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computational fluid dynamics of impinging microjet for a needle-free skin scar treatment system

COMPUTERS IN BIOLOGY AND MEDICINE 2018年 101卷 61-69页

作者： Mohizin, Abdul Roy, K. E. Reby Lee, Donghee Lee, Seung Ku Kim, Jung Kyung Kookmin Univ Grad Sch Dept Mech Engn Seoul 02707 South Korea TKM Coll Engn Dept Mech Engn Kollam 691005 Kerala India Univ Nebraska Med Ctr Dept Genet Cell Biol & Anat Omaha NE 68198 USA Union Med Co Uijeongbus Si 11787 Gyeonggi Do South Korea Kookmin Univ Grad Sch Sch Mech Engn Seoul 02707 South Korea Kookmin Univ Grad Sch Dept Integrat Biomed Sci & Engn Seoul 02707 South Korea

A needle-free injection system is a non-invasive drug delivery system, and its applications are currently being extended from the delivery of vaccines and insulin. At present, they are gaining considerable popularity in skin remodeling treatment techniques, particularly in skin rejuvenation procedures involving the injection of aesthetic materials. Although some clinical studies have been conducted to understand the mechanisms involved in these practices, an extensive study from an engineering point of view has not yet been conducted. Herein, we aim to identify the key parameters in the needle-free injection process and study their effects on microjet characteristics. The total stagnation pressure of an impinging microjet determines the penetration capabilities of the injection and is monitored with the aid of both experimental and computational tools employed on a typical commercial injector. Our findings indicated that the filling ratio and driving pressure had significant impacts on the peak and average stagnation pressures of the impinging microjet. Furthermore, the penetration characteristics of a standard nozzle and injection fluid could be controlled by an effective combination of the filling level and driving pressure, and thus, they can be considered as vital parameters when performing skin remodeling procedures.

关键词： Needle-free injection fluid-tissue interaction Microjet Skin scar treatment computational fluid dynamics simulation Stagnation pressure

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A Novel Dual Fuel Reaction Mechanism for Ignition in Natural Gas-Diesel Combustion

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ENERGIES 2019年第22期12卷

作者： Schuh, Sebastian Fruehhaber, Jens Lauer, Thomas Winter, Franz TU Wien Inst Chem Environm & Biosci Engn A-1060 Vienna Austria TU Wien Inst Powertrains & Automot Technol Getreidemarkt 9-315 A-1060 Vienna Austria

In this study, a reaction mechanism is presented that is optimized for the simulation of the dual fuel combustion process using n-heptane and a mixture of methane/propane as surrogate fuels for diesel and natural gas, respectively. By comparing the measured and calculated ignition delay times (IDTs) of different homogeneous methane-propane-n-heptane mixtures, six different n-heptane mechanisms were investigated and evaluated. The selected mechanism was used for computational fluid dynamics (CFD) simulations to calculate the ignition of a diesel spray injected into air and a natural gas-air mixture. The observed deviations between the simulation results and the measurements performed with a rapid compression expansion machine (RCEM) and a combustion vessel motivated the adaptation of the mechanism by adjusting the Arrhenius parameters of individual reactions. For the identification of the reactions suitable for the mechanism adaption, sensitivity and flow analyzes were performed. The adjusted mechanism is able to describe ignition phenomena in the context of natural gas-diesel, i.e., dual fuel combustion.

关键词： dual fuel combustion methane-propane-n-heptane mixtures ignition delay time reaction kinetics computational fluid dynamics simulation rapid compression machine shock tube sensitivity analysis flow analysis

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Experimental Research on Electrochemical Machining of an Arc-Shaped Slot Array

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INTERNATIONAL JOURNAL OF ELECTROCHEMICAL SCIENCE 2018年第10期13卷 9466-9480页

作者： Wang, Feng Zhao, Jianshe Liu, Dingming Fan, Yantao Tian, Zongjun Nanjing Univ Aeronaut & Astronaut Coll Mech & Elect Engn Nanjing 210016 Jiangsu Peoples R China

Slot array structure is widely used in the aerospace industry, precision molds, instrumentation and other fields. Electrochemical machining has a unique advantage in the fabrication of slot arrays. However, there are still problems for electrochemical machining slot arrays with complex shapes, such as poor stability, low forming accuracy and difficult processing. To improve the processing ability of arc-shaped slot arrays, the influence of electrolyte flow pattern and pressure on flow field stability in a closed channel was studied with a computational fluid dynamics simulation, and the flow pattern and pressure parameters were optimized. Moreover, comparative experiments of continuous-feed electrochemical machining mode and low-frequency oscillation assisted electrochemical machining mode were carried out based on a self-developed oscillation apparatus. The influence of auxiliary oscillation motion on the processing stability frequency, average slot width, and slot slope was analyzed, and an arc-shaped slot array with a slot width of 0.244 +/- 0.01 mm and high accuracy in shape and dimension was fabricated on a rotary workpiece.

关键词： Arc-shaped slot array Electrochemical machining Low-frequency oscillation Reverse flow computational fluid dynamics simulation

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Calculation of Reaction Force For the Gas-Blast Type Circuit breaker 2

Calculation of Reaction Force For the Gas-Blast Type Circuit...

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2nd IEEE Conference on Energy Internet and Energy System Integration (EI2)

作者： Wang, Zhijun Zhang, Hao Liu, Yapei Zhang, Bo Hao, Xiangyu State Grid Corp China Pinggao Grp Co Ltd Pingdingshan City Peoples R China

ISBN: (纸本)9781538685495

In order to explore the calculation method of the arc chamber gas reaction force and provide support for the design of the high-voltage circuit breaker mechanical transmission system, four calculation formulas of the reaction force micro-element under the four gas-solid interface conditions were derived, a test calculation case was designed and the effectiveness of the calculation method was verified. The no-arc simulation calculation model of the 252kV SF6 arc chamber was established, and the pressure distribution and the gas reaction force were obtained, the simulation results showed that: with the piston moving, the pressure inside the compression chamber increased first and then decreased, the max pressure of 1.86 MPa occurred at 0.029s;similarly, the reaction force changed with the same trend, the max reaction force of 1.95x104N occurred at 0.03s, which showed that under no-arc condition, the pressure load of the compressor chamber dominates the reaction force for arc chamber.

关键词： computational fluid dynamics simulation Reaction Force High Voltage Circuit Breaker Arc Chamber

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A Test of Possibility on Relative Humidity Function in Minor Operation Theatre

A Test of Possibility on Relative Humidity Function in Minor...

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International Conference on Advanced Manufacturing and Industry Applications (ICAMIA)

作者： Rahman, M. N. Y. Razlan, Z. M. Izham, M. Omar, M. I. Zambri, N. A. A. Shahriman, A. B. Zunaidi, I. Wan, W. K. Univ Malaysia Perlis Sch Mechatron Engn Pauh Putra Campus Arau 02600 Perlis Malaysia

High humidity air flow in Minor Operation Theatre (MOT) is undesired as it will cause discomfort to the occupant. Acceptable humidity air flow is important as it will affect the pureness of the indoor environment as well. The objective of this research work is to construct a realistic computational fluid dynamics (CFD) model of MOT for investigation. The MOT which is occupied with one unit of Air Conditioner has been selected for this study. The RH of air is analysed. The experimental data is collected by applying a digital air flow anemometer with USB interface and the channels digital handheld temperature thermometer meter data loggers for validation purpose. CFD simulation is conducted by applying ANSYS Fluent software. The experimental result and simulation is compared and validated. Based on the simulation and experiment findings, it reveals that ANSYS Fluent can be used for RH in MOT.

关键词： computational fluid dynamics simulation Minor Operation Theater Relative Humidity

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Influence of Blade Deformations on Open-Rotor Low-Speed and High-Speed Aerodynamics and Aeroacoustics 23

Influence of Blade Deformations on Open-Rotor Low-Speed and ...

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23rd AIAA/CEAS Aeroacoustics Conference

作者： Falissard, F. Boisard, R. Gaveriaux, R. Delattre, G. Gardarein, P. Chelius, A. Canard-Caruana, S. Mauffrey, Y. ONERA French Aerosp Lab Aerodynam Aerolast & Acoust Dept F-92190 Meudon France ONERA French Aerosp Lab Aerodynam Aerolast & Acoust Dept F-92322 Chatillon France

ISBN: (数字)9781624105043

ISBN: (纸本)9781624105043

This paper investigates by means of computational fluid dynamics (CFD) and acoustic analogy the influence of blade deformations on open-rotor aerodynamics and aeroacoustics for three key operating points: cruise, takeoff, and approach conditions. For each operating point, simulation results obtained with unrunning blade shapes and running blade shapes are compared with wind tunnel test measurements. Experiments show that blade deformations affect mostly the front rotor, with twist deviations at tip varying within a range of +/- 2 deg and of opposite sign between cruise and takeoff conditions. Although blade deformations are low for the rear rotor, aerodynamic performance exhibits significant variations due to the modifications of the front rotor wash. Numerical results show that accounting for blade deformations increases or decreases the thrust or power depending on the operating point and leads to a much better prediction of the open-rotor aerodynamic performance. The same comments apply for the noise prediction although differences on self-noise and interaction noise directivities are rather low.

关键词： Blade Passing Frequency Overall Sound Pressure Level Power Coefficient computational fluid dynamics simulation Transonic Wind Tunnel Reynolds Averaged Navier Stokes Airbus Fixed Wing Aircraft Flow Separation Power Spectral Density

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Coupled Flight dynamics and computational fluid dynamics simulations of Rotorcraft/Terrain Interactions

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JOURNAL OF AIRCRAFT 2017年第6期54卷 2228-2241页

作者： Oruc, Ilker Horn, Joseph F. Shipman, Jeremy Penn State Univ Dept Aerosp Engn University Pk PA 16802 USA CRAFT Tech Pipersville PA 18947 USA

The objective of this study is the investigation of rotorcraft/terrain interactions using Navier-Stokes computational fluid dynamics coupled with a helicopter flight dynamics model. In the coupled simulations, the flight dynamics model is free to move within a computational domain, where the main rotor forces are translated into source terms in the momentum equations of the computational fluid dynamics solution. Simultaneously, the computational fluid dynamics calculates induced velocities that are fed back to the simulation and affect the aeroloads in the flight dynamics. The computational fluid dynamics solver models the inflow, ground effect, and interactional aerodynamics in the flight dynamics simulation. Free-flight simulations were performed with full rotorcraft flight dynamics regulated by a dynamic inversion controller. simulation results are shown for a helicopter hovering in ground effect at different altitudes above the ground, over partial ground and sloped ground, and near a wall. A transition into forward-flight maneuver was performed, where a recirculation flow and ground vortex is shown. To verify the computational fluid dynamics predictions, predicted outwash flows were compared with recently published measurement data and showed reasonable correlation. simulations of ground effect are shown to correlate well with recent experimental measurements of the power reduction of a rotor at constant thrust near a ground plane.

关键词： Flight dynamics Rotorcraft simulations computational fluid dynamics simulation Helicopter Rotor Aerodynamic Force Coefficients Helicopter Flight dynamics Horseshoe Vortex Flight simulation Flight Deck Airframes

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Influence of Blade Deformations on Open-Rotor Low-Speed and High-Speed Aerodynamics and Aeroacoustics

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JOURNAL OF AIRCRAFT 2018年第6期55卷 2267-2281页

关键词： Overall Sound Pressure Level Blade Passing Frequency computational fluid dynamics simulation Transonic Wind Tunnel Aerodynamic Performance Power Coefficient Reynolds Averaged Navier Stokes High Aspect Ratio Airbus Fixed Wing Aircraft

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Ballistic Wave from Projectiles and Vehicles of Simple Geometry

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AIAA JOURNAL 2018年第7期56卷 2725-2742页

作者： Varnier, Jean Le Pape, Marie-Claire Sourgen, Frederic Off Natl Etud & Rech Aerosp Dept DAAC Aeroacoust F-92320 Chatillon France Off Natl Etud & Rech Aerosp Dept DMFN Fluid Mech F-92320 Chatillon France Off Natl Etud & Rech Aerosp Dept DMAE Aerothermodynam F-31400 Toulouse France

The ballistic wave is a shock wave generated by a solid body moving at supersonic speed in the atmosphere. It sounds like the crack of a whip for small projectiles and like a detonation (sonic boom) for large-sized objects. Their common signature is a N-shaped pressure profile, the formalism of which is well known but presents a practical difficulty, namely, the calculation of the shape factor, which characterizes the aerodynamic behavior of the object flying at supersonic speed. In the present Paper, we present that calculation for simple geometric shapes defined by their algebraic equations, by using both numerical and analytical approaches. The results do not seem realistic in some cases of round-tipped shapes, which leads us to adopt, in general, a simplified form for the shape factor, different from what is sometimes used in the literature. On the other hand, such an approach suggests to us to take into account separately the ogival length and the overall length of the body. To compare classic and improved models, examples of ballistic-wave calculation are given for some bullets and small-caliber shells of which the shape is roughly defined. Finally, it appears interesting to test these models on a larger scale by simulating the sonic boom of the Apollo Command Module during its atmospheric reentry and the sonic boom of the F-104 Starfighter in horizontal flight. The results obtained seem to justify the improvements proposed for the theoretical model of ballistic wave and sonic boom arising from flying objects of simple geometry.

关键词： Projectiles Shock Front Hypersonic Speed Detonation Aerodynamics Supersonic Aircraft computational fluid dynamics simulation Lift Coefficient Rockets Stagnation Point

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computational fluid dynamics simulation of formaldehyde emission characteristics and its experimental validation in environment chamber

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Journal of Chongqing University 2010年第3期9卷 124-132页

作者：刘志坚 School of Environmental and Municipal Engineering Xi'an University of Architecture and Technology

We investigated the effect of supply air rate and temperature on formaldehyde emission characteristics in an environment chamber.A three-dimensional computational fluid dynamics(CFD) chamber model for simulating formaldehyde emission in twelve different cases was developed for obtaining formaldehyde concentration by the area-weighted average *** experiments were conducted in an environment chamber to validate the simulation results of twelve different cases and the formaldehyde concentration was measured by continuous *** results show that there was good agreement between the model prediction and the experimental values within 4.3 difference for each *** CFD simulation results varied in the range from 0.21 mg/m3 to 0.94 mg/m3,and the measuring results in the range from 0.17 mg/m3 to 0.87 mg/*** variation trend of formaldehyde concentration with supply air rate and temperature variation for CFD simulation and experiment measuring was *** the existence of steady formaldehyde emission sources,formaldehyde concentration generally increased with the increase of temperature,and it decreased with the increase of air supply *** also provided some reasonable suggestions to reduce formaldehyde concentration and to improve indoor air quality for newly decorated rooms.

关键词： formaldehyde concentration environment chamber computational fluid dynamics simulation supply air rate temperature

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