A Numerical Study with Experimental Data on Risk-Averse Subcontractors in Procurement Auctions with Subcontract Bids

2021 ◽  
Author(s):  
Naoki Watanabe
Keyword(s):  
Experimental Data ◽  
Numerical Study ◽  
Procurement Auctions ◽  
Risk Averse

Oscillatory Heat Transfer in a Pipe Subjected to a Laminar Reciprocating Flow

1996 ◽  
Vol 118 (3) ◽  
pp. 592-597 ◽  
Author(s):  
T. S. Zhao ◽  
P. Cheng
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
Nusselt Number ◽  
Numerical Study ◽  
Temperature Cycle ◽  
Uniform Heat Flux ◽  
Fluid Temperature ◽  
Cycle Space ◽  
Reciprocating Flow

An experimental and numerical study has been carried out for laminar forced convection in a long pipe heated by uniform heat flux and subjected to a reciprocating flow of air. Transient fluid temperature variations in the two mixing chambers connected to both ends of the heated section were measured. These measurements were used as the thermal boundary conditions for the numerical simulation of the hydrodynamically and thermally developing reciprocating flow in the heated pipe. The coupled governing equations for time-dependent convective heat transfer in the fluid flow and conduction in the wall of the heated tube were solved numerically. The numerical results for time-resolved centerline fuid temperature, cycle-averaged wall temperature, and the space-cycle averaged Nusselt number are shown to be in good agreement with the experimental data. Based on the experimental data, a correlation equation is obtained for the cycle-space averaged Nusselt number in terms of appropriate dimensionless parameters for a laminar reciprocating flow of air in a long pipe with constant heat flux.

Numerical Simulation of Detonation Propagation in Flame Arrestor Applications

2020 ◽  
Author(s):  
Hoden A. Farah ◽  
Frank K. Lu ◽  
Jim L. Griffin
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Numerical Study ◽  
Forchheimer Equation ◽  
Detonation Propagation ◽  
Simulation Domain ◽  
Shock Transmission ◽  
Propagation Parameters ◽  
Porous Zone ◽  
Viscous Solutions

Abstract A detail numerical study of detonation propagation and interaction with a flame arrestor product was conducted. The simulation domain was based on the detonation flame arrestor validation test setup. The flame arrestor element was modeled as a porous zone using the Forchheimer equation. The coefficients of the Forchheimer equation were determined using experimental data. The Forchheimer equation was incorporated into the governing equations for axisymmetric reactive turbulent flow as a momentum sink. A 21-step elementary reaction mechanism with 10 species was used to model the stoichiometric oxyhydrogen detonation. Different cases of detonation propagation including inviscid, viscous adiabatic, and viscous with heat transfer and a porous zone were studied. A detail discussion of the detonation propagation and effect of the arrestor geometry, the heat transfer and the porous zone are presented. The inviscid numerical model solutions of the detonation propagation parameters are compared to one-dimensional analytical solution for verification. The viscous solutions are qualitatively compared to historical experimental data which shows very similar trend. The effect of the porous media parameters on shock transmission and re-initiation of detonation is presented.

Validation of Film Evaporation Model in GASFLOW-MPI

2018 ◽  
Author(s):  
Li Yabing ◽  
Zhang Han ◽  
Xiao Jianjun
Keyword(s):  
Experimental Data ◽  
Wall Temperature ◽  
Cooling System ◽  
Numerical Study ◽  
Thermal Power ◽  
Heat Removal ◽  
Air Velocity ◽  
Evaporation Model ◽  
Film Evaporation ◽  
Test Region

A dynamic film model is developed in the parallel CFD code GASFLOW-MPI for passive containment cooling system (PCCS) utilized in nuclear power plant like AP1000 and CAP1400. GASFLOW-MPI is a widely validated parallel CDF code and has been applied to containment thermal hydraulics safety analysis for different types of reactors. The essential issue for PCCS is the heat removal capability. Research shows that film evaporation contributes most to the heat removal capability for PCCS. In this study, the film evaporation model is validated with separate effect test conducted on the EFFE facility by Pisa University. The test region is a rectangle gap with 0.1m width, 2m length, and 0.6m depth. The water film flowing from the top of the gap is heated by a heating plate with constant temperature and cooled by countercurrent air flow at the same time. The test region model is built and analyzed, through which the total thermal power and evaporation rate are obtained to compare with experimental data. Numerical result shows good agreement with the experimental data. Besides, the influence of air velocity, wall temperature and gap widths are discussed in our study. Result shows that, the film evaporation has a positive correlation with air velocity, wall temperature and gap width. This study can be fundamental for our further numerical study on PCCS.

Dynamics of Evaporation and Cooling of a Water Droplet During the Early Stage of Depressurization

2009 ◽  
Author(s):  
L. Liu ◽  
Q. C. Bi ◽  
G. X. Wang
Keyword(s):  
Experimental Data ◽  
Water Droplet ◽  
Effective Conductivity ◽  
Numerical Study ◽  
Early Stage ◽  
Droplet Surface ◽  
Large Temperature ◽  
Measured Temperature ◽  
Equilibrium Evaporation ◽  
Electro Magnetic

This paper reports an experimental and numerical study of evaporation and cooling of a water droplet during the early stage of depressurization in a test vessel. During the experiment, a distilled water droplet was suspended on a thermocouple, which was also used to measure the droplet center temperature, and the droplet surface temperature was captured by an infrared thermograph. Experimental data indicated a large temperature difference within the droplet during the early stage of depressurization. A thermodynamic analysis of the experimental data found that the pressure reduction was not fast enough to induce liquid superheating and thus equilibrium evaporation was expected. A mathematical model was then constructed to simulate the droplet evaporation process. The model solves one-dimensional heat conduction equation for the temperature distribution inside the water droplet, with the convective heat transfer inside the droplet simplified through an effective conductivity factor. A simplified treatment was introduced to quantify the convective evaporation due to air movement and droplet swing induced by sudden opening of the electro-magnetic valve and the following air exiting. The model-predictions agree well with the measured temperature data, demonstrating the soundness of the present model.

LES and Hybrid RANS/LES of a Fundamental Trailing Edge Slot

2014 ◽  
Author(s):  
Elizaveta Ivanova ◽  
Gregory M. Laskowski
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Numerical Study ◽  
Mixing Layer ◽  
Detached Eddy Simulation ◽  
Trailing Edge ◽  
Adiabatic Wall ◽  
Mean Velocity ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

This paper presents the results of a numerical study on the predictive capabilities of Large Eddy Simulation (LES) and hybrid RANS/LES methods for heat transfer, mean velocity, and turbulence in a fundamental trailing edge slot. The geometry represents a landless slot (two-dimensional wall jet) with adjustable slot lip thickness. The reference experimental data taken from the publications of Kacker and Whitelaw [1] [2] [3] [4] contains the adiabatic wall effectiveness together with the velocity and the Reynolds-stress profiles for various blowing ratios and slot lip thicknesses. The simulations were conducted at three different lip thickness and several blowing ratio values. The comparison with the experimental data shows a general advantage of LES and hybrid RANS/LES methods against unsteady RANS. The predictive capability of the tested LES models (dynamic ksgs-equation [5] and WALE [6]) was comparable. The Improved Delayed Detached Eddy Simulation (IDDES) hybrid method [7] also shows satisfactory agreement with the experimental data. In addition to the described baseline investigations, the influence of the inlet turbulence boundary conditions and their implication for the initial mixing layer and heat transfer development were studied for both LES and IDDES.

Detailed Study of Front Module for Low-Emission Combustor

2020 ◽  
Author(s):  
A. Vasilyev ◽  
V. Zakharov ◽  
O. Chelebyan ◽  
O. Zubkova
Keyword(s):  
Experimental Data ◽  
Numerical Study ◽  
Flame Structure ◽  
Combustion Efficiency ◽  
Liquid Fuels ◽  
Pollutant Emission ◽  
Additional Information ◽  
Low Emission ◽  
Wide Range ◽  
To Receive

Abstract At the ASME Turbo Expo 2018 conference held in Oslo (Norway) on the 11th-15th of June 2018, the paper GT2018-75419 «Experience of Low-Emission Combustion of Aviation and Bio Fuels in Individual Flames after Front Mini-Modules of a Combustion Chamber» was published. This paper continues the studies devoted to the low-emission combustion of liquid fuels in GTE combustors. The paper presents a description of more detailed studies of the front module with a staged pneumatic fuel spray. The aerodynamic computations of the front module were conducted, and the disperse characteristics of the fuel-air spray were measured. The experimental research was carried out in two directions: 1) probing of the 3-burner sector flame tube at the distance of one third of its length (temperature field and gas sampling); 2) numerical study of the model combustor with actual arrangement of the modules in the dome within a wide range of fuel-air ratio. The calculated and experimental data of velocity field behind the front module were compared. And new data about the flame structure inside the test sector were obtained. Experimental data confirm the results of preliminary studies of the 3-burner sector: combustion efficiency is higher than 99.8%, EiNOx is at the level of 2–3 g/fuel kg at the combustor inlet air temperature of 680K and fuel-air ratio of 0.0225. The conducted research allowed to receive additional information on the influence of some design units on the pollutant emission and to estimate the different elements of computational methods for simulation of a low-emission combustor with a multi-atomizer dome.

A Numerical Study of the Hydrodynamics of Reversing Flows Around a Cylinder

1994 ◽  
Vol 116 (4) ◽  
pp. 202-208 ◽  
Author(s):  
K. Nakajima ◽  
Y. Kallinderis ◽  
I. Sibetheros ◽  
R. W. Miksad ◽  
K. Lambrakos
Keyword(s):  
Experimental Data ◽  
Finite Element Method ◽  
Stokes Equations ◽  
Numerical Study ◽  
Offshore Structures ◽  
Two Dimensions ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Random Behavior ◽  
Marching Scheme

A numerical study of the nonlinear and random behavior of flow-induced forces on offshore structures and experimental verification of the results are presented. The numerical study is based on a finite-element method for the unsteady incompressible Navier-Stokes equations in two dimensions. The momentum equations combined with a pressure correction equation are solved employing fourth-order artificial dissipation with a nonstaggered grid, instead of the more commonly used staggered meshes. The solution is advanced in time with a combined explicit and implicit marching scheme. Emphasis is placed on study of reversing flows around a cylinder. Comparisons with experimental data evaluate accuracy and robustness of the method.

scholarly journals Numerical study of a control scheme on flow-induced cavity noise

2019 ◽  
Vol 283 ◽  
pp. 09002
Author(s):  
Lulu Liu ◽  
Jin Liu ◽  
Shijin Lyu
Keyword(s):  
Experimental Data ◽  
Cavity Length ◽  
Numerical Study ◽  
Numerical Procedure ◽  
Acoustic Analogy ◽  
Cavity Depth ◽  
Eddy Simulation ◽  
Control Scheme ◽  
Large Eddy ◽  
Flow Induced Noise

A numerical procedure for flow induced cavity noise is established in the paper. The procedure is based on large eddy simulation and FW-H acoustic analogy. The computational scheme is validated by comparing with experimental data. The change of flow induced noise along with cavity length, cavity depth and velocity is studied. A noise control scheme, which includes upright grille and oblique grille, is designed for reducing the flow-induced cavity noise. It turns out that the oblique grille shows superiority in the reduction of cavity noise by modifying the flow structure of the sheat layer.

Numerical study of fluid flow and power consumption in a stirred vessel with a Scaba 6SRGT impeller

2011 ◽  
Vol 32 (4) ◽  
pp. 351-366 ◽  
Author(s):  
Houari Ameur ◽  
Mohamed Bouzit ◽  
Mustapha Helmaoui
Keyword(s):  
Experimental Data ◽  
Fluid Flow ◽  
Power Consumption ◽  
Yield Stress ◽  
Short Distance ◽  
Numerical Study ◽  
Stirred Vessel ◽  
Higher Power ◽  
Shear Thinning Fluid ◽  
Good Agreement

Numerical study of fluid flow and power consumption in a stirred vessel with a Scaba 6SRGT impeller The present work deals with agitation of non-Newtonian fluids in a stirred vessel by Scaba impellers. A commercial CFD package (CFX 12.0) was used to solve the 3D hydrodynamics and to characterise at every point flow patterns especially in the region swept by the impeller. A shear thinning fluid with yield stress was modelled. The influence of agitator speed, impeller location and blade size on the fluid flow and power consumption was investigated. The results obtained are compared with available experimental data and a good agreement is observed. It was found that an increase in blade size is beneficial to enlargement of the well stirred region, but that results in an increased power consumption. A short distance between the impeller and the tank walls limits the flow around the agitator and yields higher power consumption. Thus, the precise middle of the tank is the most appropriate position for this kind of impeller.

Numerical study of the influence of reactor design on MOCVD with a comparison to experimental data

1991 ◽  
Vol 112 (2-3) ◽  
pp. 316-336 ◽  
Author(s):  
Andrew N. Jansen ◽  
Mark E. Orazem ◽  
Bradley A. Fox ◽  
William A. Jesser
Keyword(s):  
Experimental Data ◽  
Numerical Study ◽  
Reactor Design
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