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

Abstract

Erosion experiments were performed to uncover the impact of organ-pipe chamber geometry on the frequency and erosion characteristics of self-excited cavitating waterjets. Jets emanating from self-excited nozzles with various organ-pipe geometries were investigated. The upstream and downstream contraction ratios of the organ-pipe resonator were changed respectively from 1.5 to 6 and 2 to 12. Pressure sensors and hydrophone were used to characterize jets’ frequency characteristics. Mass loss was also obtained in each of the configurations to assess the erosion performance. By tuning the self-excited frequency, the peak resonance was achieved using the nozzles with different geometries. Accordingly, the acoustic natural frequencies of various chamber geometries were obtained precisely. Results show that with increasing upstream and downstream contraction ratio of the organ-pipe chamber, the acoustic natural frequency increases monotonically due to the reduction of equivalent length, while the resonance amplitude and mass loss first increase and then decrease. There are optimum geometric parameters to reach the largest resonance amplitude and erosion mass loss: the upstream contraction ratio being between two and four, and downstream ratio being between four and seven. The effective length of the organ pipe can be calculated by the sum of the physical length and equivalent length to accurately obtain the acoustic natural frequency. Under the optimized parameters, the equivalent length can be estimated as 0.35D.

Experimental Study on the Impingement Characteristics of Self-Excited Oscillation Supercritical CO2 Jets Produced by Organ-Pipe Nozzles

“…The schematic diagram of the organ-pipe nozzle used in the experiments is shown in Figure 3. Based on previous research on the self-excited oscillating jet produced by the organ tube nozzle [37,38], preliminary experiments were carried out to determine the optimal chamber length range suitable for the experimental conditions in this study to produce strong impact pressure oscillations. Seven nozzles were tested with different oscillation chamber lengths (i.e., L c = 7.5, 9, 10.5, 12, 13.5, 15, and 16.5 mm), and other structure parameters are summarized in Table 2.…”

Research on Erosion Effect of Various Submerged Cavitating Jet Nozzles and Design of Self-Rotating Cleaning Device

“…Liu et al [17] investigated a double-hole nozzle and the aggressive ability of cavitating jets was significantly improved in contrast to the single-hole nozzle. Cai et al [18][19][20] extensively researched the cavitation characteristics of a self-resonance pulsed organ pipe nozzle. They examined the influence of nozzle geometry, including the nozzle lip and upstream and downstream contraction ratios, on these characteristics.…”

Numerical Investigation on Cavitation Jet in Circular Arc Curve Chamber Self-Excited Oscillation Nozzle

“…In addition, the grooves [20] and the roughness [21] on the inner surface of the nozzle will increase the energy disturbance of the jet and promote the generation of cavitation clouds. A study on the chamber structure of the SEON in the literature [22] showed that the pulse intensity of the cavitation jet was affected by changing the structural parameters of the SEON. The increase of pulse intensity in the self-excited oscillation cavitation jet is due to the transient accumulation and release of jet energy by the cavitation vortex ring in the self-excited oscillation chamber.…”