23-09-2016, 09:14 AM
1455790511-REDUCTIONOFFUELCONSUMPTIONININDIANTRAINBYIMPLEMENTINGAERODYNAMICSTECHNIQUES.doc (Size: 1.16 MB / Downloads: 4)
Abstract
Railway train aerodynamic problems are closely associated with the flows occurring around train. This has led to larger energy losses and performance deterioration of the train system, since the flows around train are more disturbed due to turbulence of the increased speed of the train, and consequently the flow energies are converted to aerodynamic drag, noise and vibrations.. These are of major limitation factors to the speed-up of train system.. Aerodynamics of train will be considered and hence the literature survey has been carried out in this paper. Existing prototype models be investigated and then the alterations will be made to reduce the drag and also it will help in improving fuel economy. Modeling and analyzing will be carried out in Gambit and Fluent packages respectively. Model with alterations be fabricated and tested in low speed subsonic wind tunnel. Modifying train geometry can reduce drag, improving fuel economy.
Introduction:
The investigation into the mechanics of train, bluff body aerodynamics has been a lengthy study. A large portion of the bluff body drag is associated with the extreme pressure drop in the train. Indian railway does not concentrate to reduce pressure drag over the body and interference drag between garage gaps. It is not economical to change the overall Indian train shape. Only small alteration in the shape will give the good economic result. This paper explains the reduction of drag in train using passive flow control techniques and gives positive result in fuel consumption.
1. Drag area:
Aerodynamic drag is an important factor in train fuel consumption. Pressure drag which is the main component of total drag is a result of boundary layer separation from vehicle surface.
Flow separation incurs a large amount of energy loss and limits the performance of many flow-related devices (e.g., airfoils, automobiles, train etc.). Researchers have been trying to mitigate or eliminate flow separation for over a century because of its large potential payoff in practical applications. Numerous passive and active separation control strategies have been attempted with varying degrees of success. Passive techniques involve geometric modifications to alter the flow characteristics, while active methods involve the use of flow actuators to modify the flow and therefore require external energy addition.
3. Aerodynamic effects in train:
For the purpose of development of a faster and safer train system with lower air pollution and noise, many researchers are paying much attention on the aerodynamics of high-speed railway train. These works have attention to the development of new-generation train body, rail and tunnel systems. The aerodynamic phenomena with regard to high-speed railway train are strongly dependent on the train speed. Thus, the aerodynamic problems become more important as the train speed increases.
In general, the train aerodynamics are related to aerodynamic drag, pressure variations inside train, train-induced flows, cross-wind effects, ground effects, pressure waves inside tunnel, impulse waves at the exit of tunnel, noise and vibration, etc. The aerodynamic drag is dependent on the cross-sectional area of train body, train length, shape of train fore- and after-bodies, surface roughness of train body, and geographical conditions around the traveling train. The train-induced flows can influence passengers on the platform and is also associated with the cross-sectional area of train body, train length, shape of train fore- and after-bodies, surface roughness of train body.
Drag reduction in train:
A three-dimensional near field flow analysis has been performed for axial and cross wind loading to understand the airflow characteristics surrounding a train like bluff body. Results provide associated drag for the train geometry including the exterior rearview mirror. Modifying train geometry can reduce drag, improving fuel economy
Train aerodynamics
Decreasing the fuel consumption of train, due to environmental and selling arguments reasons, concerns train manufacturers. Consequently the improvement of the aerodynamics of train shapes, more precisely the reduction of their drag coefficient, becomes one of the main topics of the automotive research sectors. Designing a train with a minimized Drag resistance provides economical and performance advantages. Decreased resistance to forward motion allows higher speeds for the same power output, or lower power output for the same speeds.
Regimes of external flow:
Consider the external flow of real fluids. The potential flow and boundary layer theory makes it possible to treat on external flow problem as consisting broadly of two distinct regimes, that immediately adjacent to the body’s surface, where viscosity is predominant and where frictional forces are generated, and that outside the boundary layer, where viscosity is neglected but velocities and pressure are affected by the physical presence of the body together with its associated boundary layer.
In addition, there is the stagnation point at the front of the body and there is the flow region behind the body (known as the wake).