International Research Journal of Engineering and Technology (IRJET) Volume: 04 Issue: 04 | Apr -2017
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e-ISSN: 2395 -0056 p-ISSN: 2395-0072
SIMULATION OF PASSENGER CAR BY ATTACHING ADD-ON DEVICE TO REDUCE DRAG FORCE BY CFD APPROACH Shashank Arya1, Pankaj Goud1, Vishal Sharma1, Shubham Mathur1, Sourabh Tripathi1, Vishal Shukla2 1
Research Scholar, Department of Mechanical Engineering, IITM College, Gwalior
2
Assistant professor, Mechanical Department , IITM College, Gwalior- 475001, Madhya pradesh ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract -
As we know the consequence of drag force over a car is increasing due to better conditions of road which leads the driver to drive a car fastly, as the car runs fastly on highway the amount of air resistance increases .this increased resistance relatively rising the fuel consumption The Research is about the simulation of passenger car by using add-on devices to reduce drag force by computational fluid dynamics (CFD) approach. A passenger car prototype is firstly prepared in CATIA software and this prototype is imported in Hyper mesh Fluent for further investigation of drag coefficient, the three aspectal computational analysis was carried out using with the help of software tools like ANSYS-CFX to simulate the flow of air around the automobiles , CFD code were used to run the simulation. The main purpose of the study is to predict the drag coefficient and lift coefficient computationally. Several factors that influence the drag coefficient such as flow separation, vortex, effect of pressure coefficient, Detail velocity profile and pressure distribution plots around the car envelopes have been presented.
other hand, Interior aerodynamics is the study of flow through passages in solid objects[1]. If air resistance can be minimized, the car will be more efficient because less energy is lost to friction[2]. Today, car designers is keen to show their designing skills over the external face of a vehicle to reduce drag force by attaching add-on devices such as spoiler, VGs, tail-plates, splines, diffuser on the body of car and these devices do not worsening the design of a car & increase its efficiency. Investigation of aerodynamic drag can be done experimentally by wind tunnel experiment and computational numerical simulation by cfd technique and software was used ANSYS FLUENT and Altair’s virtual wind tunnel, leveraging Acusolve’s CFD technology. In this paper our numerical analysis was done by cfd technology on software to cut drag force on passenger car using add-on devices spoiler, diffuser, VGs, tail plates etc. A more elaborate description of CFd technology is given below :
Key Words: Drag & lift force, Coefficient, virtual wind tunnel,
2. HOW TO UTILIZE CFD SIMULATION IN VEHICLE AERODYNAMICS & STEPS
prototype of passenger car, ANSYS-CFX, Hyper mesh fluent, spoilers, spline , tail-plate, VGs
1.INTRODUCTION “Aerodynamics” is a stem of fluid dynamics concerned with studying the movement of air, predominantly when it interacts with a moving object . Understanding the motion of air (often called a flow field) around an object enables the estimate of forces and moments acting on the object. Typical properties considered for a flow field consist of velocity, pressure, density and temperature as a function of position and time[1]. Airflow over a vehicle determines the drag forces, which in turn affects the car’s performance and efficiency testing equipment has been designed to measure both the vertical and horizontal components of air resistance on a prototype car. When a car goes faster and faster the weight of the car changes due to air resistance. Depending on the direction (upward or downward) this is called either lift or down force, respectively. The horizontal component, the drag of the prototype of car will be measured. Drag is the amount of force that the air is pushing on the car at a certain speed[2]. Aerodynamics and its analysis are basically divided into two major sub-categories, namely the exterior and interior aerodynamics. Exterior aerodynamics is the study of flow around solid objects of various shapes. On the
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Computational fluid dynamics (CFD) is one of the branches of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. Computers are used to simulate the contact of liquids and gases with Faces defined by boundary conditions. Computational Fluid Dynamic codes are prearranged around the numerical algorithms that can tackle fluid flow problems. All the CFD codes available in the market have three basic elements which split the complete analysis of the numerical experiment to be performed on the specific domain or geometry[1]. The three basic elements are-
(i) Pre-processor (ii) Solver and (iii) Post-Processor[1]
2.1 MESHING AND PRE-PROCESSING The pre-processing of the CFD process consists of the input of a flow problem by means of user-friendly programs or software and the successive transformation of this input into a form is made appropriate to use by the solver. The pre-processor is the link between the user and the solver. The user activity at the pre-processing stage of the CFD process involves the following[1]:
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