## 4 Results and Discussion
### Confirmatory Experiments  
To validate the accuracy of the simulated piston impact energy for the Type B RC-DTH air hammer, an experimental setup was constructed to measure the actual piston impact energy. The impact performance testing system, designed using the stress wave technique, consists of the following two main components: a data acquisition and analysis system and a drilling rig system. The drilling rig system is made up of a drilling apparatus, an air compressor, a damping plate, and a specialized test bit. The data acquisition and analysis system are equipped with instruments for capturing stress waves and oscillographic data, a host computer, dedicated analysis software, and a strain gauge for precise measurements. Figure 9 illustrates the testing methodology of the drop hammer calibration experiment. The piston is elevated to set heights of 1.0 m, 1.4 m, and 1.8 m, and it is then released to freely strike the test bit. The strain wave produced by the impact is captured by a strain gauge, and this procedure is carried out four times for each height. We postulate a linear correlation between the piston's impact energy and the peak strain values. Consequently, the data from each height are analyzed and compared, with any peaks that are exceptionally high or low being discarded. The average of the remaining peak values is calculated, and the equations representing these values are solved in pairs to determine the average coefficients 'a' and 'b' of the linear relationship. Based on the data presented in Table 5, the linear equation that correlates the peak of the strain wave with the gravitational potential energy of the piston is as follows:  
\[Q=1.32\mu_{2}-163.4 \tag{10}\]  
Figure 10 illustrates the assembly of the Type B RC-DTH air hammer within the impact performance real drilling testing system. The air compressor is regulated to maintain an air pressure of 1.2 MPa, while the data sampling is conducted at a frequency of 500 Hz. During the RC-DTH hammer piston impact test, the strain wave generated by the drill bit is captured. The peak value of this strain wave is then used in Equation (10) to compute the impact energy exerted by the piston. The results of these calculations are detailed in Table 6.  
The experimental findings reveal that the Type B RC-DTH air hammer's piston impact energy is roughly 285.33 J, with the final impact velocity of the piston estimated to be 10.83 m/s and an impact frequency of approximately 18 Hz. The numerical simulation, on the other hand, yields an impact energy of 148.0326 J and an impact frequency of 17.5747 Hz. The measured impact frequency is essentially consistent with the simulated frequency, and the impact energies are of a similar order of magnitude. This agreement suggests that the \begin{table}
\begin{tabular}{c c c c c c} \hline  & **Velocity/** & **Time/** & **Frequency/** & **Impact Work/** & **Impact Power/** \\  & **m/s** & **s** & **Hz** & **J** & **W** \\ \hline Base structure & 7.04 & 0.0554 & 18.05 & 123.90 & 2236.53 \\ Adjusted structure & 7.75 & 0.0558 & 17.92 & 150.16 & 2690.97 \\ Increase range/\% & 10.09 & 0.7 & \(-\)0.7 & 21.19 & 20.32 \\ \hline \end{tabular}
\end{table} 
Table 4: Comparison of impact performance parameters before and after piston structure adjustment. numerical model for the impact performance of the RC-DTH hammer is reliable and meets the anticipated standards of accuracy. In the RC-DTH hammer impact simulation model, it is imperative to set up a thin layer grid that connects the individual grids across different regions. This setup leads to a certain degree of gas pressure loss during the computational process, which in turn translates to a loss in impact energy within the simulation. The impact frequency of the Type B RC-DTH air hammer is similar to that of the GQ89 DTH hammer. However, the Type B model exhibits an impact energy that is 1.84 times greater and an impact power that is 1.74 times higher than the GQ89 model, demonstrating considerable performance enhancements. These results confirm the superior performance