Search Results

Automakers are seeking more efficient and green vehicles projects in terms of fuel consumption and CO2 emissions. Several factors are directly related to the performance and one of the most important is the aerodynamics. Cars with smooth geometries and transitions are expected to have a better aerodynamic behavior compared with the ones with rough geometries. Regardless the vehicle geometry changes, another way to improve the aerodynamics is by adding new parts, in order to improve the drag coefficient of the car. Most of the time, these parts are added but the functionality is not well defined. The main objective of this work is to identify, explain the way it should work and some applications of additional aeroparts. Those parts could be assembled in a vehicle in order to improve the drag coefficient, have a better fuel economy and lower emissions rate.

The work here presented aims to study different types of ground configurations, located at the test section of a wind tunnel and to check their influence on the drag coefficient of one car, using only computer simulations. The drag coefficient of a vehicle is one of the most important aerodynamic proprieties, and as low as this drag value can be, the car performance will increase and the fuel consumption will decrease, item which has been pursued in new vehicles. Starting from one real wind tunnel test of a small pickup, with static test section ground, a virtual model was built and tested using CFD, following the same configuration of the real test. The difference between test and simulation results was 0.25%, showing that the methodology here used is reliable. After that, two other types of ground were simulated: elevated plate and moving belt and the results show that drag value decreased 0.002 and 0.012 respectively, compared to the value obtained with static ground simulation.

Thanks to advances in Computational Fluid Dynamics - CFD codes, i.e. algorithms and turbulence models, complex CFD vehicles simulations are increasing not only in academia, but also in the industry itself. The aim of the simulations is to verify the aerodynamic behavior of a car at early stages of the project, when no prototype is available, and to reduce the total aerodynamic development time of a new vehicle. The turbulence model considered in the CFD simulation should be able to capture the main flow effects around the vehicle. Most importantly, the predicted total drag value of the vehicle has to be comparable to the values obtained in wind tunnel tests. The main focus of the presented work is a comparison of wind tunnel and CFD results of the same small production hatchback vehicle.

The brake system is of vital importance when engineering a new vehicle due to its implication with both safety and overall performance. One of the main questions that arise when designing the brake system, not only in terms of performance but also in efficiency and fuel economy is how to make a better brake rotor. When designing the brake rotor, thinking about mass reduction and design optimization is a desire not only for high-performance motorsport, but for daily user applications. The impact on the vehicle performance would lead to improved fuel economy and braking safety. In this work, we propose to exploit some characteristics that can optimize the rotor design to achieve better performance, compared to a baseline design proposed. Some constructive characteristics are kept constant such as the rotor diameter and thickness. The use of computational fluid dynamics (CFD) simulations is considered in this study as a benchmark to future physical prototypes experiments.

Autonomous vehicles, which are defined as capable of sensing environment and navigating without any human input, are the top trend of the automobilist industry in terms of technology. The computers responsible for the control are able to set the vehicle to optimum operation point. With the advent of Computational Fluid Dynamics -CFD software, it is possible to study drag reduction proposals when the vehicles drive at the velocity, which contributes to increase fuel economy. In this context, based on a sedan virtual drag model, several simulations cases were developed considering different vehicle arrays and changing the distance between each one. The study aims to demonstrate, using virtual simulations, the potential drag coefficient reduction when vehicles are moving in a constant speed and which configuration leads to better performance increment. Taking the isolated vehicle as the baseline value, all the vehicles in the different arrays were analyzed.

This work here presented shows a comparative computational fluid dynamics study of several wheel openings designs and its influences on the drag coefficient measured over a high performance sedan. For all wheels designs, two situations were compared for the same speed of 110 km/h: static wheels - fixed ground and rotating wheels - moving ground. Results show that the drag coefficient value in the rotating wheel case is lower compared to the same wheel design in the static wheel case. Flow pattern and differences are illustrated by pressure, velocity and wake contours. These differences on rotating and non-rotating wheels are important for the correct development of underbody aero parts for all kind of vehicles.

Aerodynamics plays a critical hole in open wheels race cars. The work here presented shows a comparative study of different undertrays design and their influence over the drag coefficient measured on an open wheel prototype race car, using CFD simulations in a virtual wind tunnel. For all cases, velocity was 60 km/h and it was considered both moving ground and rotating wheels to look for a more realist representation of the real interaction between car and racetrack. One model without any aero-part was taken as baseline and three different undertrays proposals were evaluated looking for an aerodynamic improvement. As final results, the drag coefficient of the proposals were ranked and compared with baseline results. Also pressure, velocity and wake images help to illustrate the improvements on the drag coefficient by using an undertray in this vehicle.

This study refers to the Computational Fluid Dynamics, demonstrating a comparative between the drag coefficient and the frontal area of a current production car with the same values obtained from a conceptual proposal of removing the outside rearview mirrors of this same vehicle. Both cases were simulated in a virtual wind tunnel with moving ground and rotating wheels condition at speed of 100 kph, aiming to represent the best way a car moving on a highway. The main objective of this paper is improving the efficiency of automotive vehicles by replacing the current outside rearview mirror for cameras placed in smaller structures. The first simulation showed that by removing the outside rearview mirrors both the frontal area of the car and the drag coefficient, which has direct influence on fuel economy calculation, are smaller compared to current solution.

Moving ground simulation plays an important role on aerodynamic studies of road vehicles, in order to reproduce the real movement condition. Due to cost of implementing a moving ground, many wind tunnels employ static ground simulation with boundary layer control. The work here presented aims to study using Computational Fluid Dynamics - CFD simulations the effect of using moving ground simulations with rotating wheels against a baseline configuration using both static ground and wheels over a small pick-up truck. The study aims to determine the influence of using different flow velocities on the drag coefficient measured over this vehicle using both ground configuration. For the cases here presented we performed steady state Reynolds-Averaged Navier-Stokes - RANS numerical simulations, following similar setup as the industry best practices and using the same mesh.

CFD is becoming very popular among the industries and the use of multiphase simulations is also increasing with more powerful CPUs and reliable CFD codes. The scope of this work is to present a mud deposition simulation methodology using CFD multiphase analysis at the CRFM of an automobile, in order to prevent low performance on the condenser or on the radiator and compromise the heat exchange performance. Mud reaches the front end of the car and results show the mud path and mud deposition on the CRFM and the blocked area.

Vehicle fuel filling may not occur the fastest way, mainly due to the filler neck geometry and low fuel flow from the pump. When the fuel tank in empty, the previous interferences are increased, once the inner pressure increases, complicating even more the fuel filling activity. Another problem that occurs due to poor filler neck design is fuel pump nozzle shut off, once the fuel flow can’t overcome the tank inner pressure causing fuel to return, turning off the pump or even leakage. The recent advances in CFD Codes and computational power allowed multiphase simulations to be performed in production level by the industries worldwide. This paper takes advantage of these advances and proposes a methodology for fuel filling simulation using multiphase CFD simulation in order to evaluate a filler neck design, by measuring the total filling time.

Considering the increment of computational power and the accuracy on the results, virtual engineering tools are becoming more popular among the industries, especially inside the automotive, seeking development time and cost reduction. Taking advantage of the modern resources, it was developed a simulation methodology in order to verify the water flow behavior from the roof to the side ditch of the vehicle's roof. Within this methodology it is possible to virtually test a vehicle without a real prototype, analyze the roof performance and suggest design changes without any prototype part being made, which implies in cost and development time reduction.

The advances in High Performance Computing-HPC and CPU's sizes and processing power, combined with new computational codes, which are capable of coupling different types of simulation, are the main contributors for the increasing number of the Multiphysics simulations inside the industry. Multiphysics are defined as simulations involving multiple physical models or multiple simultaneous physical phenomena. Among some examples, spray modeling is of great interest in several branches of the industry and, with the development on algorithms and codes, simulations presented reliable results, compared to experiments. This work aims to contribute to both Multiphysics and spray modelling by reproducing a rainstorm condition, focused on a vehicular application. This work objective is evaluate the possibility and feasibility to reproduce virtually rain storm condition on a highway checking water intrusion at Air Intake System - AIS and compare with physical test.

Within the advances in Computer Fluid Dynamics algorithms and High Performance Computing, large clusters become available at low costs allowing virtual simulations that were not possible some years ago at reasonable costs and time. This work uses intensively this condition and applies these advances on brake system optimization. The methodology developed in the present work verifies the best angular position for caliper inside the wheel to reduce the rotor temperature during braking process such as downhill procedure. Thus, this method is applied to a mini-VAN vehicle, where the best position is found, based on two design parameters: rotor temperature and convection heat transfer coefficient. This study shows that the most suitable position for initial selection is the first one.

The Ahmed Body is one of the most widely studied bluff bodies used for automotive conceptual studies and Computational Fluid Dynamics - CFD software validation. With the advances of the computational processing capacity and improvement in cluster costs, high-fidelity turbulence models, such as Detached Eddies Simulation – DES and Large Eddies Simulation – LES, are becoming a reality for industrial cases, as studied by BUSCARIOLO et al. (2016) [4], evaluating DES models to automotive applications. This work presents a correlation study between a computational and physical model of an Ahmed Body with slant angle of 0 degree, also known as a squared back. Physical results are from a wind tunnel test, performed by STRACHAN et al. (2007) [11] considering moving ground and Reynolds number of 1.7M, based on the length of the body.

Cargo trucks are one of the most important and flexible ways of moving cargo within inlands. In some countries, such as Brazil, the economy relies on them to transport all kinds of products, from field and factory to consumer. In order to reduce freight prices, beside route optimization, truck manufactures started to focus on the aerodynamics development of those vehicles, in order to improve the efficiency, reducing fuel consumption and emissions. Although the truck aerodynamics development is important, most vehicles are not manufactured or don’t consider the truck trailer, which plays a key role in the full aerodynamics performance of the truck, once it might increase the front area and also change the overall aero performance.

A real-time monitoring method for brake temperature rise in long downhill varying velocity according to a pattern to evaluate the BET (Brake Equilibrium Temperature) is expensive in time and money. The solution proposed here take advantage of recent advances in CFD Codes and computational power that allowed big models being run on clusters of production level by the industries worldwide. This paper takes advantage of these advances and proposes a methodology for Brake cooling simulation at downhill following a previously downhill map of time x velocity x pedal pressure. The methodology proposed presented 95% correlation with physical test and now is possible, in virtual word, to evaluate the entire downhill procedure for a new vehicle design before any physical prototype is available.

Within the advances in CFD codes and HPC cluster size and processing capacities, multiphase CFD simulations became more feasible not only on research projects but also in production level. This work presents a simulation analysis of an automotive vehicle crossing certain height of water and analyzing the water ingestion by the air intake system and also the pressure load due to the water level and splashes reaching the vehicle. All the calculations were performed by Computational Fluid Dynamics, considering the car crossing 300mm of water height at 20 kph with a simulation time enough to the water reaches the whole car length. Results show the water path at the snorkel region and some part pressure load examples which can be used as an input for structural simulations to evaluate this part at this particular condition.

The automakers pursue for fuel economy is increasing year after year, both by the demands of society and by political pressures, leading companies to develop new solutions and technologies in order to increase the energy efficiency of vehicles. With the advent of CFD software, it is possible to study drag reduction proposals, which contributes to increase fuel economy. In this context, based on a small sedan vehicle virtual drag model, correlated with the wind tunnel test, a conceptual wheel was assembled proposing 3 blade angles in order to verify the influence on the drag coefficient. Considering the drag contribution of wheel in total vehicle drag is around 25%, this work aims to show the sensitivity in the drag coefficient by changing the wheel rim of a small sedan vehicle.

Aerodynamics plays a key role in nowadays vehicle development, aiming efficiency on fuel consumption, which leads to a green technology. Several initiatives around the world are regulating emissions and efficiency of vehicles such as EURO for European Marketing and the INOVAR Auto Project to be implemented in Brazil on 2017. In order to meet requirements in terms of performance, especially on aerodynamics, automakers are focusing on aero-efficient exterior designs and also adding deflectors, covers, active spoilers and several other features to meet the drag coefficient. Usually, the aerodynamics properties of a vehicle are measured in both CFD simulations and wind tunnels, which provide controlled conditions for the test that could be easily reproduced. During the real operations conditions, external factors can affect the flow over the vehicle such as cross wind in open highways.