What is automotive engineering?
Automotive engineering, alongwith Aerospace Engineering and Naval Architecture, is a branch of vehicle engineering. In automotive engineering, mechanical engineering elements, electrical engineering, software engineering, and safety engineering areapplied to vehicle design, production, and operation, including motorcycles, cars, trucks, and related subsystems.
In addition, the field of automotive engineering includes modifications and modifications of vehicles. The scope of production by creating and bringing together all parts of automobiles is also part of the automotive engineering field. Automotive engineering is highly dependent on research, and mathematical models and formulas are directly applied in this area. The field of study of automotive engineering includes the design،, development, manufacturing, and testing of vehicles or vehicle parts from the design and Idea stage to the production stage. Manufacturing development and production account for the three main functions of Automotive engineering.
CFD analysis in automotive engineering
The physical aspect of the transmission phenomenon in macroscopic dimensions is regulated by Newton’s laws of motion and the basic principles of the rules of the survival of the mass, system, energy, and chemical species. Based on the nature of the problem and the quantities in question, these basic concepts can be expressed as algebraic, differential, or integral equations.
Numerical simulation is one technique that replaces governing transition equations with algebraic ones and provides a numerical description of phenomena in space or computational domains.
All engineers use one of three experimental methods, precise and numerical solutions, to find the quantities of defined issues. Numerical simulation is an excellent way to provide the quantities of transmission equations. Usually, in numerical methods, problems are solved in an attempt and error with very high repetition.
Computational fluid dynamics (CFD) can be used for conceptual studies of new designs, minor design and equipment development, troubleshooting, and redesign. CFD methods are significantly cheaper and, at the same time, much faster than laboratory methods (including wind tunnels). Another important point is that using CFD makes it easy to simulate the conditions it can provide in laboratory methods that are very difficult and sometimes impossible. For example, one of these is checking the performance of equipment at very high or very low temperatures. Addressing all details is another CFD strength point. You can extract and save data and answers for any desired point using CFD.
Undoubtedly, the automotive and rail transportation industries are one of the most important industries involved with fluid issues. Air, water, fuel, exhaust gases, coolants, Hydraulic and lubrication are the most important fluids studied in the world of land transportation, which has more than hundreds of fluid mechanics engineering issues in the design and construction of a vehicle, locomotive, wagon, and container.
Aerodynamic design, acoustic, HVAC systems, power generation, brake cooling, Hydraulic, and various internal parts such as engines, safety, and lighting are the most important areas in which the automotive and rail transport industries always use CFD.
Aerodynamics and Acoustic
Fuel consumption is an entirely familiar term for everyone, and reducing fuel consumption is one of the constant goals of designers and engineers. Today, in most countries, fuel consumption is one of the important factors in car purchases for the middle class to the bottom. The noise of the car also always harms the driver and the occupants. This noise may be from engines, pumps, suspension systems, tires, or airflow. The sound caused by the wind, or the same acoustic (aerodynamic noise), is usually produced due to the geometric shape of the vehicle and the quality of the low construction of components and their assembly. In the improper assembly of cars, aerodynamic noise is an aerodynamic vibration generator. In such a situation, in addition to producing abnormal sounds, we should wait for the vehicle to reduce the useful life of the vehicle room and sound it at a lower time.
The aerodynamics of vehicles is developed and used due to these two important issues reducing fuel consumption and aerodynamic noise (acoustic). However, it is also instrumental in solving problems such as vehicle stability at high speeds and movement in bolts. With a brief overview of the history of the land transportation industry, including riding cars, trucks, trucks, tanks, bunkers, Locomotives, and wagons, it is easy to understand the advancement of knowledge and technology in the field of aerodynamics. Aerodynamics directly impacts the appearance of all vehicles, and this effect will continue.
Reducing the amount of waste (drag) means reducing fuel consumption; therefore, to reduce fuel consumption, it is necessary to reduce the amount of waste. It is required to carefully evaluate all design concepts (apparent shapes proposed for a car or any vehicle under design) and determine their coefficient. CFD and wind tunnels are the most important tool for calculating and measuring the drag coefficient. Although the wind tunnel results are always more credible than CFD responses, it is much more expensive and slower. Today, CFD is the most used tool for determining the vehicle’s coefficient of drag.
Since the current ruling around the car is a turbulent flow, it is inherently unstable due to turmoil. On the other hand, in vehicles’ design, not a momentary amount of drag coefficient (instability caused by turbulence), but its average value is used. Therefore, the assumption of being stable in solving the flow field around vehicles to calculate the drag coefficient is perfectly appropriate. To achieve maximum accuracy in calculating the drag coefficient, it is necessary to first consider all the vehicle details in geometric modeling as much as possible. Secondly, the network produced has a maximum quality. Thirdly, higher orders for the breakdown of equations should be used, and fourthly, the appropriate turbulence model should be used. The use of RANS Turbulence models satisfies the accuracy of the calculation of the drag coefficient, but if you use models of filtered equations such as LES, you can get more accurate, although it will cost more and more time.
In the acoustic simulation, the situation is slightly different. It is recommended that the flow be solved in a transient and used LES filtered models to achieve more precision. On the other hand, aerodynamic noise occurs in more areas, or it is more intense than geometric changes are extreme in them. Therefore, it is necessary for the network produced in those areas to be sufficiently reasonable and quality—mirrors, gaps, grooves, space inside the fenders, and around the wheels. The trunk and, in general, behind the car are among the places where the highest amount of aerodynamic noise occurs. The solution to current instability, the use of the LES model, and the production of the appropriate computing network are the most important suggested solutions for simulating the aerodynamics or the same acoustics.
They say they should enjoy the path to reach their destination. In domestic and overseas trips (due to the abundance and time), the comfort and tranquility of drivers, passengers, and passengers are considered social and general comfort. Air pollution, sound pollution, heat, moisture, and cold can be very good reasons for the physical and mental harassment of humans. Headaches, dizziness, nausea, heart palpitations, etc., are the consequences of improper ventilation inside the vehicle. Also, the lack of proper ventilation has made the route of travel, the most important result being a reduction in focus with acceleration and acceleration in driving and an increase in the likelihood of accidents.
Due to the above, the importance of properly designing HVAC systems is not covered by anyone. These systems must be designed and built with the latest knowledge and technology. Many standards have been developed for air and sound pollution, maximum air speed, pressure, humidity, and temperature range suitable for all vehicles from types of riding and used to passenger and cargo wagons. The land transportation industry is also required to implement them.
Clean air supply with temperature, moisture, pressure, and, of course, the severity of the current is the main task of the HVAC and vehicle systems. To provide air conditioning inside vehicles, HVAC systems consist of three main parts: clean air supply, cooling, and heating. Since most of the above sections are associated with airflow and operating fluids, CFD is the best computing tool for studying, researching, developing, and designing HVAC systems.
It is considered at an appropriate speed and severity when discussing clean air supply, purification, and air release with authorized air pollution. The airflow reinforced by the wings passes through filters, channels, and ultimately valves into the cabin space, room, coupé, or wagons. An Incompressible, turbulent stream, assuming permanent, is an exemplary flow regime for simulating such issues. Of course, to simulate and solve the flow currents of the fan, it is necessary to consider the flow of the Paya stream, an unbreakable turbulent and rotational period.
In cooling equipment, CFD can be used to simulate the flow to study the performance of fans, evaporators, conveyors, receivers, and pressure drops in hoses and channels, along with air operating fluids, water vapor, water, or air conditioner gas coolers. This equipment’s dominant flow of turbulent incompressible current is accompanied by heat transfer. However, simulating Condensers, evaporators, and receivers, simulation of two-phase currents is recommended by transmitting mass between phases (such as water vapor to water). Also, to check the performance of the fans, it is necessary to solve the permanent flow field, incompressible, turbulent, and rotational.
In the heating system of vehicles, the flow behavior of radiators, hoses, channels, and fans is considered. Generally, the flow in the heating system is less complicated than the flow in the cooling system. Steady incompressible and turbulent flow with heat transfer is the overall flow in heating systems, whose simulation using CFD methods is routine and standard work.
Another point, technically not included in the definition of HVAC, but is mentioned in this section due to its importance in establishing the comfort and relaxation of the passengers, is acoustics and noise pollution. The simultaneous solution of flow with acoustics in the interior and exterior of vehicles is the best and, simultaneously, the most expensive method proposed. Of course, by simplifying and applying more assumptions, the complexity and accuracy of the problem can be reduced!
The last word is that modeling with full details of equipment and interior space, suitable network with a sufficient number of elements, use of appropriate disturbance model, acoustics, and also simulating multiphase flows with mass transfer (water vapor to water) are the most important challenges in using CFD are in air conditioning systems.