bluuebunny/crossref_metadata_2025 huggingface dataset:
Inviscid Flow Through a Cascade of Thick, Cambered Airfoils: Part 2—Compressible Flow
Authors: Frith D. A.
Published: November 2010

Evaluation of two-dimensional, inviscid, compressible flow through a cascade of airfoils must involve numerical methods. Some of the associated problems are avoided if the flow field is mapped to the interior of a unit circle as the airfoil boundaries become grid points of the regular array in this domain. Further, far upstream and far downstream map to points in this circle so the uniform inlet and outlet flows are simply defined. For a solution obtained in terms of a stream function the compressible flow may be derived as a numerical perturbation from an analytical, incompressible stream function. A method incorporating these features is described in detail and some results for thick, cambered airfoils in cascade are presented. As supersonic patches can exist on the airfoils for high subsonic inlet Mach numbers, a unique method of relating the density to the stream function is employed in order to enable such flows to be calculated.
A Preliminary Study of the Design of a Controller for an Automotive Gas Turbine
Authors: Winterbone D. E. , Munro N. , Lourtie P. M. G.
Published: November 2010

A feasibility study has been performed on the design of a controller for a vehicular gas turbine, in which the turbine has been simulated using a digital computer program. The use of a computer model enables the controller to be designed at the same time as the engine thus reducing development time and allowing interaction of the design requirements. This paper shows that it is possible to design a complete system by these methods, although the present controller does not yet contain all the desired features.
Dynamic Gas Temperature Measurements in a Gas Turbine Transition Duct Exit
Authors: Dils R. R.
Published: November 2010

Wide bandwidth gas temperature measurements in the transition duct exit of a gas turbine show that large gas temperature fluctuations occur at any point in the duct exit. The temperature fluctuations increase with engine thrust level, exceeding 1000 deg F at takeoff. Probabilistic and spectral analyses of the data indicate that the gas temperature fluctuations are due to nonaxial displacements of partially mixed secondary air jet zones in the transition duct exit. The jet zones are driven by the combustion processes in the forward sections of the main burner. The combustion processes regeneratively and nonlinearly amplify the longitudinal resonant acoustic pressure modes of the diffuser duct and the main burner and generate periodic velocity fluctuations in the combustion products leaving the forward sections of the main burner. Surface temperature waves induced at the leading edge of the first-stage turbine nozzle guide vanes by the main burner exhaust gases are also obtained from the data. Surface temperature fluctuations exceeding 30 deg F occur at takeoff. The fluctuations are of sufficient amplitude to cause a significant increase in the rate of oxidation of the turbine components.
Investigation of the Aerodynamic Performance of Small Axial Turbines
Authors: Ewen J. S. , Huber F. W. , Mitchell J. P.
Published: November 2010

This paper describes results of an experimental investigation of small axial turbine performance characteristics. Included are test data on the effects of the following design variables on small turbine aerodynamic efficiency: (a) blade height, (b) vane endwall contouring, (c) blade reaction, (d) blade tip clearance, (e) stage work, and (f) vane and blade airfoil row solidity. In addition, the effects of vane, blade, and disk cooling air injection on turbine efficiency are presented. The turbines evaluated were single stage, low aspect ratio configurations sized for airflows of 8 pps (3.63 kg/sec) or less and designed for inlet temperatures in the 2200-to-2500 deg F (1204-to-1371 deg C) range. The efficiency data presented in the paper cover both design and off-design velocity and pressure ratios. These data illustrate that relatively high efficiencies can be obtained in small, low aspect ratio axial turbines with an optimum design.
Low Emissions Combustion for the Regenerative Gas Turbine: Part 1—Theoretical and Design Considerations
Authors: Wade W. R. , Shen P. I. , Owens C. W. , McLean A. F.
Published: November 2010

This first part, of a two part paper, reviews the NOx emission problem of the regenerative gas turbine engine for automotive application. It discusses the problem of fuel droplet burning, which causes heterogenous combustion with resulting high flame temperatures and high levels of oxides of nitrogen. The paper proposes means to achieve homogeneous combustion and shows that, even with this approach, flame temperatures need to be closely controlled to effect a compromise between NOx, CO, and HC emissions in order to meet the stringent numerical levels of emissions specified by the Federal standards for 1976 and subsequent model year automobiles. The paper shows that combustor inlet temperature of a homogeneous system has little effect, theoretically, on computed NOx emissions expressed as grams per mile, thereby strengthening the case for the regenerative turbine engine. A design concept for homogeneous combustion with controlled flame temperature is discussed.
Drainage Systems for Condensation
Authors: Zener C. , Lavi A.
Published: November 2010

Efficient condensing surfaces are highly desirable in the design of solar sea power plants utilizing the ocean temperature difference. This paper examines a number of surface designs and presents a convenient method for optimizing the design. In particular, the various parameters of a Gregorig surface are optimized.
Estimating Precision in Heat Rate Testing
Authors: Rousseau W. H. , Milgram E. L.
Published: November 2010

Obtaining an estimate of the precision realized in heat rate testing is discussed in this paper. Heat rate precision depends largely on the scatter of the most important measurements, so we examine their scatter. All solutions proposed are based on the assumption that the data arise from a normal population, although answers are also useful for near-normal distributions. We propose a three-part procedure designed to ensure the gathering of data of a given precision with a given confidence. The procedure should fit easily into the test engineer’s routine.
Determination of Salt Deposition Rates From Drift From Evaporative Cooling Towers
Authors: Hosler C. L. , Pena J. , Pena R.
Published: November 2010

The purpose of this paper is to provide a method for estimating the deposition rate of the salt ejected in drift drops from a cooling tower in which salt water is circulated. The surface over which the salt will be distributed depends upon the wind speed, the maximum height the drops can reach, and the drop fall velocities. The drop fall velocity changes because of the evaporation in the air outside of the plume. The rate and extent of the evaporation is a function of the drop size, salt concentration, and ambient relative humidity. Three degrees of evaporation have been considered: (1) no evaporation; (2) evaporation to saturated solution and (3) evaporation to dry salt particles. For each degree of evaporation a graph was constructed that permits determination of the distance from the tower at which the salt contained in given drop size will fall. To use these graphs, the salt concentration, wind speed, and the maximum height a drop can reach must be known. The choice of the graph to be used for a particular case is made on the basis of humidity data for the site and the drift drop size. Corrections to compensate for the errors introduced by some of the assumptions are presented.
The Design and Performance of Axially Symmetrical Contoured Wall Diffusers Employing Suction Boundary Layer Control
Authors: Nelson C. D. , Yang T. , Hudson W. G.
Published: November 2010

This paper presents a procedure for the design and the performance prediction of axially symmetrical contoured wall diffusers employing suction boundary layer control. An inverse problem approach was used in the potential flow design of the diffuser wall contours. Three short (L/l ≤ 5.15), high area ratio (2.5 and 3) diffusers were tested in the study and were found to have effectiveness values in excess of 90 percent (comparable straight wall diffusers have effectiveness <40 percent) while requiring suction flows of less than 10 percent of the inlet flow. The experimentally observed flow characteristics, the stability of flows within the diffusers, are also described. Because of their high effectiveness and short length these diffusers appear to be ideally suited for use as gas turbine combustor diffusers and as turbine discharge diffusers.
The Corrosion of a 50Cr-50Ni Alloy in Liquid Vanadate Systems in the Temperature Range 750–950°C
Authors: Dooley R. B. , Wilson J. R.
Published: November 2010

A 50Cr-50Ni commercial alloy has been corroded in pure V2O5 and in vanadate melts containing sodium, sulphate, and chloride in the temperature range 750–950° C in a rotating disk apparatus. The results are discussed in terms of the material’s capability of forming a protective barrier layer and the subsequent dissolution of this layer into the liquid vanadate melt. Marked internal oxidation of a chromium rich phase has been noted throughout the temperature range. At 750 and 810° C this is associated only with chloride containing melts, but at 950° C the attack, while enhanced by chloride, also occurs in nonchloride melts.
Variable Pressure Peaking Boiler, Operation, Testing, and Control
Authors: Lansing E. G.
Published: November 2010

During the last few years many utilities have been purchasing fossil fueled power plants designed to be used for initial or future cycling service. As more large nuclear units are placed in service with their low incremental operating cost, it is anticipated that many fossil units will be operated to meet daily cycling load demands while still retaining the ability to efficiently supply a large amount of the system base load, if it is required. This paper discusses the operation and control of a gas and oil fired variable pressure drum boiler specified and designed for peaking operation at a major U. S. utility company. Operating results obtained during normal unit shutdowns, startups for morning peak load, and rapid, variable, and constant pressure load changes are presented. Also discussed are the major control system features employed for variable pressure operation as well as operation of the superheater by-pass system. The advantages of variable pressure operation are pointed out and explained along with supporting operational data.
Estimating the Uncertainty of Spacial and Time Average Measurements
Authors: Wyler J. S.
Published: November 2010

The uncertainty of average measurements has been investigated, and a generalized formula for the standard deviation of spacial and time average measurements has been derived. The special cases of spacial averages and time averages have been considered resulting in recommendations concerning choice of instrumentation and the number of time independent measurements needed. A simplified procedure for estimating the number of additional measurements required to reduce the uncertainty interval to a certain level is also presented.
The Vorbix Burner—A New Approach to Gas Turbine Combustors
Authors: Markowski S. J. , Lohmann R. P. , Reilly R. S.
Published: November 2010

The vorbix burner (acronym for Vortex Burning and Mixing) represents a new approach to a practical gas turbine combustor design. The concept exploits the Rayleigh instability of swirling flows to enhance the mixing and combustion rates. The combination of a two-stage fuel system with a piloted combustor leads to a unique high rate technique for fuel prevaporization within the combustor proper. This paper presents the fundamental concepts in the definition of the vorbix combustor and the results of exploratory tests conducted on can (tubular) and annular vorbix combustors. The results indicate that this type of combustor has unique performance characteristics that include excellent stability and high combustion efficiency over wide excursions in operating fuel air ratios in addition to substantially reduced emission levels during high power operation.
Protection of Drain Pumps Against Transient Cavitation
Authors: Liao G. S.
Published: November 2010

It has been known that drain pumps in nuclear power plants may suffer cavitation under transient turbine load reductions [1]. Although increasing the size and height of the drain tank can prevent it, such provisions are often not practical, and in some instances even not possible. Some components, such as moisture separators, normally drain through drain receivers into the surface heater or drain tank. Since the drains are at the saturation condition, the drainage is generally accomplished by gravity. This necessitates locating the moisture separators considerably above the drain tank. With a limited physical elevation of the moisture separators relative to the main turbine in connection with a low profile of nuclear power plants, it is impractical to raise the heater-drain tank system somewhat similar to the deaerator in fossil power plants. This paper explores some conceptual protective methods, and briefly discusses their pros and cons as applied to both drain pumping forward and backward systems. The method of quantitative determination of design parameters required for each protective method is either referred to or derived. Based on simplicity, economy, and reliability, this paper concludes that the drain tank pressure decay control system appears to be the most promising protective method for the drain pumping forward system, whereas either the continuous feedwater injection system or the continuous drain subcooling system is the optimum method for the drain pumping backward system.
Applicability of Axisymmetric Analysis in Predicting Supersonic Flow Through Annular Cascades
Authors: Fruehauf Hans-Heiner
Published: November 2010

Solutions of the differential equations of the axisymmetric model and circumferentially averaged solutions of the differential equations of the three-dimensional model are compared quantitatively for steady supersonic flows through rotating annular cascades. Thereby three-dimensional corrections for flow quantities, which determine the applicability of the axisymmetric analysis, are investigated as a function of geometrical and gas dynamical parameters. Finally, these three-dimensional corrections are compared to three-dimensional corrections for the solutions of the usual blade-to-blade model on cylindrical surfaces of revolution for identical annular cascades.
Secondary Flows in Compressor Bladings
Authors: Papailiou K. , Flot R. , Mathieu J.
Published: November 2010

Present-day theories for the calculation of the development of end-wall shear layers in compressors demand detailed experimental information for their modeling. Experimental results obtained from compressor and turbine cascades and from single and multistage compressors were used in order to perform a critical examination of the underlying hypotheses of the available calculation methods.
The Use of Liquid Natural Gas as Heat Sink for Power Cycles
Authors: Angelino G.
Published: November 2010

The thermodynamics of power cycles employing liquid natural gas (LNG) as heat sink is discussed. Condensation cycles in simple or in elaborate versions, employing nontoxic, nonflammable, inert organic fluids (CF4, C2F6, CHF3, C3F8), yield the best overall performance for LNG vaporization at subcritical pressure. For supercriticial vaporization, heat rejection from Brayton cycles naturally fits heat sink thermal characteristics, which results in a particularly high efficiency for closed gas cycles. If only a fraction of the cooling capability of LNG is devoted to power uses, condensation cycles are superior to gas cycles even at supercritical LNG pressures. Under the most favorable circumstances gas cycles achieve efficiencies of around 60 percent, while some elaborate condensation cycles attain the 70 percent level.
Optimum Bearing and Support Damping for Unbalance Response and Stability of Rotating Machinery
Authors: Barrett L. E. , Gunter E. J. , Allaire P. E.
Published: November 2010

This paper presents a rapid approximate method for calculating the optimum bearing or support damping for multimass flexible rotors to minimize unbalance response and to maximize stability in the vicinity of the rotor first critical speed. A multimass rotor is represented by an equivalent single-mass model for purposes of the analysis. The optimum bearing damping is expressed as a function of the bearing stiffness and rotor modal stiffness at the rigid bearing critical speed. Stability limits for aerodynamic cross coupling and viscous internal rotor friction damping are also presented. Comparison of the optimum damping obtained by this approximate method with that obtained by full scale linearized transfer matrix methods for several rotor-bearing configurations shows good agreement. The method has the advantage of being quickly and easily applied and can reduce analysis time by eliminating a time consuming search for the approximate optimum damping using more exact methods.
Performance and Economics of Advanced Energy Conversion Systems for Coal and Coal-Derived Fuels
Authors: Corman J. C. , Fox G. R.
Published: November 2010

The desire to establish an efficient Energy Conversion System to utilize the fossil fuel of the future—coal—has produced many candidate systems. A comparative technical/economic evaluation was performed on the seven most attractive advanced energy conversion systems. The evaluation maintains a cycle-to-cycle consistency in both performance and economic projections. The technical information base can be employed to make program decisions regarding the most attractive concept. A reference steam power plant was analyzed to the same detail and, under the same ground rules, was used as a comparison base. The power plants were all designed to utilize coal or coal-derived fuels and were targeted to meet an environmental standard. The systems evaluated were two advanced steam systems, a potassium topping cycle, a closed cycle helium system, two open cycle gas turbine combined cycles, and an open cycle MHD system.
Torsional Flutter in Stalled Cascade
Authors: Yashima S. , Tanaka H.
Published: November 2010

Applying free streamline theory and singularity method, a theoretical study is developed for the torsional flutter problem in fully stalled cascade. Aerodynamic moment acting on a vibrating blade is calculated for some cascade conditions. Computational results show that critical reduced frequency is much higher in the case of stalled cascade than unstalled cascade and affected by the position of pitching center. Experiments were carried out using a water tunnel with a linear cascade, and the unsteady moment acting on the vibrating blade was measured. Computational and experimental results show fairly good agreement.
Control of Steam Venting Noise in Power Plants
Authors: Floyd J. K.
Published: November 2010

Steam venting to atmosphere from piping system pressures as high as 2500 psig, as may occur during safety valve and power relief valve operation or during initial steam piping clean up, is one of the most intense sources of noise emitted by fossil and nuclear power plants. This paper discusses characteristics of sonic and turbulent vent noise. Analytical methods to estimate vent noise intensity and frequency characteristics are presented for use where unsilenced noise measurements are not feasible. Design considerations in the effective use of silencers and acoustic lagging materials are discussed. Power plant noise measurements illustrating the severity of the noise emission and its control are presented.
The Effect of Compressor Exit Flow Distribution on Air Placement in Annular Combustors
Authors: Adkins R. C.
Published: November 2010

A simple mathematical model has been devised which is intended to make a powerful aid to combustor design and development. The model has confirmed that nonuniform flow conditions at inlet to the precombustor diffuser can seriously deter combustor performance.
High Frequency Ultrasonic Evaluation of Ceramics for Gas Turbines
Authors: Derkacs T. , Matay I. M. , Brentnall W. D.
Published: November 2010

To assure reliable performance of ceramic materials in gas turbine engines, where performance at 1400°C for up to 10,000 hrs is required, it is necessary to screen out material with defects in the size range of 10 to 100 μm. Investigation of high frequency ultrasonic inspection techniques has led to development of longitudinal, shear, and surface wave methods capable of detecting defects at least down to 25 μm in size. The approach is to use a focused 45 MHz ultrasonic transducer in a pulse-echo immersion mode of operation. Inspections were performed on hot pressed silicon nitride containing natural defects, seeded inclusions and artifical surface cracks. The discussion includes a description of the inspection techniques and a presentation of the results of ultrasonic inspections, four-point-bend testing and scanning electron microscopy of defect containing specimens.
Secondary Flow in Rotating Bends
Authors: Johnson M. W.
Published: November 2010

An equation describing the development of streamwise vorticity is derived. The fluid is assumed inviscid and incompressible and to have a gradient of rotating total pressure across the streamtube. The equation is used to calculate, by finite difference techniques, the streamwise vorticity development for bends, rotating straight pipes, rotating axial to radial bends and for a rotating duct representing Eckardt’s impeller passage. The development of secondary flows in centrifugal compressors is discussed. It is concluded that the secondary flows within the boundary layer determine the position of the wake at outlet and probably influence separation. It is also concluded that the wake can be moved by altering mass flow rate, rotational speed or by introducing an inlet distortion to the flow.
Development of Gas Turbine Performance Seeking Logic
Authors: Jordan D. , Michael G. J.
Published: November 2010

Adaptive control logic has been defined for static performance optimization of variable geometry gas turbine engines. The control logic is directed toward (1) in-flight minimization of thrust specific fuel consumption, (2) test-stand automatic trimming, and (3) generation of optimum control schedules. The algorithm was evaluated by application to a nonlinear digital dynamic simulation of the F100/F401 turbofan engine throughout a range of representative flight conditions. Engine component degradations as well as mistrimmed control schedules were introduced to assess algorithm performance. Results indicate that the performance seeking algorithm offers promise for steady state performance optimization for in-flight, test-stand, and set point design optimization applications.
On the Design of High-Temperature Gas Turbine Blade Water-Cooling Channels
Authors: El-Masri M. A. , Louis J. F.
Published: November 2010

Centrifugal and Coriolis accelerations have a strong impact on the fluid dynamics and heat transfer in the various schemes of water cooling being actively considered for rotating blades in very high temperature gas turbines. Analytical studies of a thin water film in a rotating rectangular channel open to ambient pressure are presented. First, the dynamics of a thin rotating film indicate that for a certain flow rate it thins out into a stable film under the action of the Coriolis force only for a flow depth below a critical thickness. The value of the critical thickness is a function of the tilt angle between the axis of the cooling passage and the radial. Criteria for nucleation and burnout in high speed liquid films are proposed. These criteria are used to estimate the coolant requirements for representative heat fluxes at different ambient pressures. They suggest that coolant demand increases drastically with pressure. The maximum coolant demand at a fixed heat flux would occur in the neighborhood of five bars.
Measurement of Fan Vibration Using Double Pulse Holography
Authors: Hockley B. S. , Ford R. A. J. , Foord C. A.
Published: November 2010

Supersonic unstalled flutter in gas turbine fans is a self-excited instability in which mechanical vibrations give rise to unsteady aerodynamic forces which drive the mechanical vibration. The phenomenon is very sensitive to the deflected shapes of the blades and to the spatial and temporal phases of the blades’ responses. This paper is concerned with the measurement of vibrational behavior on static fans and relating it to flutter. Accurate detailed data on the blade and disk vibration mode shapes of fans up to 2.2 m diameter has been measured using double pulse laser holography. Both axial and tangential components of the blade mode shape are obtained by taking holograms from two directions. The analysis of the holograms is performed with the aid of a computer linked television system which generates the required blade mode shapes directly from the photographs of the hologram reconstructions. The disk mode measurements on real fans have shown the existence of pairs of spatially orthogonal vibration modes which have similar shapes (e.g. both 4D) but slightly different natural frequencies. This frequency split between modes means that the flutter wave will experience a cyclic variation in amplitude and propagation speed as it travels round the fan. In addition, the temporal phase angle between twist and flap in a single blade, which is generally assumed to be 90 deg, will vary from blade to blade.
Gas Turbine Combustor Cooling by Augmented Backside Convection
Authors: Evans D. M. , Noble M. L.
Published: November 2010

Traditionally, gas turbine combustor walls have been cooled by one or more of the various film cooling methods. The current motivation to control exhaust gas emission composition has led to the serious consideration of backside convection wall cooling, where the cooling air is introduced to the main gas stream not prior to the dilution zone. Due to the confined space and the severe nature of the wall cooling problem, it is essential to maximize the heat transfer/pumping power characteristic, which suggests an augmented convection technique. A particular heat transfer design of a combustor cooled by means of transverse rib turbulence promoters applied to the exterior wall of the annular spaces surrounding the primary and secondary zones is described. Analytical methods for designing such a cooling system are reviewed and a comparison between analytical and experimental results is presented.
Marine Spey—SM1A Propulsion Module
Authors: Page K. G. , Pack C. R.
Published: November 2010

The requirements for a high efficiency marine gas turbine of 10 to 12 MW output has been identified, particularly for Naval craft. The adaptation and development of a marine version of the Rolls-Royce Spey aero engine has been funded by the Ministry of Defence to meet this requirement. The most suitable version of the aero engine was found to be the TF41 jointly developed by Rolls-Royce and D.D.A. for the L.T.V. Corsair. Redesign involved removal of the bypass portion of the L.P. compressor and the full length bypass duct. Changes to other engine components have also been made to meet the new requirements, together with material changes for improved corrosion resistance. A new two stage free power turbine has been designed to provide long installed life and is not removed with the engine change unit. Particular attention has been given to the mounting system to provide high shock resistance. A full service module is being designed suitable for naval craft, but alternative lightweight installations can be provided.
Erosion-Corrosion Effects on Boiler Tube Metals in a Multisolids Fluidized-Bed Coal Combustor
Authors: Krause H. H. , Vaughan D. A. , Sexton R. W. , Boyd W. K.
Published: November 2010

Metal wastage of boiler tube materials has been measured during combustion of coal in a laboratory scale fast fluidized bed. In the multisolids fluidized-bed process, high-sulfur coal and limestone are fed to a conventional bed of selected high specific gravity materials. An entrained bed is superimposed on this dense bed, to act as the heat exchange medium. Erosion-corrosion effects were studied on simulated steam tubes (400–700°F, 204–370°C) oriented either horizontally or vertically in the bed. Results of 50-hr tests showed that the life of heat exchange tubes operating up to 650°F (343°C) in this type of combustor will depend primarily on erosion effects. Erosive wastage was greater in the dense bed than in the entrained bed, with greater losses on horizontal surfaces than on vertical surfaces. Support structures at bed temperature of 1600°F (870°C) were found to be subject to corrosion by oxidation and sulfidation reactions. High-chromium alloy steels proved to be most resistant to the erosive and corrosive effects.
Stabilizing and Destabilizing Effects of Coriolis Force on Two-Dimensional Laminar and Turbulent Boundary Layers
Authors: Koyama H. , Masuda S. , Ariga I. , Watanabe I.
Published: November 2010

To investigate the effects of Coriolis force on two-dimensional laminar and turbulent boundary layers, quantitative experiments were performed. A numerical evaluation was also carried out utilizing the Monin-Oboukhov coefficient including the effect of rotation. From the experimental results, the boundary layer development was found to be promoted on the unstable side and suppressed on the stable side, in comparison with the case of zero-rotation. In the stable boundary layer, the critical Reynolds number for relaminarization was observed to increase as rotation number was decreased. Calculated results were seen to predict the stabilizing effect of Coriolis force fairly well.
Atomization of Crude and Residual Fuel Oils
Authors: Jasuja A. K.
Published: November 2010

A study is made of the effects that fuel properties have upon the mean droplet size characteristics of three fuel atomizer types that are commonly employed in the gas turbine engine. The fuels tested included kerosine, gas oil, and a heavy residual fuel oil, and each was passed through a pressure swirl jet, a prefilming airblast, and a plain-jet airblast atomizer in turn. Tests were carried out at pressure levels close to ambient and mean drop sizes were determined using a light-scattering technique. Two main points emerge from the results: Firstly, for all atomizers tested, that the existing dropsize correlations are not sufficiently accurate for use with the high-viscosity residual fuel oils. Secondly, that the fuel dropsize decreases with the change in atomizer type from plain-jet airblast to prefilming airblast. The difference in performance of the two types of airblast atomizers is most noticeable for the residual fuel oil, particularly so at pressure drop levels of less than around five percent. Use is also made of the many data points collected to derive improved dropsize correlations which may be used over the whole range of fuels tested.
A Method to Design Shell-Side Pressure Drop Constrained Tubular Heat Exchangers
Authors: Singh K. P. , Holtz M.
Published: November 2010

In shell and tube heat exchangers, the triple segmental baffle arrangement has been infrequently used, even though the potential of this baffle system for high thermal effectiveness with low pressure drop is generally known. This neglect seems to stem from the lack of published design guidelines on the subject. Lately, however, with the rapid growth in the size of nuclear heat exchangers, the need to develop unconventional baffling pattern has become increasingly important. A method to effectively utilize the triple segmental concept to develop economical designs is presented herein. The solution technique given in this paper is based on a flow model named “Piecewise Continuous Cosine Model.” The solution procedure easily lends itself to detailed analysis to determine safety against flow-induced vibrations.
An Analysis Procedure for the Validation of On-Site Performance Measurements of Gas Turbines
Authors: Agrawal R. K. , MacIsaac B. D. , Saravanamuttoo H. I. H.
Published: November 2010

In order to ensure accuracy and credibility of an engine health monitoring system, it is vital that the measurements used in the analysis process be accurate. An analysis procedure has been developed to verify the accuracy of daily measurements taken from industrial gas turbines in the gas pipeline industry. The procedure has been extended to use the measurements to develop an engine health monitoring system for this class of equipment which is based solely on existing instrumentation. The method has been tested using field data from several gas pumping units and was found to be capable of isolating instrumentation problems and to correctly diagnose engine health deterioration.
Solving Three-Dimensional Stress Analysis Problems by a Surface Representation Alone
Authors: Thompson M.
Published: November 2010

A numerical procedure is devised for the solution of three-dimensional static problems in an homogeneous linear elastic medium by means of a surface distribution of potential functions. Once the surface distribution is known, the solution in the interior is found by integration of the distribution over the surface. The procedure involves division of only the surface into discrete areas which is an advantage over the volume divisions of the finite element method. The procedure has the benefits in initially conceiving the problem, in formalizing the data, in reduced size of matrices to solve and in ease of handling discontinuous boundary conditions. The potential function approach is extended to bodies of more than one medium and to multi-seam mining where the horizons may be differing linear elastic properties and the seam may be nonelastic and even time dependent. It is shown that the case of axisymmetry cannot be reduced to two potential functions in two dimensions.
The Calibration Correlation Function for Positive Displacement Liquid Meters
Authors: Keyser D. R.
Published: November 2010

This paper presents a correlation function for the disk type of positive displacement oil meters. This correlation will predict the shift in the calibration curve due to differences in fluid conditions with an accuracy of ±1/2 percent. The prerequisite is a valid calibration of that meter under known fluid conditions. The analysis and approach presented in this paper are applicable to all designs of positive displacement flow meters.
On Difference Methods for Shock Wave Propagation in Variable Area Ducts Including Wall Friction
Authors: Fashbaugh R. H. , Widawsky A.
Published: November 2010

Results are presented of an analytical study concerned with the prediction of the propagation of shock waves through air ducting systems. The solution is one-dimensional but is appropriate for ducts which have a variable cross-sectional area and includes attenuation due to viscous effects at the wall of the duct. Finite-difference methods are utilized to obtain an approximate solution to the basic fluid dynamic equations. Comparisons are given between analytical results and shock tube experimental data which validate the capabilities of the methods used to predict shock wave attenuation and the effect of duct area variation on shock strength.
Performance of Low-Aspect-Ratio Diffusers With Fully Developed Turbulent Inlet Flows: Part I—Some Experimental Results
Authors: McMillan O. J. , Johnston J. P.
Published: November 2010

An experimental investigation of the effects of incompressible, fully developed, turbulent inlet flow on the performance of straight, two-dimensional rectangular diffusers of low aspect ratio is presented. Results presented include flow regime information, performance curves, and total-pressure loss data for a series of diffusers of moderate non dimensional length and low aspect ratio. The results are compared to existing data and correlations and important differences are noted between the diffusers of this study and diffusers of high aspect ratio with thin to moderately thick turbulent boundary layers at inlet.
The Use of Subgrid Transport Equations in a Three-Dimensional Model of Atmospheric Turbulence
Authors: Deardorff J. W.
Published: November 2010

A three-dimensional numerical model of turbulence in an atmospheric boundary layer has been revised to utilize subgrid transport equations for the subgrid Reynolds stresses and fluxes rather than subgrid eddy coefficients. It was applied to a daytime boundary layer over heated ground in a region of horizontal area 8km square and 2km deep, utilizing 40×40×40 grid points. The constraints involved in selecting four important subgrid closure constants are discussed in some detail, along with maintenance of realizability on the subgrid scale. The results indicate that the subgrid transport equations produce subgrid Reynolds stresses and fluxes which realistically simulate the transfer of larger scale variance to subgrid scales, provided truncation errors due to advective terms are not too large. They also show the superiority of this method over the use of (nonstability dependent) nonlinear eddy coefficients in maintaining the sharpness of the inversion base which lies above the mixed layer.
An Approximate Method for the Solution of a Class of Nonlinear Equations in Fluid Mechanics and Magnetohydrodynamics
Authors: Nath G.
Published: November 2010

An approximate method has been developed to obtain a closed form solution of a class of nonlinear two-point boundary value problems. Application of this method to three problems in Fluid Mechanics and Magnetohydrodynamics, namely, Blasius boundary layer equation with suction in Newtonian and non-Newtonian fluids, and Falkner-Skan boundary layer equation with magnetic field, are presented as illustration of the method. The present results in the presence of suction or magnetic field differ from the exact results by about 1 to 2 percent.
Analysis of Flow Separation in an Annular Expansion—Contraction With Inner Cylinder Rotating
Authors: Dailey G. F. , Geiger G. E.
Published: November 2010

A three-dimensional incompressible isothermal laminar separation of a Newtonian fluid in transient and steady flow was investigated. The geometry chosen for this study was an annular expansion-contraction chamber with a rotating inner cylinder. It was found that an adaptation of a numerical solution first proposed by Fromm gave converged solutions for all Reynolds numbers in the laminar range. Theoretical computer plotted streamline patterns were superimposed on time exposure photographs of air bubbles in transparent oil. Measured static pressure differentials were compared with laminar theory. Turbulent flow was studied experimentally.
Performance Characteristics of an 8-In-Dia ASME Nozzle Operating at Compressible and Incompressible Conditions
Authors: Smith R. E. , Matz R. J.
Published: November 2010

Experimental and theoretical values of local velocity and density were determined at several axial planes within the cylindrical throat region of a standard ASME, long radius, low beta ratio nozzle. The nozzle was calibrated in compressible flow (air) over a range of throat Reynolds numbers from 500,000 to 4,000,000 and over a range of throat Mach numbers from 0.4 to critical. The nozzle was calibrated in incompressible flow (water) over a range of throat Reynolds numbers from 170,000 to 1,600,000. The behavior of the observed nozzle discharge coefficients is interpreted.
A Contribution to the Numerical Solution of Developing Laminar Flow in the Entrance Region of Concentric Annuli With Rotating Inner Walls
Authors: Coney J. E. R. , El-Shaarawi M. A. I.
Published: November 2010

The boundary layer simplification of the Navier-Stokes equations for hydrodynamically developing laminar flow with constant physical properties in the entrance region of concentric annuli with rotating inner walls have been numerically solved using a simple linearized finite-difference scheme. Additional results to those existing in the literature by Martin and Payne [1–2] will be presented here. An advantage of the analysis used in this paper is that it does not solve for the stream function and vorticity, but predicts the development of tangential, axial and radial velocity profiles directly, thus avoiding numerical differentiation. Results for the development of these velocity profiles, pressure drop and friction factor are presented for five annuli radii ratios (0.3, 0.5, 0.674, 0.727 and 0.90) at various values of the parameter Re2/Ta. The paper may be considered as a direct comparison between the boundary layer solution and the complete solution of the Navier-Stokes equations [1–2] for that special case.
Frequency Response of Fluid Lines With Turbulent Flow
Authors: Funk J. E. , Wood D. J.
Published: November 2010

A single boundary layer model to account for transient viscous effects is applied to small amplitude sinusoidally disturbed turbulent flow in a tube. The viscous dissipation is calculated using a transfer function relating the local boundary layer velocity gradient to the core velocity. A simple expression for the attenuation factor is derived and the analytical results are shown to be in excellent agreement with previously reported experimental data.
The Small Signal Response of Annular Pneumatic Transmission Lines
Authors: Moore E. F. , Franke M. E.
Published: November 2010

The small signal frequency response of rigid pneumatic transmission lines of annular cross section has been obtained. Dimensionless expressions for the velocity and temperature profiles are obtained by solving the unsteady continuity, momentum, and energy equations for the boundary conditions of isothermal walls and no-slip flow at the walls. As a consequence, shear flow effects are included. By electric-pneumatic analogy the series impedance and shunt admittance per unit length of line are obtained and used to find the characteristic impedance and propagation operator. These quantities are shown to be dependent on both the signal frequency and the radius ratio of the annular cross-section. The annular line results are compared with previously obtained results for circular and rectangular lines.
An Experimental Investigation of Transition of a Plane Poiseuille Flow
Authors: Karnitz M. A. , Potter M. C. , Smith M. C.
Published: November 2010

The transition process of laminar flow between parallel plates is investigated experimentally. This problem has recently gained much attention with several reported works; however, the maximum transition Reynolds number reported has been approximately 3000 (based on average velocity and channel height) whereas the theoretical critical Reynolds number is 7700. Primary emphasis in this work is on approaching the theoretical limit in an experimental facility. A high aspect ratio (70 to 1) channel was used with air as the fluid. As the disturbance level at the entrance to the parallel plate section was reduced the transition Reynolds number increased monotonically. At a disturbance level of 0.3 percent the transition Reynolds number was 6700. Near transition small nearly sinusoidal waves in the critical shear layer were observed. The frequency of the waves was approximately 70 hertz, close to the frequency associated with the Tollmien-Schlichting waves of the critical point of linear theory. Sinusoidal waves preceded a turbulent burst which possessed an essentially plane front as it traveled downstream. As the Reynolds number was increased the bursting rate increased and the flow eventually became completely turbulent.
Effect of Turbulence in Free Stream on Cavitation Incipience of Hydrofoil
Authors: Numachi F.
Published: November 2010

It was proved experimentally that the conditions of cavitation incipience, such as the positions of incipient cavitation bubble formation and collapse, extent of cavitation, and the propensity toward cavitation onset (in terms of cavitation coefficient or of flow velocity at cavitation incipience), are affected by the degree of turbulence present in the free stream. A side experiment was also undertaken to ascertain the validity of the use of a sphere in measuring the degree of turbulence.
Three-Dimensional Turbulent Boundary Layer in a Rotating Helical Channel
Authors: Anand A. K. , Lakshminarayana B.
Published: November 2010

An analytical and experimental investigation of the characteristics of a three-dimensional turbulent boundary layer in a rotating helical channel is reported in this paper. Expressions are developed for the velocity profiles in the inner layer, where the viscous effects dominate, and the outer layer, where the viscous effects are small. The prediction of boundary layer growth is based on the momentum integral technique. The analysis is valid for incompressible flow through a rotor blade row with small camber. The velocity profiles, wall shear stress and limiting streamline angles are measured inside the passages of a flat plate inducer at various radial and chordwise locations using rotating probes. The measurements are in general agreement with the predictions. Flow near the blade tip is found to be highly complex due to interaction of blade boundary layers and the annulus wall, resulting in appreciable radial inward flow as well as a defect in mainstream velocity near the midpassage. A wall shear stress correlation, which includes the effect of both Reynolds number and rotation parameter, is derived from the measured data.
Numerical Calculations of Turbulent Swirling Flow
Authors: Kubo I. , Gouldin F. C.
Published: November 2010

A numerical technique is developed for solving axisymmetric, incompressible, turbulent swirling flow problems. The Reynolds stresses are expressed in terms of a scalar turbulent viscosity, μt = ρCμk2/ε. The turbulent kinetic energy, k, and ε, the turbulent energy dissipation rate, are obtained by solving the corresponding transport equations; Cμ is an empirical constant. Flow calculation results are presented for the coaxial flow configuration shown in Fig. 1. Of particular interest is the presence of flow recirculation due to vortex breakdown. Effects of inner and outer swirl, axial velocity ratio and Reynolds number on the formation, size, and location of the recirculation zone are considered.
Experimental and Theoretical Studies of Two-Dimensional Fixed-Type Cavities
Authors: Furness R. A. , Hutton S. P.
Published: November 2010

Theoretical and experimental studies have been made of the growth and collapse of fixed cavities in a two-dimensional convergent-divergent nozzle. In this particular configuration an important feature was a re-entrant liquid jet which invaded the growing cavity from the downstream end, travelling upstream along the wall and interrupting the cavity when it reached the nozzle throat. A simple two-dimensional unsteady potential flow theory, developed to model the cycle, gave reasonable agreement with cinephotography and predicted the jet behavior. Because vaporization was neglected the theory overestimated the speed of the cycle.
Effect of Wetting on Friction Factors for Turbulent Flow of Mercury in Annuli
Authors: Dwyer O. E. , Hlavac P. J. , Nimmo B. G.
Published: November 2010

Friction factors were determined for fully developed turbulent flow of mercury in smooth concentric annuli under conditions where either both walls were unwetted, or both were wetted, or the inner wall was wetted and the outer one unwetted. Three radius ratios (r2/r1) were used, i.e., 2.09, 2.78, and 4.00. Unwetted walls gave the lowest friction factors, which were practically independent of the r2/r1 ratio over the limited range tested. The factors were 10 ± 1 percent higher than the commonly accepted values for smooth pipes (at the same Reynolds number). The highest friction factors were obtained with the inner wall wetted and the outer wall unwetted, and the greater the r2/r1 ratio the greater was the effect. For example, at r2/r1 = 4.00, the friction factors were 9.9% greater than for the situation when both walls were unwetted. The wetting conditions affected the location of the radius of maximum velocity (rm); and it was found that the nearer rm approached r2, the higher was the friction factor.