Effects of Nozzle Exit Angle on the Pressure Characteristics of SRWJs Used for Deep-Hole Drilling

Abstract

The self-resonating waterjet (SRWJ) has been applied in petroleum, natural gas, and mining engineering ever since its strong erosion ability in deep-hole drilling was recognized. Aiming at further improving the working efficiency of SRWJs, the effects of the exit angle of the organ-pipe nozzle on the axial pressure oscillations of the jet were experimentally studied. Six exit angles of θ = 0°, 30°, 45°, 60°, 75°, and 90° were employed in the experiment, and the axial pressure oscillation peak (Pmax) and amplitude (Pa) were used for characterizing the performance of SRWJs. It was found that the exit angle greatly affects the axial pressure oscillations, including the development trends against the standoff distance and the magnitudes of Pmax and Pa. Under testing with two inlet pressures, the exit angle of θ = 0° always resulted in the greatest Pmax and Pa within the range of the testing standoff distance. With the increase of standoff distance, both Pmax and Pa first increased and then decreased when the exit angle was 0°; while they kept decreasing when the exit angle was 30°, 45°, 60°, 75°, and 90°. Moreover, the exit angles of θ = 90° and 60°, corresponding to inlet pressures of Pi = 10 MPa and 20 MPa, led to both the minimum magnitudes of Pmax and Pa under the experimental conditions. The results also indicate that the exit angle affects the interactions between the nozzle lip and the jet and help provide information for improving the working efficiency of SRWJs in practical applications.

Effects of the exit aspect ratio of organ-pipe nozzle on the axial pressure oscillation characteristics of self-resonating waterjet

“…The experiment was carried out using a multifunctional waterjet test platform, which had been applied in our previous study. 2,3,14,15,17–26,30–31 Figure 2 shows the experimental setup, which is aimed at obtaining the values of the axial pressures of SRWJ. Since this study is a continuation of our investigations on SRWJ, it should be pointed out that the experiment process and equipment used here were the same with those in our previous ones.…”

“…A dynamic pressure transducer (Model: XPM10, Make: Measurement SPECIALTIES™) communicating with the pressure tap of the target plate was used to obtain the time-resolved axial dynamic pressure of the high-speed jet. 26,30,31 The values of the pressures were then recorded and analyzed by the data logger (Model: MX840B, Make: HBM) connected with a laptop. Furthermore, the main parameters of the two pressure transducers are displayed in Tables 1 and 2, respectively.…”

“…Besides, our previous research on the effects of the downstream contraction ratio and the exit angle of organ-pipe nozzle also indicated that the pressure oscillation characteristics of SRWJ greatly depend on the nozzle structure. 30,31…”

“…Despite the general structure design of organ-pipe nozzle has already been studied by Chahine et al., 10–12 as well as the downstream contraction ratio and the exit angle, 30,31 the exit aspect ratio of self-resonating nozzle, which can never be neglected in the fabrication, has not been studied yet. In fact, an elucidation on the effects of the exit aspect ratio of self-resonating nozzle could be much valuable.…”

Effects of Organ-Pipe Chamber Geometry on the Frequency and Erosion Characteristics of the Self-Excited Cavitating Waterjet

“…As environmentally friendly technologies, the pulsed waterjet can take advantage of the water hammer effect [11], and the cavitating waterjet can harvest the energy of cavity collapse [9,12]; both of them can significantly lower the energy consumption during the working process. It is noteworthy that a self-excited cavitating waterjet, which combines the superiority of pulsed and cavitating waterjets, can produce strong pressure oscillation and intensive cavitation erosion [13]. Thus, the self-excited cavitating waterjet has received a great deal of attention in the past decades since it was first proposed [14].…”