Katsuji Tanemoto

Aerodynamic characteristics of train/vehicles under cross winds

The aerodynamic characteristics of train/vehicles under cross winds depend on not only the shapes of the vehicles but also those of infrastructures. Accordingly three kinds of wind tunnel tests were made to evaluate the aerodynamic characteristics of typical configurations of the vehicles on typical configurations of infrastructures such as bridges and embankments. The main results obtained from the wind tunnel tests are summarized below. 1. The aerodynamic side force coefficient of the vehicle increases more as the thickness of the bridge girder becomes larger. It also increases more as the roof of the vehicle becomes edgier. 2. The aerodynamic characteristics of the vehicle on the embankment depend on the distribution of the boundary layer on the ground. The aerodynamic side force coefficient of the vehicle on a high embankment is larger than that on a low embankment.

New train regulation method based on wind direction and velocity of natural wind against strong winds

Abstract Since there have been some railway accidents caused by strong winds in recent years in Japan, it is necessary to establish effective measures to prevent wind-induced accidents and ensure safety of train operation under strong winds. On February 22, 1994, a derailment accident was caused by strong winds on the Nemuro line of Hokkaido Railway Company. Railway Technical Research Institute carried out researches on investigation of the accident and measures at this section. As countermeasures, wind barriers were installed and a new train regulation method based on not only a natural wind velocity but also a natural wind direction was applied to the section. As a result, the railway company has had much less chances of slowdown and suspending of train operation than before and never experienced cancellation of train operation.

J184024 Wind tunnel test on windbreak fence installed on railway lines

4 To improve the safety and stability of railway transport under windy conditions, windbreak fences have been installed on more and more parts of railway lines in windexposed areas in Japan. To effectively and economically install windbreak fences, we need to know the relation between the perpendicular distance from a windbreak fence to the track and reduction in aerodynamic forces on railway vehicles. For that purpose, we conducted a wind tunnel test to measure the aerodynamic forces that act on a vehicle located at different perpendicular distances from the windbreak fence. We conducted the test for the 1/40 scale vehicle model of narrow gauge train series 103 under atmospheric boundary layer condition where representative wind speed is 30 m/s, using a large-scale low-noise wind tunnel (measurement section 5 x 3 x 20 m) at the Maibara Wind Tunnel Technical Center, RTRI. We installed a windbreak fence having a porosity of 40% at a height of 2 m (in full-scale dimensions) from the rail level on the windward side of a bridge/viaduct. A three-component aerodynamic force balance inside the vehicle model measured the side force and lift working on the model and the roll moment around the car-body center. The bridge model was actually composed of two sets of single-track bridges placed in parallel, the distance between the two of which could be varied. For the test on viaduct, we made several models with different widths. See Fig.1 for a photograph of the wind tunnel test on a viaduct. Figure 2 shows the relation between the side force coefficient (non-dimensional side force coefficient based on vehicle side area and dynamic pressure of wind) on an intermediate vehicle and the perpendicular distance from the windbreak fence. Where there are no fences, the coefficient of side force is approximately 1.4 both with bridges and viaducts. Where a fence exists, the value of the coefficient at a distance of 7 m from the fence is less than half that measured when there are no fences. At a distance of 13 m or over, the coefficient is larger with bridges than with viaducts, presumably because the two sets of single-track bridges are placed apart to allow air to flow in between. In the present wind tunnel test, we used the models of vehicle and bridges/viaducts all set in a static state. Accordingly, the relative motion of the vehicle and the bridges/viaducts, which occurs in full-scale situations, was not simulated in the test. We will further study this effect of the relative motion on the estimation of the effectiveness of windbreak fences. Wind Tunnel Test on Windbreak Fence Installed on Railway Lines

Evaluation of the Influence of Anemometer Position around Railway Structures on Wind Observation Data

Anemometers are used to detect wind speed for operation control of trains. Since these anemometers usually are installed close to railway structures along sections of railway line, the wind velocity data readings may be affected by the structures. This study uses wind-tunnel tests and field wind observations to investigate the influence of the anemometer position on the wind velocity readings. Three types of railway structure were considered: a single-track bridge, a double-track viaduct and a single-track embankment. The results showed that the maximum instantaneous wind-velocities at the anemometer position on the leeward side of the railway structure were higher than those at the reference point as the wind direction against the railway track approached 90 degrees. The height of the measurement point and the size of the wind-direction angle in relation to the location of the railroad truck had an effect on the maximum instantaneous wind-velocity ratios regardless of the kind of railroad structure and location (leeward or windward) of the measurement point.

Tolerance Estimation of Human Postural Stability Against Train Drafts

A wind tunnel experiment was conducted in order to study the effects of train-generated drafts on human postural stability. In the experiment, 29 people were exposed to a transient wind force similar to a draft from a passing train, and the results suggested that both wind speed and wind duration affect postural stability. In this paper, we estimated the tolerance of postural stability against transient wind based on a statistical model and a physical model, and discussed the validity of these models.