Numerical Simulation of Human Exposure to Aerosols Generated During Compressed Air Spray-Painting in Cross-Flow Ventilated Booths

2000 ◽  
Vol 123 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Michael R. Flynn ◽  
Eric D. Sills
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Human Exposure ◽  
Cross Flow ◽  
Volatile Oil ◽  
Compressed Air ◽  
Breathing Zone ◽  
Trajectory Data ◽  
Spray Painting ◽  
Numerical Predictions

This paper examines the use of computational fluid dynamics as a tool for predicting human exposure to aerosols generated during compressed air spray painting in cross-flow ventilated booths. Wind tunnel experiments employing a mannequin and non-volatile oil provide data to evaluate the numerical predictions. Fidap (v8.01) is used to calculate the velocity field and particle trajectories, while in-house codes were developed to post-process the trajectory data into mass concentrations, size distributions, transfer efficiency, and over-spray generation rates. The predicted dimensionless breathing-zone concentration of 0.13±23 percent is in agreement with the measured value of 0.13±15 percent given the uncertainties involved in such comparisons. Computational fluid dynamics is a powerful tool capable of providing useful information to occupational hygiene engineers involved in controlling human exposures to toxic airborne contaminants.

Metal Temperature Prediction of a Dry Low NOx Class Flame Tube by Computational Fluid Dynamics Conjugate Heat Transfer Approach

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Antonio Andreini ◽  
Lorenzo Mazzei ◽  
Giovanni Riccio ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Operating Conditions ◽  
Metal Temperature ◽  
Thermal Loads ◽  
Flame Tube ◽  
Numerical Predictions ◽  
Partial Load ◽  
Critical Components

Combustor liner of present gas turbine engines is subjected to high thermal loads as it surrounds high temperature combustion reactants and is hence facing the related radiative load. This generally produces high thermal stress levels on the liner, strongly limiting its life expectations and making it one of the most critical components of the entire engine. The reliable prediction of such thermal loads is hence a crucial aspect to increase the flame tube life span and to ensure safe operations. The present study aims at investigating the aerothermal behavior of a GE Dry Low NOx (DLN1) class flame tube and in particular at evaluating working metal temperatures of the liner in relation to the flow and heat transfer state inside and outside the combustion chamber. Three different operating conditions have been accounted for (i.e., lean–lean partial load, premixed full load, and primary load) to determine the amount of heat transfer from the gas to the liner by means of computational fluid dynamics (CFD). The numerical predictions have been compared to experimental measurements of metal temperature showing a good agreement between CFD and experiments.

Comparison of four types of membrane bioreactor systems in terms of shear stress over the membrane surface using computational fluid dynamics

2013 ◽  
Vol 68 (12) ◽  
pp. 2534-2544 ◽  
Author(s):  
N. Ratkovich ◽  
T. R. Bentzen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Membrane Fouling ◽  
Two Phase Flow ◽  
Membrane Surface ◽  
Cross Flow ◽  
Membrane Bioreactors ◽  
Phase Flow ◽  
Two Phase ◽  
Computational Fluid Dynamics Cfd

Membrane bioreactors (MBRs) have been used successfully in biological wastewater treatment to solve the perennial problem of effective solids–liquid separation. A common problem with MBR systems is clogging of the modules and fouling of the membrane, resulting in frequent cleaning and replacement, which makes the system less appealing for full-scale applications. It has been widely demonstrated that the filtration performances in MBRs can be greatly improved with a two-phase flow (sludge–air) or higher liquid cross-flow velocities. However, the optimization process of these systems is complex and requires knowledge of the membrane fouling, hydrodynamics and biokinetics. Modern tools such as computational fluid dynamics (CFD) can be used to diagnose and understand the two-phase flow in an MBR. Four cases of different MBR configurations are presented in this work, using CFD as a tool to develop and optimize these systems.

Computational Fluid Dynamics Modeling of Gaseous Cavitation in Lubricating Vane Pumps: An Approach Based on Dimensional Analysis

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Umberto Stuppioni ◽  
Alessio Suman ◽  
Michele Pinelli ◽  
Alessandro Blum
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Dimensional Analysis ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Dynamic Features ◽  
Dynamics Modeling ◽  
Vane Pump ◽  
Numerical Predictions ◽  
Pressure Ripple

Abstract This paper addresses the problem of computational fluid dynamics (CFD) modeling of gaseous cavitation (GC) in lubricating positive-displacement pumps (PDPs). It is important for designers and analysts to predict the dynamic features of air release/dissolution processes which characterize this phenomenon, along with their effects on filling capability and noise-vibration-harshness behavior of the machine. The focus is on the empirical tuning of the commercial homogeneous-flow cavitation model known as dissolved gas model (DGM). Considering an automotive case study of a balanced vane pump (BVP), the effects of air modeling on numerical predictions of discharge flow/pressure ripple and volumetric efficiency have been studied. The tuning time parameters of the model have been correlated to the machine Reynolds number as part of a simplified theoretical background based on dimensional analysis. Considering experimental data at different operating conditions, the tuned model has shown a good capacity in predicting the pressure ripple and the flowrate at the discharge of the pump.

Circular Cylinder Exposed to Cross Flow Fluid Forces – Parameters of Influence – Limits of Numerical Models

2003 ◽  
Author(s):  
Christoph Reichel ◽  
Klaus Strohmeier
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Models ◽  
Lift Coefficient ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Rigid Cylinder ◽  
Fluid Forces ◽  
Wide Range ◽  
Dynamics Simulations

In many technical fields, e.g. heat exchangers, circular cylinders are involved in Fluid Structure Interaction (FSI) problems. Therefore correct frequency and magnitude of fluid forces, respectively Strouhal number, drag and lift coefficient are needed. If fluid forces are evaluated with Computational Fluid Dynamics (CFD), mostly flow around a rigid cylinder is used to verify model and numerical methods. Unfortunately experimental as well as numerical results show great variation, making verification and testing of models difficult. Reynolds number is regarded as main influencing parameter for a rigid cylinder in cross flow. Most of experimental deviations can be related to other parameters, which differ from experiment to experiment. In this paper such parameters are specified and it is shown, that a closer look is needed, if one really wants to verify a model. Besides experimental results, which can be found in literature, some parameters are investigated by numerical simulation. Like experiments CFD (Computational Fluid Dynamics) simulations show a huge bandwidth of results, even when the same turbulence model is used. Flow around cylinders separates over a wide range of Reynolds numbers. It will be demonstrated that, using CFD, large deviations in fluid forces can often be related to miscalculation of the point of separation.

scholarly journals Design and implementation of an unmanned aerial vehicle with self-propulsive wing

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401985729 ◽  
Author(s):  
Abdelrahman Kasem ◽  
Ahmad Gamal ◽  
Amr Hany ◽  
Hesham Gaballa ◽  
Karim Ahmed ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Rotational Speed ◽  
Lift Coefficient ◽  
Cross Flow ◽  
Unmanned Air Vehicle ◽  
Air Vehicle ◽  
Cross Flow Fan ◽  
High Angles Of Attack

The article aims to prove the effectiveness of the proposed unmanned air vehicle design (The Propulsive Wing) through numerical and experimental means. The propulsive wing unmanned air vehicle is a completely new class of unmanned air vehicle, making disruptive changes in the aircraft industry. It is based on a distributed cross-flow electric fan propulsion system. When the fan starts to operate, the flow is drawn from the suction surface, provided by energy through the fan and expelled out of the airfoil trailing edge (TE). This causes a significant lift increase and drag reduction with respect to ordinary aircrafts, making it perfect for applications requiring low cruise speed such as firefighting, agriculture, and aerial photography. In this early stage of the investigation, our main aim is to prove that this design is applicable and the expected aerodynamic and propulsion improvements are achievable. This is done through a two-dimensional computational fluid dynamics investigation of the flow around an airfoil with an embedded cross-flow fan near its TE. A scaled wind tunnel model of the same geometry used in the computational fluid dynamics investigation was manufactured and used to perform wind tunnel testing. The computational fluid dynamics and wind tunnel results are compared for validation. Furthermore, an unmanned air vehicle model was designed and manufactured to prove that the propulsive wing concept is flyable. The article shows that the aerodynamic forces developed on the cross-flow fan airfoil are not only functions of Reynolds number and angle of attack as for standard airfoils but also function of the fan rotational speed. The results show the great effect of the rotational speed of fan on lift augmentation and thrust generation through the high momentum flow getting out of the fan nozzle. Wind tunnel tests show that the suction effect of the fan provides stall free operation up to very high angles of attack (40 degrees) leading to unprecedented values of lift coefficient up to 5.8. The flight test conducted showed the great potential of the new aircraft to perform the expected low cruise speed and high angles of attack flight.

Computational Fluid Dynamics (CFD) Simulation of Cross-flow Mode Operation of Membrane for Downstream Processing

2019 ◽  
Vol 13 (1) ◽  
pp. 57-68 ◽  
Author(s):  
Anirban Banik ◽  
Tarun Kanti Bandyopadhyay ◽  
Sushant Kumar Biswal
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Membrane Filtration ◽  
Cfd Simulation ◽  
Cross Flow ◽  
Flow Mode ◽  
Computational Fluid Dynamics Cfd ◽  
The Cross ◽  
Fluent 6.3

Background: Membrane filtration process produced good quality of permeate flux due to which it is used in different industries like dairy, pharmaceutical, sugar, starch and sweetener industry, bioseparation, purification of biomedical materials, and downstream polishing etc. The cross-flow mode of operation has also been used to improve the quality of the Rubber Industrial effluent of Tripura, India. </P><P> Method: The Computational Fluid Dynamics (CFD) simulation of the cross-flow membrane is done by using ANSYS Fluent 6.3. The meshing of the geometry of the membrane is done by Gambit 2.4.6 and a grid size of 100674, the number of faces is 151651 and number of nodes being 50978 has been selected for the simulation purpose from the grid independence test. We have revised and included all patents in the manuscripts related to the membrane filtration unit. </P><P> Results: Single phase Pressure-Velocity coupled Simple Algorithm and laminar model is used for the simulation of the developed model and Fluent 6.3 used for the prediction of pressure, pressure drop, flow phenomena, wall shear stress and shear strain rate inside the module is studied for cross flow membrane. </P><P> Conclusion: From the study, it has been found that CFD simulated results hold good agreement with the experimental values.

Turbine Tone Noise Prediction Using a Linearized Computational Fluid Dynamics Solver: Comparison With Measurements

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Adolfo Serrano González ◽  
José Ramón Fernández Aparicio
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Acoustic Scattering ◽  
Test Facility ◽  
Flat Plates ◽  
Cold Flow ◽  
Flow Noise ◽  
Numerical Predictions ◽  
Near Term ◽  
Cfd Method

The capability of a linearized computational fluid dynamics (CFD) method for predicting turbine tone noise is investigated through comparison with measurements. To start with, a benchmark problem on flat plates is presented, and results are put together with those published by other authors. Then, numerical predictions are compared with measurements from two low-pressure turbines (LPTs), which have been tested in different facilities. The first specimen is a three-stage cold flow rig, noise tested in the Centro de Tecnologías Aeronáuticas (CTA) facility (Bilbao, Spain) in 2012 and funded by the Clean Sky EU Program. The second is the advanced near-term low emissions (ANTLE) LPT rig, full-scale, cold flow, noise tested in the twin shaft test facility (TSTF) in Rolls-Royce (Derby, UK) in 2005 and funded by the SILENCE(R) EU Funded Program. The comparison includes multistage effects, clocking sensitivities, and acoustic scattering through outlet guide vanes (OGVs).

The Application of Computational Fluid Dynamics to Railway Aerodynamics

1993 ◽  
Vol 207 (2) ◽  
pp. 133-141 ◽  
Author(s):  
A P Gaylard
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Cross Flow ◽  
Practical Application ◽  
High Speed Rail ◽  
Promising Strategy ◽  
Temperature Environment ◽  
Computational Work ◽  
Computational Fluid Dynamics Cfd

The growing application of computational fluid dynamics (CFD) to railway aerodynamics is described. After cautioning against overselling the capabilities of CFD codes, a review is presented of the more significant computational work undertaken in this field. Three recent applications of CFD are examined: (a) a high-speed rail vehicle in a cross-wind; (b) cross-flow impingement on a freight vehicle in the Channel Tunnel; (c) the temperature environment in a stationary passenger train. Comparative experimental data are offered for each of the above. An analysis of these applications is used to derive a promising strategy for the practical application of CFD.

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