城市隧道射流通风的模型实验及数值模拟

发布时间：2018-03-19 11:08

本文选题：射流通风　切入点：模型实验　出处：《西南石油大学》2015年硕士论文　论文类型：学位论文

【摘要】：纵向射流通风方式因其简易而经济被广泛应用于隧道通风系统中。通风系统中射流风机的提速和升压作用使得隧道内污染气体向洞口流动从而向外排出。本文基于相似原理进行了模型实验,通过模型实验与数值模拟相结合的方法研究了射流通风下隧道内气体的流动情况。进而,通过数值模拟值与实验值的对比,验证了数值模拟的正确性。在此基础上,又以某市一座在建的公路隧道为原型,对不同风机组合方式下隧道内气体的流动情况以及隧道洞口废气在外界不同风向时的扩散情况进行数值模拟。通过分析数值模拟的结果,确定了有利于提速和升压的风机串联组合方式以及隧道洞口外部污染区域的范围,为隧道内风机开启方式及隧道周围建筑群规划提供了参考意见。本文的主要结论如下所示： 1.通过研究多组模型实验的测量数据可知,模型隧道内不同位置的风速沿程变化呈现一定的规律性。模型隧道中线处的风速随着距风机出口距离的增加而逐渐下降；距模型隧道中线0.08m处,风速随着距风机出口距离的增加先增加后下降；距模型隧道中线0.16m处,风速沿程变化不大,在一定数值范围内波动。 2.通过对比数值模拟的计算值与模型实验的测量值可知,两者的变化趋势一致,并且数值大小基本接近。 3.采用Fluent建立三维稳态湍流模型,研究了四种不同的风机串联模式下隧道内风速和压力分布情况。将四种工况下的风速和风压进行对比,选出了一种最优的方案。由此可知,隧道内通风效果,不仅仅是取决于串联的组数,也取决于串联的模式。并且无论是哪种串联模式,相邻风机组之间的距离不宜太远,以利于升压和提速。 4.采用Fluent数值模拟了隧道洞口外静风和有风的情况下废气的扩散情况。由模拟结果可知,无风情况下废气主要向前方扩散,而有风情况下废气则主要沿风向扩散。有风情况下废气向高空扩散的速度要比无风情况下慢,距地而40m高度以下,CO的质量分数已满足规范要求。然而废气向道路两侧和隧道前方扩散的快慢则依外界风向与风速而定。
[Abstract]:The longitudinal jet ventilation is widely used in the tunnel ventilation system because of its simplicity and economy. The velocity and pressure rise of jet fan in the ventilation system make the polluted gas in the tunnel flow to the opening of the tunnel and then be discharged from the tunnel. The model experiment is carried out on the principle of similarity. The flow of gas in the tunnel under jet ventilation is studied by the combination of model experiment and numerical simulation. Furthermore, the correctness of the numerical simulation is verified by comparing the numerical simulation value with the experimental value. Taking a highway tunnel under construction in a certain city as a prototype, the flow of gas in the tunnel under different fan combinations and the diffusion of exhaust gas from the tunnel entrance in different wind directions outside the tunnel are numerically simulated. The results of the numerical simulation are analyzed. The series combination mode of fan and the scope of the polluted area outside the tunnel entrance are determined, which provides the reference for the opening mode of fan in tunnel and the planning of building group around the tunnel. The main conclusions of this paper are as follows:. 1. Through studying the measurement data of many groups of model experiments, it can be seen that the wind speed changes along different positions in the model tunnel, and the wind speed at the center of the model tunnel decreases gradually with the increase of the distance from the outlet of the fan; At 0.08m from the center of the model tunnel, the wind speed increases first and then decreases with the increase of the distance from the outlet of the wind turbine, and the wind speed fluctuates in a certain value range from 0.16m to the center line of the model tunnel. 2. By comparing the calculated value of numerical simulation with the measured value of model experiment, it can be seen that the change trend of the two values is consistent, and the numerical value is basically close to that of the model experiment. 3. Using Fluent to establish a three-dimensional steady turbulence model, the wind speed and pressure distribution in the tunnel under four different fan series modes are studied. By comparing the wind speed and the wind pressure under the four operating conditions, an optimal scheme is selected. The ventilation effect in the tunnel depends not only on the number of units in series, but also on the mode of series. 4. Fluent numerical simulation is used to simulate the diffusion of exhaust gas under the condition of static wind and wind outside the tunnel, and the simulation results show that the exhaust gas mainly diffuses forward in the case of no wind. In the case of wind, the exhaust gas diffuses mainly along the wind direction. In the case of wind, the velocity of the exhaust gas diffusing into the upper air is slower than that in the case of no wind. The mass fraction of CO below 40 m above the ground has met the requirements of the specification. However, the speed of diffusion of exhaust gas to both sides of the road and the front of the tunnel depends on the outside wind direction and wind speed.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U453.5

【参考文献】