# Characteristics of Plane Gate Vibration and Holding Force in Closing Process by Experiments
## 2 Physical Model Test  
The physical model test made of transparent Perspex plastic, at the scale 1:25, was established based on the gravity similarity criterion and flow similarity criterion. The parameters of the steel plane gate in the actual project are shown in Table 1. The physical model test was composed of five parts: tank, chamber, narrow-section, pressure hole and drainage channel (Figure 1). Two plane gates with same size were made of Perspex plastic and hydro-elastic material, respectively. Meanwhile, the hydro-elastic gate model should satisfy the structural similarity criterion to ensure the normal similitude of gate stiffness [24]. The mass and elastic modulus of hydro-elastic gate is 7.36 kg and 8 GPa, respectively.  
In the physical model test, the plane gate was connected to the servo motor by steel cable and gate operation speed was 0.005 m/s. The tension sensor with a range of 100 kg was placed to measure the holding force. Three acceleration sensors were installed near the gate lug with lateral direction (gate width direction), vertical direction (gate height direction) and horizontal direction (flow direction), successively. Pulsating pressure sensors were arranged on the gate panel and bottom edge. Meanwhile, in the case of fixed gate opening the recording of data lasted for 60 s. In the case of closing process data acquisition lasted for the duration of the operation. Data Acquisition & Signal Processing (DASP) intelligent acquisition system developed by China Orient Institute of Noise & Vibration was employed to acquire and process the data cooperated with constant current power supplier. It can simultaneously measure the gate vibration acceleration and holding force at the sampling frequency of 200 Hz [25]. Data measuring, transmission and processing are depicted in Figure 2. Besides, in the physical model test, there are two operation modes of the gate, namely fixed gate opening and closing process. Gate opening ratio \(e\) in fixed gate opening equals gate opening height dividing the height of spillway tunnel. The upstream water depths were 0.64, 0.72, 0.8 and 0.92 m in the physical model test,  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Projects** & **Prototype Plane Gate** \\ \hline Spillway tunnel & \(6\times 14\) m\({}^{2}\) (width \(\times\) height) \\ Gate slot & \(8.4\times 1.6\) m\({}^{2}\) (width \(\times\) thickness) \\ Steel plane gate & \(7\times 14.2\times 1.4\) m\({}^{3}\) (width \(\times\) height \(\times\) thickness) \\ Mass & 100 t \\ Operation speed & 1.5 m/min \\ Support type & Sliding block \\ Seal & Downstream seal \\ Gate Bottom edge & Composite type (upstream inclination angle 50\({}^{\circ}\) and down inclination angle 30\({}^{\circ}\)) \\ Operation requirement & Closing in transient flow and opening in still water \\ Elastic modulus \(E\) & 200 GPa \\ Poisson’s ratio \(\mu\) & 0.3 \\ density \(\rho\) & \(7.85\times 10^{3}\) kg/m\({}^{3}\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Parameters of the prototype gate.  
Figure 1: Schematic diagram of experiment setup.  
successively (prototype depths were 16, 18, 20 and 23 m, respectively). Downstream outflow condition is free outflow. Rectangular weir was arranged in front of the drainage channel to measure the flow rate. The water levels on the tank and the rectangular weir were measured through water level meters. In addition, in closing process, we obtained the relationship acceleration or holding force with time from the experiment. To get the vibration or holding force at a certain gate opening in closing process, we firstly assume that gate opening is linear with the time. Subsequently, the vibration or holding force is approximately equal to the results of a specific time interval in closing process. In this paper, the specific time is linear with a certain gate opening and the interval is set to 1 s with 200 data.