The Experts below are selected from a list of 165 Experts worldwide ranked by ideXlab platform
Hacialiogullari M. - One of the best experts on this subject based on the ideXlab platform.
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Active control of flow around a square prism by slot jet injection
'EDP Sciences', 2013Co-Authors: Fira E., Akansu Y.e., Hacialiogullari M.Abstract:DANTEC DYNAMICS GmbH;KAMAX Holding;LENAM s.r.o.;MIT s.r.o.;SPECION s.r.o.7th International Conference on Experimental Fluid Mechanics 2012, EFM 2012 --20 November 2012 through 23 November 2012 -- Hradec Kralove --The main aim of the experimental study is to determine both the most effective injection surface and rate in order to ensure minimum drag and fluctuating forces on a square prism subjected to crossflow. All predetermined jet injection surfaces i.e. front, side, and rear, tested separately for injection ratios of IR = 0, 1, 1.5, 2 at Reynolds number of Re = 16,000. Surface pressures were measured by differential pressure transducer whereas instantaneous velocity measurements were performed by using multichannel Constant Temperature Anemometer (CTA). It was concluded that jet injection, especially from the rear surface, brought noticeable improvements to the flow characteristics of a square prism. For rear jet configuration with IR = 1.5, the mean drag coefficient ($\overline {{C-{{\rm{DT}}}}} $) was reduced to 79.4% and CP RMS level on side surfaces was reduced to 20% of that of the single square prism. In addition, instantaneous flow visualization photographs and Strouhal number (St) distribution across the injection ratio were also presented to identify the flow patterns and underlying mechanism of drag and fluctuating force reduction of square prism with rear jet configuration. © Owned by the authors, published by EDP Sciences, 2013
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Active control of flow around a square prism by slot jet injection
'EDP Sciences', 2013Co-Authors: Fira E., Akansu Y. E., Hacialiogullari M.Abstract:7th International Conference on Experimental Fluid Mechanics (EFM) -- NOV 20-23, 2012 -- Tech Univ Liberec (TU Liberec), Hradec Kralove, CZECH REPUBLICWOS: 000319932200029The main aim of the experimental study is to determine both the most effective injection surface and rate in order to ensure minimum drag and fluctuating forces on a square prism subjected to crossflow. All predetermined jet injection surfaces i.e. front, side, and rear, tested separately for injection ratios of IR = 0, 1, 1.5, 2 at Reynolds number of Re = 16,000. Surface pressures were measured by differential pressure transducer whereas instantaneous velocity measurements were performed by using multichannel Constant Temperature Anemometer (CTA). It was concluded that jet injection, especially from the rear surface, brought noticeable improvements to the flow characteristics of a square prism. For rear jet configuration with IR = 1.5, the mean drag coefficient ((C-DT) over bar) was reduced to 79.4% and C-P RMS level on side surfaces was reduced to 20% of that of the single square prism. In addition, instantaneous flow visualization photographs and Strouhal number (St) distribution across the injection ratio were also presented to identify the flow patterns and underlying mechanism of drag and fluctuating force reduction of square prism with rear jet configuration.Dantec Dynam GmbH, Kamax Holding, LENAM s r o, MIT s r o, SPECION s r oScientific and Technological Research Council of Turkey [105M241]The authors would like to acknowledge the financial supports of the Scientific and Technological Research Council of Turkey under the contract number of 105M24
Fira E. - One of the best experts on this subject based on the ideXlab platform.
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Active control of flow around a square prism by slot jet injection
'EDP Sciences', 2013Co-Authors: Fira E., Akansu Y.e., Hacialiogullari M.Abstract:DANTEC DYNAMICS GmbH;KAMAX Holding;LENAM s.r.o.;MIT s.r.o.;SPECION s.r.o.7th International Conference on Experimental Fluid Mechanics 2012, EFM 2012 --20 November 2012 through 23 November 2012 -- Hradec Kralove --The main aim of the experimental study is to determine both the most effective injection surface and rate in order to ensure minimum drag and fluctuating forces on a square prism subjected to crossflow. All predetermined jet injection surfaces i.e. front, side, and rear, tested separately for injection ratios of IR = 0, 1, 1.5, 2 at Reynolds number of Re = 16,000. Surface pressures were measured by differential pressure transducer whereas instantaneous velocity measurements were performed by using multichannel Constant Temperature Anemometer (CTA). It was concluded that jet injection, especially from the rear surface, brought noticeable improvements to the flow characteristics of a square prism. For rear jet configuration with IR = 1.5, the mean drag coefficient ($\overline {{C-{{\rm{DT}}}}} $) was reduced to 79.4% and CP RMS level on side surfaces was reduced to 20% of that of the single square prism. In addition, instantaneous flow visualization photographs and Strouhal number (St) distribution across the injection ratio were also presented to identify the flow patterns and underlying mechanism of drag and fluctuating force reduction of square prism with rear jet configuration. © Owned by the authors, published by EDP Sciences, 2013
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Active control of flow around a square prism by slot jet injection
'EDP Sciences', 2013Co-Authors: Fira E., Akansu Y. E., Hacialiogullari M.Abstract:7th International Conference on Experimental Fluid Mechanics (EFM) -- NOV 20-23, 2012 -- Tech Univ Liberec (TU Liberec), Hradec Kralove, CZECH REPUBLICWOS: 000319932200029The main aim of the experimental study is to determine both the most effective injection surface and rate in order to ensure minimum drag and fluctuating forces on a square prism subjected to crossflow. All predetermined jet injection surfaces i.e. front, side, and rear, tested separately for injection ratios of IR = 0, 1, 1.5, 2 at Reynolds number of Re = 16,000. Surface pressures were measured by differential pressure transducer whereas instantaneous velocity measurements were performed by using multichannel Constant Temperature Anemometer (CTA). It was concluded that jet injection, especially from the rear surface, brought noticeable improvements to the flow characteristics of a square prism. For rear jet configuration with IR = 1.5, the mean drag coefficient ((C-DT) over bar) was reduced to 79.4% and C-P RMS level on side surfaces was reduced to 20% of that of the single square prism. In addition, instantaneous flow visualization photographs and Strouhal number (St) distribution across the injection ratio were also presented to identify the flow patterns and underlying mechanism of drag and fluctuating force reduction of square prism with rear jet configuration.Dantec Dynam GmbH, Kamax Holding, LENAM s r o, MIT s r o, SPECION s r oScientific and Technological Research Council of Turkey [105M241]The authors would like to acknowledge the financial supports of the Scientific and Technological Research Council of Turkey under the contract number of 105M24
Jam Hans Kuipers - One of the best experts on this subject based on the ideXlab platform.
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a combined experimental and simulation study of fluid particle heat transfer in dense arrays of stationary particles
Chemical Engineering Science, 2017Co-Authors: Kay A Buist, B J G H Backx, N Niels G Deen, Jam Hans KuipersAbstract:A novel experimental technique is introduced to study fluid-particle heat transfer in dense arrays of stationary particle. First a Constant Temperature Anemometer is reconfigured to a heat transfer probe. The thermal driving force is defined as the difference between the probe Temperature and the initial fluid Temperature and well known in our system. Second an abacus-like structure is employed to accurately control the solids volume fraction. The solids fraction was varied between 0 and 0.6 with increments of 0.1. The Reynolds number varied between 0 and 800. This combination of approaches allows for a very well-defined system, that can be studied both experimentally and numerically, and as such can serve as a validation of heat transfer studies with Direct Numerical Simulations, in fluid-particle systems. A single particle in unbounded flow, the effect of inter-particle distance and shielding effects for an inline array of three spheres as well as semi-structured arrays of particles are studied.
John Foss - One of the best experts on this subject based on the ideXlab platform.
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transient thermal response of a hot wire Anemometer
Measurement Science and Technology, 2003Co-Authors: Scott C Morris, John FossAbstract:The ability of a thermal anemometry system to accurately measure unsteady fluid velocity depends on the electrical control system as well as the thermal properties of the sensor. The present work is a numerical study of the thermal transient response of a hot-wire. A conventional Constant Temperature Anemometer with an ideal feedback amplifier as well as a pulse width modulated system were used to model the electrical current supplied to the sensor to maintain a nominally Constant sensor resistance. The agreement between these two electrical models confirmed that the response characteristics are only due to thermal effects. The thermal response was tested by providing a known input function for the cooling velocity, and comparing this with the output of the model. The first test used a step input function. It was found that the thermal transient effects along the length of the sensor caused the system to initially under predict the actual velocity increase; this was followed by an exponential increase to the steady state velocity. Secondly, the model was tested with sinusoidal inputs over a wide frequency range. The ratio: indicated-velocity/input-velocity, as a function of the input frequency was used to characterize the 'thermal frequency response'.
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processing time series data velocity shear stress from the pulse width modulated Constant Temperature Anemometer pwm cta
International Congress on Instrumentation in Aerospace Simulation Facilities, 2001Co-Authors: John Foss, Theron HicksAbstract:The digital output from the PWM-CTA represents the short duration (e.g., 20/spl mu/sec) true time average of the analog velocity or shear stress. The developed techniques to extract the moments of the velocity (or shear stress) distribution and to create a regular time series are presented.
Martin Kirchhofer - One of the best experts on this subject based on the ideXlab platform.
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particle image velocimetry and Constant Temperature Anemometer measurements of the jet produced by a centrifugal fan
Physics of Fluids, 2021Co-Authors: Dominik Hofer, Michael Krieger, Martin KirchhoferAbstract:This article presents a detailed investigation of the three-dimensional flow field produced by a small centrifugal fan used for cooling of electronic components, for instance, in the automotive industry. A particle image velocimetry (PIV) system captured numerous cross sections of the fan jet for analysis of velocity distribution and jet development. General parameters, such as the spreading rate, and flow specifics, such as the full width at half maximum contours in planes parallel to the fan outlet and the jet's rotation rate, were thus evaluated. In addition, Constant Temperature anemometry enabled a thorough investigation of the flow field at the fan's outflow port. Hot-wire measurements complement the PIV results by providing the power spectral density of the turbulent kinetic energy at several locations. Our results demonstrate that the cross-flow profile at the fan outlet consists of two counter-rotating vortices. This leads to a jet with a nearly elliptical, rotating cross section, which does not propagate in a direction perpendicular to the outlet plane. Several aspects of these distinctive flow features are evaluated and presented to provide both fluid mechanics and heat transfer engineers with (i) data on the air jet produced by a small centrifugal fan and (ii) reference data for computational fluid dynamics simulations. Despite complex flow development in the near field of the jet and the nonaxisymmetric jet contour in the intermediate field, our results are in good agreement with published data on axisymmetric jets in terms of spreading rate and the development of turbulence spectra observed in the intermediate field.