High Order Bubble Dynamics in Incompressible Liquid

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Vasilii Sharipov
Keyword(s):  
Bubble Dynamics ◽  
Pressure Change ◽  
Analytical Approximation ◽  
Industrial Applications ◽  
Oxygen Mixture ◽  
Liquid Temperature ◽  
Computationally Efficient ◽  
Liquid Pressure ◽  
Computer Codes ◽  
Fourier Equation

A semi-analytical approximation to the solution of the radial Fourier equation describing liquid temperature dynamics in the vicinity of a spherical bubble is presented. This approximation opens a possibility to construct a computationally efficient bubble model that is flexible enough to simulate different bubble dynamics behavior like bubble growth, collapse, and oscillations. In turn, it allows development of two-pressure computer codes aiming at simulation of processes in liquid with bubbles that are important for industrial applications. The model is based on the system of ordinary differential equations (ODEs) and is presented together with results of simulations and comparison with some available experimental data. Additionally, scenarios like strong bubble parameter oscillations in largely subcooled water and abrupt liquid pressure change are considered. As respective simulations show, the latter may lead to subsequent hydrogen explosion if hydrogen–oxygen mixture is presented in the bubble. This may be important for boiling water reactor piping safety analysis.

A Novel Way of Manipulating and Optimizing CAM Profiles for Internal Combustion Engines

2007 ◽  
Author(s):  
Satheesh Makkapati ◽  
Kim Ku ◽  
Steve Poe
Keyword(s):  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Computationally Efficient ◽  
Trade Offs ◽  
Cam Profile ◽  
Computer Codes ◽  
Tool Optimization ◽  
Automated Tool

Generating an optimum cam profile for an internal combustion engine application is usually a very involved process. This is because of the challenge faced by the engine engineers to perform several trade-offs between fuel economy, performance, durability and emissions. Typically, the trade offs are worked out using several computer codes and with the involvement of a cross-functional team of engineers. Hence, there is a need to develop a tool that can encapsulate the various computer codes and can manipulate the cam profile with ease. With the existence of such an automated tool, optimization of the cam profile can be achieved with a specified trade-off between the several metrics identified above. This paper describes the development of such a tool, and discusses the ingredients that make it flexible and computationally efficient. Results from the use of this tool are documented in this paper as well.

Numerical Study of the Gas-Steam Transient Behavior in the Integrated Pressurizer

2013 ◽  
Author(s):  
Lei Wu ◽  
Haijun Jia ◽  
Yang Liu
Keyword(s):  
Numerical Study ◽  
Natural Circulation ◽  
Transient Behavior ◽  
Pressure Change ◽  
Liquid Volume ◽  
Liquid Temperature ◽  
Analysis Model ◽  
Transient Characteristics ◽  
New Energy ◽  
Relap5 Code

The integrated gas-steam pressurizer stabilizes the pressure by compressing the gas and steam mixture. It has attracted much attention because of its simple structure, eliminating heating and spraying of equipment, and preventing the liquid boiling. The NHR series developed by Institute of Nuclear and New Energy Technology in Tsinghua University uses the integrated gas-steam pressurizer. The major loop thermal parameters in NHR series increased progressively, which made it suitable for heating, industrial steam supply and seawater desalinization. In order to ensure the safety of the NHR series major loop system and guarantee the natural circulation capability of the system under high temperature and pressure, the researches on the gas-steam transient characteristics of the integrated gas-steam pressurizer is needed. This paper is mainly about study on transient characteristics of the gas-steam typed pressurizer using the Relap5 code. The classic experiment on the pressure behavior of gas-steam pressurizer during the in-surge performed at MIT is considered as reference objects, and the analysis model is established by using Relap5 code. By comparing the computing results with the MIT experiment data about pressure-time, the applicability of Relap5 code for forecasting the transient behavior of the gas-steam (nitrogen) pressurizer has been verified. The results show that Relap5 code can effectively track the transient behavior of the pressure in the gas-steam pressurizer. In addition, the transient characteristics of the integrated gas-steam pressurizer in the NHR series have been studied. It is founded that the pressure and the liquid temperature adjoining to the pressurizer lag behind the power change in natural circulation loop with integrated gas-steam pressurizer, and the liquid temperature adjoining to the pressurizer and the liquid volume under the pressurizer are the main factors determining the pressure change.

Volumetric view planning for 3D reconstruction with multiple manipulators

2015 ◽  
Vol 42 (6) ◽  
pp. 533-543 ◽  
Author(s):  
Liangzhi Li ◽  
Nanfeng Xiao
Keyword(s):  
Three Dimensional ◽  
Industrial Applications ◽  
Computationally Efficient ◽  
Object Reconstruction ◽  
View Planning ◽  
Reconstruction Process ◽  
Content Type ◽  
Speed Up ◽  
Next Best View ◽  
Multiple Manipulators

Purpose – This paper aims to propose a new view planning method which can be used to calculate the next-best-view (NBV) for multiple manipulators simultaneously and build an automated three-dimensional (3D) object reconstruction system, which is based on the proposed method and can adapt to various industrial applications. Design/methodology/approach – The entire 3D space is encoded with octree, which marks the voxels with different tags. A set of candidate viewpoints is generated, filtered and evaluated. The viewpoint with the highest score is selected as the NBV. Findings – The proposed method is able to make the multiple manipulators, equipped with “eye-in-hand” RGB-D sensors, work together to accelerate the object reconstruction process. Originality/value – Compared to the existed approaches, the proposed method in this paper is fast, computationally efficient, has low memory cost and can be used in actual industrial productions where the multiple different manipulators exist. And, more notably, a new algorithm is designed to speed up the generation and filtration of the candidate viewpoints, which can guarantee both speed and quality.

scholarly journals Computationally Efficient Magnetic Position System Calibration

2020 ◽  
Vol 2 (1) ◽  
pp. 72
Author(s):  
Stefano Lumetti ◽  
Perla Malagò ◽  
Dietmar Spitzer ◽  
Sigmund Zaruba ◽  
Michael Ortner
Keyword(s):  
Degrees Of Freedom ◽  
Low Cost ◽  
Industrial Applications ◽  
Position System ◽  
Computationally Efficient ◽  
System Calibration ◽  
Practical Challenge ◽  
3D Printed ◽  
Cost Efficient ◽  
Orientation Systems

Properties such as high resolution, contactless (and thus wear-free) measurement, low power consumption, robustness against temperature and contamination as well as low cost make magnetic position and orientation systems appealing for a large number of industrial applications. Nevertheless, one major practical challenge is their sensitivity to fabrication tolerances. In this work, we propose a novel method for magnetic position system calibration based on the analytical computation of the magnetic field and on the application of an evolutionary optimization algorithm. This scheme enables the calibration of more than 10 degrees of freedom within a few seconds on standard quad-core ×86 processors, and is demonstrated by calibrating a highly cost-efficient 3D-printed 3-axis magnetic joystick.

Predictive model on the effect of restrictor on transfer function parameters on pneumatic control system

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Control System ◽  
Pressure Change ◽  
Mathematical Concept ◽  
Industrial Applications ◽  
Cross Sectional ◽  
Pneumatic Control ◽  
Functional Parameters ◽  
System P ◽  
Total Differential ◽  
Input Pressure

Mathematical model was developed to monitor and predict the influence ofrestrictor or the characteristics of the functional parameters of the transferfunction for pneumatic control system. The force acting from bellow is directlyproportional to the effective cross-sectional area of the base which yieldedextension of the bellow in both horizontal and vertical as well as its extensionrate is dependent on the influence of the restrictor. The pneumatic controllerrepresents the main force control operator in many industrial applications,where it’s static and dynamic characteristics play an important role in the overallbehavior of the control system, the total differential expression obtained in termsof restrictor pressure change per unit change in time was presented. The generalsolution equation established was resolved using the mathematical concept oflaplace transformation as well as application of partial fraction which yields,The effect of the restrictor on the characteristics of the pressure was monitored,predicted and simulated using the MATLAB program approach. Result obtainedreveals increase in restrictor pressure with increase in time. Restrictor pressureis influence by the capacitance, input pressure of bellow characteristics as well asother functional parameters.

scholarly journals Microfluidics approach to investigate foam hysteretic behaviour

2019 ◽  
Vol 23 (12) ◽  
Author(s):  
Leslie Labarre ◽  
Daniele Vigolo
Keyword(s):  
Foam Stability ◽  
Sodium Dodecyl ◽  
Surface Elasticity ◽  
Industrial Applications ◽  
Gas Pressure ◽  
Step Test ◽  
Liquid Pressure ◽  
Hysteretic Behaviour ◽  
Static Conditions ◽  
Foam Pattern

Abstract Foam stability often refers to the foam left to evolve with time in static conditions. However, in everyday life, foams are submitted to numerous deformations. A feature of foam stability is represented by the foam’s ability to resist to the deformation and to recover its initial properties after deformation. The technique developed here allows for a qualitative evaluation of the property of foam recovery after a deformation in a flow-focusing microfluidic device. The foam hysteretic behaviour was evaluated by introducing the analogous of a standard three-step test in which the recovery of viscosity is commonly studied over three deformation stages. The foam behaviour is analysed over an induced cycle of ascendant and descendant deformation at the wall, well controlled by varying the gas pressure for a constant liquid pressure. Thus, the recovery of the two-row foam pattern used as reference is studied after a high deformation phase corresponding to the bamboo pattern and the level of hysteresis is measured qualitatively. The samples investigated comprise a range of Newtonian aqueous solutions containing 5 cmc (critical micellar concentration) of sodium dodecyl sulphate (SDS). A retardation effect was observed leading to hysteresis caused by the increase in viscosity. A higher surface elasticity produced a smaller but non-negligible hysteresis due to an excess in elastic energy caused by the increase of the duration of the bubble rearrangements. The present study has gone some way towards enhancing our understanding of the mechanisms triggering or enhancing foam hysteresis in a microchannel. The findings will be of interest to many industrial processes where foams are submitted to a series of deformation steps along the process line from food industrial applications to biological systems. Graphical abstract A schematic of the three-step test consisting in an ascending and descending pressure ramps obtained by varying the gas pressure for a constant liquid pressure.

Approximating EHL Film Thickness Profiles Under Transient Conditions

2002 ◽  
Vol 124 (3) ◽  
pp. 443-447 ◽  
Author(s):  
S. Messe´ ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Analytical Approximation ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Numerical Techniques ◽  
Transient Conditions ◽  
Entrainment Velocity ◽  
Thickness Profile ◽  
Ehl Contact

In ElastoHydrodynamic Lubrication (EHL), transient processes are much more common than stationary ones. Predicting the film thickness under steady state conditions has become straight forward. Using numerical methods, the effect of transient conditions on the film thickness profile can be computed. However, those analyses are very time consuming even using advanced numerical techniques. As such, they are inadequate for industrial applications as design and development. This paper shows that under certain assumptions, an approximate formula of the transient film thickness profile can be derived under transient operating conditions. The variations can occur in the geometry, the load or the hydrodynamic velocity. The theory can handle all variations separately, or even a combination of several parameters varying simultaneously. The analytical approximation obtained is rather good apart from the constriction at the contact edge(s). This approach can be applied to any set of time dependent conditions (load, speed, geometry). As an example an EHL contact is studied in which reversal of the entrainment velocity occurs.

Analysis of exploitation‐induced gravity changes at Wairakei Geothermal Field

Geophysics ◽  
1986 ◽  
Vol 51 (8) ◽  
pp. 1647-1660 ◽  
Author(s):  
Richard G. Allis ◽  
Trevor M. Hunt
Keyword(s):  
Geothermal Field ◽  
Gravity Change ◽  
Gravity Models ◽  
Liquid Temperature ◽  
Surrounding Area ◽  
Liquid Pressure ◽  
Induced Gravity ◽  
Gravity Changes ◽  
Flow Equilibrium ◽  
The 1960S

Gravity changes (corrected for subsidence) of up to -1 000 (±300) μGal have occurred in the [Formula: see text] area of the production bore field at Wairakei, and smaller decreases extend over a [Formula: see text] surrounding area. The largest part of these decreases occurred during the 1960s; since then the net gravity change for the whole field has been zero, indicating mass flow equilibrium. The principal causes of gravity change have been deep liquid pressure drawdown which resulted in formation of a steam zone, subsequent saturation changes in the steam zone, liquid temperature decline, and groundwater level changes. Gravity models suggest saturation of the steam zone was 0.7 (±0.1) in 1962 and decreased to 0.6 by 1972. Gravity increases in the northern and eastern bore field since the early 1970s are attributed to cool water invading the steam zone.

Isentropic Formulation of the Linearized Euler Equations For Perfectly Premixed Combustion Systems

2021 ◽  
Author(s):  
Pedro Romero Vega ◽  
Thomas Hofmeister ◽  
Gerrit Heilmann ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer
Keyword(s):  
Heat Release ◽  
Turbulent Flows ◽  
Euler Equations ◽  
Acoustic Waves ◽  
Energy Equation ◽  
Industrial Applications ◽  
Computationally Efficient ◽  
Mean Flow ◽  
Linearized Euler Equations ◽  
Damping Rate

Abstract The linearized Euler equations (LEE) provide an accurate — yet computationally efficient — description of propagation and damping of acoustic waves in geometrically complex, non-uniform reactive mean flows like those found in gas turbine combustion chambers. However, direct application of the LEE to perfectly premixed combustors with highly turbulent flows overestimates entropy waves as the LEE solution inherently contains coupled acoustic, vortical and entropy modes. In the present work, the LEE are decomposed into isentropic and non-isentropic parts ultimately obtaining a simplified set of isentropic LEE, in which only acoustic and vortical modes propagate. In the isentropic LEE, only continuity and momentum equations need to be solved. The energy equation is replaced by the isentropic relation between acoustic pressure and density. From the decomposition, the unsteady heat release term, which acts as a source in the energy equation, naturally arises as a source in the continuity equation. This way, the thermoacoustic coupling is still preserved in the isentropic formulation. The derived isentropic set of equations is first tested with a one-dimensional benchmark configuration consisting of a mean flow temperature jump, non-uniform mean flow velocity and unsteady heat release sources. Solutions of the non-isentropic and isentropic set of LEE are compared and the avoidance of entropy waves proved. Finally, isentropic LEE are used for reproducing the frequency of the self-excited first transversal mode of a lab-scale swirl-stabilized premixed combustor. Furthermore, isentropic and non-isentropic LEE solutions are compared. The non-isentropic LEE yield too high levels of entropy at the combustor exit that may explain the increased damping rate of the non-isentropic LEE solution compared to the isentropic LEE solution. This shows the relevance of isentropic LEE for correctly predicting thermoacoustic stability limits at high frequencies in relevant industrial applications.

Bubble Formation and Behaviour Under Hypergravity Conditions

2010 ◽  
Author(s):  
Anna Eiden ◽  
Christina Giannopapa ◽  
Balazs Toth ◽  
Alan Dowson
Keyword(s):  
Water Column ◽  
Bubble Size ◽  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Bubble Formation ◽  
Industrial Applications ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Rates ◽  
Aerospace Applications

Bubble formation and behaviour have been studied over decades, but the complex two-phase flow phenomena involved are still not fully understood. In view of the importance of two-phase flow processes in a broad range of industrial applications, such as the chemical process industry, food industry and aerospace applications, it is crucial to obtain a detailed understanding of single and multiple bubble dynamics. Gravity plays an important role in bubble formation and behaviour. Several studies have been conducted on single bubble formation under microgravity conditions, but the effects of gravitational accelerations much larger than on Earth have not been previously documented. In order to gain a full understanding of the effect of gravity on the bubble dynamics and in view of industrial applications, particularly aerospace applications, it is essential to examine bubble formation and behaviour under hypergravity conditions. Bubble formation and behaviour at the surface of a porous material and at a nozzle were investigated at hypergravity levels of 1–20g using the Large Diameter Centrifuge (LDC) at ESA/ESTEC. The formation of air bubbles through a porous filter into a water column was recorded under hypergravity conditions and the obtained data were analysed qualitatively. A decrease in bubble size and an increase in bubble formation frequency with increasing hypergravity levels could be clearly observed. Data for the experiments on air and oil bubble formation at a nozzle into a water column were recorded under hypergravity conditions using a high speed camera (for different nozzle sizes and air/oil flow rates). For the recorded data from the experiments on air and oil bubble formation at a nozzle, a decrease in bubble size and an increase in bubble formation frequency with increasing gravitational acceleration could be observed qualitatively. Quantitative analysis of the data obtained for the experiments on air bubble formation at a nozzle clearly showed a decrease in average bubble diameter with increasing hypergravity levels. The effect of the nozzle diameter on the bubble size was shown to be small and the bubble diameter was larger for higher flow rates.

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