scholarly journals Analysis of the Effect of Inlet Velocity on Cooling Speed in a Refrigerated Container using CFD simulations

CFD letters ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 55-62
Author(s):  
Muhammad Arif Budiyanto ◽  
Nadhilah Suheriyanto
Keyword(s):  
High Speed ◽  
Fluid Dynamic ◽  
Computational Fluid Dynamic Simulation ◽  
Cfd Simulations ◽  
Cooling Performance ◽  
Inlet Velocity ◽  
Low Speed ◽  
Perishable Goods ◽  
Cooling Speed ◽  
Fan Speed

The use of refrigerated containers continues to increase rapidly in line with global trade, this kind of container is commonly used to deliver perishable cargo from producers to consumers over great distances, even between continents. To avoid perishable goods from damages, the temperature inside refrigerated containers was controlled and maintained to keep the cooling performance. The purpose of this study is to investigate the effect of variation inlet velocity on the cooling speed inside a refrigerated container. This study was conducted through a computational fluid dynamic simulation validated with experimental results. The simulation was carried out on the variations of inlet velocity based on low-speed fan mode at 4 m/s equal to 32 circulations/hour, and high-speed fan mode at 10 m/s equal to 80 circulations/hour. The results of the simulation show that the greater the inlet fan speed, the faster the cooling speed. The finding of this study is the cooling speed time of high cube refrigerated container with the low-speed fan is 28 minutes and the high-speed fan is 40 minutes.

Computational Analyses of an In-Vitro Aneurysm Model Based on Three-Dimensional Angiography With Comparison to Phase Contrast Magnetic Resonance Imaging and Dye Injection Studies

2010 ◽  
Author(s):  
Stephanie M. George ◽  
Pierre Watson ◽  
John N. Oshinski ◽  
Charles W. Kerber ◽  
Daniel Karolyi ◽  
...  
Keyword(s):  
High Speed ◽  
Phase Contrast ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Cerebral Aneurysms ◽  
Computational Fluid Dynamic Simulation ◽  
Poor Correlation ◽  
Aneurysm Model

Computational fluid dynamic simulation (CFD) is a valuable tool that has been used to understand some of the fundamental conditions of cerebrovascular flow. Current methods include anatomic modeling of cerebral aneurysms derived from vascular imaging such as MRA, CTA, and three-dimensional angiography. The input blood flow waveforms can be represented from either mathematical models or physiologic sampling of flow with phase contrast MR techniques or particle image velocimetry (1). While there has been general acceptance of the validity of computational fluid dynamics, some research suggests that there can be poor correlation between CFD flow calculations and directly measured flow (2). Therefore, the purpose of this study is to qualitatively compare flow patterns in a cerebral aneurysm model using data derived from three sources: (i) direct phase contrast MRA measurement in the model; (ii) CFD simulation using computer models created from three dimensional angiography, and (iii) previously published high speed injection dye studies.

Effect of Container Stack Arrangements on the Power Optimization of a Container Ship

2012 ◽  
Vol 28 (01) ◽  
pp. 10-19
Author(s):  
Khairul Hassan ◽  
Maurice F. White ◽  
Cosmin Ciorta
Keyword(s):  
High Speed ◽  
Flow Direction ◽  
Fluid Dynamic ◽  
Aerodynamic Resistance ◽  
Computational Fluid Dynamic Simulation ◽  
Design Tool ◽  
Optimal Arrangement ◽  
Power Requirement ◽  
Air Resistance ◽  
Propulsion Power

When considering the design of a ship, an important objective is to always try and develop one that allows for maximum cargo capacity with the lowest propulsion power requirement while providing a sufficient amount of strength and stability for its safe operation. The ship with the lowest propulsion power consumes the least amount of fuel and produces the lowest amount of exhaust gas that may be harmful to the environment. In some cases, the aerodynamic resistance can be neglected, but for a high speed vessel such as a modern containership, the air resistance can be in the range of 2% to 10% of the total resistance. Aerodynamic resistance can therefore have a significant effect on power requirements and is strongly influenced by the height, breadth, and the number of container stacks on the deck. The freeboard, beam of the ship, deck house design, ship speed, wind speed, and water flow direction will also contribute significantly to a ship's resistance and required propulsive power. This paper outlines the application of computational fluid dynamic simulation as a design tool to find a strategy for the optimal arrangement of the container stacks on deck so that the vessel uses the lowest effective propulsion power to achieve a fuel efficient ship. It is deduced that an optimal stack arrangement can reduce air resistance by about 30%.

scholarly journals Numerical Simulation of Oil Jet Lubrication for High Speed Gears

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Tommaso Fondelli ◽  
Antonio Andreini ◽  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Lorenzo Cipolla
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Low Pressure ◽  
Adaptive Meshing ◽  
Viscous Effects ◽  
Cfd Simulations ◽  
Oil Jet ◽  
Oil Injection ◽  
Bypass Ratio

The Geared Turbofan technology is one of the most promising engine configurations to significantly reduce the specific fuel consumption. In this architecture, a power epicyclical gearbox is interposed between the fan and the low pressure spool. Thanks to the gearbox, fan and low pressure spool can turn at different speed, leading to higher engine bypass ratio. Therefore the gearbox efficiency becomes a key parameter for such technology. Further improvement of efficiency can be achieved developing a physical understanding of fluid dynamic losses within the transmission system. These losses are mainly related to viscous effects and they are directly connected to the lubrication method. In this work, the oil injection losses have been studied by means of CFD simulations. A numerical study of a single oil jet impinging on a single high speed gear has been carried out using the VOF method. The aim of this analysis is to evaluate the resistant torque due to the oil jet lubrication, correlating the torque data with the oil-gear interaction phases. URANS calculations have been performed using an adaptive meshing approach, as a way of significantly reducing the simulation costs. A global sensitivity analysis of adopted models has been carried out and a numerical setup has been defined.

Computational and Experimental Study of Hot Streak Transport Within the First Stage of a Gas Turbine

2019 ◽  
Author(s):  
Paolo Gaetani ◽  
Giacomo Persico ◽  
Lorenzo Pinelli ◽  
Michele Marconcini ◽  
Roberto Pacciani
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Fluid Dynamic ◽  
Spatial Coherence ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Complex Flow ◽  
Cfd Simulations ◽  
Azimuthal Position ◽  
Aero Engines

Abstract The paper discusses the migration, the interaction with the blades, and the attenuation of hot streaks generated by combustor burners, during their propagation within the first turbine stage of aero-engines. Experiments and Computational Fluid Dynamic (CFD) simulations were carried out in the framework of the European Project RECORD and on its follow-up. Measurements considering burner-representative temperature perturbations injected upstream of an un-cooled high-pressure gas turbine stage were performed in the high-speed closed-loop test-rig of the Politecnico di Milano (Italy). The hot streaks were injected in streamwise direction at the stage inlet in four different circumferential positions with respect to the stator blade. They feature a 20% over-temperature with respect to the main flow. Detailed temperature measurements as well as unsteady aerodynamic measurements upstream and downstream of the blade rows were performed. Time-accurate CFD simulations of the flow upstream and within the turbine stage were performed with the TRAF code, developed by the University of Florence. Measurements show a relevant attenuation of hot streaks throughout their transport within the stator and the rotor blade rows, highly depending on the injection azimuthal position. The perturbations were observed to lose their spatial coherence, especially in the transport within the rotor, and to undergo severe spanwise migration. Simulations exhibit a good agreement with the experiments on the measurement planes and allow tracking the complex flow phenomena occurring within the blade rows. Finally the aerodynamic and thermal implications of the inlet temperature perturbations are properly highlighted and discussed.

Do You Name Speedy Objects Faster Than Slow Objects: SPEEDED NAMING OR NAMING SPEED? THE AUTOMATIC EFFECT OF OBJECT SPEED ON PERFORMANCE

2018 ◽  
Author(s):  
Moshe Shay Ben-Haim ◽  
Eran Chajut ◽  
Ran Hassin ◽  
Daniel Algom
Keyword(s):  
High Speed ◽  
Mental Representations ◽  
Reading Aloud ◽  
Naming Task ◽  
Naming Speed ◽  
Low Speed ◽  
Everyday Objects ◽  
Pictures And Words

we test the hypothesis that naming an object depicted in a picture, and reading aloud an object’s name, are affected by the object’s speed. We contend that the mental representations of everyday objects and situations include their speed, and that the latter influences behavior in instantaneous and systematic ways. An important corollary is that high-speed objects are named faster than low-speed objects despite the fact that object speed is irrelevant to the naming task at hand. The results of a series of 7 studies with pictures and words support these predictions.

scholarly journals Splatters and Aerosols Contamination in Dental Aerosol Generating Procedures

2021 ◽  
Vol 11 (4) ◽  
pp. 1914
Author(s):  
Pingping Han ◽  
Honghui Li ◽  
Laurence J. Walsh ◽  
Sašo Ivanovski
Keyword(s):  
Particle Size ◽  
Disease Transmission ◽  
High Speed ◽  
Low Speed ◽  
Dental Procedures ◽  
Dental Equipment ◽  
Produce Contamination ◽  
Fluorescein Dye ◽  
Filter Papers ◽  
Airborne Disease

Dental aerosol-generating procedures produce a large amount of splatters and aerosols that create a major concern for airborne disease transmission, such as COVID-19. This study established a method to visualise splatter and aerosol contamination by common dental instrumentation, namely ultrasonic scaling, air-water spray, high-speed and low-speed handpieces. Mock dental procedures were performed on a mannequin model, containing teeth in a typodont and a phantom head, using irrigation water containing fluorescein dye as a tracer. Filter papers were placed in 10 different locations to collect splatters and aerosols, at distances ranging from 20 to 120 cm from the source. All four types of dental equipment produced contamination from splatters and aerosols. At 120 cm away from the source, the high-speed handpiece generated the greatest amount and size (656 ± 551 μm) of splatter particles, while the triplex syringe generated the largest amount of aerosols (particle size: 1.73 ± 2.23 μm). Of note, the low-speed handpiece produced the least amount and size (260 ± 142 μm) of splatter particles and the least amount of aerosols (particle size: 4.47 ± 5.92 μm) at 120 cm. All four dental AGPs produce contamination from droplets and aerosols, with different patterns of distribution. This simple model provides a method to test various preventive strategies to reduce risks from splatter and aerosols.

scholarly journals Simulation of Hydraulic Cylinder Cushioning

2021 ◽  
Vol 13 (2) ◽  
pp. 494
Author(s):  
Antonio Algar ◽  
Javier Freire ◽  
Robert Castilla ◽  
Esteban Codina
Keyword(s):  
Dynamic Model ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Computational Fluid Dynamic Simulation ◽  
Hydraulic Cylinder ◽  
Outlet Port ◽  
Optimal Behavior ◽  
Radial Movement ◽  
Mechanical Shocks ◽  
Radial Gap

The internal cushioning systems of hydraulic linear actuators avoid mechanical shocks at the end of their stroke. The design where the piston with perimeter grooves regulates the flow by standing in front of the outlet port has been investigated. First, a bond graph dynamic model has been developed, including the flow throughout the internal cushion design, characterized in detail by computational fluid-dynamic simulation. Following this, the radial movement of the piston and the fluid-dynamic coefficients, experimentally validated, are integrated into the dynamic model. The registered radial movement is in coherence with the significant drag force estimated in the CFD simulation, generated by the flow through the grooves, where the laminar flow regime predominates. Ultimately, the model aims to predict the behavior of the cushioning during the movement of the arm of an excavator. The analytical model developed predicts the performance of the cushioning system, in coherence with empirical results. There is an optimal behavior, highly influenced by the mechanical stress conditions of the system, subject to a compromise between an increasing section of the grooves and an optimization of the radial gap.

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