## 4 Experimental Analyses
### Multi-Factor Coupling Analysis of the Air Pressure Curves  
To explore the influence of different parameters on the air pressure changes inside and outside the car, the air pressure changes inside and outside the KLK2 elevator car are analyzed under different operating parameters and the structure parameters of the IE-FF of the car. The numerical analysis is used to solve the law of air pressure changes inside and outside the car under different parameters. The specific simulation analysis process is shown in Figure 11. Ansys 2020/ICEM/CFD is utilized to mesh the model. The maximum element size meshed in the elevator car is 100 mm, the maximum element size meshed in the ventilation gap of car wall is 3 mm, the maximum element size meshed in the ventilation gap of car door is 3 mm, the maximum element size meshed in the air inlet is 200 mm, the maximum element size meshed in the ait outlet is 200 mm, and the maximum element size meshed in the hoistway wall is 200 mm. The boundary conditions  
Figure 10: Air pressure value curves (measured by experiments) inside the elevator car. (**a**) At the same height (\(H=217\) m) and different speeds; and (**b**) at the same speed (\(v=10\)m/s) and different heights. of the elevator car and the hoistway walls are set as wall, boundary conditions of the car wall ventilation gap and car door ventilation gap are set as interior, and the boundary conditions of the air inlet is set as the velocity-inlet and the boundary conditions of the air outlet is set as pressure-inlet. The specific running parameters are set as is needed. Based on the simulation analysis results, the influence of maximum running speed, running acceleration, lifting height, air leakage of the car, and speed of the fans of the ventilation system on the air pressure inside and outside the car is analyzed. (1) The influence of elevator maximum running speed. For traditional low-speed elevators, the maximum running speed will not have a large impact on the air pressure inside and outside the car since the airflow speed in the hoistway is small relative to the car. However, with the increase of elevator speed, the problem of elevator aerodynamic characteristics has gradually become prominent, and the air pressure distribution outside the car has become more and more complicated. As the speed of the elevator increases, the air pressure outside the car fluctuates between \(\pm 100\) Pa, which is smaller than the low-speed elevators. The air pressure fluctuation outside the car will be transmitted to the inside of the car through the ventilation system and the leakage gap. According to numerical simulation, the influence of the elevator running speed on the air pressure inside and outside the car is shown in Figure 12. It can be seen that, when the overall lifting height of the elevator remains unchanged, the air pressure change amplitude caused by the speed increase is small, but it indirectly leads to an increase in the air pressure change rate, thus affecting the passenger ear comfort. (2) The influence of elevator running acceleration. By selecting three different elevator running accelerations, the relationship between the air pressure change inside and outside the car and the elevator acceleration is obtained, as shown in Figure 13. During the high-speed elevator operation, the air pressure change rate inside the car is not fixed. During the starting and braking of the elevator, the running acceleration also has an impact on the air pressure change inside the car, which directly affects the time for the air pressure change rate inside the car from slow to fast. Figure 11: Simulation analysis process of the air pressure change inside and outside the car. (3) The influence of elevator lifting height. The elevator runs in a vertical shaft, and the distribution of atmospheric pressure in the vertical direction changes linearly. It can be seen from Figure 10b that the elevator lifting height directly affects the air pressure change inside and outside the car.