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Cavitation research with computational fluid dynamics:From Euler-Euler to Euler-Lagrange approach

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Journal of Hydrodynamics 2024年第1期36卷 1-23页

作者： Bin Ji Zi-yang Wang Huai-yu Cheng rickard E.Bensow State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan430072China Department of Mechanics and Maritime Sciences Chalmers University of TechnologyGothenburgSweden

Unsteady cavitating flow often contains vapor structures with a wide range of different length scales,from micro-bubbles to large cavities,which issues a big challenge to precisely investigate its evolution mechanism by computational fluid dynamics(CFD)*** present work reviews the development of simulation methods for cavitation,especially the emerging Euler-Lagrange ***,the progress of the numerical investigation of hot and vital issues is discussed,including cavitation inception,cloud cavitation inner structure and its formation mechanism,cavitation erosion,and cavitation *** is indicated that the Euler-Lagrange method can determine cavitation inception point *** cloud cavitation,the Euler-Lagrange method can reveal the source of microbubbles and their distribution law inside the shedding *** method also has advantages and great potential in assessing cloud cavitation-induced erosion and *** the ever-growing demands of cavitation simulation accuracy in basic research and engineering applications,how to improve the Euler-Lagrange method’s stability and applicability is still an open *** further promote the application of this advanced CFD simulation technology in cavitation research,some key issues are to be solved and feasible suggestions are put forward for further work.

关键词： numerical simulation Euler-Euler method Euler-Lagrange method bubble dynamicsgy,Gothenburg,Sweden

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人类仍在演化吗

教师博览（上旬刊） 2024年第3期 68-70页

作者： [英]Ian rickard 牙牙(译) 不详

1965年,鲁道夫·扎林格为时代生活丛书绘制了一幅插画,随后引来无数人模仿和嘲讽。插画原稿名为“进步的行进”,左侧描绘了一个黑猩猩形态的生物,右侧则以一个可以说是体态健美的欧洲裔男性结束。

关键词：插画鲁道夫黑猩猩

Delivery of inert gas through a vertical borehole using inert gas generator: A theoretical study

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International Journal of Mining Science and Technology 2020年第4期30卷 501-510页

作者： rickard Hansen Sustainable Minerals Institute The University of QueenslandBrisbaneQueensland 4072Australia

The delivery of the inert gas through a vertical borehole using inert gas generator or IGG is *** limitations and/or transient effects are *** the analysis,the borehole diameter,borehole length,type of borehole and partial condensation prior to entering the borehole were varied.A choked flow will occur for a contraction exit or borehole of 0.3 m in diameter if no condensation prior to the contraction *** partial condensation takes place,a borehole diameter of 0.3 m will be possible if almost 50%of the water vapour ***,pressure losses along boreholes with a diameter of 0.3 or 0.4 m are significant and could pose a challenge if trying to mitigate the pressure *** a booster fan prior to the inlet of the 0.4 m lined borehole would still be a *** corresponding case with a 0.5 m borehole presents much more favourable pressure *** 0.5 m diameter lined borehole should be regarded as the lower *** rapid heating of the unlined borehole surface will increase the risk of thermal spallation and possibly imposing *** the mechanisms during gas delivery will increase the likelihood of a successful inertisation.

关键词： GAG Inert gas Condensation Pressure loss Choked flow Gas velocity Borehole Heat transfer

Fire behavior of mining vehicles in underground hard rock mines

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International Journal of Mining Science and Technology 2017年第4期27卷 627-634页

作者： Hansen rickard Malmfaltens Brandkonsult Taljstensagen Nykoping 611 67 Sweden

The results from a number of investigations and fire experiments are presented and analyzed in order to characterize the fire behavior of mining vehicles in underground hard rock mines. The analysis also includes fire safety and fire protection measures with respect to the mining vehicle fire *** studies on fires in underground hard rock mines have shown that vehicles or mobile equipment are the dominant sources of fire. A better knowledge about the fire behavior of vehicles in underground hard rock mines is therefore needed. During the analysis the direction and flow rate of the ventilation in a drift was found to have a significant impact on the fire behavior, causing for example flame tilt with rapid fire spread. The shielded sections of a vehicle will be less affected by the ventilation flow resulting in for example a decreased flame spread. It was also found that spray fires may result in considerable heat release rate but are generally of shorter duration and will not make any significant contributions to the overall heat release rate of the fully developed vehicle fire. The fire duration of a loader tire from a full-scale fire experiment was found to be at least 200 min and will largely determine the total fire duration of the vehicle. A different scenario with different conditions with for example a slower flame spread resulted in an even longer fire duration. The radiative and convective fraction will be a key factor when determining the heat transfer mechanisms involved in a fire and will vary from material to *** show that the radiative fraction of the tire fires on two mining vehicles is significantly lower than found in earlier experiments. The design and construction of the mining vehicle will have an important impact on the fire behavior and could possibly mitigate the consequences of a fire and allow fire personnel to extinguish a fire that otherwise would have had a too high heat release rate.

关键词： Fire behavior Mining vehicle Underground mine Full-scale fire experiments

Retardation of an IGG gas flow along a mine drift due to condensation and temperature decrease

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International Journal of Mining Science and Technology 2019年第6期29卷 831-839页

作者： rickard Hansen Sustainable Minerals Institute The University of Queensland

The progress of the GAG gas flow in a conveyor drift is *** output of a calculation model is evaluated and compared with experimental results from full-scale inertisation *** presenting the fastest and most extensive condensation of water resulted in well fitted arrival times of the GAG gas front.A common denominator for the two sets of expressions is that the type of flow is considered and thus better fitted to the actual flow *** model was further refined to include the surface roughness factor in the condensation calculations,which resulted in time lengths even closer to the measured time *** measured rapid temperature increase at certain positions along the conveyor drift was found to fit well with the calculated GAG gas front arrival at the corresponding *** magnitude of the GAG flow was found to have a large impact on the arrival time of the GAG gas *** and understanding the GAG gas behaviour would increase the likelihood of successful inertisation of all or part of a mine.

关键词： GAG Inert gas Condensation Temperature decrease Gas velocity Mine drift

Fire behaviour of multiple fires in a mine drift with longitudinal ventilation

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International Journal of Mining Science and Technology 2019年第2期29卷 245-254页

作者： rickard Hansen Sustainable Minerals Institute The University of Queensland

The fire behaviour involving multiple fires in a mine drift with longitudinal ventilation was analysed. The conditions and fire phenomena occurring were described. The analysis was based upon experimental data from model-scale fire experiments. A fire involving several fuel items may lead to flames tilted horizontally and filling up the entire cross section, leading to earlier ignition, higher fire growth rates, higher fire spread rate and severe fire behaviour. Longer flame lengths will also result due to decreased air entrainment. A correlation for the continuous flame length was proposed. The results of the analysis will help identifying and preventing potentially dangerous fire situations with several large combustible items distributed along a mine drift.

关键词： Multiple fires Mine drift Fire spread Flame length Fire growth

Hydrodynamic mechanisms of aggressive collapse events in leading edge cavitation

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Journal of Hydrodynamics 2020年第1期32卷 6-19页

作者： Mohammad Hossein Arabnejad Ali Amini Mohamed Farhat rickard EBensow Department of Mechanics and Maritime Sciences Chalmers University of TechnologyGothenburgSweden Laboratory for Hydraulic Machines EPFLLausanneSwitzerland

Transient cavities generated from unsteady leading-edge cavitation may undergo aggressive collapses which are responsible for cavitation *** this paper,we studied the hydrodynamic mechanisms of these events in the leading edge cavitation fonned over a modified NACA0009 hydrofoil using experimental and numerical *** the experimental investigation,high-speed visualization(HSV)and paint test are employed to study the behavior of the cavitating flow at σ=1.25,α=5°,U∞=20 m/*** the numerical part,the same cavitating flow is simulated using an inviscid density-based compressible solver with a barotropic cavitation *** numerical results are first compared with the experimental HSV to show that the simulation is able to reproduce the main features of the cavitating ***,as the compressible solver is capable of capturing the shock wave upon the collapse of cavities,the location of collapse events with high erosion potential are *** location of these collapse events are compared with the paint test results with a qualitatively good *** is clearly observed,in both the experiments and the numerical simulation,that there exists four distinct regions along the hydrofoil with higher risks of erosion:(1)A very narrow strip at the leading edge,(2)an area of accumulated collapses at around 60 percent of the sheet cavity maximum length,(3)an area around the closure line of the sheet cavity with the highest erosion damage,and(4)a wide area close to the trailing edge with dispersed collapse events.A combined analysis of the experimental and numerical results reveals that the small-scale structures generated by secondary shedding are more aggressive than the large-scale cloud cavities(primary shedding).It is also observed that the high risk of cavitation erosion in regions 2 and 3 is mainly due to the collapses of the small cavity structures that are formed around the sheet cavity closure line or the rolling cloud cavity.

关键词： Hydrodynamic mechanisms aggressive collapse events high-speed visualization(HSV) paint test compressible simulation of cavitating flows

Experimental analysis of tip vortex cavitation mitigation by controlled surface roughness

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Journal of Hydrodynamics 2020年第6期32卷 1059-1070页

作者： Urban Svennberg Abolfazl Asnaghi Robert Gustafsson rickard E.Bensow Kongsberg Hydrodynamic Research Centre Kongsberg Maritime ABKristinehamnSweden Department of Mechanics and Maritime Sciences Chalmers University of TechnologyGothenburgSweden

This study presents results of experiments where roughness applications are evaluated in delaying the tip vortex cavitation inception of an elliptical ***-speed video recordings and laser doppler velocimetry(LDV)measurements are employed to provide further details on the cavitation behavior and tip vortex flow properties in different roughness pattern *** angular momentum measurements of the vortex core region at one chord length downstream of the tip indicate that roughness leads to a lower angular momentum compared with the smooth foil condition while the vortex core radius remains similar in the smooth and roughened *** observations show that the cavitation number for tip vortex cavitation inception is reduced by 33%in the optimized roughness pattern compared with the smooth foil condition where the drag force increase is observed to be around 2%.During the tests,no obvious differences in the cavitation inception properties of uniform and non-uniform roughness distributions are ***,the drag force is found to be higher with a non-uniform roughness distribution.

关键词： Roughness tip vortex mitigation cavitation suppression

Improving rail vehicle dynamic performance with active suspension

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High-Speed Railway 2023年第1期1卷 23-30页

作者： Sebastian Stichel rickard Persson Rocco Giossi KTH Royal Institute of Technology KTH Railway GroupTeknikringen 8S-10044 StockholmSweden

Today,it is difficult to further improve the dynamic performance of rail vehicles with conventional passive ***,simplified vehicle respectively running gear layouts that significantly could reduce vehicle weights are difficult to realize with modern requirements on passenger vibration comfort and wheel and rail *** suspension is a powerful technology that can improve the vehicle dynamic performance and make simplified vehicle concepts *** KTH Railway group has,together with external partners,investigated active suspensions both numerically and experimentally for 15 *** paper provides a summary of the activities and the most important *** major project carried out in close collaboration with the vehicle manufacturer Bombardier and the Swedish Transport Administration was the Green Train project,where a 2-car EMU test bench was used to demonstrate different active *** ongoing projects,a concept of single axle-single suspension running gear is developed with active suspension both for comfort improvement and reduced wheel wear in *** results from on-track tests in the Green Train project were so good that the technology is now implemented in commercial trains and the simulation results for the single-axle running gear are very promising.

关键词： Rail Vehicle dynamics Active suspension Ride comfort Active wheelset steering Wheel wear