scholarly journals Aerodynamic Architectural Features to Mitigate Peak Pressures over Low-Rise Buildings

2021 ◽  
Vol 84 (2) ◽  
pp. 24-38
Author(s):  
Yasser M. El-Okda ◽  
Mohamed S. Emeara
Keyword(s):  
Heat Transfer ◽  
Adverse Effects ◽  
Pressure Distribution ◽  
Wind Engineering ◽  
Pressure Measurements ◽  
Suction Pressure ◽  
Research Facility ◽  
Engineering Research ◽  
Architectural Features ◽  
Peak Pressures

A number of aerodynamic devices to perturb or modify the flow over low-rise buildings are proposed. The purpose of these devices is to reduce the adverse effects of wind over low-rise buildings and to mitigate the pressures on the roofs to lower vacuum levels. Pressure measurements were performed on a scaled down model of the well-known TTU experimental building of the Wind Engineering Research Facility (WERFL) at TTU University. Different results were obtained: reduction of average peek vacuum, smoothing of windward pressure distribution on the roof and narrowing and localizing of the suction pressure zones on the roof. Results that may be of interest to other disciplines such as heat transfer are also reported.

Enhanced Convective Heat Transfer in Nongas Generating Nanoparticle Thermites

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
S. W. Dean ◽  
M. L. Pantoya ◽  
A. E. Gash ◽  
S. C. Stacy ◽  
L. J. Hope-Weeks
Keyword(s):  
Heat Transfer ◽  
Flame Propagation ◽  
High Velocity ◽  
Thermal Equilibrium ◽  
Peak Pressure ◽  
Oxidation Mechanism ◽  
Pressure Measurements ◽  
Gas Generation ◽  
Peak Pressures ◽  
Shell Fragments

Flame propagation and peak pressure measurements were taken of two nanoscaled thermites using aluminum (Al) fuel and copper oxide (CuO) or nickel oxide (NiO) oxidizers in a confined flame tube apparatus. Thermal equilibrium simulations predict that the Al+CuO reaction exhibits high gas generation and, thus, high convective flame propagation rates while the Al+NiO reaction produces little to no gas and, therefore, should exhibit much lower flame propagation rates. Results show flame propagation rates ranged between 200 m/s and 600 m/s and peak pressures ranged between 1.7 MPa and 3.7 MPa for both composites. These results were significantly higher than expected for the Al+NiO, which generates virtually no gas. For nanometric Al particles, oxidation has recently been described by a melt-dispersion oxidation mechanism that involves a dispersion of high velocity alumina shell fragments and molten Al droplets that promote a pressure build-up by inducing a bulk movement of fluid. This mechanism unique to nanoparticle reaction may promote convection without the need for additional gas generation.

Friction of outer rotor affecting friction torque characteristics in an internal gear pump

2014 ◽  
Vol 229 (16) ◽  
pp. 3013-3026 ◽  
Author(s):  
Yoshiharu Inaguma
Keyword(s):  
Pressure Distribution ◽  
Friction Force ◽  
Significant Loss ◽  
Friction Torque ◽  
The Body ◽  
Gear Pump ◽  
Suction Pressure ◽  
Outer Rotor ◽  
Internal Gear ◽  
Outer Circumference

This article presents the friction torque in an internal gear pump and the friction force between an outer circumference of an outer rotor and a body, which causes a significant loss, has been investigated. When in use at a high pressure, the pump has a large friction torque due to the friction force acting on the outer rotor circumference. This friction force is caused by imbalanced force acting on the outer rotor. As well as by a positioning suction and a delivery port, the force can be reduced by setting a suction pressure recess in a section of the outer rotor circumference. In this study, through the measurement of the friction torque in an actual pump and the pressure distribution on the outer circumference of the outer rotor, it is investigated how the suction pressure recess can change the force acting on the outer rotor. The actual internal gear pump without the suction pressure recess has a large friction torque, and it corresponds to a large force on the outer rotor, which is calculated from the pressure distributions on the inside and outside of the outer rotor. In addition, on the basis of the measured friction torque of the test pump and the force acting on the outer rotor, calculated using the results of the pressure distribution, the coefficient of friction between the outer rotor circumference and the body can be estimated.

Foot Function in Patients With Surgically Treated Preaxial Polydactyly of the Foot Compared With Age- and Sex-Matched Healthy Controls

2018 ◽  
Vol 40 (4) ◽  
pp. 414-421
Author(s):  
Elise B. Burger ◽  
Shaktie A. Lalé ◽  
Steven E. R. Hovius ◽  
Christianne A. van Nieuwenhoven ◽  
Sicco A. Bus
Keyword(s):  
Pressure Distribution ◽  
Plantar Pressure ◽  
Healthy Controls ◽  
Level Of Evidence ◽  
Cross Sectional ◽  
Aesthetic Appearance ◽  
Patient Reported ◽  
Foot Function ◽  
Peak Pressures ◽  
Age And Sex

Background: Treatment of preaxial foot polydactyly, a duplication of the first ray, consists of excision of an extra ray, aiming to improve shoe fitting and aesthetic appearance, while maintaining foot function. Currently, the effect of excision on foot function and foot-related patient experiences is unclear. Methods: A cross-sectional comparison between 37 children treated for preaxial foot polydactyly and 37 age- and sex-matched healthy controls was performed. Dynamic foot function was assessed using plantar pressure measurements and static foot characteristics by physical examination. Patient-reported outcomes for foot function and footwear were evaluated, using the Oxford Ankle Foot Questionnaire for Children (score, 0-100). Results: Compared with controls, patients had significantly lower median peak pressures at the hallux (148 kPa [IQR, 98-245] vs 272 kPa [IQR, 205-381], P < .001) and significantly higher peak pressures at the second metatarsal (217 kPa [IQR, 147-338] vs 166 kPa [IQR, 141-235], P = .002) and third to fifth metatarsals (214 kPa [IQR, 147-290] vs 161 kPa [IQR, 135-235], P < .001). Additionally, patients had a more medially deviated hallux, both while seated (15 degrees (IQR, 11-20) vs 12 degrees [IQR, 10-15], P = .001) and standing (20 degrees [IQR, 15-26] vs 18 degrees [IQR, 15-20], P = .001). No significant correlation between peak pressure distribution and hallux deviation was found. Patients reported minimal problems with foot function (87.5 [IQR, 64.6-100]), but distinct problems with footwear use (50.0 [IQR, 25.0-100]). Conclusion: Patients with surgically treated preaxial foot polydactyly had a substantially altered plantar pressure distribution with more lateral foot progression than healthy controls. Although an increased hallux deviation was not related to altered foot function, it seemed to be the reason for the patient-perceived problems with footwear. Level of Evidence: Level III, comparative series.

Heat Transfer and Pressure Distribution in Open Cavity Flow

1967 ◽  
Vol 89 (1) ◽  
pp. 103-108 ◽  
Author(s):  
A. F. Emery ◽  
J. A. Sadunas ◽  
M. Loll
Keyword(s):  
Heat Transfer ◽  
Pressure Distribution ◽  
Flat Plate ◽  
Cavity Flow ◽  
Rectangular Cavity ◽  
Open Cavity ◽  
Transfer Coefficients ◽  
Transient Techniques ◽  
Heat Transfer Coefficients ◽  
Mach 3

The heat transfer and pressure distribution in a rectangular cavity in a Mach 3 flow were investigated for a rectangular and an inverted-wedge recompression step. Noticeable differences between the results for the two steps were found in the recovery factors, but no real differences were detected in the heat-transfer coefficients or the velocity profiles. Heat-transfer coefficients in the cavity were determined by transient techniques and were found to range from 50 to 110 percent of the flat-plate value just prior to the expansion step.

HP Vane Aerodynamics and Heat Transfer in the Presence of Aggressive Inlet Swirl

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Imran Qureshi ◽  
Andy D. Smith ◽  
Thomas Povey
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Three Dimensional ◽  
Leading Edge ◽  
Good Deal ◽  
Vortex Center ◽  
Research Facility ◽  
Lean Burn ◽  
Numerical Predictions ◽  
The Impact

Modern lean burn combustors now employ aggressive swirlers to enhance fuel-air mixing and improve flame stability. The flow at combustor exit can therefore have high residual swirl. A good deal of research concerning the flow within the combustor is available in open literature. The impact of swirl on the aerodynamic and heat transfer characteristics of an HP turbine stage is not well understood, however. A combustor swirl simulator has been designed and commissioned in the Oxford Turbine Research Facility (OTRF), previously located at QinetiQ, Farnborough UK. The swirl simulator is capable of generating an engine-representative combustor exit swirl pattern. At the turbine inlet plane, yaw and pitch angles of over ±40 deg have been simulated. The turbine research facility used for the study is an engine scale, short duration, rotating transonic turbine, in which the nondimensional parameters for aerodynamics and heat transfer are matched to engine conditions. The research turbine was the unshrouded MT1 design. By design, the center of the vortex from the swirl simulator can be clocked to any circumferential position with respect to HP vane, and the vortex-to-vane count ratio is 1:2. For the current investigation, the clocking position was such that the vortex center was aligned with the vane leading edge (every second vane). Both the aligned vane and the adjacent vane were characterized. This paper presents measurements of HP vane surface and end wall heat transfer for the two vane positions. The results are compared with measurements conducted without swirl. The vane surface pressure distributions are also presented. The experimental measurements are compared with full-stage three-dimensional unsteady numerical predictions obtained using the Rolls Royce in-house code Hydra. The aerodynamic and heat transfer characterization presented in this paper is the first of its kind, and it is hoped to give some insight into the significant changes in the vane flow and heat transfer that occur in the current generation of low NOx combustors. The findings not only have implications for the vane aerodynamic design, but also for the cooling system design.

The Use of Thermography in Verification Tests of a Prototype Calorimeter Chamber

2014 ◽  
Vol 223 ◽  
pp. 238-245
Author(s):  
Tomasz Samborski ◽  
Andrzej Zbrowski
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Adverse Effects ◽  
Knowledge Base ◽  
Outer Surface ◽  
Thermal Conditions ◽  
Test Stand ◽  
Potential Threat ◽  
Proper Functioning ◽  
Control Methodology

The article discusses the use of thermography in verification tests of a prototype calorimeter chamber constituting a part of a test stand for actuators used in smoke and ventilation systems. Based on the prototype control methodology developed at the ITeE – PIB, the authors identified areas posing a potential threat to the proper functioning of the system. The measurements of the temperature distribution on the outer surface of the chamber in the identified areas (trouble spots) are shown. The measurements were taken in thermal conditions related to tests conducted in compliance with the procedures of normative environmental investigations. The article also discusses the scope of activities that need to be taken in order to eliminate the adverse effects of heat transfer (thermal bridges, welds, etc.). Based on the thermographic tests, the authors proposed some guidelines to be included in the knowledge base used in the design of similar systems.

Measurement of Seat Pressure Distributions

1987 ◽  
Vol 29 (5) ◽  
pp. 563-575 ◽  
Author(s):  
Delia Treaster ◽  
W. S. Marras
Keyword(s):  
Pressure Distribution ◽  
Video Signals ◽  
Optical Reflection ◽  
Pressure Distributions ◽  
Experimental Apparatus ◽  
Image Digitization ◽  
Novel Method ◽  
Measurement And Evaluation ◽  
Peak Pressures ◽  
Chair Design

Knowledge of seating pressures is important for proper chair design. This study demonstrates the usefulness of a new methodology for measuring pressure distributions. It refines and advances an optical-reflection technique introduced several years ago. In this way precise quantitative measures of the pressure distribution can be obtained. Video image digitization, which converts analog video signals to digital ones, provided data in a form that could be easily submitted for computer analysis. Additionally, a novel method of analysis is presented that allows for the measurement and evaluation of the distribution of seated pressures, rather than peak pressures alone. A preliminary experiment with eight subjects was conducted to demonstrate the validity of the experimental apparatus and the data treatment.

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