Search Results

This paper is an attempt to estimate the traffic demand of private vehicles in the Philippines and Thailand toward 2030. Estimation of road traffic volume is one of the most important elements for determining fuel consumption and emission gas levels. The level of passenger car ownership is still low, but there has been a distinct shift toward passenger cars due to the lack of mass transport. In Asian countries, inspection and maintenance and emission standards are the most important policy measures. The projections of car stock are evaluated as the emissions of PM, CO and NOx by applying these policy measures in the case of Thailand.

To get the useful information for a ventilation in tunnels, two-dimensional turbulence flow fields around trucks in tunnels are, as the first step, calculated numerically, while changing the vehicular gap and ejecting speed of gas exhausted from the rear of truck. In addition, to compare the calculated and measured results, the flow patterns in tunnel are visualized by an optical method of laser light sheet and pressure distributions along to center line of the truck are measured by a pressure transducer. Consequently, relationships between the flow and diffusion patterns of exhausted gas and aerodynamic characteristics around the truck are discussed for various vehicular gaps. Furthermore, the pressure coefficients and flow patterns obtained by calculation are found to be in reasonable agreement with those obtained from measurement.

Much attention has been paid in recent years to the enhancement of automobile performance and the improvement of fuel consumption at high speeds. Accordingly, it has become necessary to acquire a precise grasp of automobiles aerodynamic characteristics [1, 2, 3, 4, 5]. Compared with automobiles, however, the general level of interest in the aerodynamic characteristics of snowmobiles has remained low. This relative lack of interest is attributable to the fact that, because the area of the front projection of a snowmobile is comparatively small and the vehicle itself is very light, little emphasis has been placed on fuel economy. Moreover, it is attributable to the facts that improvements in aerodynamic characteristics of snowmobiles do not produce the dramatic effects that they do in automobiles, and finally because of the lack of strong demands in society for such improvement.

For the past several years, construction of Japanese road network has maintained a rapid pace, but those roads, having many automotive tunnels, are affected by mountainous topography. The air pollution in tunnels by exhaust gases from cars, especially those from large-size vehicles, has become problematical in Japan. The purpose of this paper is to clarify the flow behavior, especially wake structure behind trucks, and their aerodynamics characteristics at overtaking in road vehicle tunnels with digital image processing technique and three dimensinoal numerical analysis.

It is very difficult to measure and analyze the internal flows of torque converters because of their complicated construction. In this report, an attempt is made to calculate the characteristics of torque converters by the combination of a one-dimensional flow theory and a finite difference calculation. From the computed results however, it is significant to note, that this experimental result is more useful as a rational design procedure than the pure angular momentum theory.