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Numerical prediction of the performance of marine propellers using computational fluid dynamics simulation with transition-sensitive turbulence model

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART M-JOURNAL OF ENGINEERING FOR THE MARITIME ENVIRONMENT 2019年第2期233卷 515-527页

作者： Helal, Mohamed M. Ahmed, Tamer M. Banawan, Adel A. Kotb, Mohamed A. VSE Corp Alexandria Egypt Alexandria Univ Fac Engn Dept Naval Architecture & Marine Engn Alexandria Egypt Arab Acad Sci Technol & Maritime Transport Coll Engn & Technol Dept Marine Engn Alexandria Egypt

Determining and understanding the performance characteristics of marine propellers by experiments is quite a complex and costly task. Numerical predictions using computational fluid dynamics simulations could be a valuable alternative provided that the laminar-to-turbulent transition flow effects are fundamentally understood with the suitable numerical models developed. Experience suggests that the use of classical turbulent flow models may lead to high discrepancies especially at low rotational speeds where the effects of fluid flow transition from the laminar to the turbulent state may influence the predicted propeller's performance. This article proposes a complete and detailed procedure for the computational fluid dynamics simulation of non-cavitating flow over marine propellers using the "k-kl-omega" transition-sensitive turbulence model. Results are evaluated by "ANSYS FLUENT 16" for the "INSEAN E779A" propeller. Comparisons against the fully turbulent standard "k-epsilon" model and against experiments show improved agreement in way of flow transition zones at lower rotational speeds, that is, at low Reynolds numbers.

关键词： computational fluid dynamics simulation marine propellers performance characteristics ANSYS FLUENT transition-sensitive turbulence models fully turbulent models

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Determination of Optimum Rotational Speed of the Heat Wheel through computational fluid dynamics simulation

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GAZI UNIVERSITY JOURNAL OF SCIENCE 2019年第1期32卷 205-215页

作者： Sozen, Adnan Ciftci, Erdem Gazi Univ Fac Technol Dept Energy Syst Engn TR-06500 Ankara Turkey

Heat wheel is a kind of regenerative heat exchanger mostly used in Heating, Ventilation and Air Conditioning (HVAC) systems for two main goals;energy recovery from the waste heat and / or dehumidification of the air. Performance of the heat wheel utilized merely for energy recovery has been numerically investigated in this study. For the aim of determining the optimum rotational speed, three different angular velocities have been used under the transient conditions. The findings obtained from the analysis have been compared to a validated experimental study in literature. Consequently, it has been observed that they are in good agreement each other.

关键词： Heat wheel Energy recovery Performance Efficiency computational fluid dynamics simulation

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computational fluid dynamics simulation OF THREE-DIMENSIONAL PARALLEL JETS

COMPUTATIONAL FLUID DYNAMICS SIMULATION OF THREE-DIMENSIONAL...

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作者： Zhihang Liu Georgia Institute of Technology

学位级别：硕士

High-speed air jets are often used in industries for manufacturing thin fibers through a process known as melt-blowing (MB). For a high quantity of fibers to be produced, many small-scale jets placed side by side are used. These jets draw the air from the same compressed air storage tank. Therefore, the fiber formation is critically dependent on the aerodynamics of the jet flow field. Real word MB devices always have complicated internal structures such as mixing chambers and air channels between the air tank and the jet exit, which may trigger flow instabilities and generate a turbulent cross flow at the jet exit. The turbulent unsteady flow would have a significant impact on the formation of fibers and nonwoven webs. The purpose of this study is to understand the effect of the internal geometry on the jet flow field and explore passive concepts for prevention of flow instabilities within the flow passages. This study consists of three parts. A baseline case without any passive fluctuation reduction devices was studied to understand the mechanism of the instability and to investigate the details of the internal flow field. Next, a wire mesh screen was placed between the air plates and the die tip, to study its effect on both the velocity and pressure distribution across the screen. Finally, a honeycomb structure was installed near the exit of last mixing chamber. The effectiveness of these two flow fluctuation reduction devices was compared in detail using time series measurements and time-dependent flow field contours.

关键词： computational fluid dynamics simulation Parallel impinging jets Melt-blowing process Flow fluctuation reduction

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Optimal design of a pipe isolation plugging tool using a computational fluid dynamics simulation with response surface methodology and a modified genetic algorithm

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ADVANCES IN MECHANICAL ENGINEERING 2017年第10期9卷

作者： Zhao, Hong Hu, Hao-Ran China Univ Petr Coll Mech & Transportat Engn 18 Fuxue Rd Beijing 102249 Peoples R China

In this work, the flow effects on an isolation plugging tool in a pipeline were numerically investigated using computational fluid dynamics. The study focused on optimal parameter design for the isolation plugging tool, which reduced the unsteady force effects on the x and y directions of the flow field. First, three-dimensional models of the isolation plugging tool and pipe were built. The velocity, pressure, and force analysis on the flow past the isolation plugging tool were investigated via computational fluid dynamics simulation. Second, a combination of design parameter ratios was selected using the Box-Behnken method for a series of numerical experiments. From the simulation results, three regression total force models were determined for the x, y, and z directions using response surface methodology. A modified genetic algorithm was proposed to optimize the design parameter ratios for the isolation plugging tool based on the regression models. The optimum parameter ratios were chosen and verified using the simulation results.

关键词： Isolation plugging tool computational fluid dynamics simulation total force response surface methodology modified genetic algorithm

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computational fluid dynamics simulation of Tip-to-Tail for Hypersonic Test Vehicle

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JOURNAL OF PROPULSION AND POWER 2015年第5期31卷 1370-1379页

作者： Dharavath, Malsur Manna, P. Chakraborty, Debasis Def Res & Dev Lab Directorate Computat Dynam Hyderabad 500058 Andhra Pradesh India

computational fluid dynamics simulations are carried out for a complete hypersonic vehicle integrating both external (nonreacting) and internal (reacting) flow together to calculate the scramjet combustor performance and vehicle net thrust minus drag. simulations are carried out for a flight Mach number of about six. Three-dimensional Navier-Stokes equations are solved along with the shear stress transport k-omega turbulence model and single-step chemical reaction based on fast chemistry. The Lagrangian particle tracking method for droplets is used for combustion of kerosene fuel. Flow is largely nonuniform at the inlet of the combustor. Mass flow of ingested air increases with increase in angle of attack. Because of more combustion of fuel, wall surface pressure is higher for alpha = 6 deg compared with alpha = 0 deg. Combustion efficiency and thrust achieved are found to increase with the increase in angle of attack. Considerable amount of thrust is obtained from a single expansion ram nozzle and achievement of positive thrust-drag for the whole vehicle is demonstrated. The computational analysis of the whole vehicle provides net forces and moments of the whole vehicle, which is very useful for the mission analysis of the vehicle.

关键词： computational fluid dynamics simulation Combustors Angle of Attack Freestream Mach Number Kerosene Scramjet Engines Combustion Efficiency Mass Flow Rate Hypersonic Vehicles Shear Stress

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computational fluid dynamics simulation of Hybrid Rockets of Different Scales

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JOURNAL OF PROPULSION AND POWER 2015年第5期31卷 1458-1469页

作者： Lazzarin, M. Faenza, M. Barato, F. Bellomo, N. Bettella, A. Pavarin, D. Univ Padua Interdept Ctr Space Studies & Activ CISAS G Colom I-35131 Padua Italy Univ Padua CISAS G Colombo I-35131 Padua Italy

CFX software is used to simulate different hybrid rocket configurations, applying liquid N2O as the oxidizer and paraffin as the fuel. This work is the prosecution of a previous paper analyzing liquid injection in a lab-scale hybrid rocket. It is focused on the formulation of the most suitable simulation technique to represent another type of liquid injector, compared with the one described in the previous paper. It also aims at extending the computational fluid dynamics simulation approach to hybrid rockets of larger scales. To validate computational fluid dynamics output, experimental results coming from both a laboratory scale and an increased-scale engine have been used. The different geometries studied include an increased-scale engine with a cylindrical grain having no diaphragm, the same rocket with a one-hole diaphragm inside the fuel grain, and a lab-scale rocket with a one-hole diaphragm. simulations are steady state, and combustion derives from a single-phase chemical reaction. Liquid injection is fully simulated for the oxidizer, but paraffin entrainment is neglected for the fuel. computational fluid dynamics results show a good agreement with the corresponding experiments for the ballistic parameters of interest in this study: chamber pressure, efficiency, and C*. computational fluid dynamics results prove that the simulation technique proposed can be applied to any hybrid rocket scale.

关键词： Hybrid Rocket computational fluid dynamics simulation Rockets Precombustion Chamber Numerical Modeling Mass Flow Rate Combustion Efficiency Rocket Engine Performance Discharge Coefficient Antoine Equation

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Thermal protective performance evaluation of fire proof garment eliminating air gaps effect based on computational fluid dynamics simulation

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JOURNAL OF FIRE SCIENCES 2015年第6期33卷 445-458页

作者： Wang, Zhaoli Li, Jun Tian, Miao Donghua Univ Coll Fash & Design Shanghai 200051 Peoples R China Donghua Univ Protect Clothing Res Ctr Shanghai 200051 Peoples R China Donghua Univ Minist Educ Key Lab Clothing Design & Technol Shanghai 200051 Peoples R China Cornell Univ Cornell Performance Apparel Design Lab Ithaca NY 14853 USA

To evaluate thermal protective performance of fire proof garment under flash fire exposures, it is important to discuss garment heat transfer characteristics eliminating the effect of air gaps between garment and body. In this study, a test of flame manikin clothed with close-fitting garment was designed. And a three-dimensional transient heat transfer computational fluid dynamics simulation of the test was achieved to gain the garment surface temperature. By means of three-dimensional body scanner, Geomagic and Gambit software, we developed a method of three-dimensional geometrical modeling of the full-scale close-fitting clothed manikin. The accuracy of the computational fluid dynamics simulation was validated by actual experiments. It was found that the average incident heat flux to the exterior of the Nomex (R) IIIA garment is not 84kW/m(2), the value measured in nude manikin tests, but the value is 11% lower than it. This will help to set more accurate boundary conditions on garment surface in further simulations.

关键词： Flame manikin test thermal protective performance computational fluid dynamics simulation heat-resistant garments flash fire

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computational fluid dynamics simulation of Regression Rate in Hybrid Rockets

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JOURNAL OF PROPULSION AND POWER 2013年第6期29卷 1445-1452页

作者： Lazzarin, M. Barato, F. Bettella, A. Pavarin, D. Univ Padua Ctr Studies & Activ Space CISAS I-35131 Padua Italy Univ Padua CISAS Dept Mech Engn I-35131 Padua Italy

computational fluid dynamics has been applied to the simulation of hybrid rockets using O-2 as the oxidizer and hydroxyl-terminated polybutadiene or high-density polyethylene as the fuel. simulations have been carried out using predefined fuel and oxidizer mass flow rates, and calculating the fuel mass flow rate as a function of the wall heat flux. In this second case, the calculated regression rate has been compared to the average value derived from the reference experiments;no tuning coefficients have been introduced. computational fluid dynamics results are compared with the corresponding experiments in the literature. In those tests where regression rate is calculated as a function of the wall heat flux, the fuel grain is divided into segments and its average value is plotted as a function of the average oxidizer mass flux in the combustion chamber. computational fluid dynamics regression rate is underestimated by 30% for high-density polyethylene and 50% for hydroxyl-terminated polybutadiene if only convective heat exchange is accounted for. For hydroxyl-terminated polybutadiene at relatively low gaseous oxygen, the radiative heat transfer contribution to the total heat flux is not negligible, and this is confirmed by computational fluid dynamics: when radiative heat flux is taken into account, the error on regression rate is reduced to 15% and its value is overestimated. computational fluid dynamics does not correctly predict regression rate modulus, but it correctly calculates the n parameter of the regression rate formulation r = aG(ox)(n).

关键词： Hybrid Rocket computational fluid dynamics simulation Hydroxyl Terminated Polybutadiene Total Mass Flow Rate High Density Polyethylene Heat Flux Precombustion Chamber Radiative Heating Radiative Heat Transfer Rocket Performance

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computational fluid dynamics simulation of a Post-Crash Aircraft Fire Test

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JOURNAL OF AIRCRAFT 2013年第1期50卷 164-175页

作者： Wang, Zhaozhi Jia, Fuchen Galea, Edwin R. Ewer, John Univ Greenwich Fire Safety Engn Grp London SE10 9LS England

In this paper the computational fluid dynamics fire-field model SMARTFIRE is used to simulate a full-scale aircraft-cabin fire test conducted within the U.S. Federal Aviation Administration furnished C-133 test facility in order to provide further validation for the software. The experiment involves exposing the interior cabin materials to an external fuel fire, noting the subsequent spread of the external fire to the cabin interior and the onset of flashover, which occurs at approximately 210 s. The computational fluid dynamics fire simulations presented in this study make use of a range of sophisticated sub-models including a flame-spread model, the eddy-dissipation model, a toxicity model, and a multi-ray radiation model. The models' ability to simulate the fire conditions within the aircraft cabin is demonstrated through its ability to 1) reproduce the measured trends in temperatures and heat fluxes at the seat tops, 2) reproduce toxic gases concentrations at locations of interest, 3) provide a reasonable prediction of the time to flashover (220 s), and 4) produce reasonable agreement with the observed fire dynamics. The predicted time to flashover is shown to be sensitive to material properties such as ignition temperature of seat materials and not very sensitive to the cabin panel thickness.

关键词： computational fluid dynamics simulation Aircrafts Combustion Products Heat Flux Federal Aviation Administration Material Properties Aircraft Cabin Polypropylene Kerosene Fuselages

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computational fluid dynamics simulation OF A SINGLE CYLINDER RESEARCH ENGINE WORKING WITH BIODIESEL

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THERMAL SCIENCE 2013年第1期17卷 195-203页

作者： Moldovanu, Dan Burnete, Nicolae Tech Univ Cluj Napoca Automot Dept Cluj Napoca Romania

The main objective of the paper is to present the results of the computational fluid dynamics simulation of a direct injection single cylinder engine using diesel, biodiesel, or different mixture proportions of diesel and biodiesel and compare the results to a test bed measurement in the same functioning point. The engine used for verifying the results of the simulation is a single cylinder research engine from AVL with an open engine control unit, so that the injection timings and quantities can be controlled and analyzed. In Romania, until the year 2020 all the fuel stations are obliged to have mixtures of at least 10% biodiesel in diesel. The main advantages using mixtures of biofuels in diesel are: the fact that biodiesel is not harmful to the environment;in order to use biodiesel in your engine no modifications are required;the price of biodiesel is smaller than diesel and also if we compare biodiesel production to the classic petroleum based diesel production, it is more energy efficient;biodiesel assures more lubrication to the engine so the life of the engine is increased;biodiesel is a sustainable fuel;using biodiesel helps maintain the environment and it keeps the people more healthy.

关键词： computational fluid dynamics simulation single cylinder research engine biodiesel rapeseed oil

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