## 4 Experimental Results and Analysis
### Experimental Results and Analysis of Pressure Performance
However, because the ability generated by the chemical reaction is not extracted at this time, the energy is converted into the internal energy of the gas, to ensure that the pressure in the optical cavity rises rapidly. At t = 11.5 s, the energy generated by the chemical reaction begins to be extracted. However, during this period, the pressure in the chamber does not decrease; instead, it shows a more gradual increase. During the entire energy extraction period, the pressure in the optical cavity increased from 1.4 \(\mathrm{P_{D}}\) to 1.8 \(\mathrm{P_{D}}\), which exceeded the upper limit of pressure for the normal operation of the chemical reaction platform. Figure 14 shows the extracted energy and power curves of the reaction experiment when test piece 1# and the chemical reaction platform were docked. The results in the figure show that the working state of the chemical reaction platform was poor, the power curve exhibited a large fluctuation, and the power exhibited a significant decline in the second half of the experiment. According to the analysis of the results in Figure 11, the reason for the poor working state of the chemical reaction platform is that the pressure in the optical cavity is excessively high, resulting in failure to establish the expected flow state in the optical cavity. Further analysis shows that because the central nozzle of experiment 1# and the peripheral nozzle were in the same section, the supersonic exhaust gas flow area in the optical cavity is small, resulting in blockage, and the pressure in the optical cavity is excessively high. Figure 13: Variation in pressure in the reaction cavity during operation with supersonic diffuser 1#. Figure 15 shows the energy and power curves of the chemical reaction platform when docked in experiment 2# and experiment 3#, respectively. The results in the figure show that owing to the stable pressure and flow field in the optical cavity, the energy and power curves are relatively full during the entire reaction period, there is no significant fluctuation or power decline, and the power value is increased by approximately 32% (experiment 2#) and 27% (experiment 3#), respectively, compared with that when the platform works independently. This indicates that using an active supercharging supersonic diffuser can improve the performance of the chemical reaction platform. Figures 16 and 17 show the pressure change curves for the time cavities of test pieces 2# and 3# when docked with the reaction platform. The initial pressures of the vacuum tank were approximately 2.9 \(\mathrm{P_{D}}\) and 3.9 \(\mathrm{P_{D}}\), and the active gas flow was 1.0 \(\mathrm{m_{D}}\). As shown in the figure, after the diffuser was started, the pressure in the optical cavity rapidly dropped to approximately 0.6 \(\mathrm{P_{D}}\) and remained stable. Once the reaction platform was started, the  
Figure 14: Variation in energy power during operation with supersonic diffuser 1#. Figure 15: Variation in energy power during operation with supersonic diffusers 2# and 3#. pressure in the optical cavity increased owing to the entry of the reaction gas. Following the generation of energy extraction from the reaction, the pressure in the optical cavity dropped to 0.6 P\({}_{\rm D}\), and the pressure in the optical cavity remained stable at 0.6 P\({}_{\rm D}\) during the entire experiment. This indicates that the problem of excessive optical cavity pressure in experiment 1# did not occur in experiments 2# and 3#. This is because the central nozzle was installed downstream of the peripheral nozzle in experiments 2# and 3#, which reduced local obstruction and eliminated the phenomenon of airflow blockage. Figure 16: Variation in pressure in the reaction cavity during operation with supersonic diffuser 2#. Figure 17: Variation in pressure in the reaction cavity during operation with supersonic diffuser 3#.