- 學位論文
隧道內行車之模擬分析
Numerical Analysis of Vehicles Traveling in a Road Tunnel
摘要
本研究以Gambit 2.2.30軟體簡單繪製隧道和汽車結構，再用Fluent 6.2.16軟體來模擬各種行車情況的流場，其中Fluent的動態網格必須以C語言驅動。本論文先比較車輛在寬敞空間與隧道內行駛的差異，進而探討車輛在隧道內會車或超車時的流場反應。分析目標為比較左向和右向車輛在不同的速度下會車以及快車和慢車在不同的速度下超車的模擬結果，以及分析在會車點與超車點前後兩車互相影響時的氣動力變化。模擬結果顯示：(1) 車輛在寬敞空間與隧道內行駛時， 隧道內的車輛左右壓力呈現非左右對稱的現象。所以車輛有可能被推向隧道壁。(2) 隧道內高速開車時，因為隧道壁面的影響而對車輛產生側向力與橫擺力矩，使得高速車輛在隧道內較不容易控制的情形。 (3) 在隧道內會車時，兩車車速相差越大，瞬間改變的壓力值也相應越大。(4) 在隧道內超車時，對慢車而言兩車速度相差越大，瞬間改變的壓力值也相應越大；而對快車而言，兩車速度相差越小，壓力改變幅度越大。(5) 在隧道內會車或超車，都會對車輛產生橫擺力矩為害行車的安全性，以及俯仰跟側傾力矩，影響行車的舒適性。
並列摘要
This study constructed the structures of the tunnel and vehicles using a commercial software, Gambit version 2.2.30. Then, the numerical analysis was performed on the flow field around traveling vehicles using Fluent version 6.2.16. In this case, the moving grid (dynamic mesh) available in Fluent was activated through C programming. In the beginning, the situations of a vehicle traveling in an open space and a tunnel were compared. After that, the flow fields corresponding to vehicle meeting and passing were investigated. The goal of analysis was focused the aerodynamics characteristics when two vehicles of different speeds were meeting or overtaking. The current results show: (1) Unlike traveling in the open space, the vehicle traveling in a tunnel experiences a non-symmetric pressure distribution on its surface. As a result, the vehicle is pushed to the tunnel wall. (2) While driving at a high speed in the tunnel, the vehicle is affected by the additional side force and yaw moment the tunnel wall produces making it more difficult to maneuver. (3) When two vehicles meet in a tunnel, the instantaneous change in pressure ratio increases with the difference in the vehicle speeds. (4) When a fast vehicle is passing a slow vehicle in a tunnel, the instantaneous change in maximum pressure acting on the slow vehicle increases with the difference in the vehicle speeds. In contrast, the instantaneous change in maximum pressure acting on the fast vehicle increases when the difference in the vehicle speeds reduces. (5) For vehicles meeting or passing inside the tunnel, aerodynamic forces on the vehicles will produce yaw moment, which jeopardizes the vehicle safety, as well as pitch and roll moments, which influence the vehicle comfortness.