scholarly journals Study of transient condensation occurring during the starting of the evaporation of a droplet deposited on a heated substrate

2020 ◽  
Vol 24 (6 Part B) ◽  
pp. 4075-4087
Author(s):  
Dorra Khilifi ◽  
Walid Foudhil ◽  
Kamel Fahem ◽  
Souad Harmand ◽  
Jabrallah Ben
Keyword(s):  
Numerical Study ◽  
Marangoni Effect ◽  
Local Region ◽  
Simulation Code ◽  
Water Steam ◽  
Heated Substrate ◽  
Complex Process ◽  
Depth Study ◽  
Condensation Phenomenon ◽  
Evaporation Kinetics

The evaporation of a drop deposited on a heated substrate is a complex process, which combines several phenomena such as the Marangoni effect, mass and thermal transfers, etc. We developed, in this paper, a mathematical model and a numerical simulation code used to carry out an in-depth study about the evaporation of a drop deposited on a heated substrate surrounded by air. This numerical study was supported by experimental work. The numerical findings obtained showed the existence of a condensation phenomenon for certain configurations. At the beginning of the experiment, the evaporation started at the triple point. However, a local region of the interface remained relatively cold. In this region, the concentration gradient (Cv, Csat) directed from the liquid-gas interface to the air resulted in condensation of water steam. Although this phenomenon is temporary and visible only at the start of evaporation process, its study makes it possible to better understand and optimize the evaporation kinetics.

scholarly journals Experimental and Numerical Study on the Thermal Performance of a Water/Steam Cavity Receiver

Energies ◽  
2013 ◽  
Vol 6 (3) ◽  
pp. 1198-1216 ◽  
Author(s):  
Nan Tu ◽  
Jinjia Wei ◽  
Jiabin Fang
Keyword(s):  
Thermal Performance ◽  
Numerical Study ◽  
Water Steam

Numerical Study on Effect of Pressure on Behavior of Bubble Coalescence by Using CMFD Simulation

2018 ◽  
Author(s):  
Ayako Ono ◽  
Takayuki Suzuki ◽  
Hiroyuki Yoshida
Keyword(s):  
Fluid Dynamics ◽  
Numerical Study ◽  
Light Water Reactor ◽  
Bubble Coalescence ◽  
Bottom Surface ◽  
Pressure Condition ◽  
Basic Study ◽  
Simulation Code ◽  
Light Water ◽  
System Pressure

The mechanism of critical heat flux (CHF) for higher system pressure remains to be clarified, even though it is important to evaluate the CHF for the light water reactor (LWR) which is operated under the high pressure condition. In this study, the process of bubble coalescence was simulated by using a computational multi-fluid dynamics (CMFD) simulation code TPFIT under various system pressure in order to investigate the behavior of bubbles as a basic study. The growth of bubbles was simulated by blowing of vapor from a tiny orifice simulating bubble bottom. One or four orifices were located on the bottom surface in this simulation study. The numerical simulations were conducted by varying the pressure and temperature.

scholarly journals Numerical study of sediment transport in Thu-Bon estuary and coastal areas of Hoi-An City

2022 ◽  
Vol 964 (1) ◽  
pp. 012001
Author(s):  
Nguyen Thong ◽  
Ho Tuan Duc ◽  
Phan Quang Hung ◽  
Tran Hai Yen
Keyword(s):  
Sediment Transport ◽  
Numerical Study ◽  
Monsoon Season ◽  
Sand Dunes ◽  
Coastal Areas ◽  
Main Trend ◽  
North Coast ◽  
Northeast Monsoon ◽  
The North ◽  
Depth Study

Abstract The area of Cua-Dai estuary and the coastal areas of Hoi-An City have experienced complicated erosion and sedimentation in recent years. Along the coast of Hoi-An, erosion often occurs, whereas in the area of Cua-Dai River, there is an accretion phenomenon that obstructs the waterway navigation from Cua-Dai to Cu-Lao-Cham. Occurrence of sand dunes in the offshore location of Cua-Dai has been recorded at a number of times in recent years. Studying the process of bed morphological change due to the sediment transport in the Thu-Bon river and the influence of monsoons in the area allows to explain the above phenomenon thus an in-depth study to propose appropriate solutions. This study used the numerical model Telemac which combines the hydro-morphodynamic and wave modules. The simulation results show that the main trend of coastal currents caused by tides and waves tends to go southward, leading to coastal erosion especially in the northeast monsoon season as well as sedimentation in the estuarine area. In addition, the model also shows the crucial role of waves in shoreline erosion, with the degree of erosion in the north coast near Cua-Dai being more severe than the southern coast, through the formation of local eddy flow on the north coast.

scholarly journals Some Basic Elements to Achieve a Future 1D Simulation of Wave Propagation in I.C.E. Pipes

2002 ◽  
Author(s):  
David Chalet ◽  
Pascal Chesse ◽  
Jean-Franc¸ois Hetet ◽  
Xavier Tauzia
Keyword(s):  
Boundary Conditions ◽  
Numerical Study ◽  
Dead Zone ◽  
Pressure Ratio ◽  
Selection Criterion ◽  
Numerical Algorithms ◽  
Flow Simulation ◽  
Computational Time ◽  
Simulation Code ◽  
Zone Length

The assumption of one-dimensional unsteady flows in the inlet and exhaust systems of turbocharged diesel engines is widely used although multi-dimensional simulations using fluid dynamics are also possible. However, difficulties persist concerning the boundary conditions, particularly at the pipe ends (inflow or outflow) and at the intra-pipe boundary conditions (sudden or gradual area changes, bends, junctions, etc.). This paper focuses on the two first steps leading to a 1D flow simulation code: the selection of a numerical scheme and the study of an open end boundary condition. The first section compares several numerical algorithms, including Lax-Wendoff, Flux-Corrected-Transport methods (FCT), and Harten-Lax-Leer (Riemann solver), extended to the second order. The selection criterion is the best compromise between numerical instabilities and computational time. A numerical study using the Fluent CFD code is then presented on a constant area duct in order to determine some characteristics at the pipe end, specifically the dead zone length and the throat area. Finally, a model parameterized by the pressure ratio between inlet and outlet is proposed.

Numerical Study of the Characteristics of Rotary Spool Orifice in Water Hydraulics

2014 ◽  
Vol 716-717 ◽  
pp. 662-669
Author(s):  
Jin Jun Wu ◽  
You Sheng Yang ◽  
Jing Yuan Li ◽  
Ge Gang Yu ◽  
Zong Xia Jiao
Keyword(s):  
Steady State ◽  
High Performance ◽  
Numerical Study ◽  
Tap Water ◽  
Control Valve ◽  
Control Element ◽  
Steady State Flow ◽  
Pressure Drops ◽  
State Flow ◽  
Depth Study

The rotary control orifice, in which the relative angular openings are adjusted by the rotary motion of the spool, thus controlling the flow area and the flow passing through, is a basic control element of hydraulic control valve. It has several advantages, such as little minimal steady flow rate, good anti-contamination, small driving power, small opening and shutting shock, and etc., over the translational control orifice. The working medium is tap water. A model is developed and numerical studies are carried out to investigate the hydrodynamic characteristics of the rotary control orifice, including flow and pressure field, flow characteristics, flow torque. The relationships between the flow and the pressure drops, the efflux angle and the angular openings, the steady-state flow torque and the pressure drops as well as the angular openings are obtained. The results show that a) the orifice geometries have great effects on the efflux angle and the steady-state flow torque; b) Under the same openings and flow direction, the efflux angle is almost constant under different pressure drops. It is larger for meter-in flow than for meter-out flow and decreases with the increase of openings; c) The steady-state flow torque (including meter-in flowTsfinand meter-out flowTsfout) is proportional to the pressure drops and first increases and then decreases with the increase of openings, finally reaches zero at the fully opened position; d) The friction moment is proportional to the rotary speed so as the transient flow induced moment to the rotary acceleration. The in-depth study of the drag moment of rotary control orifice helps to design high performance rotary servo valve for robots. The in-depth study of the rotary control orifice provides a basis for developing high performance rotary control valve.

Numerical Study on Evolution of Sessile Water Droplets During Evaporation

2012 ◽  
Author(s):  
Dinghua Hu ◽  
Huiying Wu ◽  
Xinyu Wu
Keyword(s):  
Contact Angle ◽  
Numerical Study ◽  
Concentration Field ◽  
Marangoni Effect ◽  
Simple Expression ◽  
Vapor Concentration ◽  
Contact Radius ◽  
Iteration Algorithm ◽  
Dimensionless Time ◽  
Water Droplets

The evaporation of sessile water droplets has been investigated numerically in this paper. A numerical model based on the quasi-stationary assumptions is established for describing the evaporation dynamics. Droplets are assumed to be pinned and axisymmetric on a substrate during the evaporation, and the influence of Marangoni effect on the evaporation has been taken into account. In a self-consistent way, the vapor concentration field in the gas phase, the velocity field in the liquid phase, and the temperature field in both liquid and gas phases have been calculated using the finite element method (FEM). A novel iteration algorithm is proposed to study the time evolution of contact angle. From the numerical results, we derived a universal correlation of the contact angle with the dimensionless time. The correlation, which is validated against experimental data from open literature, is independent on the contact radius, substrate temperature and ambient humidity. Base on this correlation, a simple expression has been further developed to estimate the evaporation time, and the predictions are in good agreement with the experimental results from open literature. The work in this paper provides an extensive understanding of the evaporation of sessile droplets.

scholarly journals MECHANISMS FOR UPD ANISMS FOR UPDATING THE INSTI TING THE INSTITUTIONAL SYSTEM OF STEM OF LEADING AND MANAGING PERSONNEL

2020 ◽  
Vol 4 (2) ◽  
pp. 226-232
Author(s):  
Murat Utepbergenovich Atamuratov ◽  
Keyword(s):  
The State ◽  
Political Education ◽  
Political Activity ◽  
The Political ◽  
Personnel Policy ◽  
Complex Process ◽  
Depth Study ◽  
Institutional System

This article discusses the issues raised by the country's leader about the state personnel policy in Uzbekistan and the spiritual and political education of managerial personnel. The role of managerial personnel in raising the development of Uzbekistan to a new level, objective and subjective conditions, and factors of increasing political activity are analyzed. The article highlights such problems as: the problem of increasing the political activity of young managers, an in-depth study of history, an analysis of specific patterns in the complex process of democratization

A numerical study of high pressure turbine forced response in the presence of damaged nozzle guide vanes

2007 ◽  
Vol 111 (1125) ◽  
pp. 751-757 ◽  
Author(s):  
L.di Mare ◽  
M. Imregun ◽  
A. D. Smith ◽  
R. Elliott
Keyword(s):  
High Pressure ◽  
Numerical Study ◽  
Guide Vane ◽  
Flow Simulation ◽  
Forced Response ◽  
High Pressure Turbine ◽  
Simulation Code ◽  
Engine Order ◽  
Viscous Compressible Flow ◽  
Nozzle Guide

Abstract This paper reports results from numerical computations of low engine order and blade-passing forced response on the rotor of a high pressure turbine due to severe damage to a single nozzle guide vane. The computations are performed using a time-domain, nonlinear viscous compressible flow simulation code. The flow and the levels of forcing for a few selected modes are compared for the undamaged and the damaged configurations. The results show that the response in various modes is affected to a different extent by the damage. The main blade-passing response was found to be largely unaffected, if not marginally reduced. On the other hand, the vibration levels for some modes were seen to be up to eight times higher because of the low-order excitation harmonics created by the damaged passage.

Sign in / Sign up

Export Citation Format

Share Document