Download or read book Experimental Study and Numerical Modeling of Gas Flow in Microchannels and Micronozzles written by and published by . This book was released on 2005 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the course of this research effort gas flows in microchannels and micronozzles were studied both experimentally and numerically. For the experimental study a flow visualization system was built and used to Study gas flows in microscale. Gas velocity measurements in microscope were conducted using both Laser Induced Fluorescence technique in conjunction with Image Correlation Velocimetry and Molecular Tagging Velocimetry technique. For the numerical study three different approaches were utilized. Continuum computational fluid dynamics was first used to study gas flows in microchannels and micronozzles. For micronozzles, effects of geometrical scaling down and different gas propellants were studied. For microchannels, slip versus no-slip boundary condition and compressibility and rarefaction effects were studied. Secondly, Direct simulation Monte Carlo (DSMC) method was used to study low Reynolds number flows in a conical micronozzle. The DSMC simulations were compared with the continuum model and available experimental data, and also used to study propellant gas temperature effect on the generated thrust Thirdly, a Unified Flow Solver that utilizes hybrid approach using deterministic Boltzmann solver for highly non-equilibrium flows at high Knudsen number and continuum solvers for low Knudsen numbers was tested and demonstrated for gas flows in microscale. Tested cases included gas flows in both microchannels and micronozzles.

Download or read book Numerical Modeling of Gas Flows in Micronozzles written by Omer San and published by . This book was released on 2007 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Study and Numerical Simulation of Periodic Bubble Formation at Submerged Micron sized Nozzles with Constant Gas Flow Rate written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Modeling and Experimental Investigation of Gas liquid Slug Formation in a Microchannel T junction written by Rafael Mattos dos Santos and published by . This book was released on 2007 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gas-liquid two-phase flow in a microfluidic T-junction with nearly square microchannels of 113 mum hydraulic diameter was investigated experimentally and numerically. Air and water superficial velocities were 0.018-0.791 m/s and 0.042-0.757 m/s, respectively. Three-dimensional modeling was performed with computational fluid dynamics (CFD) package FLUENT and the volume-of-fluid (VOF) model. 3D modeling resolved surface tension effects more accurately than 2D simulation. Slug flow (snapping/breaking/jetting) and stratified flow were observed experimentally. From numerical results void fraction followed a linear relationship with the homogeneous void fraction; two-phase frictional pressure drop fitted the Lockhart-Martinelli correlation with a Chisholm constant of 5; and the contact angle value affected the shape and size of gas slugs and determined the occurrence of liquid film and corner flow. Correlations were developed for prediction of flow parameters. Higher experimental velocity slip caused by gas inlet pressure build-up can result in deviation from numerical predictions.

Download or read book Gas Flows in Microsystems written by Lucien Baldas and published by MDPI. This book was released on 2019-10-28 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last two decades have witnessed a rapid development of microelectromechanical systems (MEMS) involving gas microflows in various technical fields. Gas microflows can, for example, be observed in microheat exchangers designed for chemical applications or for cooling of electronic components, in fluidic microactuators developed for active flow control purposes, in micronozzles used for the micropropulsion of nano and picosats, in microgas chromatographs, analyzers or separators, in vacuum generators and in Knudsen micropumps, as well as in some organs-on-a-chip, such as artificial lungs. These flows are rarefied due to the small MEMS dimensions, and the rarefaction can be increased by low-pressure conditions. The flows relate to the slip flow, transition or free molecular regimes and can involve monatomic or polyatomic gases and gas mixtures. Hydrodynamics and heat and mass transfer are strongly impacted by rarefaction effects, and temperature-driven microflows offer new opportunities for designing original MEMS for gas pumping or separation. Accordingly, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on novel theoretical and numerical models or data, as well as on new experimental results and technics, for improving knowledge on heat and mass transfer in gas microflows. Papers dealing with the development of original gas MEMS are also welcome.

Download or read book Experimental and Numerical Modeling of Rarefied Gas Flows Through Orifices and Short Tubes written by and published by . This book was released on 2005 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow through circular orifices with thickness-to-diameter ratios varying from 0.015 to 1.2 is studied experimentally and numerically with kinetic and continuum approaches. Helium and nitrogen gases are used in the range of Reynolds numbers from 0.02 to over 700. Good agreement between experimental and numerical results is observed for mass flow and thrust corrected for the experimental facility background pressure. For thick-to-thin orifice ratios of mass flow and thrust vs pressure, a minimum is established. The thick orifice propulsion efficiency is much higher than that of a thin orifice. The effects of edge roundness and surface specularity on a thick orifice specific impulse were found to be relatively small.

Download or read book Microscale and Nanoscale Heat Transfer written by Mourad Rebay and published by CRC Press. This book was released on 2016-01-06 with total page 499 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microscale and Nanoscale Heat Transfer: Analysis, Design, and Applications features contributions from prominent researchers in the field of micro- and nanoscale heat transfer and associated technologies and offers a complete understanding of thermal transport in nano-materials and devices. Nanofluids can be used as working fluids in thermal system

Download or read book Gas Flow and Heat Transfer in Microchannels written by Stephen Edward Turner and published by . This book was released on 2003 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Nanotechnology Research and Application 2012 Edition written by and published by ScholarlyEditions. This book was released on 2012-12-26 with total page 14170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Nanotechnology Research and Application / 2012 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Nanotechnology. The editors have built Advances in Nanotechnology Research and Application / 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Nanotechnology in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Advances in Nanotechnology Research and Application / 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book A THEORETICAL AND EXPERIMENTAL STUDY OF GAS FLOW THROUGH CLOTH OVER A RANGE OF PRESSURES AND TEMPERATURES written by FREDERICK O. SMETANA and published by . This book was released on 1962 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation and Experimental Verification of Gas Flow Through Packed Beds written by Shankar Natarajan and published by . This book was released on 2003 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical and Experimental Analysis of Flows Generated by Temperature Fields in Rarefied Gas written by Jie Chen and published by . This book was released on 2016 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a numerical and experimental analysis of internal rarefied gas flows induced by temperature fields. In rarefied gases, a flow can be generated by solely applying a tangential temperature gradient along a wall: without any initial pressure gradient, the gas macroscopically moves from the cold toward the hot region. This phenomenon is the so-called thermal creep or thermal transpiration effect. It is the main operating principle of the Knudsen pump, which can generate gas pumping without the need of any moving parts. The main aspect of this work is centered on numerical investigations of thermal transpiration flows in three new possible configurations of Knudsen pumps. For that goal, a numerical model for slip flows has been developed in which the appropriate slip boundary conditions are implemented in a commercial CFD code and a DSMC code has been adapted for studying transition flows in complex geometries. The pumping effect of curved-channel Knudsen pumps, the thermal transpiration flows through tapered channels and between two ratchets surfaces at different uniform temperatures have been investigated. In addition, an experimental study of thermal transpiration flow through a single micro-tube has been carried out on a new experimental set-up designed to be adaptable for testing thermally driven flows through various kinds of microchannels or generated by autonomous Knudsen compressors.

Download or read book Numerical Simulation of Low speed Gas Flows in Microchannels written by C. Chung and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Information Preservation Methods for Modeling Micro scale Gas Flows written by Quanhua Sun and published by . This book was released on 2003 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Study of Gas Flow in a Curved Channel written by V. B. Panfilovich and published by . This book was released on 1974 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation and Experimental Analysis of Gas Solid Flow Systems written by Hamid Arastoopour and published by . This book was released on 1999 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Analytical Numerical Model for Two Phase Slug Flow Through a Sudden Area Change in Microchannels written by and published by . This book was released on 2016 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this article, two new analytical models have been developed to calculate two-phase slug flow pressure drop in microchannels through a sudden contraction. Even though many studies have been reported on two-phase flow in microchannels, considerable discrepancies still exist, mainly due to the difficulties in experimental setup and measurements. Numerical simulations were performed to support the new analytical models and to explore in more detail the physics of the flow in microchannels with a sudden contraction. Both analytical and numerical results were compared to the available experimental data and other empirical correlations. Results show that models, which were developed based on the slug and semi-slug assumptions, agree well with experiments in microchannels. Moreover, in contrast to the previous empirical correlations which were tuned for a specific geometry, the new analytical models are capable of taking geometrical parameters as well as flow conditions into account.