is neglected and as a result the algorithm is simple and efficient. In the exact approach, the velocities and density are computed throughout the three dimensional flow field by employing Fast Fourier Transform in the tangential direction. The results of the approximate and exact approach are compared for the case of a high speed (subsonic) radial-inflow turbine and it is shown that the difference between the blade shapes computed by the two methods is well within the manufacturing tolerances. The flow through the designed impeller is analysed by using three dimensional inviscid and viscous time marching programs and very good correlations between the specified and computed rV¯θ is obtained.
The Application of Active Magnetic Bearings to a Power Turbine
Authors: Brailean Gordon E. , Grasdal Warren M. , Kulle Vaclav , Oleksuk Cal P. , Peterson Robert A.
Published: March 2015

This paper describes the application of active magnetic bearings to a power turbine. In particular, extensive redesign of the power turbine shaft and casing to accommodate the magnetic bearings is discussed. The combination of engineering problems unique to power turbines (large gyroscopic effects, high axial loading and elevated temperatures) are detailed. A description of some of the assembly problems and specialized tooling is included along with preliminary operating experiences.
Design and Performance Features of the Marine LM1600 Gas Turbine
Authors: Thames J. M. , Stueber H. B. , Vincent C. T.
Published: March 2015

The GE LM1600 gas turbine is a lightweight, efficient prime mover for commercial and military marine applications. This gas turbine is a derivative of the F404 fighter jet engine whose mission objectives strongly emphasize reliability and ease of maintenance in an austere marine environment. These objectives were important to the U.S. Navy because the F/A-18 fighter jets powered by this engine are based on aircraft carriers where parts warehousing and maintenance capabilities are limited. To achieve these objectives, component designs were simplified and the total number of components was substantially reduced.

These features and its modular construction make the LM1600 attractive for marine applications. Numerous marine propulsion system configurations are possible, including various combinations with diesel engines and steam gas turbines as well as options for shaft or electric drive. The first commercial installation of the marine LM1600 gas turbine is in progress and sea trials will commence in late 1990.

This paper describes the design, performance, installation, and maintenance features of the marine LM1600 gas turbine.
High Temperature Corrosion Resistance of Mechanically Alloyed Products in Gas Turbine Environments
Authors: Smith G. D. , Fischer J. J.
Published: March 2015

The high temperature corrosion performance of the heat resistant, mechanically alloyed, oxide dispersion strengthened alloys, INCOLOY® alloy MA 956, INCONEL® alloy MA 754, INCONEL alloy MA 760 and INCONEL alloy MA 6000 is described in this paper. Oxidation and oxidation-sulfidation data for a range of temperatures and environmental conditions are presented, along with comparative data on five wrought alloys. Scale types are related to performance.
Effects of Surface Roughness, Freestream Turbulence, and Incidence Angle on the Performance of a 2-D Compressor Cascade
Authors: Elrod W. C. , King P. I. , Poniatowski E. M.
Published: March 2015

The effects of surface roughness, freestream turbulence, and incidence angle on the performance of a two-dimensional compressor cascade were investigated. The test section consisted of seven NACA 65-A506 airfoils arranged in a linear cascade. Four different surface roughness conditions were applied to the first 25 percent chord on the suction surface of each of the five middle blades in the cascade. Freestream turbulence levels of approximately one and seven percent were used. Incidence angles of −3, zero and +3 degrees were investigated. Of the three parameters tested, freestream turbulence exerted the largest influence on blade performance. The total pressure loss coefficient increased with increased roughness and was reduced for large turbulence. Changes in flow incidence had a lesser effect on the performance of the blade.
Basic Features of Speed Induced Transient Behaviour of Axial Flow Compressors
Authors: Tang G. C.
Published: March 2015

An investigation is presented of basic features of speed induced transient behaviours of axial compression system. A non–linear model is developed for prediction of the transient response due to speed variation. Generally, the operating point forms a loop during an accelerating process. A small B or great rate of change in speed leads to a large loop. In the hysteresis region of the characteristic of the compressor, there are four possible solutions: steady flow with the compressor working on the unstalled part of the characteristic; steady flow with the operating point first getting across the stall limit then going back to the initial point; rotating stall and surge. Two critical values of the B parameter are identified, on which the system response depends. They are: Br, at which transition from rotating stall to surge occurs, and Bs, at which that from surge to steady flow takes place. Br and Bs are found to vary with some factors concerned. Their variation with the initial point, rate of the change in speed and the time lag constant are also studied.
Flowfield Calculation in Compressor Operating With Distorted Inlet Flow
Authors: Joubert H.
Published: March 2015

In order to improve the air inlet engine compatibility, SNECMA has carried out since several years an important effort to predict the effect of distorted inlet flow on compressor stability.

Two different methods are developed:

In the first one, the Euler equations are integrated in 2D blade to blade surface with a distorted inlet flow. This method is used to compare different profiles, in particular influence of the chord length is presented.

In the second one, the aerodynamic behaviour of a multistage compressor operating in distorted inlet flow is calculated with a three dimensional method. This model is based on Euler equations resolution outside the rows.

An actuator disk model is used to represent the response of the blade rows.

The behaviour of a three stage axial compressor has been studied. The loss of surge margin and the pressure distortion transfer are compared with experimental data.
Experimental Investigation of the Stalled Flow in a Centrifugal Pump-Turbine With Varied Diffuser
Authors: Ubaldi Marina , Zunino Pietro
Published: March 2015

Detailed measurements have been made of the stalled flow in a centrifugal pump-turbine model operating in air. Instantaneous velocity, total pressure and flow angle have been measured with hot wire and pressure probes at the impeller inlet and outlet and in the vaned diffuser for several pump operating points, ranging from nominal to very low flow rates.

Three distinct stall phenomena have been found to affect the pump operation at reduced flow rates. The unsteady characteristics of these unstable flows have been analysed both in time and in frequency domain by means of Fourier transforms of the velocity signals. The changes in the flow structure, correlated to the occurrence of the observed stall conditions, have been investigated by means of phase-locked ensemble averages of the instantaneous velocity components at the impeller outlet and surveys of the mean total pressure and absolute flow angle distributions within the diffuser passages.
A Boundary Layer Transition Correlation for Concave Surfaces
Authors: Hachem Farouk , Johnson Mark W.
Published: March 2015

The boundary layer profile is observed to be highly distorted by the momentum transfer associated with Taylor-Gortler vortices. This distortion has the effect or increasing the boundary layer growth rate and modifying the start-or-transition momentum thickness Reynolds numbers from the flat plate value. For modest curvatures, the vortices carry turbulence towards the blade which promotes transition, but as the curvature is increased further, the boundary layer profile shape is stabilised and transition is delayed. A model for the distorted boundary layer is presented and is used to predict the boundary layer growth rate and correlate the start or transition results in terms of the momentum thickness and blade radius Reynolds numbers and the free stream turbulence level. The degree or profile distortion needs to be accounted for when predicting the end or transition.
Vortex Control Over End Wall Flow in Compressor Cascades
Authors: Tang Yan-Ping , Chen Mao-Zhang
Published: March 2015

Three methods of vortex control over the end wall flow in compressor cascades have been investigated experimentally. The total pressure loss at the exit of a linear compressor cascade is reduced 6.5%, 10.5% and 26.5% respectively by these methods for different incidences over a range of moderate-high values. The physics of these methods has been discussed and some new concepts of vortex control techniques in compressor cascades have been proposed.
An Interactive System to Integrate the Design, Analysis, and Manufacture of Centrifugal Compressor Impellers
Authors: Crouse James E. , Sorokes James M.
Published: March 2015

This paper presents the impeller design system developed at Dresser-Rand using Bezier polynomials in cylindrical coordinates. A discussion of the basic techniques utilized in the code is presented as are sample graphic outputs generated to aid the user in the design process. The paper also describes some of the output options and how results may be interfaced with other analytical, drafting, and manufacturing software. Comments are included regarding the increased productivity, accuracy, and quality which resulted directly from use of this code and its support routines.
A Prediction of 3-D Viscous Flow and Performance of the NASA Low-Speed Centrifugal Compressor
Authors: Moore John , Moore Joan G.
Published: March 2015

A prediction of the three-dimensional turbulent flow in the NASA Low-Speed Centrifugal Compressor Impeller has been made. The calculation was made for the compressor design conditions with the specified uniform tip clearance gap. The predicted performance is significantly worse than that predicted in the NASA design study. This is explained by the high tip leakage flow in the present calculation and by the different model adopted for tip leakage flow mixing. The calculation gives an accumulation of high losses in the shroud/pressure-side quadrant near the exit of the impeller. It also predicts a region of meridional backflow near the shroud wall. Both of these flow features should be extensive enough in the NASA impeller to allow detailed flow measurements, leading to improved flow modelling. Recommendations are made for future flow studies in the NASA impeller.
Boundary Layer and Navier-Stokes Analysis of a NASA Controlled-Diffusion Compressor Blade
Authors: Ho Y. K. , Walker G. J. , Stow P.
Published: March 2015

Performance calculations for a NASA controlled-diffusion compressor blade have been carried out with a coupled inviscid-boundary layer code and a time-marching Navier-Stokes solver. Comparisons with experimental test data highlight and explain the strengths and limitations of both these computational methods. The boundary layer code gives good results at and near design conditions. Loss predictions however deteriorated at off-design incidences. This is mainly due to a problem with leading edge laminar separation bubble modelling; coupled with an inability of the calculations to grow the turbulent boundary layer at a correct rate in a strong adverse pressure gradient. Navier-Stokes loss predictions on the other hand are creditable throughout the whole incidence range, except at extreme positive incidence where turbulence modeling problems similar to those of the coupled boundary layer code are observed. The main drawback for the Navier-Stokes code is the slow rate of convergence for these low Mach number cases. Plans are currently under review to address this problem. Both codes give excellent predictions of the blade surface pressure distributions for all the cases considered.
Effects of Chordwise Displacement and Nonrigid Section Deformation on Unsteady Aerodynamic Response of Subsonic and Supersonic Oscillating Cascades
Authors: Namba Masanobu , Toshimitsu Kazuhiko
Published: March 2015

The double linearization theory is applied to lightly loaded two-dimensional subsonic and supersonic cascades undergoing oscillation with chordwise displacement or nonrigid section deformation. Numerical examples demonstrating parametric dependence of unsteady aerodynamic work on blades are presented. The chordwise displacement can be favorable or unfavorable for stabilizing the translational oscillation, depending upon the phase difference between the chordwise and normal components of the blade motion. For supersonic cascades the role of the effect of displacement of shock reflection points on unsteady aerodynamic response is significantly enhanced by the chordwise blade motion. The unsteady aerodynamic work for nonrigid section deformation is substantially influenced by steady loading.
Design of Shroud Interface-Angle to Minimize the Forced Vibration of Blades
Authors: Wang J. H. , Yau H. L.
Published: March 2015

The blades with integral shrouds have been used widely in industry. The blades are brought together via the contact of shroud interfaces. Because the angle of shroud interface can alter the damping of the interfaces and the coupling effect among the blades, knowing how to design the shroud angle is important. In this work, the theoretical shroud model was first verified experimentally, and then used to investigate the effect of shroud angle on the resonant responses excited by wake flow. The results show that a small shroud angle is superior than large shroud angle to minimize the resonant vibration. However, a critical static interface preload should be selected to avoid the weak coupling effect.
Development of Silicon Nitride Engine Components for Advanced Gas Turbine Applications
Authors: Busovne B. J. , Pollinger J. P.
Published: March 2015

The development and fabrication of reliable high temperature-high strength silicon nitride rotors by Garrett Ceramic Components for the Advanced Turbine Technology Applications Project (ATTAP) is discussed. The current status of rotor net-shape forming capability, achievable mechanical properties, NDE development/implementation, and statistical process control results will be presented.
Options in Gas Turbine Power Augmentation Using Inlet Air Chilling
Authors: Ondryas Igor S. , Wilson Dwayne A. , Kawamoto Marvin , Haub Gary L.
Published: March 2015

Gas Turbine Power Augmentation in a Cogeneration Plant using inlet air chilling is investigated. Options include absorption chillers, mechanical (electric driven) chillers, thermal energy storage. Motive energy for the chillers is steam from the gas turbine exhaust or electrical energy for mechanical chillers. Chilled water distribution in the inlet air system is described. Overall economics of the power augmentation benefits is investigated.
Development of an Efficient Oil Film Damper for Improving the Control of Rotor Vibration
Authors: Zhang Shiping , Yan Litang
Published: March 2015

An efficient oil film damper known as porous squeeze film damper (PSFD) was developed for more effective and reliable vibration control of high speed rotors based on the conventional squeeze film damper (SFD). The outer race of the PSFD is made of permeable sintered porous metal materials. The permeability allows some of the oil to permeate into and seep out the porous matix, with remarkebly improvement of the squeeze film damping properties. The characteristics of PSFD oil film stiffness and damping coefficients and permeability, also, the steady state unbalance response of a simple rigid rotor and flexible Jeffcott’s rotor supported on PSFD and SFD are investigated. A typical experiment is presented. Investigations show that the nonlinear vibration characteristis of the unpressurized SFD system such as bistable jump phenomena and “lockup” at rotor pin–pin critical speeds could be avoided and virtually disappear under much greater unbalance level with properly designed PSFD system. PSFD has the potential advantages to operate effectively under relative large unbalance conditions.
Laser Velocimeter Measurements in a Centrifugal Pump With a Synchronously Orbiting Impeller
Authors: Beaudoin Ronald J. , Miner Steven M. , Flack Ronald D.
Published: March 2015

Velocity profiles were measured in the impeller of a centrifugal pump with a two directional laser velocimeter. Blade to blade profiles were measured at four circumferential positions and four radii within and one outside the four bladed impeller. Data is presented herein at two circumferential and three radial locations. The pump was tested in two configurations; with the impeller running centered within the pump, and with the impeller orbiting with a synchronous motion (ϵ/r2). Variation in velocity profiles among the individual passages in the orbiting impeller were found. At design flow rate, these variations ranged from 30 to 60 percent for the radial component, and 15 to 25 percent for the tangential component. Tangential velocity profiles near the impeller exit (r/r2 = 0.973) were near uniform across each individual passage. Differences in the magnitude of the exit tangential velocities among the passages, however, were detected. Systematic differences in the velocity profile shapes of the centered and orbiting impellers were in general not measured, the only exception being at r/r2 = 0.973 at 40% of the design flow rate. At this condition, two distinct radial velocity profiles were measured. Two of the impeller passages of the orbiting impeller contained a recirculation region covering 20–30% of the blade passage while the other two passages contained no recirculation region. The centered impeller also contained this region of reverse flow. Finally, velocity data was numerically integrated to find the forces and stiffnesses due to momentum fluxes on the impeller for the orbiting condition.
An Examination of the Contributions to Loss on a Transonic Turbine Blade in Cascade
Authors: Mee D. J. , Baines N. C. , Oldfield M. L. G. , Dickens T. E.
Published: March 2015

Experiments to measure losses of a linear cascade of transonic turbine blades are reported. Detailed measurements of the boundary layer at the rear of the suction surface of a blade and examination of wake traverse data enable the individual components of boundary layer, shock and mixing loss to be determined. Results indicate that each component contributes significantly to the overall loss in different Mach number regimes. Traverses in the near wake of the blade indicate the way in which the wake develops and facilitate examination of the development of the mixing loss.
Evaluating Thermographic Phosphors in an Operating Turbine Engine
Authors: Noel B. W. , Borella H. M. , Lewis W. , Turley W. D. , Beshears D. L. , Capps G. J. , Cates M. R. , Muhs J. D. , Tobin K. W.
Published: March 2015

The results of a field test in a commercial turbine engine showed that we can remotely measure the temperature of engine components in operating engines using thermographic phosphors. The remote-measurement method exploits the temperature dependence of the characteristic decay time of the laser-induced fluorescence of thermographic phosphors. This paper summarizes recent work leading up to and including a successful test of the thermographic-phosphor method in an operating turbine engine.
Advanced Technology Programs for Small Turboshaft Engines: Past, Present, Future
Authors: Johnson Edward T. , Lindsay Howard
Published: March 2015

This paper addresses approximately 15 years of advanced technology programs sponsored by the United States Army Aviation Applied Technology Directorate and its predecessor organizations and conducted by GE Aircraft Engines (GEAE). Included in these programs is the accomplishment of (1) the 1,500 shp demonstrator (GE12) which led to the T700, and (2) the 5,000 shp Modern Technology Demonstrator Engine (MTDE/GE27). Also included are several advanced technology component programs which have been completed or are ongoing through the early 1990’s. The goals for the next generation of tri-service small advanced gas generator demonstration programs are shown. A prediction is thus made of the advancements required to fulfill the aircraft propulsion system established by the DoD/NASA Integrated High Performance Turbine Engine Technology (IHPTET) initiative through the year 2000.
Transient Control of an Expander Driven Generator in an FCCU Application
Authors: Sorokes James , Kidd H. Allan
Published: March 2015

Successfully modeling an expander driven generator for a power recovery process is absolutely essential to satisfy the high reliability requirement of three years continuous operation demanded by users. The model, simulation and resultant control system design discussed considers the pressure control requirements of upstream separators, process piping configurations, performance characteristics of the rotating equipment, process valve design and finally process controller algorithms. Several examples of process simulation studies performed will be presented.
Modification of a General Electric 7001B Turbine for Increased Reliability by Using 7001E Parts
Authors: Prugger David K. , McDermott William J.
Published: March 2015

Parts of the latest design, incorporating improvements developed over 19 years of operating experience, can be utilized on the Model 7001B gas turbines.

This paper describes the initial application of the 7001E technology to an entire turbine retrofit. Component design improvements, interfaces, and limitations are described as well as expected reliability improvements.

Emphasis will be given to Field Service Engineering experience in installing this first change, since labor can be a significant part of the conversion.
Laser Two-Focus Anemometry Investigation of the Flow Field Within a Supersonic Axial Compressor Rotor
Authors: Trebinjac Isabelle , Vouillarmet André
Published: March 2015

Laser anemometer measurements have been performed within and downstream of a supersonic single-stage high-pressure compressor. At design point and with standard upstream conditions the maximum relative Mach number varies from 1.3 at the tip to 1.1 at the hub. The stage total pressure ratio is 1.84 and the specific mass flow 180 kg/s/m2. The laser two-focus anemometer has been completely designed in the Laboratory; its originality being the use of a counting technique instead of the classical multichannel analyzer one. The data acquisition and reduction procedures are presented here.

A comprehensive evaluation of the global flow-field is in the scope of this paper. For that, the intra-blade flow field is described and the shock pattern is discussed. Furthermore, the experimental results are compared with both inviscid and viscous three-dimensional numerical simulations. The viscous computation is based on the Navier-Stokes solution using a mixing length turbulence model. The good agreement observed in this last case shows off the necessity of taking into account the viscous effects in a supersonic compressor flow calculation.
A Comparison of Zero and One Equation Turbulence Modelling for Turbomachinery Calculations
Authors: Dawes W. N.
Published: March 2015

The aim of this paper is to compare viscous predictions for two turbomachinery geometries performed with a simple mixing length turbulence model and a more advanced transport equation approach. The mixing length approach is simple and crude, but cheap; more sophisticated transport schemes are more physical but more expensive. This paper compares the performance of two standard models, in one host code, with experimental data for axial turbine secondary flow development and for axial compressor blade loss-incidence variation. Although the more sophisticated turbulence model does produce detail improvements in the quality of the predictions, as far as loss generation is concerned it is concluded there is little difference between the two models. The reasons for this are discussed in some detail.
Dawes and Denton Codes Applied to a Transonic Compressor Rotor
Authors: Von Backström T. W.
Published: March 2015

The three-dimensional viscous transonic time marching Denton code L0SS3D, and Dawes code BTOB3D are applied to the first stage rotor of the NACA 5-stage transonic compressor. Computing time per solution on a mini-supercomputer was about 9 hours for a mesh of 65 000 points. LOSS3D predicted pressure ratio and loss distributions reasonably well at design point, but did not quite satisfy the convergence criteria. BT0B3D tended to overpredict the total pressure ratio over the outer half of span due to an underprediction of loss in the complicated separated flow region triggered by shock boundary layer interaction on the suction surface, but prediction was good at 90% speed where shock boundary layer interaction was less severe. The use of a computationally convenient excessively large tip clearance is not recommended when shock-boundary layer interaction is expected, especially at off-design conditions.
ATTAP/AGT101: Year 2 Progress in Ceramic Technology Development
Authors: Kidwell J. R. , Lindberg L. J. , Morey R. E.
Published: March 2015

In the second year of a five-year Department of Energy (DOE) funded program, the Advanced Turbine Technology Applications Project (ATTAP) pushed ceramic automotive gas turbine technology state-of-the-art forward in:

• Ceramic materials assessment and characterization

• Ceramic impact damage assessment

• Ceramic combustor evaluation

• Turbine inlet particle separator development

• Impact-tolerant turbine designs

• Net-shape ceramic component fabrication

Materials characterization progressed from specimens to cut-up components. Impact damage threshold velocities were measured, using graphite projectiles against specimens and full-size rotors. Lean-burn ceramic combustor evaluations included ignition and carbon formation tests with DF-2, JP-4, and ethanol fuels. A third-generation ceramic turbine inlet particle separator demonstrated 97.5-percent effectiveness against rotor-damaging graphite particles. Improved ceramic component design capabilities are providing lower-stress components for incorporation into the critical hot flow path. Component fabrication development focussed on net-shape forming techniques, using Taguchi experiments.

ATTAP is funded by DOE and administered by NASA under Contract DEN3-335.
Closed Brayton Cycle Engine Application to Emerging Unmanned Underwater Vehicle Missions
Authors: Harper Allen D. , Jansen Jeffrey S.
Published: March 2015

Propulsion system definition to support emerging unmanned underwater vehicle (UUV) studies becomes of increasing significance as mission complexity grows. Substantial experience in the design of closed Brayton cycle (CBC) engines for marine applications has been applied to a range of UUV requirements and the results of system integration/conceptual design studies are described in this paper. The focus is on the heat engine; prior efforts have treated the associated thermochemical heat sources. Extensive use has been made of the pioneering efforts conducted 10 to 15 years ago. Some comparisons are given with competing propulsion system approaches (e.g., electrical systems), but these are not the focus of this paper since comparisons of this type have already been presented.
Overtip Pressure Measurements in a Cold-Flow Turbine Rig
Authors: Kingcombe R. C. , Smith I. M. , Steeden R. V.
Published: March 2015

In shroudless axial turbines the flow over the tips of the rotor blades is complex and accounts for significant loss of efficiency. In order to investigate the structure of this overtip flow, a row of high frequency response miniature pressure transducers was mounted in the casing of a cold flow turbine rig in the region swept by the rotor tips.
Chemical Stripping of Honeycomb Airseals: Overview and Update
Authors: Galel Zev , Brindisi Frank , Nordstrom Donald
Published: March 2015

Chemical stripping of the braze joint on honeycomb airseals is discussed as an improvement over mechanical methods, which reduce part wall thickness below acceptable limits. Chemical stripping has been successfully tested for a range of parts with different braze alloy / base metal combinations. Advantages and disadvantages of this approach are discussed, along with optional methods that enhance the replenishment of the chemical solution within the honeycomb cell.
Influence of High Rotational Speeds on the Heat Transfer and Discharge Coefficients in Labyrinth Seals
Authors: Waschka W. , Wittig S. , Kim S.
Published: March 2015

Heat transfer and leakage loss measurements were obtained for compressible flows in typical straight-through labyrinth seals with high rotational speeds. The experiments are an extension of our earlier measurements in a stationary test facility. In order to ensure direct comparisons to the original experiments, the principal dimensions of the test facility and gas dynamic parameters of the hot gas were kept similar. The new study encompasses a wide range of Taylor numbers, Reynolds numbers and clearances between the rotating annular fins and the stationary shroud. Heat transfer coefficients are determined for the stator as well as for the rotor. Temperature measurements along the cooled rotor were performed utilizing a high accuracy telemetric system. Continuous clearance control was achieved by employing specially designed gauges. Detailed pressure and temperatur measurements in the axial as well as in the circumferential direction were performed. Heat transfer coefficients and loss parameters are presented and compared with those obtained under steady state conditions.
Heat Transfer in Rotating Serpentine Passages With Smooth Walls
Authors: Wagner J. H. , Johnson B. V. , Kopper F. C.
Published: March 2015

Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large scale, multi–pass, smooth–wall heat transfer model with both radially inward and outward flow. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages (coolant–to–wall temperature ratio, Rossby number, Reynolds number and radius–to–passage hydraulic diameter ratio). These four parameters were varied over ranges which are typical of advanced gas turbine engine operating conditions. It was found that both Coriolis and buoyancy effects must be considered in turbine blade cooling designs and that the effect of rotation on the heat transfer coefficients was markedly different depending on the flow direction. Local heat transfer coefficients were found to decrease by as much as 60 percent and increase by 250 percent from no rotation levels. Comparisons with a pioneering stationary vertical tube buoyancy experiment showed reasonably good agreement. Correlation of the data is achieved employing dimensionless parameters derived from the governing flow equations.
A Control System for a High-Quality Generating Set Equipped With a Two-Shaft Gas Turbine
Authors: Kumakura H. , Matsumura T. , Tsuruta E. , Watanabe A.
Published: March 2015

A control system has been developed for a high-quality generating set (150kW) equipped with a two-shaft gas turbine featuring a variable power turbine nozzle. Because this generating set satisfies stringent frequency stability requirements, it can be employed as the direct electric power source for computer centers without using constant-voltage, constant-frequency power supply systems. Conventional generating sets of this kind have normally been powered by single-shaft gas turbines which have a larger output shaft inertia than the two-shaft version. Good frequency characteristics have also been realized with the two-shaft gas turbine, which provides superior quick start ability and lower fuel consumption under partial loads.
Computational Fluid Dynamic Applications for Jet Propulsion System Integration
Authors: Tindell R. H.
Published: March 2015

The impact of computational fluid dynamics (CFD) methods on the development of advanced aerospace vehicles is growing stronger year by year. Design engineers are now becoming familiar with CFD tools and are developing productive methods and techniques for their applications. This paper presents and discusses applications of CFD methods used at Grumman to design and predict the performance of propulsion system elements such as inlets and nozzles. The paper demonstrates techniques for applying various CFD codes and shows several interesting and unique results. A novel application of a supersonic Euler analysis of an inlet approach flow field, to clarify a wind tunnel-to-flight data conflict, is presented. In another example, calculations and measurements of low-speed inlet performance at angle of attack are compared. This is highlighted by employing a simplistic and low-cost computational model. More complex inlet flow phenomena at high angles of attack, calculated using an approach that combines a panel method with a Navier-Stokes (N-S) code, is also reviewed. The inlet fluid mechanics picture is rounded out by describing an N-S calculation and a comparison with test data of an offset diffuser having massively separated flow on one wall. Finally, the propulsion integration picture is completed by a discussion of the results of nozzle-afterbody calculations, using both a complete aircraft simulation in a N-S code, and a more economical calculation using an equivalent body of revolution technique.
Dynamic Simulation of Compressor Station Operation Including Centrifugal Compressor and Gas Turbine
Authors: Botros K. K. , Campbell P. J. , Mah D. B.
Published: March 2015

Dynamic simulation of the operation of a compressor station requires mathematical modelling of the dynamic behaviour of the compressor unit and various piping elements. Such models consist of large systems of non-linear partial differential equations describing the pipe flow together with non-linear algebraic equations describing the quasi-steady flow through various valves, constrictions and compressors. In addition, the models also include mathematical descriptions of the control system which consists of mixed algebraic and ordinary differential (mad) equations with some inequalities representing controllers’ limits.

In this paper a numerical technique for the solution of the gas dynamics equations is described, which is based on the transfer matrix formulation relating the state vector time-difference at one side of an element to that on the other side. This approach facilitates incorporation of all elements transfer matrices into an overall transfer matrix according to the system geometrical connectivity. The paper also presents simulation results and comparison with actual field measurements of three case histories: 1) simulation of a compressor surge protection control process; 2) unit startup; and 3) slow transient of a compressor station responding to changes in the discharge pressure set point. Good agreement between simulation results and field measurements is demonstrated.
The Aerodynamic and Mechanical Performance of a High Pressure Turbine Stage in a Transient Wind Tunnel
Authors: Sheard A. G. , Ainsworth R. W.
Published: March 2015

A new transient facility for the study of time mean and unsteady aerodynamics and heat transfer in a high pressure turbine has been commissioned and results are available. A detailed study has been made of aspects of the performance and behaviour relevant to turbine mechanical design, and an understanding of the variation of the turbine operating point during the test, crucial to the process of valid data acquisition, has been obtained.

In this paper the outline concept and mode of operation of the tubine test facility are given, and the key aerodynamic and mechanical aspects of the facility’s performance are presented in detail. The variation of those parameters used to define the turbine operating point during facility operation are examined, and the accuracy with which the turbine’s design point was achieved calculated. Aspects of the mechanical performance which are presented include the results of a finite element stress analysis of the loads in the turbine under operating conditions, and the performance of the rotor bearing system under these arduous load conditions. Both of these aspects present more information than has been available hitherto.

Finally, the future work programme and possible plans for further facility improvement are given.
Engine Performance Monitoring and Troubleshooting Techniques for the CF-18 Aircraft
Authors: Cue R. W. , Muir D. E.
Published: March 2015

The F404-GE-400 engines of the CF-18 aircraft are the first engines of the Canadian Forces to be maintained under a formal on-condition maintenance program. In support of this program, the Canadian Forces are developing advanced troubleshooting and performance monitoring procedures based on information recorded by the aircraft In-flight Engine Condition Monitoring System (IECMS). A suite of computer programs has been developed which enables maintenance personnel to access, display and analyze in-flight event data recorded by the IECMS and to track the performance of individual engines based on “health indices” derived from the IECMS takeoff ground roll recordings. The new techniques have been under evaluation at each of the CF-18 main operating bases for a period of approximately 14 months. Results to-date indicate that the IECMS recordings provide a considerable amount of information of benefit to engine technicians and maintenance planners.
Three-Dimensional Flowfields Inside a Transonic Compressor With Swept Blades
Authors: Hah C. , Wennerstrom A. J.
Published: March 2015

The concept of swept blades for a transonic or supersonic compressor was reconsidered by Wennerstrom in the early 1980s. Several transonic rotors designed with swept blades have shown very good aerodynamic efficiency. The improved performance of the rotor is believed to be due to reduced shock strength near the shroud and better distribution of secondary flows.

A three-dimensional flowfield inside a transonic rotor with swept blades is analyzed in detail experimentally and numerically. A Reynolds-averaged Navier-Stokes equation is solved for the flow inside the rotor. The numerical solution is based on a high-order upwinding relaxation scheme, and a two-equation turbulence model with a low Reynolds number modification is used for the turbulence modeling. To properly predict flows near the shroud, the tip-clearance flow also must be properly calculated. The numerical results at three different operating conditions agree well with the available experimental data and reveal various interesting aspects of shock structure inside the rotor.
Construction of a 700MW Combined Cycle Plant for YANAI Power Station No. 1
Authors: Shirakura S. , Ando N. , Hoshino K.
Published: March 2015

The Chugoku Electric Power Co., Ltd. is currently constructing a 700MW combined cycle power plant at Yanai, Yamaguchi Prefecture, based on new design concepts.

This power plant consists of six single-shaft combined cycle units with construction in two phases.

Operation of the first phase, which includes three units with an output of 350 MW, will begin in November, 1990; operation of the second phase, which also includes three units with an output of 350 MW, will begin in December, 1992.

The notable features of this power plant are: High efficiency; short starting and stopping time; suitability for daily start/stop and large load variations; thorough NOx countermeasures; easy-to-use man-machine interface control systems; and short construction period based on improvement of construction methods.

The NOx countermeasures for the gas turbines are based on a newly-developed dry low NOx combustor which is designed so that the NOx emission level is 75 ppm or less for the entire load.

A functionally and hierarchically distributed digital control system has been used for the plant control system, so that the reliability, maintenability, and controllability will be improved.

In particular, an improvement was made to the man-machine interface. A CRT operation system and a large 110-inch screen are used together with an operation support system and a power plant office automation system.

Equipment installation is proceeding smoothly and field testing of the first units will begin in April, 1990.

Because this power plant is located in the Inland Sea National Park, thorough consideration has been taken in its appearance, such as color coordination, and landscaping of the power station area.
Comparison of Inviscid Computations With Theory and Experiment in Vibrating Transonic Compressor Cascades
Authors: Gerolymos G. A. , Blin E. , Quiniou H.
Published: March 2015

The prediction of unsteady flow in vibrating transonic cascades is essential in assessing the aeroelastic stability of fans and compressors. In the present work an existing computational code, based on the numerical integration of the unsteady Euler equations, in blade-to-blade surface formulation, is validated by comparison with available theoretical and experimental results. Comparison with the flat plate theory of Verdon is, globally, satisfactory. Nevertheless, the computational results do not exhibit any particular behaviour at acoustic resonance. The use of a 1-D nonreflecting boundary condition does not significantly alter the results. Comparison of the computational method with experimental data from started and unstarted supersonic flows, with strong shock waves, reveals that, notwithstanding the globally satisfactory performance of the method, viscous effects are prominent at the shock wave/boundary layer interaction regions, where boundary layer separation introduces a pressure harmonic phase shift, which is not presicted by inviscid methods.
Surface treatments to reduce leakage current in In0.53Ga0.47As p-i-n diodes
Authors: Gaur Abhinav , Manwaring Ian , Filmer Matthew J. , Thomas Paul M. , Rommel Sean L. , Bhatnagar Kunal , Droopad Ravi
Published: March 2015

The impact of mesa surface conditions on the dark current of a homojunction In0.53Ga0.47 As p-i-n diode has been investigated. Three treatments were performed on mesa structures with a 100 nm i-layer—sidewall exposure to O2 plasma, sulfide treatment, and divinylsiloxane-bis-benzocyclobutene (BCB) passivation that resulted in perimeter normalized current, J1, of 0.01 A/cm, 0.35 μA/cm, and 35 nA/cm, respectively. This study spanned several days and it was shown that sulfide layer, unless properly capped, deteriorates over time whereas the BCB passivation properly encapsulates the mesa and does not degrade for longer periods of time.
Arc plasma synthesized Si nanotubes: A promising low turn on field emission source
Authors: Joshi Padmashree D. , Tank Chiti M. , Kamble Shalaka A. , Joag Dilip S. , Bhoraskar Sudha V. , Mathe Vikas L.
Published: March 2015

Here, the authors report the field emission investigations of silicon nanotubes (SiNTs) synthesized by vapor phase condensation method in DC arc plasma reactor. The SiNTs have diameters in the range of 10–15 nm and length of a few 100 nm. A maximum current density of 4.2 mA/cm2 has been attained. The turn on field, defined for obtaining a current density of 10 μA/cm2, is found to be 1.9 V/μm. The specimen exhibits a good emission current stability at 1 μA over a period of 3 h. The field enhancement factor, β, is estimated to be ∼5534. The current stability is quantified in terms of standard deviation and its magnitude has been measured to be only 9.7% with respect to the average value.
Evaluating the dual target binding capabilities of immobilized aptamers using flow cytometry
Authors: Dunaway Adam B. , Sullivan Richard S. , Siegel Katherine J. , Milam Valeria T.
Published: March 2015

In the current study, the authors quantify the binding activity of particle-immobilized DNA aptamers to their nucleotide and non-nucleotide targets. For the purposes of this work, DNA and vascular endothelial growth factor (VEGF) binding analysis was carried out for VEGF-binding aptamers and compared to that of an ampicillin-binding aptamer as well as a non-aptamer DNA probe. Binding analysis followed incubation of one target type, coincubation of both DNA and VEGF targets, and serial incubations of each target type. Moreover, recovery of aptamer binding activity following displacement of the DNA target from aptamer:DNA duplexes was also explored. Flow cytometry served as the quantitative tool to directly monitor binding events of both the DNA target and protein target to the various aptamer and non-aptamer functionalized particles. The current work demonstrates how processing steps such as annealing and binding history of particle-immobilized aptamers can affect subsequent binding activity. To this end, the authors demonstrate the ability to fully recover DNA target binding activity capabilities and to partially recover protein target binding activity.
Towards a complete physically based forecast model for underwater noise related to impact pile driving
Authors: Fricke Moritz B. , Rolfes Raimund
Published: March 2015

An approach for the prediction of underwater noise caused by impact pile driving is described and validated based on in situ measurements. The model is divided into three sub-models. The first sub-model, based on the finite element method, is used to describe the vibration of the pile and the resulting acoustic radiation into the surrounding water and soil column. The mechanical excitation of the pile by the piling hammer is estimated by the second sub-model using an analytical approach which takes the large vertical dimension of the ram into account. The third sub-model is based on the split-step Padé solution of the parabolic equation and targets the long-range propagation up to 20 km. In order to presume realistic environmental properties for the validation, a geoacoustic model is derived from spatially averaged geological information about the investigation area. Although it can be concluded from the validation that the model and the underlying assumptions are appropriate, there are some deviations between modeled and measured results. Possible explanations for the observed errors are discussed.
Comment on “Relative variance of the mean squared pressure in multimode media: Rehabilitating former approaches” [J. Acoust. Soc. Am. 136, 2621–2629 (2014)]
Authors: Davy John L. , Weaver Richard L.
Published: March 2015

Models for the statistics of responses in finite reverberant structures, and in particular, for the variance of the mean square pressure in reverberation rooms, have been studied for decades. It is therefore surprising that a recent communication has claimed that the literature has gotten the simplest of such calculations very wrong. Monsef, Cozza, Rodrigues, Cellard, and Durocher [(2014). J. Acoust. Soc. Am. 136, 2621–2629] have derived a modal-based expression for the relative variance that differs significantly from expressions that have been accepted since 1969. This Comment points out that the Monsef formula is clearly incorrect, and then for the interested reader, points out the subtle place where they made their mistake.