Drag Reduction of TVS Scooty using a Windshield for the Rider Comfort Improvement

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Sudhir Kumar Singh ◽  
B.P. Agrawal ◽  
Brahma Nand Agrawal ◽  
Kaushalendra Kumar Dubey ◽  
Sanjeev Kumar Sharma ◽  
...  
Keyword(s):  
Aerodynamic Force ◽  
Neck Region ◽  
Vehicle Speed ◽  
Baseline Model ◽  
Wind Noise ◽  
Pressure Drag ◽  
Computational Fluid Dynamics Cfd ◽  
The Stability ◽  
Two Wheeler ◽  
Rider Comfort

Rider comfort and safety has become an essential theme in the design of two-wheeler vehicles. Comfort incorporates wind noise, air pressure on the rider, visibility and the stability of the Scooty handle. Rider comfort and the potential aerodynamics concern have encouraged the current authors to carry out the Computational Fluid Dynamics (CFD) analysis of TVS pep+ Scooty. Numerical computations were carried out using the standard k-ε turbulence model to examine the aerodynamic force coefficients, pressure distribution, velocity vector and streamlines around the Scooty and rider. Simulations were done for a range of speed on an existing and redesigned model of Scooty with a different windshield height. The simulation result shows that there is a reduction in the coefficient of drag (Cd) from 1.58 (baseline model) to 0.95 (model 3) at a speed of 60kmph. The pressure contour reveals the inclusion of the windshield of height 130mm in the baseline model has diminished the pressure drag on the rider. Visual of velocity contour depicts that the velocity of the air decrease above the neck region with in-creasing windshield height at a vehicle speed 120kmph. This study reinforces the need of windshield height of 150mm in the baseline model to avoid unwanted aerodynamic benefits on the rider.

Ground Flutter Simulation Test Based on Reduced Order Modeling of Aerodynamics by CFD/CSD Coupling Method

2019 ◽  
Vol 11 (01) ◽  
pp. 1950008
Author(s):  
Binwen Wang ◽  
Xueling Fan
Keyword(s):  
Aerodynamic Force ◽  
Test System ◽  
Simulation Test ◽  
Robust Controller ◽  
Test Technique ◽  
Reduced Order ◽  
Aerodynamic Model ◽  
Flutter Boundary ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Flutter is an aeroelastic phenomenon that may cause severe damage to aircraft. Traditional flutter evaluation methods have many disadvantages (e.g., complex, costly and time-consuming) which could be overcome by ground flutter test technique. In this study, an unsteady aerodynamic model is obtained using computational fluid dynamics (CFD) code according to the procedure of frequency domain aerodynamic calculation. Then, the genetic algorithm (GA) method is adopted to optimize interpolation points for both excitation and response. Furthermore, the minimum-state method is utilized for rational fitting so as to establish an aerodynamic model in time domain. The aerodynamic force is simulated through exciters and the precision of simulation is guaranteed by multi-input and multi-output robust controller. Finally, ground flutter simulation test system is employed to acquire the flutter boundary through response under a range of air speeds. A good agreement is observed for both velocity and frequency of flutter between the test and modeling results.

Investigation of sustainability of lubricated journal bearing under relevant design parameters

2018 ◽  
Vol 70 (4) ◽  
pp. 789-804 ◽  
Author(s):  
M.M. Shahin ◽  
Mohammad Asaduzzaman Chowdhury ◽  
Md. Arefin Kowser ◽  
Uttam Kumar Debnath ◽  
M.H. Monir
Keyword(s):  
Aspect Ratio ◽  
Elastic Strain ◽  
Journal Bearing ◽  
Design Parameters ◽  
Content Type ◽  
Computational Fluid Dynamics Cfd ◽  
Stress Formation ◽  
Bearing Design ◽  
The Stability ◽  
Bearing Friction

Purpose The purposes of the present study are to ensure higher sustainability of journal bearings under different applied loads and to observe bearing performances such as elastic strain, total deformation and stress formation. Design/methodology/approach A journal bearing test rig was used to determine the effect of the applied load on the bearing friction, film thickness, lubricant film pressure, etc. A steady-state analysis was performed to obtain the bearing performance. Findings An efficient aspect ratio (L/D) range was obtained to increase the durability or the stability of the bearing while the bearing is in the working condition by using SAE 5W-30 oil. The results from the study were compared with previous studies in which different types of oil and water, such as Newtonian fluid (NF), magnetorheological fluid (MRF) and nonmagnetorheological fluid (NMRF), were used as the lubricant. To ensure a preferable aspect ratio range (0.25-0.50), a computational fluid dynamics (CFD) analysis was conducted by ANSYS; the results show a lower elastic strain and deformation within the preferable aspect ratio (0.25-0.50) rather than a higher aspect ratio using the SAE 5W-30 oil. Originality/value It is expected that the findings of this study will contribute to the improvement of the bearing design and the bearing lubricating system.

A numerical approach for the assessment of crosswind effects on barrier-protected trains running on bridges

2021 ◽  
Author(s):  
Giuseppe Porpiglia ◽  
Paolo Schito ◽  
Tommaso Argentini ◽  
Alberto Zasso
Keyword(s):  
Wind Tunnel ◽  
Velocity Profile ◽  
Wind Velocity ◽  
Aerodynamic Force ◽  
Numerical Approach ◽  
Aerodynamic Performance ◽  
Vehicle Speed ◽  
Initial Condition ◽  
Cfd Analyses ◽  
Moving Train

<p>This paper introduces a new methodology to assess the influence of a windscreen on the crosswind performance of trains running on a bridge. Considering the difficulties encountered in both carrying out wind tunnel tests that consider the vehicle speed or complete CFD analyses, a simplified CFD approach is here discussed. Instead of simulating simultaneously the windscreen plus the moving train, the numerical problem is split into two parts: firstly, a simulation of the windshield alone is used to extract the perturbed velocity profile at the railway location; secondly, this profile used as an inlet condition for the wind velocity acting on an isolated train. The method is validated against a complete train plus windshield simulation in terms of pressure distribution and aerodynamic force coefficients on the train, and flow streamlines. This approach opens to the possibility of evaluating the aerodynamic performance of a vehicle on bridges considering bridge and vehicle as separated. Wind velocity profiles measured on the bridge during a wind tunnel campaign could be used as the initial condition for numerical simulations on vehicles.</p>

Interfacial Interactions

2010 ◽  
pp. 128-177
Author(s):  
Wei Ge ◽  
Ning Yang ◽  
Wei Wang ◽  
Jinghai Li
Keyword(s):  
Temporal Distribution ◽  
Gravitational Potential Energy ◽  
Immersed Boundary ◽  
Immersed Boundary Methods ◽  
Additional Information ◽  
Mesoscale Structures ◽  
Computational Fluid Dynamics Cfd ◽  
Spatio Temporal ◽  
Drag Models ◽  
The Stability

The drag interaction between gas and solids not only acts as a driving force for solids in gas-solids flows but also plays as a major role in the dissipation of the energy due to drag losses. This leads to enormous complexities as these drag terms are highly non-linear and multiscale in nature because of the variations in solids spatio-temporal distribution. This chapter provides an overview of this important aspect of the hydrodynamic interactions between the gas and solids and the role of spatio-temporal heterogeneities on the quantification of this drag force. In particular, a model is presented which introduces a mesoscale description into two-fluid models for gas-solids flows. This description is formulated in terms of the stability of gas-solids suspension. The stability condition is, in turn, posed as a minimization problem where the competing factors are the energy consumption required to suspend and transport the solids and their gravitational potential energy. However, the lack of scale-separation leads to many uncertainties in quantifying mesoscale structures. The authors have incorporated this model into computational fluid dynamics (CFD) simulations which have shown improvements over traditional drag models. Fully resolved simulations, such as those mentioned in this chapter and the subject of a later chapter on Immersed Boundary Methods, can be used to obtain additional information about these mesoscale structures. This can be used to formulate better constitutive equations for continuum models.

Drag Reduction Through Changes in Cabin Geometry and Trailer Gap of Heavy-Duty Trucks

Volume 1 ◽  
2004 ◽  
Author(s):  
M. Lakshman ◽  
K. Aung
Keyword(s):  
Numerical Simulations ◽  
Aerodynamic Drag ◽  
Cost Savings ◽  
Vehicle Speed ◽  
Fuel Cost ◽  
Heavy Duty ◽  
Cross Sectional ◽  
Computational Fluid Dynamics Cfd ◽  
Imported Oil ◽  
Fuel Costs

Reduction of aerodynamic drag of heavy-duty trucks can significantly save fuel costs and US dependence on the imported oil. Reduction of aerodynamic drag by 30% can result in fuel cost savings in billions of dollars every year. Aerodynamic drag of truck depends on the frontal cross-sectional area and the speed of the vehicle. In addition, the gap between the cabin and the trailer significantly affect the drag of the truck. This paper investigates how changes in the cabin geometry and the trailer gap can reduce the aerodynamic drag using numerical simulations. The numerical simulations were carried out using Computational Fluid Dynamics (CFD) software, CFX-5.5, from AEA Technologies (now owned by ANSYS). Effects of vehicle speed, cabin geometry, and trailer gap on the aerodynamic drag were investigated.

Numerical and Experimental Investigation of the CeCOST Swirl Burner

2018 ◽  
Author(s):  
Erdzan Hodzic ◽  
Senbin Yu ◽  
Arman Ahamed Subash ◽  
Xin Liu ◽  
Xiao Liu ◽  
...  
Keyword(s):  
High Speed ◽  
Swirling Flow ◽  
Combustion Process ◽  
Stability Limit ◽  
Swirl Burner ◽  
Current Configuration ◽  
Stable Case ◽  
Eddy Simulation ◽  
Computational Fluid Dynamics Cfd ◽  
The Stability

Clean technology has become a key feature due to increasing environmental concerns. Swirling flows, being directly associated with combustion performance and hence minimized pollutant formation, are encountered in most propulsion and power-generation combustion devices. In this study, the development process of the conceptual swirl burner developed at the Swedish National Centre for Combustion and Technology (CeCOST), is presented. Utilizing extensive computational fluid dynamics (CFD) analysis, both the lead time and cost in manufacturing of the different burner parts were significantly reduced. The performance maps bounded by the flashback and blow-off limits for the current configuration were obtained and studied in detail using advanced experimental measurements and numerical simulations. Utilizing high speed OH-chemiluminescence, OH/CH2O-PLIF and Large Eddy Simulation (LES), details of the combustion process and flame-flow interaction are presented. The main focus is on three different cases, a stable case, a case close to blow-off and flashback condition. We show the influence of the flame on the core flow and how an increase in swirl may extend the stability limit of the anchored flame in swirling flow burners.

scholarly journals Research of the Design Feasibility of a 3-Wheel Electric Vehicle with a Simplified Control System

2020 ◽  
Vol 14 (1) ◽  
pp. 32-35
Author(s):  
Srđan Medić ◽  
Veljko Kondić ◽  
Tihomir Mihalić ◽  
Vedran Runje
Keyword(s):  
Control System ◽  
Electric Vehicle ◽  
Fem Analysis ◽  
Steering Wheel ◽  
Circular Path ◽  
Main Concern ◽  
The Finite Element Method ◽  
Vehicle Aerodynamics ◽  
Computational Fluid Dynamics Cfd ◽  
The Stability

The need for a simple, customised electric vehicle (EV) has inspired the research of the possibility to build a simple EV tailored for the specific needs of the buyer. This paper is focused on the concept of an EV with no conventional control mechanism. In this paper, a research of user needs, vehicle dynamics, vehicle aerodynamics, type of drive and batteries was carried out. EV aerodynamics characteristics were simulated by using the Computational Fluid Dynamics (CFD) software. The control system was designed in correlations with the maximal safe velocity and the radius of EV turning on a circular path. The stability of the EV, concerning the vehicle turning over and wheels slipping while driving in the curves, was the main concern of this paper. The steering wheel and brake pad were replaced with a control stick. Using the Finite Element Method (FEM) analysis, key parts of the construction were constructed.

Combined Effects of Waves and Currents on Offshore Pipeline Bundles

2007 ◽  
Author(s):  
M. H. Kamarudin ◽  
K. P. Thiagarajan ◽  
A. Czajko
Keyword(s):  
Flow Behavior ◽  
Hydrodynamic Characteristics ◽  
Equivalent Diameter ◽  
Offshore Pipelines ◽  
Main Pipe ◽  
Offshore Pipeline ◽  
Waves And Currents ◽  
Industry Practice ◽  
Computational Fluid Dynamics Cfd ◽  
The Stability

It is common practice to accompany offshore pipelines by smaller diameter service lines or umbilicals to create a bundle. This gives rise to the so-called piggyback configuration. The flow behavior around the bundle is not well-known, leading to concerns on the stability of the configuration. This paper investigates the influence of the piggyback on the hydrodynamic loadings on the bundle in wave plus current condition using Computational Fluid Dynamics (CFD). Key parameters of the configuration that were investigated were the orientation of the smaller pipe with respect to the main pipeline and the flow conditions (different Keulegan-Carpenter numbers). The gap between the seabed and the main pipe was set to zero for all cases investigated. It was found that the hydrodynamic characteristics of the main pipe were significantly influenced by the presence of the piggyback. The numerical results also showed that the orientation of the piggyback plays an essential role in determining the drag, lift and inertia coefficients for the bundle. This phenomenon is explained by examining the vortex flow patterns around the cylinders. It is shown that the established industry practice of assuming the hydrodynamic characteristics of the bundle to be the same as an equivalent diameter cylinder may underestimate the forces on the bundle, and lead to a non-conservative design.

Stability of Controlled Road Vehicles: A Preliminary Fundamental Study

2015 ◽  
Author(s):  
Fabio della Rossa ◽  
Massimiliano Gobbi ◽  
Giampiero Mastinu ◽  
Carlo Piccardi ◽  
Giorgio Previati
Keyword(s):  
Autonomous Vehicles ◽  
Autonomous Vehicle ◽  
Preliminary Investigation ◽  
Basin Of Attraction ◽  
Lateral Acceleration ◽  
Steering Wheel ◽  
Vehicle Speed ◽  
Vehicle Model ◽  
The Stability ◽  
Positive Effect

A comparison of the lateral stability behaviour between an autonomous vehicle, a vehicle with driver and a vehicle without driver (fixed steering wheel) is made by introducing a simple mathematical model of a vehicle running on even road. The mechanical model of the vehicle has two degrees of freedom and the related equations of motion contain the nonlinear tyre characteristics. The driver is described by a well-known model proposed in the literature. The autonomous vehicle has a virtual driver (robot) that behaves substantially like a human, but with its proper reaction time and gain. The road vehicle model has been validated. The study of vehicle stability has to be based on bifurcation analysis and a preliminary investigation is proposed here. The accurate computation of steady-state equilibria is crucial to study the stability of the three kinds of vehicles here compared. The stability of the bare vehicle without driver (fixed steering wheel) is studied in a rather complete way referring to a number of combinations of tyre characteristics. The (known) conclusion is that the understeering vehicle is stable at each lateral acceleration level and at each vehicle speed. The additional (partially unknown) conclusion is that the vehicle (model) with degradated tyres may exhibit a huge number of different bifurcations. The driver has many effects on the stability of the vehicle. One positive effect is to eliminate the many possible different equilibria of the bare vehicle and keep active one single equilibrium only. Another positive effect is to broaden the basin of attraction of stable equilibria (at least at relatively low speed). A negative effect is that, even for straight running, the driver seem introducing a subcritical Hopf bifurcation which limits the maximum forward speed of some understeering vehicles (that could run faster with fixed steering wheel). Both the mentioned positive and negative effects appear to be applicable to autonomous vehicles as well. Further studies could be useful to overcome the limitations on the stability of current autonomous vehicles that have been identified in the present research.

Thermal Modeling of Plated-Through Hole Vias in a FBGA Package

2003 ◽  
Author(s):  
X. Howard Sun ◽  
Z. Zhao ◽  
R. Sahan
Keyword(s):  
Cross Section ◽  
Compact Model ◽  
Junction Temperature ◽  
Cfd Simulations ◽  
Baseline Model ◽  
Small Individual ◽  
Plated Through Hole ◽  
Computational Fluid Dynamics Cfd ◽  
Die Temperature ◽  
Through Hole

The objective of this study is to compare different geometric models to represent thermal vias (plated though holes - PTH) in the substrate of a 196-ball FBGA package. The baseline model, which models each via individually as PTHs, was compared with models that model each via individually by solid cylinders and square cross-section prismatic blocks, and a compact model that models all vias by one prismatic block. The computational fluid dynamics (CFD) simulations were carried out using Icepak®. It was found that all simplifications led to some degree of under-prediction of the junction temperature. The results showed that the detailed models with the cylindrical cross-section and the square cross-section under-predicted the junction temperature by about 3–4% compared to the baseline model. The compact model, however, under-predicted the junction temperature by about 10% compared to the baseline model. The explanation for this error produced by the compact model is that it cannot model the constriction effect of the small individual thermal vias. The conclusion of this study is that all simplifications led to some degree of under-prediction of the junction temperature, and the popular technique to model the thermal vias by a block can lead to appreciable errors in predicting the die temperature.

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