Aerodynamic Analysis on Noise Generated from Automotive Side Mirror Using CFD

Computational analysis of flowing exhaust gases inside a non-perforated silencer chamber of a commercially available three-cylinder inline four-stroke spark-ignition engine and in a modified perforated design was conducted and their respective levels of performance were predicted. Study on the existing and proposed silencer designs was carried out by way of computational fluid dynamics (CFD) analysis, structural analysis and modal analysis. Modal analysis has been performed in order to compute up to six fundamental frequencies on the aforementioned structure for analysing the response spectra for obtaining the natural frequencies at different modes of excitation. A reduction of 23.8% and 23.6% in the maximum values of static pressure and total pressure, respectively, has been observed for the proposed perforated model against the existing non-perforated silencer. The maximum acoustic power level and the maximum surface acoustic power level were found to be 9.5% and 7.3% respectively, less for the proposed design.

In this study, the effects of classical side mirrors and side-view cameras on the aerodynamic drag coefficient of a city bus model were investigated with Computational Fluid Dynamics (CFD). The surface profile of 1/5 scale bus was modeled with CATIA v5 program. Aerodynamic analyzes were per-formed with ANSYS Fluent® v18. Reynolds Average Navier-Stokes (RANS)-based Reynolds Stress Model (RSM) was used as the turbulence model. The ground effect was taken into consideration in all analyzes. The solution do-main for 5% blockage ratio was created. Inflation layers are used on the ve-hicle surface regarding velocity changes due to viscous effects. The mesh number independence of analyzes was examined for the bus model without side mirrors and provided for 1.3 M mesh element. The Reynolds number in-dependence of the analysis was investigated by using the optimum number of mesh. Free flow velocity of 90 m/s and above were found to be adequate for Reynolds number independence. The drag coefficient was calculated for the bus with side mirrors by using optimum mesh and wind speed as well. The drag coefficients for the bus with side mirrors and side view cameras were de-termined 0.53 and 0.521 respectively.

Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicles (UAVs) offer significant advantages in operations requiring both vertical lift and efficient forward flight. However, VTOL aircraft design is challenge in terms of stability, control, and aerodynamic efficiency across flight regimes. Aerodynamic analysis is conducted to determine the variations of pressure distributions, lift and drag forces and center-of-pressure (CP) movement all of which are important towards design optimization and control modeling. This study focuses on aerodynamic analysis of a small VTOL fixed-wing UAV without using any additional actuators or complex tilting mechanisms. The designed UAV only uses the regular control surfaces such as Aileron, Rudder and Elevator of the fixed wing aircraft for maneuverability. Computational fluid dynamics (CFD) has become a essential tool in aerodynamic design and analysis. Studies of flyingwing VTOL UAVs revealed that CFD is effective in the prediction of stability and flow separation which is critical in transition controllability [1]. The structural and CFD studies were also coupled which showed that aeroelastic effects at high lift and inertia can be critical to performance and safety [2]. CFD has also been useful in wing and fuselage optimization to minimize drag and preserve lift as well as in the prediction of aerodynamic coefficients by use of turbulence models to provide reliable control inputs [3]. In addition to CFD, low-order methods like XFLR5 have been used to facilitate initial design through evaluation of centerof-gravity balance and optimization of wing geometry under structural constraints [4] [5]. On this basis, th present work implements CFD and XFLR5 to examine the aerodynamic forces, pressure field, and CP-CG interaction in a fixed-wing UAV-VTOL.

Statement of the Problem: A mineral trioxide aggregate (MTA) apical plug is commonly applied prior to endodontic treatment of open-apex teeth. However, difficult application and condensation of MTA in the apical region is a drawback of this technique.Purpose: This study aimed to compare the microleakage of MTA apical plug applied by the manual technique and indirect use of ultrasonic with different powers.Materials and Method: In this in vitro, experimental study, divergent open apices were created in 48 single-rooted, single-canal teeth using ProFile. The teeth were randomly divided into four experimental groups (n=10). All groups received 5-mm thick MTA apical plug at the apical region using one of the following methods. In group 1, MTA was manually condensed while in groups 2-4, indirect ultrasonic energy with minimum, medium, and maximum power levels was used for MTA plug condensation. After setting of MTA, the apical microleakage of the MTA plug was quantified using the fluid filtration method. Data were analyzed using the Mann-Whitney and Kruskal-Wallis tests (p< 0.05).Results: Significant differences were noted in microleakage of MTA plug between the manual group and ultrasonic groups with medium (p= 0.043) and maximum (p= 0.029) power levels. No significant difference was noted in microleakage of other groups (p> 0.05).Conclusion: Considering the current results, it seems that application of MTA with indirect ultrasonic energy at medium or high power level would decrease the microleakage of MTA plug in open-apex root canals.

A summary of the computational aerodynamic performance tools and analyses for the development of the Surfing Aircraft Vortices for Energy (SAVE) formation flight concept is presented. Aerodynamic analysis is accomplished using several, multi-fidelity prediction methods, including a vortex lattice method (VLM) approach, a panel method to model body effects, and a high-fidelity hybrid computational fluid dynamics (CFD) method that couples a Reynolds Averaged Navier-Stokes (RANS) flow solver for the near-body simulation with a quasi-3D RANS approach for the evolution of wakes over long longitudinal distances. Computational analysis is used to develop a comprehensive aerodynamic database for flight simulation and control law design, to develop a drag benefit “map”, which is used to determine the optimum location of the trailing airplane relative to the leading airplane wake, and to compare with flight-derived performance data to validate the use of CFD for the SAVE program. Finally, an extension of the hybrid CFD method and initial results for a 3-airplane echelon formation to highlight the multiple wake interaction effects and complex flow physics is presented.

Numerical investigation of whistling sound in narrow-gap flow of automobile side mirror

Considerable improvements in the aerodynamic performance of a vertical axis wind turbine (VAWT) can be achieved by integrating computational fluid dynamics (CFD) simulation and wind tunnel investigation in their design improvement. With the growing demand for energy worldwide, conventional sources are becoming more scarce and expensive. Wind is among the most popular and fastest growing sources of alternative energy in the world. It is an inexhaustible, indigenous resource, pollution-free, and available almost any time of the day, especially in coastal regions. Industry experts predict that, with proper development, wind energy could provide 20% of the nation’s energy needs. Vertical axis wind turbines (VAWTs) may be as efficient and practical as, and simpler, and significantly cheaper to build and maintain than, horizontal axis wind turbines (HAWTs). They have other inherent advantages; for example, they always face the wind. VAWTs include both a drag-type configuration, such as the Savonius rotor, and a lift-type configuration, such as the Darrieus rotor. The Savonius wind turbine is the simplest. Its operation depends on the difference in drag force when the wind strikes either the convex or concave part of its semi-cylindrical blades. It is good at self-starting and works independently of wind direction. However, its efficiency is relatively lower than that of the lift-type VAWTs. Due to its simple design and low construction cost, Savonius rotors are primarily used for water pumping and to generate wind power on a small scale and its large starting torque makes it suitable for starting other types of wind turbines that have inferior starting characteristics. Recently, some generators with high torque at low rotational speed, suitable for small-scale wind turbines, have been developed, suggesting that Savonius rotors may yet be used to generate electric power. The main goal of this research work is to improve the aerodynamic performance of the three bladed vertical axis Savonius wind turbine. Based on this goal, the objective of this project is to study the performance characteristics of the Savonius wind turbine scale models both experimentally and numerically. The turbine scale models will have different designs with different overlap ratios (ratio of gap between two adjacent blades and the rotor diameter) and without overlap within three blades. The experimental measurements and testing will be conducted in front of a low speed subsonic wind tunnel at different Reynolds number and the computational fluid dynamic (CFD) flow simulation around those design models will be performed by commercial CFD software FLUENT and GAMBIT.

The Planar Inlet Design and Analysis Process (PINDAP) is a collection of software tools that allow the efficient aerodynamic design and analysis of planar (two -dimensional and axisymmetric) inlets. The aerodynamic analysis is performed using the Wind -US computational fluid dynamics (CFD) program. A major ele ment in PINDAP is a Fortran 90 code named PINDAP that can establish the parametric design of the inlet and efficiently model the geometry and generate the grid for CFD analysis with design changes to those parameters. The use of PINDAP is demonstrated for subsonic, supersonic, and hypersonic inlets.

The development of large medium-speed catamarans aims increasing economic viability and reducing the possible negative influence on the environment of fast sea transportation. These vessels are likely to operate at hump speed where wave-making can be the dominating component of the total resistance. Shallow water may considerably amplify the wave-making and hence the overall drag force. Computational fluid dynamics is used to predict the drag force of medium-speed catamarans at model and full scale in infinite and restricted water to study the impact on the resistance. Steady and unsteady shallow-water effects that occur in model testing or full-scale operation are taken into account using computational fluid dynamics as they are inherently included in the mathematical formulations. Unsteady effects in the ship-model response were recorded in model test experiments, computational fluid dynamics simulations and full-scale measurements and found to agree with each other. For a medium-speed catamaran in water that is restricted in width and depth, it was found that computational fluid dynamics is capable of accurately predicting the drag with a maximum deviation of no more than 6% when compared to experimental results in model scale. The influences of restricted depth and width were studied using computational fluid dynamics where steady finite width effects in shallow water and finite depth effects at finite width were quantified. Full-scale drag from computational fluid dynamics predictions in shallow water ( h/L = 0.12 – 0.17) was found to be between full-scale measurements and extrapolated model test results. Finally, it is shown that current extrapolation procedures for shallow-water model tests over-estimate residuary resistance by up to 12% and underestimate frictional forces by up to 35% when compared to validated computational fluid dynamics results. This study concludes that computational fluid dynamics is a versatile tool to predict the full-scale ship resistance to a more accurate extent than extrapolation model test data and can also be utilised to estimate model sizes that keep finite-water effects to an agreed minimum.

An investigation into the aerodynamic characteristics has been presented for a bio-inspired flapping wing aircraft. Firstly, a mechanism has been developed to transform the usual rotation powered by a motor to a combined flapping and pitching motion of the flapping wing. Secondly, an experimental model of the flapping wing aircraft has been built and tested to measure the motion and aerodynamic forces produced by the flapping wing. Thirdly, aerodynamic analysis is carried out based on the measured motion of the flapping wing model using an unsteady aerodynamic model (UAM) and validated by a computational fluid dynamics (CFD) method. The difference of the average lift force between the UAM and CFD method is 1.3%, and the difference between the UAM and experimental results is 18%. In addition, a parametric study is carried out by employing the UAM method to analyze the effect of variations of the pitching angle on the aerodynamic lift and drag forces. According to the study, the pitching amplitude for maximum lift is in the range of 60°~70° as the flight velocity decreases from 5 m/s to 1 m/s during landing.

Aerodynamics analysis has become a mindset for high performance vehicles. This is because it provides valuable insight on a vehicle motion during different phases. There are vast varieties of software available like ANSYS Workbench, Star CCM+, Autodesk Simulation, SimFlow, FeatFlow, Autodesk Inventor etc. Amongst these softwares, Star CCM+ and ANSYS Workbench are the most widely used. Normally, it is observed that considerable users are confused in choosing the right software for CFD simulation because of a large variety of commercially available softwares. The present study provides comparative results to users of Computational Fluid Dynamics (CFD) with the driven case study. In the present case, authors chose the most commonly used CFD softwares, the ANSYS Workbench Fluent and the Star CCM+. Polyhedral meshing was applied on computer aided model of a car in both of these softwares. It has been found that coefficients of drag and lift achieved by aerodynamic analysis of a car are in a small marginal approximation between both ANSYS Workbench Fluent and Star CCM+ softwares. In the case of Star CCM+, CD was around 0.261 and CL was 0.07; however, in the case of ANSYS Workbench Fluent approximations were found to be 0.271 for CD and 0.05 for CL.

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Formula SAE Collegiate Competition teams now regularly integrate aerodynamic body kits with their vehicles which have significant benefits in producing downforce. This use of body kits (or aero packages) and the improvement to vehicle aerodynamics they provide, have resulted in these systems becoming a necessity for any team wishing to remain competitive in Formula SAE (FSAE). To address this the Lawrence Technological University (LTU) Formula SAE team incorporated an aerodynamic body kit into their 2018 vehicle. Using computational fluid dynamics (CFD) an aerodynamic analysis was performed comparing the efficacy of a car that did not have an aero package to a car that did. Two separate simulation programs were employed to effectively and accurately assess this change. By using both SolidWorks and SimScale software to generate data, the results of each were compared to assess the accuracy of each. These programs were selected due to their accessibility to engineering students, as well as their parent companies being LTU Formula SAE team sponsors. Simulations were run under different conditions to determine the optimal design of the aero package, as well as to understand how the body kit performed at different velocities. It is expected that the approaches used and understanding gained from this initial effort will serve as a foundational body-of-knowledge for future LTU teams. Those LTU teams each year will be able to modify and refine these now-available CFD tools to assess and optimize their aero package for each new vehicle they design and build annually.&lt;/div&gt;&lt;/div&gt;

CFD study and experimental validation of trickle bed hydrodynamics under gas, liquid and gas/liquid alternating cyclic operations

Analysis of aerodynamic characteristics of car diffuser for dissimilar diffuser angles on Sedan’s using CFD

This paper describes the design and development of surfboard-fins as products for marine sports. The purpose of the research is to improve turning ability by reducing drag force on the fins. Design modification was conducted, based on conventional fins, to increase turning ability and lower drag force. Three modified center-fins and three modified side-fins were selected. The design process involved 3D-CAD fin configuration models created with ProENGINEER Wildfire and utilized computational fluid dynamics from 3D-CAD data. Solid forms, which are required in this study since fin configuration is streamlined, are difficult to use in 3D-CAD software. Therefore, a surface element software (NURBS) developed by a propeller maker in Japan was used and the fins were converted into solid forms. After producing the fin models, the performance of factors such as turning ability and drag force were calculated using computational fluid dynamics. A flow experiment was conducted using a flow water tank in Western Hiroshima Prefecture Industrial Research Institute. This report commences with an explanation of the modifications on the fin models to improve turning ability and lower the drag force. It is then followed by the flow analysis using computational fluid dynamics software and the flow experimental results.