摘要
本文以现场实测和风洞及水槽模拟实验结果为依据,论述了不同类型不同高度的挡风墙及铁路路堤对大风特性和车辆横风气动特性的诸多影响。
Based on the results obtained from field measurement and laboratory simulation in wind tunnel and water channel, the effects of wind brak wall and embankment on wind characteristics and lateral aerodynamic characteristics of railway cars have been described. The main conclusions are as follows.1. The mean wind speed profile above the embamkment can be expressed by index low except onto 1m. And the a decreases with the increase of embankment height H.2. The turbulence arc about the same within 10m above the embankment. And the Ix also decreases with the increase of H. 3. It is very significant that the effect of wind break wall on wind characteristics. Yielding a strong shear effect after the squeezing flow passes across the wind break wall, the shear layer is very stable and thin; and can be well described by function relationships. Under the shear layer, there is a wake region behind the wind break wall. The mean wind speed in this region sharply decreases by about 80%, and the turbulence increase by three times, and the mean wind speed profile can be well expressed by the function form, as shown in Fig. 4.4. It is slight that effects of embankment on lateral aerodynamic characteristics of box car. The Cx and Cy value slightly decrease with the increase of H, and the Cmz value is about the same on different heights of embankment, as shown in Tablel 1.5. The Cmz will suddenly drop in accordance with the increase of height of wind break wall. When the wind break wall height hD is equal to 3m or so, the Cmz value is basically less than zero.6. Fig 6 shows the pressure distribution of box car. It can be seen that with the increase of hD, the positive pressure region of windward side gradually reduces until finally changes into a nagative pressure area. and the peak suction of the roof moves backward and tends to be level off . and the negative pressure at the bottom surface also tends to level off, but the change of the negative pressure of lee side is slight. Fig. 7 shows a separation bubble occurs at the windward side of roof when ho value is about equal to that of Fig. 6. c.7. The Cy value is sensitive to a and Ix.
出处
《空气动力学学报》
CSCD
北大核心
1990年第4期430-436,共7页
Acta Aerodynamica Sinica
关键词
防风
风特性
横风气动特性
铁路
wind break wall, embankment, wind characteristics,railway car, lateral aerodynamic characteristics.
