Experimental Study on the Unsteady Natural Cloud Cavities: Influence of Cavitation Number on Cavity Evolution and Pressure Pulsations

Sun, Tiezhi; Zhang, Xiaoshi; Zhang, Jianyu; Wang, Cong

doi:10.3390/jmse9050487

Cited by 9 publications

(3 citation statements)

References 32 publications

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“…The method of time-frequency can not only give the frequency of the pressure pulsation but also show the information about the frequency domain representation changes with time. This method is using a short-time Fourier transform (STFT) to transform the time domain signal of pressure pulsation [30][31][32]. The source signal is divided into several small signal segments by the window function.…”

Section: Resultsmentioning

confidence: 99%

Experimental Investigation of Unsteady Pressure Pulsation in New Type Dishwasher Pump with Special Double-Tongue Volute

Zhu

Zhang

et al. 2021

Machines

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A pressure pulsation experiment of a dishwasher pump with a passive rotation double-tongue volute was carried out and compared with the pressure pulsation of a single-tongue volute and a static double-tongue volute. The pressure pulsation of the three volute models was compared and analyzed from two aspects of different impeller speeds and different monitoring points. The frequency domain and time–frequency domain of pressure pulsation were obtained by a Fourier transform and short-time Fourier transform, respectively. The results showed that the average pressure of each monitoring point on the rotating double-tongue volute was the smallest and that on the single-tongue volute was the largest. When the impeller rotates at 3000 rpm, there were eight peaks and valleys in the pressure pulsation time domain curve of the single-tongue volute, while the double-tongue volute was twice that of the single-tongue volute. Under different impeller speeds, the changing trends of pressure pulsation time and frequency domain curves of static and rotating double-tongue volutes at monitoring point p1 are basically the same. Therefore, a volute reference scheme with passive rotation speed is proposed in this study, which can effectively improve the flow pattern and reduce pressure inside the dishwasher pump, and also provide a new idea for rotor–rotor interference to guide the innovation of dishwashers.

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Section: Resultsmentioning

confidence: 99%

Experimental Investigation of Unsteady Pressure Pulsation in New Type Dishwasher Pump with Special Double-Tongue Volute

Zhu

Zhang

et al. 2021

Machines

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“…Research on cavity resistance reduction has been conducted by several countries, including the United States, Russia, China, France, Japan, Ukraine, the Netherlands, and others [6][7][8][9][10]. With the introduction of decarbonization regulations such as the Energy Efficiency Design Index, the Energy Efficiency Existing Ship Index, and the Carbon Intensity Indicator, shipowners, ship operators, and charterers are keen to ensure that their ships are as energy-efficient as possible and follow the IMO's decarbonization targets.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study on the Resistance of a High-Speed Air Cavity Craft

Song

et al. 2023

JMSE

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For the marine industry, resistance reduction can reduce energy consumption and achieve protection of the marine environment. The use of air lubrication to reduce the resistance of ships is one of the most important ways. With this technology, high-speed air cavity crafts show immense potential as they can be utilized in various marine activities, such as emergency rescue, supply, and maritime security. Through experiments, this study presents an in-depth analysis of the effects of bubble chamber pressure and initial stern inclination on the resistance of high-speed air cavity crafts at different speeds. The results show that air pressure has a significant impact on resistance. It was found that as the speed of the ship increased, the resistance reduction effect became more prominent under the same pressure conditions. Moreover, the resistance tended to stabilize when the pressure reached a certain value. In addition to the air pressure, the longitudinal inclination does have an effect on resistance reduction. To achieve better resistance reduction, the initial stern inclination angle should be chosen appropriately. Furthermore, adjusting the angle with speed changes can optimize the resistance reduction effect. This experimental study provides critical support for conducting further research on high-speed air cavity crafts. The findings offer valuable insights into improving hull forms, guiding host selection, and assessing performance.

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“…Zhao et al [19] observed the cavitation development and projectile's movement at different speeds with high-speed cameras. Sun et al [20] described the bubble evolution under different cavitation numbers and obtained the time-frequency characteristics of the pressure pulsation with closed-loop water tunnels and sampling systems.…”

Section: Introductionmentioning

confidence: 99%

Experimental Research on Cavitation Evolution and Movement Characteristics of the Projectile during Vertical Launching

Chen

Shi

Pan

et al. 2021

JMSE

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Aiming at the problem of unsteady cavitation during a projectile’s vertical water-exit process, scaled model experiments were carried out based on the self-designed underwater launch platform and high-speed cameras, which focus on changes in cavitation shape and projectile posture. In this paper, the general process of the cavitation evolution and projectile’s movement is described; the relationship between the re-entry jet, local cavitation number and cavitation stability is discussed. Meanwhile, the effect of head forms and launch speeds on the cavitation evolution and movement characteristics is analyzed, including 60° cone, 90° cone and hemispherical head with velocity of 16.8 m/s, 18.5 m/s and 20.0 m/s, whose launch cavitation number is 0.714, 0.589 and 0.504. The results show that the attached cavities fall off from the bottom up under the influence of the end-re-entry jet and the shedding frequency declines when the launch cavitation number decreases. The cavitation growth of 60° cone is easily disturbed by the air mass near the launcher, the cavitation development of 90° cone is characterized by small-scale and high-frequency growth and shedding, while the hemispherical head is not prone to cavitation. Moreover, increasing the speed can improve the stability of cavitation development and the projectile’s movement.

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Experimental Study on the Unsteady Natural Cloud Cavities: Influence of Cavitation Number on Cavity Evolution and Pressure Pulsations

Cited by 9 publications

References 32 publications

Experimental Investigation of Unsteady Pressure Pulsation in New Type Dishwasher Pump with Special Double-Tongue Volute

Experimental Investigation of Unsteady Pressure Pulsation in New Type Dishwasher Pump with Special Double-Tongue Volute

An Experimental Study on the Resistance of a High-Speed Air Cavity Craft

Experimental Research on Cavitation Evolution and Movement Characteristics of the Projectile during Vertical Launching

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