bluuebunny/crossref_metadata_2025 huggingface dataset:
Pumping Speed Measurement and Analysis for the Turbo Booster Pump
Authors: Jou R. Y. , Tzeng S. C. , Liou J. H.
Published: March 2007

This study applies testing apparatus and a computational approach to examine a newly designed spiral‐grooved turbo booster pump (TBP), which has both volume type and momentum transfer type vacuum pump functions, and is capable
of operating at optimum discharge under pressures from approximately 1000 Pa to a high vacuum. Transitional flow pumping speed is increased by a well‐designed connecting
element. Pumping performance is predicted and examined via two computational approaches, namely the computational fluid dynamics (CFD) method and the direct simulation Monte Carlo (DSMC) method. In CFD analysis, comparisons of measured and calculated inlet pressure in the slip and continuum flow demonstrate the accuracy of the
calculation. Meanwhile, in transition flow, the continuum model of CFD is unsuitable for calculating such rarefied gas. The pumping characteristics for a full 3D model on a rotating frame in transition and molecular regimes thus are simulated using the DSMC method and then confirmed experimentally. However, when the Knudsen number is in the
range 0.5 < Kn < 0.1, neither CFD computation nor DSMC simulation is suitable for analyzing the pumping speed of the turbo booster pump. In this situation, the experimental
approach is the most appropriate and effective method for analyzing pumping speed. Moreover, the developed pump is tested using assessment systems constructed according to ISO and JVIS‐005 standards, respectively. Comparisons are also made with other turbo pumps. The compared results show that the turbo booster pump presented here has good
foreline performance.
Numerical and Experimental Investigations of the Cavitating Behavior of an Inducer
Authors: Bakir F. , Rey R. , Gerber A. G. , Belamri T. , Hutchinson B.
Published: March 2007

A robust CFD model is described, suitable for general three‐dimensional flows with extensive cavitation at large density ratios. The model utilizes a multiphase approach, based on volume‐scalar‐equations, a truncated Rayleigh‐Plesset equation for bubble dynamics, and specific numerical modifications (in a finite‐volume solution approach) to promote robust solutions when cavitation is present. The model
is implemented in the CFD software CFX TASCflow 2.12. The validation of the model was done on an inducer designed and tested at LEMFI. First, The physical model and
the numerical aspects are described. Then, the experimental and numerical methodologies, at cavitating regime, are presented. Finally, for several flow rates, the comparisons between experimental and simulated results on the overall performances,
head drop and cavitation figures, are discussed. For a range of flow rates, good agreement between experiment and prediction was found.
Predictive Failure of Cylindrical Coatings Using Weibull Analysis
Authors: Vlcek Brian L. , Hendricks Robert C. , Zaretsky Erwin V.
Published: March 2007

Rotating, coated wiping rollers used in a high‐speed printing application failed primarily from fatigue. Two coating materials were evaluated: a hard, cross‐linked, plasticized polyvinyl chloride (PVC) and a softer, plasticized PVC. A total of 447 tests was conducted with these coatings in a production facility. The data were evaluated using Weibull analysis. The softer coating produced more than twice the life of the harder cross‐linked coating and reduced the wiper replacement rate by two‐thirds, resulting in minimum production interruption.
Parametric Study of Greitzer′s Instability Flow Model Through Compressor System Using the Taguchi Method
Authors: Ng Eddie Yin-Kwee , Liu Ningyu , Tan Shin Yi
Published: March 2007

The occurrence of stall and surge is caused by instability of the flow through the compressor system. These two phenomena often result in serious mechanical problems for the compressor. The scope of this article includes a review and parametric study on the characteristics of stall and surge and their mathematical modeling.

In this article, Greitzer′s B‐parameter model is applied for analyzing the stall and surge characteristics. Based on this model, a total of four parameters—B, G, K, and LC—in the model are highlighted in order to establish the influence of each parameter on the system. Parameters B, G, and K are all dimensionless constants while LC is the effective length of the compressor duct.

Here, the governing equations of stall and surge behavior are solved numerically using fourth‐order Runge‐Kutta method. The Taguchi method is then used to analyze the results
generated to obtain the extent of effects of the parameters on the system by varying the parameters in a series of combinations. Finally, a thorough analysis is carried out on the results generated from the Taguchi method and the graphs. It is found that parameter K is the deciding factor in the position of the cross point whereas parameter B is the most important one in changing the length of time needed for the compressor to reach its steady state.
Optimization of Meridional Flow Channel Design of Pump Impeller
Authors: Miyauchi Sunao , Horiguchi Hironori , Fukutomi Jun-ichirou , Takahashi Akihiro
Published: March 2007

The meridional flow channel design of a pump impeller affects its performance. However, since so many design parameters exist, a new design method is proposed in which a meridional and blade‐to‐blade flow channel is designed by the parallel use of the circulation distribution provided by the designer. Thus, an optimization method was used to design an axis‐symmetrical meridional flow channel from the circulation distribution. In addition, the inverse design method proposed by Zangeneh et al. (1996) was employed to design a three‐dimensional blade‐to‐blade flow channel from
the circulation distribution and the optimized meridional shape. In this article, a few design examples and these Computational Fluid Dynamics (CFD) validations are also given.
Interaction of Squeeze Film Dampers and Hole Feed Systems and Its Influence on the Dynamics of a Jeffcott Rotor
Authors: Rodrigues Fabiano A. , Thouverez Fabrice , Jezequel Louis
Published: March 2007

The oil feeding of a squeeze film damper through holes can be an interesting solution to improve the damper′s energy dissipation capability since it increases the journal′s effective squeezing surface. While groove feeding has been extensively studied, only a few works have addressed the problem of hole fed dampers. The squeeze film damper model may be able to estimate the pressure at the feed holes as well as the flow into the film. A fundamental issue in the modeling of the hole feed system is the choice of the adequate boundary conditions. Existing published models consider the supply pressure to be constant at a specific section of the hydraulic system. The pressures at the oil injection holes are then obtained via local flow balances taking into account a linear flow resistance across the feed conduits. The model developed
in the present work is based on the application of the simplified form of the energy equation commonly used in hydraulics, with approximate pressure drop coefficients. As
a boundary condition we impose the power supplied to the pump. The nonlinear hydraulics problem is coupled with the squeeze flow and the Newton–Raphson method is employed to solve the set of nonlinear equations. The influence of the hole feed system on the unbalance response and stability of a Jeffcott rotor is analyzed in regards to the number of feed holes and the power supplied to the pump. The feed system behavior is also studied.
A Magnetorheological Fluid Damper for Rotor Applications
Authors: Forte P. , Paternò M. , Rustighi E.
Published: March 2007

Even though we are still far from industrial applications, in the last decade there has been increasing attention directed toward the employment of electrorheological (ER) and magnetorheological (MR) fluids in active bearings and active squeeze film dampers in rotordynamics. MR fluids react to magnetic fields undergoing reversible changes in their mechanical characteristics, viscosity, and stiffness in particular. In previous literature, some applications of ER fluids in rotor squeeze film dampers can be found; however, on the contrary, little is reported on similar test rigs set up for MR dampers. In this work, the design of an MR squeeze film damper is presented and discussed. A numerical simulation has been carried out in order to evaluate the dynamic behavior of the damped rotor as a function of the magnetic field strength. The test rig is made of a slender shaft supported by two oilite bearings and an unbalanced disk. The damper is interfaced with the shaft through a rolling bearing. Electric coils generate the magnetic field whose
field lines cross the MR film. Since the damping characteristics can be varied continuously by controlling the magnetic field, it is possible to have the optimum conditions for each regime of rotational speed. Preliminary tests are encouraging.
Fault Diagnosis in a Centrifugal Pump Using Active Magnetic Bearings
Authors: Nordmann Rainer , Aenis Martin
Published: March 2007

The number of rotors running in active magnetic bearings (AMBs) has increased over the last few years. These systems offer a great variety of advantages compared to conventional systems. The aim of this article is to use the AMBs together with a developed built‐in software for identification, fault detection, and diagnosis in a centrifugal pump. A single‐stage pump representing the turbomachines is investigated.
During full operation of the pump, the AMBs are used as actuators to generate defined motions respectively forces as well as very precise sensor elements for the contactless
measurement of the responding displacements and forces. In the linear case, meaning small motions around an operating point, it is possible to derive compliance frequency
response functions from the acquired data. Based on these functions, a model‐based fault detection and diagnosis is developed which facilitates the detection of faults
compared to state‐of‐the‐art diagnostic tools which are only based on the measurement of the systems outputs, i.e., displacements. In this article, the different steps of the model‐based diagnosis, which are modeling, generation of significant features, respectively symptoms, fault detection, and the diagnosis procedure itself are presented and in particular, it is shown how an exemplary fault is detected and identified.
Proposition of Unique Pumping System with Counter‐Rotating Mechanism
Authors: Kanemoto Toshiaki , Oba Shin
Published: March 2007

Turbo‐pumps have weak points, such as when the pumping operation becomes unstable in the rising portion of the head characteristics and/or the cavitation occurs under the intolerably low suction head. To overcome both weak points simultaneously, this article proposes a unique pumping system with counter‐rotating mechanism, which consists of two stage impellers and a peculiar motor with double rotors. The front and the rear impellers are driven by the inner and the outer rotors of the motor, respectively, keeping the relative rotational speed constant and counter‐balancing the rotational torque. Such driving conditions not only smartly improve the unstable performance at lower discharge, but also suppress the cavitation at higher discharge, in the optimum cooperation with the impeller works and the rotor outputs.
Higher Order Rotating Cavitation in an Inducer
Authors: Fujii Akira , Azuma Seiji , Yoshida Yoshiki , Tsujimoto Yoshinobu , Horiguchi Hironori , Watanabe Satoshi
Published: March 2007

In the present study, a higher order rotating cavitation predicted by the stability analysis was identified through the measurements of inlet pressure fluctuations and blade stress fluctuations. The propagation speed ratio of the higher order rotating cavitation is approximately 5, and the amplitude of the blade stress fluctuation caused by this rotating cavitation is the same level as that by the conventional rotating cavitation. In addition, a higher order cavitation surge was observed at the transition point from the conventional to the higher order rotating cavitation.
Deflections and Strains in Cracked Shafts due to Rotating Loads: A Numerical and Experimental Analysis
Authors: Bachschmid N. , Tanzi E.
Published: March 2007

In this article, the deflections of a circular cross‐section beam presenting a transverse crack of different depths, due to different loads (bending, torsion, shear, and axial loads), are analyzed with the aid of a rather refined 3‐D model, which takes into account the nonlinear contact forces in the cracked area. The bending and shear loads are applied in several different angular positions, in order to simulate a rotating load on a fixed beam, or, by changing the reference system, a fixed load on a rotating beam. Torsion and axial loads are instead fixed with respect to the beam.

Results obtained for the rotating beam can then be used for the analysis of cracked, horizontal axis heavy rotors, in which the torsion is combined to the bending load. The effect
of friction is also considered in the cracked area. The characteristic “breathing” behavior of the cracked area has been analyzed and compared to that one obtained with a rather simple 1‐D model. The differences in results with respect to those which can be obtained by means of the approach based on fracture mechanics are emphasized.

In order to highlight the effect of the presence of the crack, the deflections of the uncracked beam loaded with the same loads are subtracted from the deflections of the
cracked beam.

Finally, a cracked specimen has been extensively analyzed by means of several strain gauges, for analyzing the strain distribution on the outer surface around the crack, in different loading conditions. Consistent pre‐stresses have been found, which influence the breathing behavior. The experimental results have been compared to those obtained with
the 1‐D linear model.
The Flow Rate Influence on the Interaction of a Radial Pump Impeller and the Diffuser
Authors: Akhras A. , El Hajem M. , Champagne J.-Y. , Morel R.
Published: March 2007

This article presents the results of a detailed flow investigation within a centrifugal pump equipped with a vaned diffuser. The measurements were made with a laser Doppler velocimeter and were carried out at different operating points. The flow was investigated for different rotor–stator relative positions.

Unsteady velocity measurements, obtained in phase with the rotor angular position, gave access to the flow inside the impeller channels where three sections were explored. In the diffuser, five sections were studied. Thus, time resolved details of the flow were examined for a better understanding of the complex unsteady flow existing between the two interacting blade rows.

Results obtained at different operating conditions show that the rotor‐stator interaction is affected by the diffuser position and the flow rate.
Nonlinear Normal Modes of a Rotating Shaft Based on the Invariant Manifold Method
Authors: Legrand Mathias , Jiang Dongying , Pierre Christophe , Shaw Steven W.
Published: March 2007

The nonlinear normal mode methodology is generalized to the study of a rotating shaft supported by two short journal bearings. For rotating shafts, nonlinearities are generated by forces arising from the supporting hydraulic bearings. In this study, the rotating shaft is represented by a linear beam, while a simplified bearing model is employed so that the nonlinear supporting forces can be expressed analytically. The equations of motion of the coupled shaft‐bearings system are constructed using the Craig–Bampton method of component mode synthesis, producing a model with as few as six degrees of freedom (d.o.f.). Using an invariant manifold approach, the individual nonlinear normal modes of the shaft‐bearings system are then constructed, yielding a
single‐d.o.f. reduced‐order model for each nonlinear mode. This requires a generalized formulation for the manifolds, since the system features damping as well as gyroscopic and
nonconservative circulatory terms. The nonlinear modes are calculated numerically using a nonlinear Galerkin method that is able to capture large amplitude motions. The shaft
response from the nonlinear mode model is shown to match extremely well the simulations from the reference Craig–Bampton model.
Development of the Floating Centrifugal Pump by Use of Non Contact Magnetic Drive and Its Performance
Authors: Uno Mitsuo , Masuzoe Takaaki , Aotani Isamu , Oba Shin , Kanemoto Toshiaki
Published: March 2007

This article focuses on the impeller construction, non contact driving method and performance of a newly developed shaftless floating pump with centrifugal impeller. The drive principle of the floating impeller pump used the magnet induction method similar to the levitation theory of the linear motor. In order to reduce the axial thrust by the pressure different between shroud and disk side, the balance hole and the aileron blade were installed in the floating impeller. Considering the above effect, floating of an impeller in a pump was realized. Moreover, the performance curves of a developed pump are in agreement with a general centrifugal pump, and the dimensionless characteristic curve also agrees under the different rotational speed due to no mechanical friction of the rotational part. Therefore, utility of a non contacting magnetic‐drive style pump with the floating impeller was made clear.
Adiabatic Effectiveness and Heat Transfer Coefficient of Shaped Film Cooling Holes on a Scaled Guide Vane Pressure Side Model
Authors: Dittmar Jan , Schulz Achmed , Wittig Sigmar
Published: March 2007

The demand of improved thermal efficiency and high power output of modern gas turbine engines leads to extremely high turbine inlet temperature and pressure ratios. Sophisticated cooling schemes including film cooling are widely used to protect the vanes and blades of the first stages from failure and to achieve high component lifetimes.
In film cooling applications, injection from discrete holes is commonly used to generate a coolant film on the blade′s surface.

In the present experimental study, the film cooling performance in terms of the adiabatic film cooling effectiveness and the heat transfer coefficient of two different injection configurations are investigated. Measurements have been made using a single row of fanshaped holes and a double row of cylindrical holes in staggered arrangement. A scaled test model was designed in order to simulate a realistic distribution of Reynolds number and acceleration parameter along the pressure side surface of an actual turbine guide vane. An infrared thermography measurement system is used to determine highly resolved distribution of the models surface temperature. An in-situ calibration procedure is applied using single embedded thermocouples inside the measuring plate in order to acquire accurate local temperature data.

All holes are inclined 35° with respect to the model′s surface and are oriented in a streamwise direction with no compound angle applied. During the measurements, the influence of blowing ratio and mainstream turbulence level on the adiabatic film cooling effectiveness and heat transfer coefficient is investigated for both of the injection configurations.
Shape Optimization of a Labyrinth Seal Applying the Simulated Annealing Method
Authors: Schramm V. , Denecke J. , Kim S. , Wittig S.
Published: March 2007

In the present work, an environment for the shape optimization of a labyrinth seal is described. A program for a parameterized, automated grid generation is coupled with
a commercial Computational Fluid Dynamics (CFD) flow solver and an optimization algorithm. Standard optimization strategies, like gradient‐based methods, mostly are
trapped to local optima. Therefore, the simulated annealing method is applied. It allows the finding of global minima or maxima of arbitrary functions.

The presented optimization method is used to minimize the leakage through a three‐finned, stepped labyrinth seal. For the optimization, the step position and the step height are chosen to be variable. The characteristics of the flow fields of selected seal configurations are compared and discussed against the background of the leakage behavior of the seal.
Study on the Performance of a Sirocco Fan (Flow Around the Runner Blade)
Authors: Adachi Tsutomu , Sugita Naohiro , Yamada Yousuke
Published: March 2007

Initially in this research, effects of blade inlet and outlet
angles on the performance were considered by measuring
performances. Twelve impellers with various blade angles
were used for the measurements. The most suitable inlet and
outlet angles and the inclination angle were acquired. Then,
measurements on the inlet and outlet flows and their axial
and circumferential distributions were taken for various operating
conditions at the various measuring positions. The
turning angles through the blade were calculated from these
measured results. The inlet and outlet flows of the sirocco
fan are not uniform around the circumference. The distributions
of the flow have some relations with the development
of flow in the inlet part and in the casing. Discussions were
made on the flow to have a improved performance.
On Using the Transfer Matrix Formulation for Transient Analysis of Nonlinear Rotor Bearing Systems
Authors: Liew A. , Feng N. S. , Hahn E. J.
Published: March 2007

For many years transfer matrices have been used to evaluate
the steady‐state vibration response of linear rotor bearing
systems. More recently, they have been used to evaluate
the steady‐state periodic vibration response of nonlinear
rotor bearing systems. For quasi‐periodic and chaotic response,
a transient solution is mandated and transient solution
software can also be gainfully used to evaluate the
stability of the above‐mentioned periodic solutions. To date,
transient solutions generally necessitate a different lumped
parameter discretization of the rotor and involve solving simultaneously
the differential equations for every degree of
freedom. This article shows how transient analysis can be
performed while maintaining the transfer matrix lumped
parameter discretization. The technique is illustrated for a
non symmetric unbalanced flexible rotor supported on hydrodynamic
journal bearings or deep‐groove ball bearings.
Rotating Stall in Centrifugal Compressor Vaneless Diffuser: Experimental Analysis of Geometrical Parameters Influence on Phenomenon Evolution
Authors: Ferrara Giovanni , Ferrari Lorenzo , Baldassarre Leonardo
Published: March 2007

The rotating stall is a key problem for achieving a good
working range of a centrifugal compressor and a detailed
understanding of the phenomenon is very important to anticipate
and avoid it. Many experimental tests have been
planned by the authors to investigate the influence on stall
behavior of different geometrical configurations. A stage
with a backward channel upstream, a 2‐D impeller with a
vaneless diffuser and a constant cross‐section volute downstream,
constitute the basic configuration. Several diffuser
types with different widths, pinch shapes, and diffusion ratios
were tested. The stage was instrumented with many fast
response dynamic pressure sensors so as to characterize inception
and evolution of the rotating stall. This kind of analysis
was carried out both in time and in frequency domains.
The methodology used and the results on phenomenon evolution
will be presented and discussed in this article.
Effect of Turn Region Treatments on the Pressure Loss Distribution in a Smooth Square Channel with Sharp 180° Bend
Authors: Rao D. V. Ratna , Babu Chakka Sarat , Prabhu S. V.
Published: March 2007

An experimental investigation is carried out to study the
effect of several turn treatments like single guide vane (short
and long) and multiple guide vanes on the pressure drop distribution
in a square cross‐sectioned smooth channel with a
sharp 180° bend. The sharp 180° turn is obtained by dividing
a rectangular passage into two square channels using a
divider wall with a rounded tip at the location where the
flow negotiates the turn. The study is carried out for a divider
wall thickness to hydraulic diameter (W/D) of 0.2 for Reynolds numbers of 13,500 and 17,000. The pressure drop distribution normalized with the mainstream fluid dynamic
pressure head is presented for the outer surfaces. The results
indicate that the shape and position of the guide vanes significantly affect the pressure losses associated with coolant flows through a sharp 180° bend. Properly shaped 180° vanes located in the center of the bend decrease the overall pressure
drop by as much as 40–45% compared to the no guide vane
within the bend.
Part I—Theoretical Model for a Synchronous Thermal Instability Operating in Overhung Rotors
Authors: Balbahadur A. C. , Kirk R. G.
Published: March 2007

Atheoretical model has been developed for a synchronous
thermal instability that is caused by differential viscous
shearing in bearings of overhung rotors. This model employs
an unbalance threshold criterion for instability instead
of utilizing a traditional frequency‐domain stability analysis.
The current model will be used to investigate several case
studies for both plain and tilting pad journal bearing rotors
in the second part of this article.
Part II—Case Studies for a Synchronous Thermal Instability Operating in Overhung Rotors
Authors: Balbahadur A. C. , Kirk R. G.
Published: March 2007

In Part I, a theoretical model was developed for a synchronous
thermal instability that is caused by differential
viscous shearing in bearings of overhung rotors. This second
part used computer programs, which were based on the
theoretical model, to examine various case studies that pertain
to this thermal instability. Both plain and tilting pad
journal bearing rotors were examined and good agreement
was found between the theoretical predictions and the practical
results.
Unsteady Interaction Between a Transonic Turbine Stage and Downstream Components
Authors: Davis Roger L. , Yao Jixian , Clark John P. , Stetson Gary , Alonso Juan J. , Jameson Antony , Haldeman Charles W. , Dunn Michael G.
Published: March 2007

Results from a numerical simulation of the unsteady flow
through one quarter of the circumference of a transonic
high‐pressure turbine stage, transition duct, and low‐pressure
turbine first vane are presented and compared with
experimental data. Analysis of the unsteady pressure field resulting
from the simulation shows the effects of not only the
rotor/stator interaction of the high‐pressure turbine stage
but also new details of the interaction between the blade and
the downstream transition duct and low‐pressure turbine
vane. Blade trailing edge shocks propagate downstream,
strike, and reflect off of the transition duct hub and/or downstream
vane leading to high unsteady pressure on these
downstreamcomponents. The reflection of these shocks from the downstream components back into the blade itself has
also been found to increase the level of unsteady pressure
fluctuations on the uncovered portion of the blade suction
surface. In addition, the blade tip vortex has been found to
have a moderately strong interaction with the downstream
vane even with the considerable axial spacing between the
two blade‐rows. Fourier decomposition of the unsteady surface
pressure of the blade and downstream low‐pressure turbine
vane shows the magnitude of the various frequencies
contributing to the unsteady loads. Detailed comparisons
between the computed unsteady surface pressure spectrum
and the experimental data are shown along with a discussion
of the various interaction mechanisms between the blade,
transition duct, and downstream vane. These comparisons
show‐overall good agreement between the simulation and experimental
data and identify areas where further improvements
in modeling are needed.
A Nonlinear Model for Prediction of Dynamic Coefficients in a Hydrodynamic Journal Bearing
Authors: Sawicki Jerzy T. , Rao T. V. V. L. N.
Published: March 2007

This paper investigates the variation of nonlinear stiffness
and damping coefficients in a journal orbit with respect
to equilibrium position. The journal orbit is obtained by
the combined solution of equations of motion and Reynolds
equation. In the linearized dynamic analysis, dynamic pressure
is written as a perturbation of static pressure and pressure
gradients at equilibrium position. However, in order
to obtain nonlinear dynamic coefficients about equilibrium
position, the dynamic pressure gradients in the orbit are
also written as the first order perturbation of static pressure
gradients and higher order pressure gradients for displacement
and velocity perturbations. The dynamic coefficients
are functions of bearing displacement and velocity perturbations.
The higher order pressure gradients at equilibrium
position are evaluated at various eccentricity ratios and L/D
ratios of 0.5 and 1.0. The variation of nonlinear dynamic
coefficients is analyzed for three Sommerfeld numbers of
a two‐axial groove journal bearing under the action of an
external synchronous load along and perpendicular to the
radial journal load. Results indicate that the oil film nonlinearities
affect the journal motion at lower eccentricity ratios
(higher Sommerfeld numbers) with wide variation in stiffness
and damping coefficients.
Film Cooling Effectiveness Data for Simple InjectionGeometries: A Collection of Three‐Axis Plots
Authors: Stone L. D. , Goldstein R. J.
Published: March 2007

A three‐axis plot of laterally averaged film cooling effectiveness versus blowing rate and versus dimensionless distance
downstream is a sufficiently compact representation of film cooling effectiveness data for injection through a row of holes
or two rows of holes to enable easy, global comparisons among a variety of data sets. By plotting data from several film
cooling studies conducted at the University of Minnesota, the dominant roles played by density ratio, hole spacing, and
surface curvature become apparent. It is also seen that a slot‐plate prediction/correlation from two‐dimensional film cooling
studies makes an excellent standard of comparison for all film cooling studies, even though the more commonly encountered
(two‐axis) comparisons using standardized nondimensional parameters do not usually suggest this.
Brush Seal Performance and Durability Issues Basedon T‐700 Engine Test Results
Authors: Hendricks R. C.
Published: March 2007

The integrity and performance of brush seals have been established. Severe bench and engine tests have shown high initial
wear or rub‐in rates, material smearing at the interface, and bristle and rub‐runner wear, but the brush seals did not fail.
Short‐duration (46 hr) experimental T‐700 engine testing of the compressor discharge seal established over 1‐percent engine
performance gain (brush versus labyrinth). Long‐term gains were established only as leakage comparisons, with the brush
at least 20 percent better at controlling leakage. Long‐term materials issues, such as wear and ultimately seal life, remain
to be resolved. Future laeeds are cited for materials and analysis tools that account for heat generation, thermomechanical
behavior, and tribological pairing to enable original equipment manufacturers to design high‐temperature, high‐surface‐speed
seals with confidence.
Effects of Hydrostatic Pocket Shape on the FlowPattern and Pressure Distribution
Authors: Braun M. J. , Dzodzo M.
Published: March 2007

The flow in a hydrostatic pocket is numerically simulated using a dimensionless formulation of the 2‐D Navier‐Stokes
equations written in primitive variables, for a body fitted coordinates system, and applied through a collocated grid. In
essence, we continue the work of Braun et al. 1993a, 1993b] and extend it to the study of the effects of the pocket geometric
format on the flow pattern and pressure distribution. The model includes the coupling between the pocket flow and a finite
length feedline flow, on one hand, and the pocket and its adjacent lands on the other hand. In this context we shall present,
on a comparative basis, the flow and the pressure patterns at the runner surface for square, ramped‐Rayleigh step, and arc
of circle pockets. Geometrically all pockets have the same footprint, same lands length, and same capillary feedline. The
numerical simulation uses the Reynolds number based on the lid(runner) velocity and the inlet jet strength F as the dynamic similarity parameters. The study aims at establishing criteria for the optimization of the pocket geometry
in the larger context of the performance of a hydrostatic bearing.
Vibrational Diagnostics of Rotating MachineryMalfunctions
Authors: Muszynska Agnes
Published: March 2007

This paper outlines rotating machinery malfunction diagnostics using vibration data in correlation with operational process
data. The advantages of vibration monitoring systems as a part of preventive/predictive maintenance programs are
emphasized. After presenting basic principles of machinery diagnostics, several specific malfunction symptoms supported
by simple mathematical models are given. These malfunctions include unbalance, excessive radial load, rotor‐to‐stator
rubbing, fluid‐induced vibrations, loose stationary and rotating parts, coupled torsional/lateral vibration excitation, and rotor
cracking. The experimental results and actual field data illustrate the rotor vibration responses for individual malfunctions.
Application of synchronous and nonsynchronous perturbation testing used for identification of basic dynamic characteristics
of rotors is presented. Future advancements in vibration monitoring and diagnostics of rotating machinery health are
discussed. In the Appendix, basic instrumentation for machine monitoring is outlined.
The Effect of Surface Roughness of a Body in the HighReynolds‐Number Flow
Authors: adachi Tsutomu
Published: March 2007

In this paper, first, the principle, structures, operations, and performances of the cryogenic wind tunnel are described. By changing the pressure, temperature and velocity of gas a high Reynolds‐number flow (5 × 104 < Re < 107) can be obtained. From the research results, a high Reynolds‐number flow with comparatively low power, LN consumptions was attained. It was with Mach‐number independent of each other, o show some examples of high Reynolds‐number flow, the effects of surface roughness and grooves on the surface of a cylinder on the flow are measured using models with various values of roughness and size. A model test of an airship was also conducted. With the high Reynolds‐number flow, the thickness of
the boundary layer becomes thinner. Then the surface conditions of a body have great effect on the flow phenomena and on the drag of the body. Some attempts to reduce the drag of the body were shown.
Dynamics of Vertical Axis Wind Turbines(Darrieus Type)
Authors: El-Sayed A. F. Abdel Azim , Hirsch C. , Derdelinckx R.
Published: March 2007

A computing package that combines finite element methods for evaluating the resonance frequencies and modes of turbine subcomponents (blade, tower and shaft) together with the aerodynamic calculations for forces and moments taking into
consideration the dynamic stall as well as the dynamic response is developed. This method was applied to a realistic VAWT; namely; the PIONEER I built in the Netherlands by Fokker company. A reasonable agreement between the calculated and field results was predicted.
Measurements of Basic Performances for WaterjetPropulsion Systems in Water Tunnel
Authors: Fujisawa Nobuyuki
Published: March 2007

Experimental techniques are described in detail for evaluating the system and the unit performances of waterjet propulsion systems in a water tunnel. The measured performances of pump and propulsion of the model systems are in reasonable
agreement with the field experiment with prototype craft. Measurements are also made for the losses in the intake and the nozzle. The optimization study of the water jet systems is conducted by simulating the change of the nozzle outlet diameter with the variable nozzle arrangement. It is suggested that the nozzle outlet diameter should be decreased as the craft velocity increases to obtain an optimum propulsive efficiency in a wide range of craft velocity.
The Use of Transition Region Characteristics to Improve the Numerical Simulation of Heat Transfer in Bypass Transitional Flows
Authors: Simon Frederick F.
Published: March 2007

A method is presented for improving the numerical prediction of bypass transition heat transfer on a flat plate in a high‐disturbance environment with zero or favorable pressure gradient. The method utilizes low Reynolds number k‐ε turbulence models in combination with the characteristic parameters of the transition region. The parameters representing the characteristics of the transition region used are the intermittency, transition length and turbulent spot properties. An analysis is made of the transition length in terms of turbulent spot variables. The nondimensional spot formation rate,
required for the prediction of the transition length, is shown by the analysis to be a function of the spot spreading angle, the dimensionless spot velocity ratio and the dimensionless spot area ratio. The intermittency form of the k‐ε equations was
derived from conditionally averaged equations which have been shown to be an improvement over global‐time‐averaged equations for the numerical calculation of the transition region. The numerical predictions are in general good agreement
with the experimental data and indicate the potential use of the method in accelerating flows. Turbulence models of the k‐ε type are known to underpredict the transition length. The present work demonstrates how incorporating transition region
characteristics improves the ability of two‐equation turbulence models to simulate bypass transition for flat plates with potential application to turbine vanes and blades.
Dynamic Analysis of Composite Rotors
Authors: Singh S. P. , Gupta K.
Published: March 2007

An outline of formulation based on a layerwise beam theory for unbalance response and stability analysis of a multi mass, multi bearing composite rotor mounted on fluid film bearings is presented. Disc gyroscopics and rotary inertia effects are
accounted for. Material damping is also taken into account. The layerwise theory is compared with conventionally used equivalent modulus beam theory. Some interesting case studies are presented. The effect of various parameters on dynamic behavior and stability of a composite rotor is presented.
Turbulence and Scale Measurements in a Square Channel with Transverse Square Ribs
Authors: Rivir Richard B. , Chyu Mingking K. , Maciejewski Paul K.
Published: March 2007

Hot‐wire measurements of the mean flow, turbulence characteristics, and integral scale in a square channel roughened with transverse ribs mounted on two opposing sidewalls are presented for three rib configurations: single rib, in‐line multiple ribs,
and staggered multiple ribs. Test conditions for multiple ribs use p/H = 10, H/D 0.17, and Re⁡D 23,000. Measured results highlight the spatial distribution and evolution of turbulence intensity and integral scale from the flow entrance of the first period to the developed regime near the exit of the third period. The highly turbulent, shear layer initiated near the trailing upper‐edge of a rib elevates the turbulence level in the mainstream of the channel. The magnitude of turbulence intensity in the channel core rises from 0.7% in the approaching flow to about 20–25% near the exit of the third period. The integral scale dominating the mainstream flow increases from approximately one‐half the rib‐height, 0.5H, in the approaching flow to 1.5‐2.5H behind the first rib and further downstream.
System Identification Methods for Dynamic Testing of Fluid‐Film Bearings
Authors: Sawicki Jerzy T. , Adams Maurice L. , Capaldi Russell J.
Published: March 2007

There are various system identification approaches typically used to extract the rotordynamic coefficients from simultaneously measured dynamic force and motion signals. Since the coefficient values extracted can vary significantly as a function of the system identification approach used, more attention is needed to treat this issue than is typically included in the rotor dynamics literature. This paper describes system identification and data reduction methods used for extracting rotordynamic coefficients of fluid‐film journal bearings. Data is used from a test apparatus incorporating a double‐spoolshaft spindle which permits independent control over the journal spin speed and the frequency of an adjustable‐magnitude circular orbit, for both forward and backward whirling. For example, a least squares linear regression on the force‐displacement equations of the experiment provides only one of the rational approaches to extract the anisotropic rotordynamic coefficients (stiffness, damping and fluid inertia effects). Rotordynamic coefficients are also extracted with both first and second order orbital frequency dependencies. To assess the quality of the measured signals, coherence functions are calculated to relate the time‐averaged input motion signals and the time‐averaged output force signals.
Film Cooling from a Single Row of Compound AngleHoles at High Blowing Ratios
Authors: Ligrani Phillip M. , Lee Joon Sik
Published: March 2007

Experimental results are presented which describe the development and structure of flow downstream of a single row of holes with compound angle orientations producing film cooling at high blowing ratios. This film cooling configuration is important because similar arrangements are frequently employed on the first stage of rotating blades of operating gas turbine engines. With this configuration, holes are spaced 6d apart in the spanwise direction, with inclination angles of 24 degrees, and angles of orientation of 50.5 degrees. Blowing ratios range from 1.5 to 4.0 and the ratio of injectant to freestream density is near 1.0. Results show that spanwise averaged adiabatic effectiveness, spanwise‐averaged iso‐energetic Stanton number ratios, surveys of streamwise mean velocity, and surveys of injectant distributions change by important amounts as the blowing ratio increases. This is due to injectant lift‐off from the test surface just downstream of the holes.
Improvement of Stability of Rotor System by Introducing a Hydraulic Damper into an Active JournalBearing
Authors: Krodkiewski J. M. , Cen Y. , Sun L.
Published: March 2007

Modelling and analysis of a rotor‐‐bearing system with a new type of active oil bearing is
presented. The active bearing is supplied with a flexible sleeve whose deformation can be
changed during operation of the rotor. The flexible sleeve is also a part of a hydraulic damper
whose parameters can be controlled during operation as well.

Finite Element Method (FEM) and the Guyan condensation technique was utilised to
create mathematical model of both, the rotor and the flexible sleeve. The hydrodynamic
pressure distribution in the oil film, for the instantaneous position of the flexible sleeve and
rotor, was approximated by Reynolds equation.

The mathematical model of motion of a rotor system with the described active bearing
developed in this paper allowed the influence of the introduced hydraulic damper on stability
of the rotor‐bearing system to be investigated. Results of the computer simulation shows that
within a large region of configuration parameters of the rotor bearing system, the self exciting
vibration can be eliminated or greatly reduced during operation by properly controlled
deformation of the flexible sleeve and optimal choice of the hydraulic damper parameters.
A Dynamic Analysis of a Flexible Rotor in Ball Bearingswith Nonlinear Stiffness Characteristics
Authors: Lee Dong-Soo , Choi Dong-Hoon
Published: March 2007

This paper presents an effective analysis approach for a flexible rotor in ball bearings with
nonlinear stiffness characteristics to obtain realistic dynamic behavior results. The ball bearing
is modeled in five degrees of freedom and the nonlinear stiffness characteristics of the
bearing are completely described as functions of combined loads and spin speed. For dynamic
behavior analysis of the nonlinear rotor‐bearing system, a transfer‐matrix method is
iteratively used until the bearing displacements and the shaft displacements at every bearing
location converge to the same values. The results show that the nonlinear stiffness characteristics
of ball bearings significantly influence system dynamic behaviors and the proposed
analysis approach for the nonlinear rotor‐bearing system is effective.
3‐D Viscous Flow Analysis of an Axial Flow PumpImpeller
Authors: Miner Steven M.
Published: March 2007

A commercial CFD code is used to compute the flow field within the first stage impeller of
a two stage axial flow pump. The code solves the 3‐D Reynolds Averaged Navier Stokes
equations in a rotating cylindrical coordinate system using a standard k − ε turbulence model. Stage design parameters are, rotational speed 870 rpm,
flow coefficient φ = 0.12, head coefficient ψ = 0.06, and specific speed 2.86 (8070 US). Results from the study include
relative and absolute velocities, flow angles, and static and total pressures. Comparison is
made to measured data available for the same impeller at two planes, one upstream of the
impeller and the other downstream. The comparisons are for circumferentially averaged
results and include axial and tangential velocities, impeller exit flow angle, static pressure,
and total pressure. Results of this study show that the computational results closely match
the shapes and magnitudes of the measured profiles, indicating that CFD can be used to
accurately predict performance.
Air‐Turbine with Self‐Pitch‐Controlled Blades for Wave Energy Conversion (Estimation of Performances in Periodically Oscillating Flow)
Authors: Setoguchi T. , Raghunathan S. , Takao M. , Kaneko K.
Published: March 2007

In the development of an air‐turbine with self‐pitch‐controlled blades for wave energy conversion,
existence of hysteretic characteristics in a reciprocating flow has been examined. In
order to clarify the validity of the analysis, a numerical simulation has been made by use of
the experimental results obtained from a steady unidirectional flow condition. The comparison
between the analysis and experiment has shown that the quasi‐steady analysis is
reasonable accurate for predicting the performance. The running and starting characteristics
have also been investigated analytically taking into account the blade turning process
during pitch.
Investigation of the Flow in Pelton Turbinesand the Influence of the Casing
Authors: Matthias Heinz-Bernd , Prost Josef , Rossegger Christian
Published: March 2007

At the institute for waterpower and pumps at the University of Technology Vienna we do a
lot of research work observing the flow in the casing and the buckets of Pelton turbines. One
interest of our research is to find criteria to estimate the influence of the splash water
distribution in the casing on the turbine efficiency. Knowing the splash water distribution it
is further possible to develop methods to provide visual documentation of the flow in and
around the buckets from the beginning to the end of interaction.

Our measurements have been done on a single jet Pelton turbine with a runner pitch
diameter of 420 mm. Our research shows that the casing has great influence to the operation
of a Pelton turbine and so it is very important to include the casing as an important factor in
all investigations. Aluminum honeycombs have been successful to bring the splashing water
under control and to make good visual documentations of the flow.