Flow and Temperature Profile Independence of Flow Measurements Using Long Acoustic Waves

1984 ◽  
Vol 106 (1) ◽  
pp. 18-20 ◽  
Author(s):  
Baldwin Robertson
Keyword(s):  
Temperature Profile ◽  
Acoustic Waves ◽  
Sound Speed ◽  
Cutoff Frequency ◽  
Longitudinal Component ◽  
Wave Number ◽  
Cross Sectional ◽  
Flow Measurements ◽  
Local Sound ◽  
Sectional Shape

An expansion in powers of V/c is derived for the wave number of the fundamental sound mode in a flow conduit, where V is the velocity of fluid in the conduit and c is the local sound speed. Both V and c are assumed to be independent of the longitudinal coordinates and of the time, but may have arbitrary profiles. The calculation applies to frequencies well below the cutoff frequency of the conduit, which may have an arbitrary cross-sectional shape. To lowest order, the wave number depends only on the average of the longitudinal component of V and is independent of its profile.

Pressure Waves in Horizontal Liquid-Filled Flexible Tubes

1965 ◽  
Vol 7 (4) ◽  
pp. 380-390 ◽  
Author(s):  
M. P. Paidoussis
Keyword(s):  
Wave Velocity ◽  
High Pressures ◽  
Long Waves ◽  
Circular Cylinders ◽  
Wave Number ◽  
Cross Sectional ◽  
Propagation Of Waves ◽  
Sectional Shape ◽  
Internal Pressures ◽  
Flexible Tubes

This paper deals with the velocity of propagation of waves in flexible liquid-filled tubes lying on a flat horizontal surface. The tubes considered are of sufficiently small rigidity that their cross-sectional shape is determined by the internal hydrostatic pressure, lying quite flat when empty. It is shown that at low internal pressures very long waves propagate essentially as gravity waves in a canal. The wave velocity increases with the internal pressure and, at the same time, is increasingly affected by the extensibility of the tube wall. At very high pressures, long waves propagate essentially as axisymmetric waves in distensible circular cylinders. The calculated and measured velocities of propagation of very long waves are in substantial agreement. The system is frequency dispersive and the wave velocity rapidly increases with the wave number. An approximate analysis is presented, applying only when the tube contains little liquid, establishing the mechanism underlying this behaviour. This is qualitatively supported by experimental observations.

On the cross-sectional shape of the cellulose crystallites in the tunicate Halocynthia papillosa

1990 ◽  
Vol 48 (3) ◽  
pp. 566-567
Author(s):  
J.-F. Revol ◽  
Y. Van Daele ◽  
F. Gaill
Keyword(s):  
Contrast Imaging ◽  
Animal Kingdom ◽  
Bright Field ◽  
Field Mode ◽  
Cross Sectional ◽  
Ultrathin Sections ◽  
The Cross ◽  
Sectional Shape ◽  
Valonia Ventricosa ◽  
C Nmr

The only form of cellulose which could unequivocally be ascribed to the animal kingdom is the tunicin that occurs in the tests of the tunicates. Recently, high-resolution solid-state l3C NMR revealed that tunicin belongs to the Iβ form of cellulose as opposed to the Iα form found in Valonia and bacterial celluloses. The high perfection of the tunicin crystallites led us to study its crosssectional shape and to compare it with the shape of those in Valonia ventricosa (V.v.), the goal being to relate the cross-section of cellulose crystallites with the two allomorphs Iα and Iβ.In the present work the source of tunicin was the test of the ascidian Halocvnthia papillosa (H.p.). Diffraction contrast imaging in the bright field mode was applied on ultrathin sections of the V.v. cell wall and H.p. test with cellulose crystallites perpendicular to the plane of the sections. The electron microscope, a Philips 400T, was operated at 120 kV in a low intensity beam condition.

Automated 3D measurement of fiber cross section morphology in handsheets

2012 ◽  
Vol 27 (2) ◽  
pp. 264-269 ◽  
Author(s):  
Christian Lorbach ◽  
Ulrich Hirn ◽  
Johannes Kritzinger ◽  
Wolfgang Bauer
Keyword(s):  
Image Analysis ◽  
Cross Section ◽  
Cross Sections ◽  
Image Plane ◽  
3D Measurement ◽  
Cross Sectional ◽  
Fiber Cross Section ◽  
Fiber Wall ◽  
Sectional Shape ◽  
Cross Section Geometry

Abstract We present a method for 3D measurement of fiber cross sectional morphology from handsheets. An automated procedure is used to acquire 3D datasets of fiber cross sectional images using an automated microtome and light microscopy. The fiber cross section geometry is extracted using digital image analysis. Simple sample preparation and highly automated image acquisition and image analysis are providing an efficient tool to analyze large samples. It is demonstrated that if fibers are tilted towards the image plane the images of fiber cross sections are always larger than the true fiber cross section geometry. In our analysis the tilting angles of the fibers to the image plane are measured. The resulting fiber cross sectional images are distorted to compensate the error due to fiber tilt, restoring the true fiber cross sectional shape. We use an approximated correction, the paper provides error estimates of the approximation. Measurement results for fiber wall thickness, fiber coarseness and fiber collapse are presented for one hardwood and one softwood pulp.

Study of Correctly Expanded Sonic Jet with Air Tabs

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Arun Prasad R ◽  
Thanigaiarasu S ◽  
Sembaruthi M ◽  
Rathakrishnan E
Keyword(s):  
Numerical Study ◽  
Cross Sectional ◽  
Potential Core ◽  
Convergent Nozzle ◽  
Jet Mixing ◽  
Pressure Profiles ◽  
Constant Diameter ◽  
Sonic Jet ◽  
Sectional Shape ◽  
Length Reduction

AbstractThe present numerical study is to understand the effect of air tabs located at the exit of a convergent nozzle on the spreading and mixing characteristics of correctly expanded sonic primary jet. Air tabs used in this study are two secondary jets issuing from constant diameter tubes located diametrically opposite at the periphery of the primary nozzle exit, normal to the primary jet. Two air tabs of Mach numbers 1.0 to 1.4, in steps of 0.1 are considered in this study. The mixing modification caused by air tabs are analysed by considering the mixing of uncontrolled (free) primary jet as a reference. Substantial enhancement in jet mixing is achieved with Mach 1.4 air tabs, which results in 80 % potential core length reduction. The total pressure profiles taken on the plane (YZ) normal to the primary jet axis, at various locations along the primary jet centreline revealed the modification of the jet cross sectional shape by air tabs. The stream-wise vortices and bifurcation of the primary jet caused by air tabs are found to be the mechanism behind the enhanced jet mixing.

Experimental investigation and optimization on field shaper structure parameters in magnetic pulse welding

2021 ◽  
pp. 095440542110148
Author(s):  
Yingzi Chen ◽  
Zhiyuan Yang ◽  
Wenxiong Peng ◽  
Huaiqing Zhang
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
Light Metal ◽  
Magnetic Pulse ◽  
Cross Sectional ◽  
Magnetic Pulse Welding ◽  
Pulse Welding ◽  
Sectional Shape ◽  
Welding System ◽  
The Magnetic Field

Magnetic pulse welding is a high-speed welding technology, which is suitable for welding light metal materials. In the magnetic pulse welding system, the field shaper can increase the service life of the coil and contribute to concentrating the magnetic field in the welding area. Therefore, optimizing the structure of the field shaper can effectively improve the efficiency of the system. This paper analyzed the influence of cross-sectional shape and inner angle of the field shaper on the ability of concentrating magnetic field via COMSOL software. The structural strength of various field shapers was also analyzed in ABAQUS. Simulation results show that the inner edge of the field shaper directly affects the deformation and welding effect of the tube. So, a new shape of field shaper was proposed and the experimental results prove that the new field shaper has better performance than the conventional field shaper.

Blast Wave Shaping by Altering Cross‐Sectional Shape

2021 ◽  
Author(s):  
Kelly Williams ◽  
Martin J. Langenderfer ◽  
Gayla Olbricht ◽  
Catherine E. Johnson
Keyword(s):  
Blast Wave ◽  
Cross Sectional ◽  
Sectional Shape

Numerical simulation of strain rate effect on the inelastic behavior of metal matrix composites

2017 ◽  
Vol 24 (2) ◽  
pp. 279-288
Author(s):  
Qiang Chen ◽  
Zhi Zhai ◽  
Xiaojun Zhu ◽  
Caibin Xu ◽  
Xuefeng Chen
Keyword(s):  
Strain Rate ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Plastic Region ◽  
Micromechanical Model ◽  
Matrix Composites ◽  
Cross Sectional ◽  
Axis Orientation ◽  
Array Pattern ◽  
Sectional Shape

AbstractThe primary goal of this paper is to investigate the combined effects of strain rate and microscopic parameters (fiber off-axis orientation, array pattern and cross-sectional shape) on the mechanical behavior of metal matrix composites (MMCs). To this end, a rate-dependent micromechanical model by the combination of finite-volume theory and Bodner-Partom viscoplastic model is developed to analyze the inelastic response of MMCs. In the simulations, the fibers are modeled as linearly elastic while the metal matrix exhibits viscoplasticity. The macroscopic stress-strain response, local stress and strain fields are obtained simultaneously. An acceptable agreement has been found between the model’s prediction and finite-element results, which demonstrates the good predictive capabilities of the proposed method. It is concluded that the composite response is strongly affected by strain rate, fiber array pattern and cross-sectional shape in the elastic-plastic region but to a lesser extent in the elastic region. Furthermore, the clustering array provides stiffer response than random and square ones; the square fiber predicts stiffer response than circular and elliptical ones. However, increasing the strain rate will weaken the influence of clustering array and square fibers.

Numerical Modeling and Experimental Studies of the Operational Parameters of the Earth-To-Air Heat Exchanger of the Geothermal Ventilation System

2021 ◽  
Vol 23 ◽  
pp. 42-64
Author(s):  
Boris Basok ◽  
Ihor Bozhko ◽  
Maryna Novitska ◽  
Aleksandr Nedbailo ◽  
Myroslav Tkachenko
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Ventilation System ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Operational Parameters ◽  
Cross Sectional ◽  
Distinctive Features ◽  
Sectional Shape ◽  
Experimental Bench

This article is devoted to the analysis of the heat engineering characteristics of the operation of an Earth-to-Air Heat Exchanger, EAHE, with a circular cross-sectional shape, which is a component of the geothermal ventilation system. The authors analyzed literature sources devoted to the research of heat exchangers of the soil-air type of various designs and for working conditions in various soils. Much attention is paid to the issues of modeling the operation of such heat exchangers and the distinctive features of each of these models. Also important are the results of experimental studies carried out on our own experimental bench and with the help of which the numerical model was validated. The results of these studies are the basis for the development of a method for determining the optimal diameter of an EAHE under operating conditions for soil in Kyiv, Ukraine.

Effect of Damping Constants and Stress Distribution on the Resonance Response of Members

1953 ◽  
Vol 20 (2) ◽  
pp. 201-209
Author(s):  
B. J. Lazan
Keyword(s):  
Stress Distribution ◽  
Amplification Factor ◽  
Engineering Practice ◽  
Distribution Factor ◽  
Mathematical Relationship ◽  
Cross Sectional ◽  
Resonance Response ◽  
Properties Of Materials ◽  
Material Factor ◽  
Sectional Shape

Abstract The amplitude of vibration of a member at resonance, as defined by its resonance amplification factor, is analyzed in relationship to the damping properties of materials. Data are presented on damping energy to indicate the effect of stress magnitude, stress history, and temperature. Based on the mathematical relationship found to exist between damping and stress magnitude the resonance amplification factors are determined for a variety of direct stress members and beams. It is shown that the amplification in vibration caused by resonance may be considered to be the product of three basic factors, i.e., (a) the material factor, (b) the cross-sectional shape factor, and (c) the longitudinal stress-distribution factor. The first of these factors may be calculated from the damping and dynamic modulus properties of the material and the last two from the shape and loading characteristics of the member. Diagrams are presented to show these basic factors as functions of the damping exponent and other variables for members commonly encountered in engineering practice. Experimental data are presented to confirm the equations derived for resonance amplification factor of members having various shapes and stress distribution.

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