bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal Expressed Emotion Related to Attachment Disorganization in Early Childhood: A Preliminary Report
Authors: Jacobsen Teresa , Hibbs Euthymia , Ziegenhain Ute
Published: August 2003

Using a longitudinal sample of children, this study examined the relation between maternal Expressed Emotion (EE) and mother‐child attachment disorganization at age 6 years. A nonclinical sample of 33 children (at ages 12 months and 18 months) from Berlin, Germany participated with their mothers in Ainsworth's Strange Situation. Thirty‐two children were again observed with their mothers at age 6 years in a standard laboratory attachment observation. At the time of the 6‐year assessment, maternal EE was assessed based on a Five‐Minute Speech Sample. Mothers also completed the Life Events Questionnaire, a measure of family stress, and the Present State Examination, a measure of maternal depression.

Maternal Expressed Emotion was significantly linked to mother‐child attachment security at age 6 years. Further analyses revealed that High EE was most closely linked to the disorganized attachment pattern at age 6 years, an at‐risk attachment pattern that has been associated with intrusive and hostile maternal behavior. The relationship was upheld when other relevant variables, including infant attachment disorganization and a measure of perceived family stress, were simultaneously considered. The study provides independent validation of Expressed Emotion as a measure of relationship quality in early childhood. It also provides a basis for the further investigation of the nature of the relation between maternal Expressed Emotion and attachment disorganization.
Expressed Emotion, Parenting Stress, and Adjustment in Mothers of Young Children with Behavior Problems
Authors: Baker Bruce L. , Heller Tracy L. , Henker Barbara
Published: August 2003

Expressed Emotion (EE), a measure of the emotional climate of the family, predicts subsequent adjustment of adults with mental disorder (Leff & Vaughn, 1985). Despite the acknowledged importance of the family in childhood disorders, there have been relatively few studies of expressed emotion with adolescents and school‐aged children and virtually none focused on preschoolers. The present study utilized the Five Minute Speech Sample (FMSS) to examine how Expressed Emotion relates concurrently and longitudinally to child problem status in a community sample of 112 preschool‐aged children. At preschool, the proportion of high EE increased significantly across three child groups: Comparison (8.1%), Borderline Problem (15.8%), and High Problem (41.2%) ; however, preschool EE was not predictive of subsequent child status at 1st grade. Expanded FMSS codes, tapping positive affect and worry about the child, were also related to child problem group at preschool and were predictive of subsequent child status at 1st grade. Because parents' stress and adjustment were also highly related to child problem group status, we examined whether the FMSS codes were essentially a proxy for these or whether they explained unique variance. In two stepwise regressions on preschool child group status (divided by total problems and by externalizing problems), maternal stress was the only variable to enter. Also, in predicting to 1st grade externalizing child group status, only maternal stress entered. Discussion focused on the extension of the EE construct and other FMSS coding to young children, and the need to recognize that to some extent these variables may reflect maternal stress and adjustment.
Mother's Attachment Concerns Regarding Spouse and Infant's Temperament as Modulators of Maternal Separation Anxiety
Authors: Mayseless Ofra , Scher Anat
Published: August 2003

The modulators of maternal separation anxiety were examined in a longitudinal study with 97 mothers of infants from 3 to 9 months of age. The objective of the study was to examine the joint contribution of the mother's attachment concerns as related to her husband together with the perception of the infant's temperament to her concerns over separation from her child. Maternal worries about separation from 3‐month‐old infants predicted maternal separation anxiety when infants were 9 months old. Mother's attachment to her husband and her perception of her child's temperament further predicted maternal separation anxiety at 9 months over and above the worries at 3 months. Mothers who feared dependent relationships with their husbands experienced high levels of maternal separation anxiety. This tendency was particularly marked when the infant was perceived as adaptable at 3 months. In addition, secure mothers, namely, mothers low in fear of abandonment and in fear of being dependent, increased their maternal separation anxiety as a function of their infant's perceived unadaptability.
The Mass Media and the Prevention of Child Behavior Problems: The Evaluation of a Television Series to Promote Positive Outcomes for Parents and Their Children
Authors: Sanders Matthew R. , Montgomery Danielle T. , Brechman‐Toussaint Margaret L.
Published: August 2003

This paper examines the impact of a 12‐episode television series, “Families”, on disruptive child behavior and family adjustment. This media intervention comprises the first of a five‐level early intervention parenting and family support strategy, known as Triple P (Positive Parenting Program). Fifty‐six parents of children aged between 2 and 8 years were randomly assigned to either watching the television series or to a waitlist control group. Compared to the control group, parents in the television viewing (TV) condition reported significantly lower levels of disruptive child behavior and higher levels of perceived parenting competence, immediately following intervention. Prior to intervention approximately 42.9% of the children in the TV condition were in the clinically elevated range for disruptive child behavioral problems. This had reduced to 14.3% following intervention. In addition, a high level of consumer acceptability was reported by parents in the TV condition. All post‐intervention effects were maintained at 6‐month follow‐up. Implications for public health approaches to family mental health are discussed.
Mechanotransduction by intraganglionic laminar endings of vagal tension receptors in the guinea‐pig oesophagus
Authors: Zagorodnyuk Vladimir P. , Chen Bao Nan , Costa Marcello , Brookes Simon J. H.
Published: September 2003

Vagal mechanoreceptors to the guinea‐pig oesophagus, recorded extracellularly, in vitro, fired spontaneously at 3.3 ± 0.2 Hz, (n= 75, from 57 animals), and had low thresholds to circumferential stretch. In this study, we have investigated whether mechanotransduction by intraganglionic laminar endings (IGLEs) directly relies on mechano‐gated ion channels, or whether it is due to chemical activation by neurotransmitters (glutamate or ATP) released from other cells during mechanical distortion. Rapid distortion of focal transduction sites (IGLEs) evoked action potentials with a latency of < 10 ms. Antagonists to ionotropic (AP5, memantine and 6,7‐dinitroquinoxaline‐2,3‐dione (DNQX)) and metabotropic glutamate receptors (N‐phenyl‐7‐(hydroxyimino)cyclopropa[b]chromen‐1a‐carboxamide (PHCCC) and (RS)‐a‐methyl‐4‐phosphono‐phenylglycine (MPPG)) did not affect mechano‐transduction. Glutamate, NMDA and the selective mGluR group II and III agonists, (2R, 4R)‐APDC and l‐AP4, had no effect on spontaneous or stretch‐induced firing. The P2X purinoreceptor agonist, α,β‐methylene ATP, caused concentration‐dependent excitation of vagal mechanoreceptors (EC50= 22.2 µm) which was blocked by the non‐selective P2 antagonist PPADS (30 µm). On its own, PPADS affected neither stretch‐induced firing nor spontaneous firing. Neither Ca2+‐free solution (1 mm EDTA, 3.6 mm Mg2+) solution nor Cd2+ (100 µm) blocked stretch‐induced firing. Thus chemical transmission is not involved in activation of vagal mechanoreceptors. The blocker of stretch‐activated channels, Gd3+ (300 µm), did not inhibit stretch‐induced firing. However, benzamil (100 µm) significantly inhibited spontaneous and distension‐evoked firing in a stretch‐dependent manner; proportionally greater inhibition was seen with larger stretches. The results suggest that IGLEs of vagal tension receptors directly transduce mechanical stimuli probably via benzamil‐sensitive, Gd3+‐insensitive, stretch‐activated ion channels, and that chemical transmission is not involved in transduction.
Group II metabotropic glutamate receptor modulation of excitatory transmission in rat subthalamic nucleus
Authors: Shen Ke‐Zhong , Johnson Steven W.
Published: September 2003

Patch pipettes were used to record currents in whole‐cell configuration to study the effects of group II metabotropic glutamate receptor (mGluR) stimulation on synaptic transmission in slices of rat subthalamic nucleus. Evoked glutamatergic excitatory postsynaptic currents (EPSCs) were reversibly reduced by the selective group II mGluR agonist (2’S,2’R,3’R)‐2‐(2’,3’‐dicarboxycyclopropyl)glycine (DCG IV) in a concentration‐dependent manner, with an IC50 of 0.19 ± 0.05 µm. DCG IV (1 µm) had no effect on inhibitory postsynaptic currents mediated by GABA. DCG IV‐induced inhibition of EPSCs was reversed by the selective group II mGluR antagonist LY 341495 (100 nm) and mimicked by another selective group II agonist (2S,1’S,2’S)‐2‐(carboxycyclopropyl)glycine (l‐CCG‐I). Inhibition of EPSC amplitude by DCG IV and l‐CCG‐I was associated with an increase in the paired‐pulse ratio of EPSCs. The protein kinase C (PKC) activator phorbol 12‐myristate 13‐acetate (2 µm) reduced the inhibitory effect of DCG IV on EPSCs. However, the response to DCG IV was not affected by the protein kinase A (PKA) activator forskolin (20 µm), by the adenylyl cyclase inhibitor MDL 12230A (20 µm), or by the phosphodiesterase inhibitor Ro 20–1724 (50 µm). DCG IV‐induced inhibition of EPSCs was reduced by the non‐selective protein kinase inhibitors H‐7 (100 µm), H‐8 (50 µm) and HA‐1004 (100 µm). These results suggest that group II mGluR stimulation acts presynaptically to inhibit glutamate release by a PKC‐dependent mechanism in the subthalamic nucleus.
Improving the Efficiency of the Trent 500-HP Turbine Using Nonaxisymmetric End Walls—Part I: Turbine Design
Authors: Brennan G. , Harvey N. W. , Rose M. G. , Fomison N. , Taylor M. D.
Published: August 2003

This paper describes the redesign of the HP turbine of the Rolls-Royce Trent 500 engine, making use of nonaxisymmetric end walls. The original, datum turbine used conventional axisymmetric end walls, while the vane and (shrouded) rotor aerofoil profiles were nominally the same for the two designs. Previous research on the large-scale, low-speed linear cascade at Durham University (see Hartland et al., 1998, “Non-Axisymmetric End Wall Profiling in a Turbine Cascade,” ASME 98–GT-525), had already demonstrated significant potential for reducing turbine secondary losses using nonaxisymmetric end walls-by about one third. This paper shows how a methodology was derived from the results of this research and applied to the design of the single-stage Trent 500-HP turbine (model rig). In particular, the application of a new linear design system for the parametric definition of these end wall shapes (described in Harvey et al., 1999, “Non-Axisymmetric Turbine End Wall Design: Part I Three-Dimensional Linear Design System,” ASME 99–GT-337) is discussed in detail.
Green’s Functions and Boundary Integral Analysis for Exponentially Graded Materials: Heat Conduction
Authors: Gray L. J. , Kaplan T. , Richardson J. D. , Paulino G. H.
Published: August 2003

Free space Green’s functions are derived for graded materials in which the thermal conductivity varies exponentially in one coordinate. Closed-form expressions are obtained for the steady-state diffusion equation, in two and three dimensions. The corresponding boundary integral equation formulations for these problems are derived, and the three-dimensional case is solved numerically using a Galerkin approximation. The results of test calculations are in excellent agreement with exact solutions and finite element simulations.
Local Mass/Heat Transfer on Turbine Blade Near-Tip Surfaces
Authors: Jin P. , Goldstein R. J.
Published: August 2003

Local mass transfer measurements on a simulated high-pressure turbine blade are conducted in a linear cascade with tip clearance, using a naphthalene sublimation technique. The effects of tip clearance (0.86–6.90% of chord) are investigated at an exit Reynolds number of 5.8×105 and a low turbulence intensity of 0.2%. The effects of the exit Reynolds number 4−7×105 and the turbulence intensity (0.2 and 12.0%) are also measured for the smallest tip clearance. The effect of tip clearance on the mass transfer on the pressure surface is limited to 10% of the blade height from the tip at smaller tip clearances. At the largest tip clearance high mass transfer rates are induced at 15% of curvilinear distance Sp/C by the strong acceleration of the fluid on the pressure side into the clearance. The effect of tip clearance on the mass transfer is not very evident on the suction surface for curvilinear distance of Ss/C<0.21. However, much higher mass transfer rates are caused downstream of Ss/C≈0.50 by the tip leakage vortex at the smallest tip clearance, while at the largest tip clearance, the average mass transfer is lower than that with zero tip clearance, probably because the strong leakage vortex pushes the passage vortex away from the suction surface. High mainstream turbulence level (12.0%) increases the local mass transfer rates on the pressure surface, while a higher mainstream Reynolds number generates higher local mass transfer rates on both near-tip surfaces.
Measurement and Analysis of Ingestion Through a Turbine Rim Seal
Authors: Gentilhomme O. , Hills N. J. , Turner A. B. , Chew J. W.
Published: August 2003

Experimental measurements from a new single stage turbine are presented. The turbine has 26 vanes and 59 rotating blades with a design point stage expansion ratio of 2.5 and vane exit Mach number of 0.96. A variable sealing flow is supplied to the disk cavity upstream of the rotor and then enters the annulus through a simple axial clearance seal situated on the hub between the stator and rotor. Measurements at the annulus hub wall just downstream of the vanes show the degree of circumferential pressure variation. Further pressure measurements in the disk cavity indicate the strength of the swirling flow in the cavity, and show the effects of mainstream gas ingestion at low sealing flows. Ingestion is further quantified through seeding of the sealing air with nitrous oxide or carbon dioxide and measurement of gas concentrations in the cavity. Interpretation of the measurements is aided by steady and unsteady computational fluid dynamics solutions, and comparison with an elementary model of ingestion.
Spatially Resolved Heat Transfer and Friction Factors in a Rectangular Channel With 45-Deg Angled Crossed-Rib Turbulators
Authors: Ligrani P. M. , Mahmood G. I.
Published: August 2003

Spatially resolved Nusselt numbers, spatially averaged Nusselt numbers, and friction factors are presented for a stationary channel with an aspect ratio of 4 and angled rib turbulators inclined at 45 deg with perpendicular orientations on two opposite surfaces. Results are given at different Reynolds numbers based on channel height from 10,000 to 83,700. The ratio of rib height to hydraulic diameter is .078, the rib pitch-to-height ratio is 10, and the blockage provided by the ribs is 25% of the channel cross-sectional area. Nusselt numbers are given both with and without three-dimensional conduction considered within the acrylic test surface. In both cases, spatially resolved local Nusselt numbers are highest on tops of the rib turbulators, with lower magnitudes on flat surfaces between the ribs, where regions of flow separation and shear layer reattachment have pronounced influences on local surface heat transfer behavior. The augmented local and spatially averaged Nusselt number ratios (rib turbulator Nusselt numbers normalized by values measured in a smooth channel) vary locally on the rib tops as Reynolds number increases. Nusselt number ratios decrease on the flat regions away from the ribs, especially at locations just downstream of the ribs, as Reynolds number increases. When adjusted to account for conduction along and within the test surface, Nusselt number ratios show different quantitative variations (with location along the test surface), compared to variations when no conduction is included. Changes include: (i) decreased local Nusselt number ratios along the central part of each rib top surface as heat transfer from the sides of each rib becomes larger, and (ii) Nusselt number ratio decreases near corners, where each rib joins the flat part of the test surface, especially on the downstream side of each rib. With no conduction along and within the test surface (and variable heat flux assumed into the air stream), globally-averaged Nusselt number ratios vary from 2.92 to 1.64 as Reynolds number increases from 10,000 to 83,700. Corresponding thermal performance parameters also decrease as Reynolds number increases over this range, with values in approximate agreement with data measured by other investigators in a square channel also with 45 deg oriented ribs.
Heat Transfer in Rotating Rectangular Cooling Channels AR=4 With Dimples
Authors: Griffith Todd S. , Al-Hadhrami Luai , Han Je-Chin
Published: August 2003

As the world of research seeks ways of improving the efficiency of turbomachinery, attention has recently focused on a relatively new type of internal cooling channel geometry, the dimple. Preliminary investigations have shown that the dimple enhances heat transfer with minimal pressure loss. An investigation into determining the effect of rotation on heat transfer in a rectangular channel (aspect ratio=4:1) with dimples is detailed in this paper. The range of flow parameters includes Reynolds number Re=5000-40000, rotation number Ro=0.04-0.3 and inlet coolant-to-wall density ratio Δρ/ρ=0.122. Two different surface configurations are explored, including a smooth duct and dimpled duct with dimple depth-to-print diameter δ/Dp ratio of 0.3. A dimple surface density of 10.9 dimples/in2 was used for each of the principal surfaces (leading and trailing) with a total of 131 equally spaced hemispherical dimples per surface; the side surfaces are smooth. Two channel orientations of β=90 and 135 deg with respect to the plane of rotation are explored to determine channel orientation effect. Results show a definite channel orientation effect, with the trailing-edge channel enhancing heat transfer more than the orthogonal channel. Also, the dimpled channel behaves somewhat like a 45 deg angled rib channel, but with less spanwise variations in heat transfer.
Comparison of Stresses in Center-Wound Rolls From Two Linear Elastic Models
Authors: Debesis and W. R. , Burns S. J.
Published: August 2003

Two linear elastic models for describing stresses in center-wound rolls have been compared. One model includes wound on residual strains from the web while the other uses a clamped on stress boundary condition. The stress and displacement solutions to these two models, in the linear elastic limit, are shown to have analytical differences, and similarities.
Elastic Waves Induced by Surface Heating in a Half-Space
Authors: Blanchard J. P.
Published: August 2003

Rapid surface heating will induce waves in an elastic material. Closed-form solutions for the resulting longitudinal and transverse thermal stresses are derived using Laplace Transforms. The model is one-dimensional, consisting of a half-space subjected to a step change in the surface heating. The transverse stress at the wave peak is found to exceed the surface stress for short times, while for long times the surface stress far exceeds either of the stresses at the wave peak. Both the longitudinal and transverse stresses at the peak of the wave reach steady-state values after a few dimensionless times.
Constraint Forces and the Method of Auxiliary Generalized Speeds
Authors: Djerassi S. , Bamberger H.
Published: August 2003

This paper deals with noncontributing forces, usually called constraint forces or reaction forces, arising in simple, nonholonomic multibody systems. These forces are related to two kinds of constraints, namely, kinematical constraints—derived from kinematical requirements, and auxiliary constraints, introduced for the purpose of constraint forces determination. Here, the method of “auxiliary generalized speeds” is used to bring into evidence constraint forces related to the two kinds of constraints. It is shown that auxiliary generalized speeds can always be chosen in a way that gives rise to additional equations each having one measure number of a constraint force as an unknown. Motion equations can thus be generated and solved without regard to constraint forces determination; and constraint forces can be determined with no matrix inversion, at a minimal computational cost.
Rolls Royce/Allison 501-K Gas Turbine Antifouling Compressor Coatings Evaluation
Authors: Caguiat Daniel E.
Published: August 2003

The Naval Surface Warfare Center, Carderock Division (NSWCCD) Gas Turbine Emerging Technologies Code 9334 was tasked by NSWCCD Shipboard Energy Office Code 859 to research and evaluate fouling resistant compressor coatings for Rolls Royce Allison 501-K Series gas turbines. The objective of these tests was to investigate the feasibility of reducing the rate of compressor fouling degradation and associated rate of specific fuel consumption (SFC) increase through the application of anti-fouling coatings. Code 9334 conducted a market investigation and selected coatings that best fit the test objective. The coatings selected were Sermalon for compressor stages 1 and 2 and Sermaflow S4000 for the inlet guide vanes and remaining 12 compressor stages. Both coatings are manufactured by Sermatech International, are intended to substantially decrease blade surface roughness, have inert top layers, and contain an anti-corrosive aluminum-ceramic base coat. Sermalon contains a Polytetrafluoroethylene (PTFE) topcoat, a substance similar to Teflon, for added fouling resistance. Tests were conducted at the Philadelphia Land Based Engineering Site (LBES). Testing was first performed on the existing LBES 501-K17 gas turbine, which had an uncoated compressor. The compressor was then replaced by a coated compressor and the test was repeated. The test plan consisted of injecting a known amount of salt solution into the gas turbine inlet while gathering compressor performance degradation and fuel economy data for 0, 500, 1000, and 1250 KW generator load levels. This method facilitated a direct comparison of compressor degradation trends for the coated and uncoated compressors operating with the same turbine section, thereby reducing the number of variables involved. The collected data for turbine inlet, temperature, compressor efficiency, and fuel consumption were plotted as a percentage of the baseline conditions for each compressor. The results of each plot show a decrease in the rates of compressor degradation and SFC increase for the coated compressor compared to the uncoated compressor. Overall test results show that it is feasible to utilize antifouling compressor coatings to reduce the rate of specific fuel consumption increase associated with compressor performance degradation.
Effect of Unsteady Stator Wake—Rotor Double-Leakage Tip Clearance Flow Interaction on Time-Average Compressor Performance
Authors: Sirakov Borislav Todorov , Tan Choon-Sooi
Published: August 2003

A study has been conducted, using unsteady three-dimensional Reynolds-averaged Navier-Stokes simulations to determine the impact on rotor performance of the interaction between upstream (steady defect and time-varying defect) stator wakes and rotor tip clearance flow. The key effects of the interaction between steady stator wakes and rotor tip clearance flow are: 1) a decrease in loss and blockage associated with tip clearance flow; 2) an increase in passage static pressure rise. Performance benefit is seen in the operability range from near design to high loading. The benefit is modest near design and increases with loading. Significant beneficial changes due to the stator-rotor interaction occur when the phenomenon of tip clearance flow double-leakage is present. Double-leakage occurs when the tip clearance flow passes through the tip gap of the adjacent blade. It is detrimental for compressor performance. The effect of strong stator-rotor interaction is to suppress double-leakage on a time-average basis. Double-leakage typically takes place at high loading but can be present at design condition as well, for modern highly loaded compressor. A benefit due to unsteady interaction is also observed in the operability range of the rotor. A new generic causal mechanism is proposed to explain the observed changes in performance. It identifies the interaction between the tip clearance flow and the pressure pulses, induced on the rotor blade pressure surface by the upstream wakes, as the cause for the observed effects. The direct effect of the interaction is a decrease in the time-average double-leakage flow through the tip clearance gap so that the stream-wise defect of the exiting tip flow is lower with respect to the main flow. A lower defect leads to a decrease in loss and blockage generation and hence an enhanced performance compared to that in the steady situation. The performance benefits increase monotonically with loading and scale linearly with upstream wake velocity defect. With oscillating defect stator wakes, rotor performance shows dependence on oscillation frequency. Changes in the tip region occur at a particular reduced frequency leading to (1) decrease in blockage, and (2) increase in passage loss. The changes in rotor performance at a particular reduced frequency are hypothesized to be associated with the inherent unsteadiness of the tip clearance vortex and its resonance behavior excited by the oscillating wakes.
Assessing Viscous Body Forces for Unsteady Calculations
Authors: Xu L.
Published: August 2003

A strategy has been developed to model the three-dimensional unsteady flows through turbomachines subject to nonaxisymmetric flow/geometrical conditions such as low order distortions with relatively long length-scale unsteadiness, by modeling the viscous effects as local source terms for a coarse computational mesh, but not calculating them directly. In general full annulus multi-row calculations are required for such flows, but currently the computational resources are devoted to resolving detailed viscous flow very close to the walls, which in some cases is not the center of concern. By avoiding resolving detailed viscous effects the model can accelerate the calculation by at least two orders of magnitude. The method has been illustrated to be able to resolve disturbances down to the blade passing frequency and give good estimates of overall unsteady blade forces due to blade row interactions. Obviously, the correct modeling of the viscous body force as source terms in the governing equations is the key for accuracy of such calculations. Different ways of constructing/approximating the viscous body force term are discussed and their adequacy in unsteady flow calculations is assessed. It is found that in general the viscous force is relatively small compared to the total blade force, even smaller the unsteady fluctuation of the viscous force and a simple drag coefficient model is quite adequate to model both time mean and dynamic viscous effects. However, for the cases when separations are present variations in the drag coefficient may become large and more detailed modeling may be required.
A Unified Approach for Designing a Radial Flow Gas Turbine
Authors: Ebaid M. S. Y. , Bhinder F. S. , Khdairi G. H.
Published: August 2003

Radial flow turbo machines have been used for a long time in a variety of applications such as turbochargers, cryogenics, auxiliary power units, and air conditioning of aircraft cabins. Hence numerous papers have been written on the design and performance of these machines. The only justification for yet another paper is that it would describe a unified approach for designing a single stage inward flow radial turbine comprising a rotor and the casing. The current turbine is designed to drive a direct-coupled permanent magnet high-speed alternator running at 60000 rpm and developing a maximum of 60 kW electrical power. The freedom of choice of the tip diameter and the tip width of the rotor that would be necessary for optimum isentropic efficiency of the turbine stage was restricted by the specified rotational speed and power output. Hence, an optimization procedure was developed to determine the principal dimension of the rotor. The mean relative velocity in the rotor passages in the direction of the flow would be accelerated but flow velocity on the blade surfaces experiences a significant space rate of deceleration. The rate of deceleration can be controlled by means of a proper choice of the axial length of the rotor. A prescribed mean stream velocity distribution procedure was used to spread the rate of deceleration of the mean flow velocity along the meridional length of the flow passages. The nozzle-less volute casing was designed to satisfy the mass flow rate, energy and angular momentum equations simultaneously. This paper describes the work undertaken to design both the rotor and the casing. The work was motivated by the growing interest in developing gas turbine based hybrid power plant for road vehicles. The authors believe that the paper would lead to a stimulating discussion.
A Novel Transient Liquid Crystal Technique to Determine Heat Transfer Coefficient Distributions and Adiabatic Wall Temperature in a Three-Temperature Problem
Authors: Chambers Andrew C. , Gillespie David R. H. , Ireland Peter T. , Dailey Geoffrey M.
Published: August 2003

Transient liquid crystal techniques are widely used for experimental heat transfer measurements. In many instances it is necessary to model the heat transfer resulting from the temperature difference between a mixture of two gas streams and a solid surface. To nondimensionally characterize the heat transfer from scale models it is necessary to know both the heat transfer coefficient and adiabatic wall temperature of the model. Traditional techniques rely on deducing both parameters from a single test. This is a poorly conditioned problem. A novel strategy is proposed in which both parameters are deduced from a well-conditioned three-test strategy. The heat transfer coefficient is first calculated in a single test; the contribution from each driving gas stream is then deduced using additional tests. Analytical techniques are developed to deal with variations in the temperature profile and transient start time of each flow. The technique is applied to the analysis of the heat transfer within a low aspect ratio impingement channel with initial cross flow.
An Investigation on Turbine Tip and Shroud Heat Transfer
Authors: Chana Kam S. , Jones Terry V.
Published: August 2003

Detailed experimental investigations have been performed to measure the heat transfer and static pressure distributions on the rotor tip and rotor casing of a gas turbine stage with a shroudless rotor blade. The turbine stage was a modern high pressure Rolls-Royce aero-engine design with stage pressure ratio of 3.2 and nozzle guide vane (ngv) Reynolds number of 2.54E6. Measurements have been taken with and without inlet temperature distortion to the stage. The measurements were taken in the QinetiQ Isentropic Light Piston Facility and aerodynamic and heat transfer measurements are presented from the rotor tip and casing region. A simple two-dimensional model is presented to estimate the heat transfer rate to the rotor tip and casing region as a function of Reynolds number along the gap.
Thermodynamic Analyses of Wet Compression Process in the Compressor of Gas Turbine
Authors: Zheng Qun , Sun Yufeng , Li Shuying , Wang Yunhui
Published: August 2003

Thermodynamic model of wet compression process is established in this paper. The topics of ideal wet compression process, actual wet compression process, water droplet evaporative rate, wet compression work, inlet evaporative cooling, concept of wet compression efficiency, aerodynamic breaking of water droplets etc. are investigated and discussed in this paper.
A Numerical Investigation on the Influence of Lateral Boundaries in Linear Vibrating Cascades
Authors: Corral Roque , Gisbert Fernando
Published: August 2003

The effect of the finite extent of linear cascades on the unsteady pressure distribution of vibrating blades is assessed by means of a numerical study. The span of a reference cascade made up of flat plates has been changed to investigate its influence on the computed influence coefficients. It is concluded that the number of passages required to match a solution obtained with a traveling-wave mode strongly depends on the interblade phase angle under consideration and that existing linear vibrating cascade facilities have a marginal resolution to accurately match CFD analysis that assume that the blade is vibrating in a traveling-wave mode.
Aerodynamic-Rotordynamic Interaction in Axial Compression Systems—Part II: Impact of Interaction on Overall System Stability
Authors: Al-Nahwi Ammar A. , Paduano James D. , Nayfeh Samir A.
Published: August 2003

This paper presents an integrated treatment of the dynamic coupling between the flow field (aerodynamics) and rotor structural vibration (rotordynamics) in axial compression systems. This work is motivated by documented observations of tip clearance effects on axial compressor flow field stability, the destabilizing effect of fluid-induced aerodynamic forces on rotordynamics, and their potential interaction. This investigation is aimed at identifying the main nondimensional design parameters governing this interaction, and assessing its impact on overall stability of the coupled system. The model developed in this work employs a reduced-order Moore-Greitzer model for the flow field, and a Jeffcott-type model for the rotordynamics. The coupling between the fluid and structural dynamics is captured by incorporating a compressor pressure rise sensitivity to tip clearance, together with a momentum based model for the aerodynamic forces on the rotor (presented in Part I of this paper). The resulting dynamic model suggests that the interaction is largely governed by two nondimensional parameters: the sensitivity of the compressor to tip clearance and the ratio of fluid mass to rotor mass. The aerodynamic-rotordynamic coupling is shown to generally have an adverse effect on system stability. For a supercritical rotor and a typical value of the coupling parameter, the stability margin to the left of the design point is shown to decrease by about 5% in flow coefficient (from 20% for the uncoupled case). Doubling the value of the coupling parameter not only produces a reduction of about 8% in the stability margin at low flow coefficients, but also gives rise to a rotordynamic instability at flow coefficients 7% higher than the design point.
Concepts of Separated J-Integrals, Separated Energy Release Rates, and the Component Separation Method of the J-Integral for Interfacial Fracture Mechanics
Authors: Nishioka T. , Syano S. , Fujimoto T.
Published: August 2003

First, this paper presents the concepts of separated J-integrals and separated energy release rates. The path-independent separated J-integrals have the physical significance of energy flows into an interfacial crack tip from adjacent individual material sides or, equivalently, separated energy release rates. Thus, the J-integral and the energy release rate can be evaluated by the sum of the path-independent separated J-integrals. Second, the relations between the separated J-integrals and the stress intensity factors are derived. Third, the component separation method of the J-integral is extended for interfacial crack problems to allow accurate evaluation of the stress intensity factors. Finally, pertinent numerical analyses are carried out to demonstrate the usefulness of the separated J-integrals and the component separation method.
General Solutions of Anisotropic Laminated Plates
Authors: Yin W.-L.
Published: August 2003

Anisotropic laminates with bending-stretching coupling possess eigensolutions that are analytic functions of the complex variables x+μky, where the eigenvalues μk and the corresponding eigenvectors are determined in the present analysis, along with the higher-order eigenvectors associated with repeated eigenvalues of degenerate laminates. The analysis and the resulting expressions are greatly simplified by using a mixed formulation involving a new set of elasticity matrices A*, B*, and D*. There are 11 distinct types of laminates, each with a different expression of the general solution. For an infinite plate with an elliptical hole subjected to uniform in-plane forces and moments at infinity, closed-form solutions are obtained for all types of anisotropic laminates in terms of the eigenvalues and eigenvectors.
A Dynamic Generalized Self-Consistent Model for Wave Propagation in Particulate Composites
Authors: Yang R.-B.
Published: August 2003

Wave propagations in an inhomogeneous medium (e.g., voids, particles, defects, inclusions) undergo multiple scattering which results in a frequency-dependent velocity and attenuation of coherent wave. The aim of this study is to analyses multiple scattering of plane compressional and shear waves in a composite containing randomly distributed spherical inclusions in a homogenous isotropic medium. To calculate effective wave numbers of ultrasonic waves propagating in the heterogeneous material, a generalized self-consistent multiple scattering model is used in this study. Numerical results for the effective phase velocity and attenuation of both P and SV waves are calculated for a wide range of frequencies and concentrations. The proposed dynamic generalized self-consistent model for particulate composites recovers both well-known static effective moduli in the static limit and the results at higher frequencies and concentrations agree well with published experimental data.
Dynamic Response of Kirchhoff Plate on a Viscoelastic Foundation to Harmonic Circular Loads
Authors: Sun L.
Published: August 2003

In this paper Fourier transform is used to derive the analytical solution of a Kirchhoff plate on a viscoelastic foundation subjected to harmonic circular loads. The solution is first given as a convolution of the Green’s function of the plate. Poles of the integrand in the integral representation of the solution are identified for different cases of the foundation damping and the load frequency. The theorem of residue is then utilized to evaluate the generalized integral of the frequency response function. A closed-form solution is obtained in terms of the Bessel and Hankel functions corresponding to the frequency response function of the plate under a harmonic circular load. The result is partially verified by comparing the static solution of a point source obtained in this paper to a well-known result. This analytical representation permits one to construct fast algorithms for parameter identification in pavement nondestructive test.
Frequency Analysis of Rotating Conical Panels: A Generalized Differential Quadrature Approach
Authors: Ng T. Y. , Li H. , Lam K. Y. , Chua C. F.
Published: August 2003

Based on the generalized differential quadrature (GDQ) method, this paper presents, for the first instance, the free-vibration behavior of a rotating thin truncated open conical shell panel. The present governing equations of free vibration include the effects of initial hoop tension and the centrifugal and Coriolis accelerations due to rotation. Frequency characteristics are obtained to study in detail the influence of panel parameters and boundary conditions on the frequency characteristics. Further, qualitative differences between the vibration characteristics of rotating conical panels and that of rotating full conical shells are investigated. To ensure the accuracy of the present results using the GDQ method, comparisons and verifications are made for the special case of a stationary panel.
A Novel Transient Heater-Foil Technique for Liquid Crystal Experiments on Film-Cooled Surfaces
Authors: Vogel G. , Graf A. B. A. , von Wolfersdorf J. , Weigand B.
Published: August 2003

A novel transient measurement technique has been developed for determining the heat transfer characteristics in the presence of film cooling (heat transfer coefficient and adiabatic film-cooling effectiveness). The method is based on a transient heater foil technique, where a non-homogeneous surface heat flux is applied to the test surface. A regression analysis of multiple transient liquid crystal experiments is used to obtain the heat transfer characteristics. The method introduced here has the advantage that the (often not known) heat flux distribution at the surface is not needed for the analysis of the measured data. The method is used to study the influence of several heater foil configurations on a flat plate with film cooling, elucidating the effect of different thermal boundary conditions on film-cooling performance. The obtained data is also compared to results presented in literature and good agreement is found.
Comparisons of High-Reynolds-Number EVM and DSM Models in the Prediction of Heat and Fluid Flow of Turbine Blade Cooling Passages
Authors: Okita Yoji , Iacovides Hector
Published: August 2003

This paper presents computations of flow and heat transfer through passages relevant to those used to internally cool gas-turbine blades, using high-Reynolds-number models of turbulence. Three types of internal flows are first examined, which between them contain all the main elements found in blade cooling passages; developing flow through a heated straight duct rotating orthogonally, repeating flow and heat transfer through a straight ribbed duct and flow and heat transfer through a round-ended U-bend of strong curvature square and of cross-section. Next, flows influenced by a combination of these elements are computed. The main objective is to establish how reliably, industry-standard high-Reynolds-number models can predict flow and wall-heat transfer in blade-cooling passages. Two high-Reynolds-number models have been used, the standard version of the high-Re k-ε (EVM) model and the basic high-Re model of stress transport (DSM). In all the cases the second-moment closure (DSM) consistently produced flow and thermal predictions that are closer to available measurements than those of the EVM model. Even the high-Re DSM predictions, however, are not in complete agreement with the experimental data. Comparisons with predictions of earlier studies that use low-Re models of turbulence show that at least some of the remaining differences between the current predictions and experimental data are due to the use of the wall-function approach.
Effect of Internal Coolant Crossflow on the Effectiveness of Shaped Film-Cooling Holes
Authors: Gritsch Michael , Schulz Achmed , Wittig Sigmar
Published: August 2003

Film-cooling was the subject of numerous studies during the past decades. However, the effect of flow conditions on the entry side of the film-cooling hole on film-cooling performance has surprisingly not received much attention. A stagnant plenum which is widely used in experimental and numerical studies to feed the holes is not necessarily a right means to re-present real engine conditions. For this reason, the present paper reports on an experimental study investigating the effect of a coolant crossflow feeding the holes that is oriented perpendicular to the hot gas flow direction to model a flow situation that is, for instance, of common use in modern turbine blades’ cooling schemes. A comprehensive set of experiments was performed to evaluate the effect of perpendicular coolant supply direction on film-cooling effectiveness over a wide range of blowing ratios (M=0.5…2.0) and coolant crossflow Mach numbers Mac=0…0.6. The coolant-to-hot gas density ratio, however, was kept constant at 1.85 which can be assumed to be representative for typical gas turbine applications. Three different hole geometries, including a cylindrical hole as well as two holes with expanded exits, were considered. Particularly, two-dimensional distributions of local film-cooling effectiveness acquired by means of an infrared camera system were used to give detailed insight into the governing flow phenomena. The results of the present investigation show that there is a profound effect of how the coolant is supplied to the hole on the film-cooling performance in the near hole region. Therefore, crossflow at the hole entry side has be taken into account when modeling film-cooling schemes of turbine bladings.
Some Observations on Uncertainties and the Verification and Validation of a Simulation
Authors: Coleman Hugh W.
Published: August 2003

In this note, my objectives are to clarify the ideas in a previously published quantitative verification and validation (V&V) approach that is based on experimental uncertainty analysis concepts; to suggest a new viewpoint (and nomenclature) for assessment of the results of V&V efforts; and to discuss an inherent ambiguity in the interpretation of results of grid refinement studies that are used in verification approaches.
On the Linear Encroachment in Two-Immiscible Fluid Systems in a Porous Medium
Authors: Vafai Kambiz , Alazmi Bader
Published: August 2003

A careful review to the previous study of Srinivasan and Vafai on the linear encroachment in two-immiscible fluid systems in a porous medium reveals some typos in their analytical solution. In the present study, an accurate analytical solution, which accounts for boundary and inertia effects, is obtained to predict the movement of the interfacial front and corrections to previous results are provided wherever necessary. Despite the similarity in the general behavior of the present accurate solution and the previous one, the existence of an accurate analytical solution is essential for future numerical and experimental studies.
Fluid Dynamic Aspects of Electrostatic Precipatators: Turbulence Characteristics in Scale Models
Authors: Coghe Aldo , Mantegna Michele , Sotgia Giorgio
Published: August 2003

The present work originated in an investigation on fluid dynamic aspects of electrostatic precipitators performed on scale models of an industrial apparatus. The experimental analysis of velocity and turbulence distribution, performed by hot-wire anemometry, confirmed that significant turbulence levels are found inside particle collectors. In fact, components used to spatially smooth the flow and lower its velocity peaks, such as hoods with wide divergence angles, turning vanes, and perforated plates, may also act as sources of turbulence and reduce the efficiency of electrostatic precipitators. These observations prompted a deeper analysis, both analytical and experimental, of the turbulence decay downstream perforated screens. A new simple semi-empirical model of turbulence decay is proposed, which has shown reasonably good agreement with experimental data, even at short downstream distance from the perforated plate, 50 to 250 hydraulic diameters.
Modeling of Turbulent Fluid Flow Over a Rough Wall With or Without Suction
Authors: Gre´goire G. , Favre-Marinet M. , Amand F. Julien Saint
Published: August 2003

The turbulent flow close to a wall with two-dimensional roughness is computed with a two-layer zonal model. For an impermeable wall, the classical logarithmic law compares well with the numerical results if the location of the fictitious wall modeling the surface is considered at the top of the rough boundary. The model developed by Wilcox for smooth walls is modified to account for the surface roughness and gives satisfactory results, especially for the friction coefficient, for the case of boundary layer suction.