An Investigation Into the Effect of Subcooled Liquid Inertia on Flowrate Induced Transient Flow Surges in Horizontal Condensing Flow Systems

2003 ◽  
Author(s):  
Chris J. Kobus
Keyword(s):  
Experimental Data ◽  
Large Scale ◽  
Transient Flow ◽  
Salient Feature ◽  
Analytical Tool ◽  
Predictive Capability ◽  
Subcooled Liquid ◽  
Flow Systems ◽  
Tube Type ◽  
Complete Condensation

The objective of this research is to investigate large-scale transient flow surges of condensate leaving horizontal in-tube condensing flow systems, due to perturbations in the inlet vapor flowrate, and the influence of the subcooled condensate inertia on these surges. In a tube-type condenser involving complete condensation, it has been seen that small changes in the inlet vapor flowrate momentarily cause large transient flow surges in the outlet liquid flowrate. A System Mean Void Fraction (SMVF) Model is developed for predicting these flow surge characteristics. Experimental data are also presented, showing both the influence of subcooled liquid inertia, and the very good predictive capability of the SMVF Model. The salient feature of the SMVF Model is its simplicity that, with an experimentally verified predictive capability, enhances the models’ utility as an analytical tool as well as a tool for educational purposes.

An Experimental and Theoretical Investigation Into Thermally Governed Transient Flow Surges in Two-Phase Condensing Flow

1977 ◽  
Vol 99 (4) ◽  
pp. 561-567 ◽  
Author(s):  
G. L. Wedekind ◽  
B. L. Bhatt
Keyword(s):  
Experimental Data ◽  
Transient Flow ◽  
Vapor Flow ◽  
Transient Phenomenon ◽  
Two Phase ◽  
Subcooled Liquid ◽  
Measured Flow ◽  
Tube Type ◽  
Complete Condensation ◽  
Small Change

The specific transient phenomenon under consideration is the outlet flowrate of subcooled liquid from a tube-type condenser where complete condensation takes place. Experimental data are presented which indicates that a small change in the inlet vapor flow-rate will momentarily cause a very large transient surge in the outlet flowrate of subcooled liquid. These experimentally measured flow transients are predicted quite accurately using a system mean void fraction model. Also, some preliminary results are presented which indicate the influence of throttling at the condenser outlet as a means of attenuating the transient overshoot characteristics.

An Investigation Into the Effect of Subcooled Liquid Inertia on Flow-Change-Induced Transient Flow Surges in Horizontal Condensing Flow Systems

2005 ◽  
Vol 127 (11) ◽  
pp. 1280-1284 ◽  
Author(s):  
C. J. Kobus
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Transient Flow ◽  
Phase Region ◽  
Complex Nature ◽  
Vapor Flow ◽  
Two Phase ◽  
Subcooled Liquid ◽  
Flow Systems ◽  
Final Steady State

The objective of this research is to investigate large-scale transient flow surges of the condensate leaving in-tube condensing flow systems because of perturbations in the inlet vapor flow rate, and the influence of the subcooled liquid inertia of the condensate on these transient responses. Small changes in the inlet vapor flow rate momentarily cause large transient flow surges in the outlet liquid flow rate. Condensate inertia is seen to destabilize the system into an underdamped behavior where the flow rate can overshoot the final steady-state position several times. A one-dimensional, two-fluid, distributed parameter system mean void fraction (SMVF) model of the time-dependent distribution of liquid and vapor within the two-phase region is developed for predicting these transient characteristics, which it is seen to do quite well, especially when consideration is given to the complex nature of the problem.

Modeling the Thermally Governed Transient Flow Surges in Multitube Condensing Flow Systems With Thermal and Flow Distribution Asymmetry

1989 ◽  
Vol 111 (3) ◽  
pp. 786-791 ◽  
Author(s):  
G. L. Wedekind ◽  
B. L. Bhatt
Keyword(s):  
Flow Rate ◽  
Transient Flow ◽  
Liquid Flow Rate ◽  
Flow Distribution ◽  
Vapor Flow ◽  
Tube Model ◽  
Condenser Tube ◽  
Tube System ◽  
Tube Type ◽  
Complete Condensation

In a tube-type condenser involving complete condensation, small changes in the inlet vapor flow rate momentarily cause very large transient surges in the outlet liquid flow rate. An equivalent single-tube model is proposed that predicts these transient flow surges for a multitube system. The model, based upon a system mean void fraction model developed earlier, includes the effects of thermal and flow distribution asymmetry associated with each individual condenser tube in the multitube system. Theoretical and experimental verification for a two-tube system is presented.

Transient and Frequency Response Characteristics of Two-Phase Condensing Flows: With and without Compressibility

1980 ◽  
Vol 102 (3) ◽  
pp. 495-500 ◽  
Author(s):  
B. L. Bhatt ◽  
G. L. Wedekind
Keyword(s):  
Experimental Data ◽  
Two Phase ◽  
Response Characteristics ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Condensing Flows ◽  
Flux Model ◽  
Tube Type ◽  
Complete Condensation ◽  
Compressibility Effects

In a tube-type condenser, involving complete condensation, small changes in the inlet vapor flowrate momentarily cause very large transient surges in the outlet liquid flowrate. Experimental data are presented which indicate that compressibility effects tend to attenuate the amplitude of these flow surges. The system mean void fraction model was extended to include compressibility effects and its predictions are shown to agree well with experimental data. The model is further extended to predict the response characteristics to an oscillatory inlet flowrate and compared with predictions based upon the drift-flux model.

Predicting the Effect of Tire Tread Pattern Design on Thick Film Wet Traction

1977 ◽  
Vol 5 (1) ◽  
pp. 6-28 ◽  
Author(s):  
A. L. Browne
Keyword(s):  
Experimental Data ◽  
Network Design ◽  
Thick Film ◽  
Digital Computer ◽  
Analytical Tool ◽  
Design Practice ◽  
Pattern Design ◽  
Performance Results ◽  
Good Agreement

Abstract An analytical tool is presented for the prediction of the effects of changes in tread pattern design on thick film wet traction performance. Results are reported for studies in which the analysis, implemented on a digital computer, was used to determine the effect of different tread geometry features, among these being the number, width, and lateral spacing of longitudinal grooves and the angle of zigzags in longitudinal grooves, on thick film wet traction. These results are shown to be in good agreement with experimental data appearing in the literature and are used to formulate guidelines for tread groove network design practice.

scholarly journals A study of computational methods for wake structure and base pressure prediction of a generic SUV model with fixed and rotating wheels

2017 ◽  
Vol 231 (9) ◽  
pp. 1222-1238 ◽  
Author(s):  
David Forbes ◽  
Gary Page ◽  
Martin Passmore ◽  
Adrian Gaylard
Keyword(s):  
Experimental Data ◽  
Computational Methods ◽  
Large Scale ◽  
Ground Plane ◽  
Computational Cost ◽  
Rear Wheel ◽  
Base Pressure ◽  
Detached Eddy Simulation ◽  
Wake Structure ◽  
Wake Interactions

This study is an evaluation of the computational methods in reproducing experimental data for a generic sports utility vehicle (SUV) geometry and an assessment on the influence of fixed and rotating wheels for this geometry. Initially, comparisons are made in the wake structure and base pressures between several CFD codes and experimental data. It was shown that steady-state RANS methods are unsuitable for this geometry due to a large scale unsteadiness in the wake caused by separation at the sharp trailing edge and rear wheel wake interactions. unsteady RANS (URANS) offered no improvements in wake prediction despite a significant increase in computational cost. The detached-eddy simulation (DES) and Lattice–Boltzmann methods showed the best agreement with the experimental results in both the wake structure and base pressure, with LBM running in approximately a fifth of the time for DES. The study then continues by analysing the influence of rotating wheels and a moving ground plane over a fixed wheel and ground plane arrangement. The introduction of wheel rotation and a moving ground was shown to increase the base pressure and reduce the drag acting on the vehicle when compared to the fixed case. However, when compared to the experimental standoff case, variations in drag and lift coefficients were minimal but misleading, as significant variations to the surface pressures were present.

Investigation on hydrodynamic forces leading to coarse particle entrainment using Large-Eddy Simulations

2021 ◽  
Author(s):  
Gaston Latessa ◽  
Angela Busse ◽  
Manousos Valyrakis
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Large Scale ◽  
Large Eddy Simulations ◽  
Flow Conditions ◽  
Mean Flow ◽  
Protection Measures ◽  
Practical Applications ◽  
Particle Entrainment ◽  
Large Eddy

<p>The prediction of particle motion in a fluid flow environment presents several challenges from the quantification of the forces exerted by the fluid onto the solids -normally with fluctuating behaviour due to turbulence- and the definition of the potential particle entrainment from these actions. An accurate description of these phenomena has many practical applications in local scour definition and to the design of protection measures.</p><p>In the present work, the actions of different flow conditions on sediment particles is investigated with the aim to translate these effects into particle entrainment identification through analytical solid dynamic equations.</p><p>Large Eddy Simulations (LES) are an increasingly practical tool that provide an accurate representation of both the mean flow field and the large-scale turbulent fluctuations. For the present case, the forces exerted by the flow are integrated over the surface of a stationary particle in the streamwise (drag) and vertical (lift) directions, together with the torques around the particle’s centre of mass. These forces are validated against experimental data under the same bed and flow conditions.</p><p>The forces are then compared against threshold values, obtained through theoretical equations of simple motions such as rolling without sliding. Thus, the frequency of entrainment is related to the different flow conditions in good agreement with results from experimental sediment entrainment research.</p><p>A thorough monitoring of the velocity flow field on several locations is carried out to determine the relationships between velocity time series at several locations around the particle and the forces acting on its surface. These results a relevant to determine ideal locations for flow investigation both in numerical and physical experiments.</p><p>Through numerical experiments, a large number of flow conditions were simulated obtaining a full set of actions over a fixed particle sitting on a smooth bed. These actions were translated into potential particle entrainment events and validated against experimental data. Future work will present the coupling of these LES models with Discrete Element Method (DEM) models to verify the entrainment phenomena entirely from a numerical perspective.</p>

Thermal Laser Separation – A Novel Dicing Technology Fulfilling the Demands of Volume Manufacturing of 4H-SiC Devices

2015 ◽  
Vol 821-823 ◽  
pp. 528-532 ◽  
Author(s):  
Dirk Lewke ◽  
Karl Otto Dohnke ◽  
Hans Ulrich Zühlke ◽  
Mercedes Cerezuela Barret ◽  
Martin Schellenberger ◽  
...  
Keyword(s):  
Experimental Data ◽  
Process Control ◽  
Tool Wear ◽  
Large Scale ◽  
State Of The Art ◽  
Scale Production ◽  
High Quality ◽  
Large Scale Production ◽  
Laser Separation

One challenge for volume manufacturing of 4H-SiC devices is the state-of-the-art wafer dicing technology – the mechanical blade dicing which suffers from high tool wear and low feed rates. In this paper we discuss Thermal Laser Separation (TLS) as a novel dicing technology for large scale production of SiC devices. We compare the latest TLS experimental data resulting from fully processed 4H-SiC wafers with results obtained by mechanical dicing technology. Especially typical product relevant features like process control monitoring (PCM) structures and backside metallization, quality of diced SiC-devices as well as productivity are considered. It could be shown that with feed rates up to two orders of magnitude higher than state-of-the-art, no tool wear and high quality of diced chips, TLS has a very promising potential to fulfill the demands of volume manufacturing of 4H-SiC devices.

scholarly journals Understanding the physical properties that control protein crystallization by analysis of large-scale experimental data

2008 ◽  
Vol 27 (1) ◽  
pp. 51-57 ◽  
Author(s):  
W Nicholson Price II ◽  
Yang Chen ◽  
Samuel K Handelman ◽  
Helen Neely ◽  
Philip Manor ◽  
...  
Keyword(s):  
Experimental Data ◽  
Physical Properties ◽  
Large Scale ◽  
Protein Crystallization ◽  
Control Protein
Sign in / Sign up

Export Citation Format

Share Document