# Design of a New Supersonic Shock Wave Generator and Application in Power Generation
## 4 Design of a Power Generation System Driven by Supersonic Shock Waves
### Power Generation Experiments and Analysis  
Figure 14 shows the execution screen of the power generation monitoring software. This monitoring software can execute the automatic control program shown in Figure 13. The control parameters set by the user are displayed in the upper left corner of the execution screen in Figure 14, such as the minimum tank pressure (\(P_{tmin}\)), minimum rotation speed (\(S_{min}\)), and delay time (\(T_{d}\)), where \(P_{tmin}\) = 3.5 kg/cm\({}^{2}\), \(S_{min}\) = 1200 rpm, and \(T_{d}\) = 2 s. The square light \"Low pressure\" on the left side of the screen indicates whether the tank pressure is too low (\(p_{t}<P_{tmin}\)), the red light means too low, and the green light means sufficient. The square light \"Low rotation\" indicates whether the rotational speed is insufficient (\(s_{r}<S_{min}\)). The circular light \"Activation\" represents the activation of shock wave output. The sampling rate, elapsed time, and number of data records are displayed at the bottom of the screen. Figure 13: The control process of shock wave-driven power generation. During the monitoring process of the shock-driven power generation, the system will automatically capture six measurement data, including storage tank pressure \(p_{t}\), output pressure \(p_{o}\), rotation speed \(s_{r}\), gas flow rate \(f_{g}\), voltage \(V_{p}\), and current \(I_{p}\), at a sampling rate of once every 0.2 s. The curves of these measurement data are displayed in the six curve graphs in the center of the screen in Figure 14. From the comparison of the tank pressure \(p_{t}\) curve and the output pressure \(p_{o}\) curve, we can see that \(p_{t}\) can be inflated to about 5 kg/cm\({}^{2}\geq P_{tmin}\) = 3.5 kg/cm\({}^{2}\) each time (steps (2) and (3) in Figure 13). After the shock wave, \(p_{o}\) first appears as steep wave (pulse), and then an output pressure of about 0.5 kg/cm\({}^{2}\) lasts for 2 (\(T_{d}\)) seconds. During this time, \(p_{t}\) drops to a low point (steps (4) and (5)). At this time, if \(s_{r}\geq S_{min}\), we wait for \(s_{r}\) to drop. When \(s_{r}<S_{min}\), the system inflate \(p_{t}\) again and re-enter the next cycle (steps (6) and (7)). We can see from the speed curve in the screen that the system controls the speed, \(s_{r}\), of the connecting rod at around 1200 rpm (\(S_{min}\)), and the speed, \(s_{r}\), determines the size of the output voltage, \(V_{p}\). When the monitoring process is completed, the system automatically saves the set parameters and all measured curve data to the file for subsequent power generation performance analysis. Figure 15 shows a display screen of the results of a power generation monitoring experiment. This screen displays six curves from top to bottom; they are the curves of pressure (including yellow storage tank pressure \(p_{t}\) and red output pressure \(p_{o}\)), gas flow rate \(f_{g}\), rotation speed \(s_{r}\), voltage \(V_{p}\), current \(I_{p}\), and power \(E_{p}\), where \(E_{p}=V_{p}\cdot I_{p}\). The X-axis of each graph is in the same time sequence. Users can simultaneously scroll the X-axis display range of the six graphs through the sliding bar on the upper right side of the screen to observe the power generation performance in each period. We mark five time points, A, B, C, D, and E, on the X-axis of Figure 15. The A-B period is the power generation period when no load (zero bulbs) is turned on at the power output end, while the B-C, C-D and D-E periods are the power generation periods when one, two, and three light bulbs are turned on respectively. It can be seen from the \(I_{p}\) curve in the figure that the \(I_{p}\) and \(E_{p}\) in the A-B period (zero bulbs) are both zero, while the \(I_{p}\) and \(E_{p}\) in the one-bulb, two-bulb, and two-bulb periods gradually increase, indicating that the greater the load (the greater the number of light bulbs), the larger both the \(I_{p}\) and \(E_{p}\).