With the rapid development of high-speed railway in China, caused when the high speed train aerodynamic issues are also increasingly prominent, especially when the two trains passing each other when the air flow between the two vehicles being squeezed on the train surface pressure of a strong transient the impact of window glass may cause damage by pneumatic impact, if the incoming pressure wave of passenger compartment seal could also lead to poor passengers tinnitus, dizziness and other symptoms. In addition, cars will also be alternating the impact of the aerodynamic forces and moments, the train could trigger the horizontal and vertical vibration, and snake-like movement, not only exacerbated the wheel and rail wear, affecting train safe and stable operation, and serious cases even give rise to the train derailment, overturning and other major incidents. However, the car will open wire high-speed train and air pressure wave force (moment) variation, and the size of the main factors that affect them, such as two-train speed, train dimensions and spacing, line spacing or car specific relationship between parameters is still lacking. When the train speed through the sound barrier, the train winds have a great load of air pressure fluctuation in the sound barrier on the fatigue life of the sound barrier has a great influence, once the sound barrier for the destruction of strength or fatigue failure, and could threaten driving safety. In order to achieve high-speed train safety, comfort, low energy consumption, etc., must be the process of aerodynamic characteristics of trains passing intensive research. Paper, based on three-dimensional, viscous, unsteady, compressible, unsteady flow equations and the k-ε turbulence model, using CFD finite volume method and moving grid of a high-speed trains will be open air pressure waves and air force car (moment) was simulated. Analysis of the train crossing when the body surface pressure and aerodynamic forces (moments) of the change process, get the train along the longitudinal pressure wave peak, the vertical distribution, as well as between the cars aerodynamic forces similarities and differences. 6 by calculating the line spacing to a variety of train speeds under the stationary bike in accordance with the fair, fair and non-isokinetic isokinetic intersection of the pressure wave and air force (moment), to find out the speed of the train to arbitrary pressure waves and air force rendezvous (moment) method of the size, the car will be pressure waves and air force (moment) and the speed of trains passing by, line spacing and distance between vehicles quantitative relationship. In addition, analysis of the intersection when the train constant 3 and 2 different types of pressure wave height and aerodynamic noise barrier for high-speed railway and high-speed trains to the design. The results show that: (1) train crossing, the body surface, the car will be the measuring point pressure and aerodynamic forces of the cars and the end of the first wave size and shape of the peaks and the velocity of the flow where the direction and size. (2) the car will train with the air pressure wave force (moment) the size of the intersection not only with the size of train speed, and faster than through the relative speed and relative speed of the train there is a function of the ratio.When the train speed in any intersection when the car will peak and amplitude of pressure wave velocity ratio is 6 times the relative polynomial; aerodynamic drag coefficient and relative velocity ratio of 4 times polynomial; aerodynamic side force coefficient and relative faster than the 2 power polynomial; aerodynamic lift coefficient, roll moment coefficient, pitching moment coefficient, moment coefficient and the deflection is relatively faster than the train are 3 power polynomial. (3) the car will be pressure waves and air force (moment) and the line spacing or distance between vehicles negative exponential relationship. (4) decreases with the relative velocity ratio, pressure wave and air force (moment) relative to the first wave coda down, so the intersection is not constant in the high-speed train, the intersection with the rear when the train harmful levels of aerodynamic characteristics may be much larger than the intersection with the aerodynamic characteristics of train-truck. (5) aerodynamic pitching moment, yaw moment in the train crossing the peak occurred during the 6 months, change of direction 4 times greater impact on the smooth operation of the train. (6) different structural forms of air suffered by the force of sound barrier is not the same: the unit length of the sound barriers on the tower minimum power of the bullied, the largest inverted L-type sound barrier, within the 45 ° type of tilting center; sound barrier over by the aerodynamic the train speed increases, aerodynamic force and train speed is proportional to the square; simply repeating what barrier height increases, the air force had been increased accordingly.
Key words: high-speed train; will car pressure wave; aerodynamic characteristics; numerical simulation
No comments:
Post a Comment