Abstract
This work presents the research results of the aerodynamic brake influence, mounted on the high-speed train's roof, on the flow field and overall braking force. The train consists of two locomotives at each end and four passenger cars between, with 121m of overall length. Aerodynamic brakes are designed to generate braking force by means of increasing the aerodynamic drag by opened panels over the train. Flow simulations were made by Fluent 12.1 software, for the train without and with one, two and three aerodynamic brakes, and velocities of 30, 50 and 70m/s. Drag force per unit panel area was determined as a function of train's velocity and the brake position. Contributions to train's gross braking force of each brake, obtained by simulations were: for first 24%, for second 15% and third 14.8%, and showed, also with panels' pressure distribution, good correlation with the aerodynamic drag calculations for flat plate orthogonally disposed to flow stream.
Highlights
The aerodynamic brakes, designed in the form of panels mounted over the roof of high speed train, have a task to generate the drag force by increasing the aerodynamic drag in open position
It could be seen that high-pressure in front of the panel was largest for the train velocity of 70m/s, as expectable
The force of aerodynamic drag is proportional to the square of train velocity, pulling out of panels over the train can create a braking force with defined intensity that becomes more significant by increasing the train velocity
Summary
The aerodynamic brakes, designed in the form of panels mounted over the roof of high speed train, have a task to generate the drag force by increasing the aerodynamic drag in open position. The brake that is in open position blocks the air stream and causes the overpressure appearances in front of and under-pressure behind of braking panel. In Fig.1.a and 1.b, the first brake position was shown at the distance of 6m behind the train nose, and in Fig. 1.c the placement of second brake, which was placed at 17m behind the first one. 2. THE AERODYNAMIC DRAG OF THE FLATE PLATE PLACED ORTHOGONALLY TO THE FREE STREAM. Calculation results for the aerodynamic drag per flat plate unit area, for the velocities of V = 30, 50 and 70m/s, are given in the Table 1
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