Abstract
As a highly efficient and energy-saving cavitation method, Venturi cavitation is widely used in many industrial fields. This study synchronously investigated the cavity behavior and its corresponding wall static pressure characteristics in Venturi channels with various divergence angles to research the role of the divergence angle in cavity shape and the wall static pressure oscillation. Five rectangular Venturi channels with different divergence angles (4°, 6°, 8°, 10°, and 12°) were tested at the cavitation number (0.3–1.0). Based on the dynamic behaviour of gas–liquid interface, three cavity shedding types were identified: front shedding (I), central shedding (II) and tail shedding (III). A modified correlation for predicting average cavity length was proposed with the consideration of the effect of the divergence angle. Combined with the wall static pressure characteristics, as the divergence angle increased, the wall static pressure fluctuation in the Venturi became more intense. According to the wall static pressure oscillation characteristics, for the larger divergence angles (θ = 6°, 8°, 10° and 12°), the wall static pressure oscillation frequency was the same as the cavity shedding frequency and increased with the increase of the divergence angle. For smaller divergence angle (θ = 4°), no definite periodicity in pressure oscillation frequency could be observed.
Highlights
As a highly efficient and energy-saving cavitation method, Venturi cavitation is widely used in many industrial fields
Three typical cavitation shedding patterns are identified based on the following criteria: (I) front shedding (0 ≤ xs/Lmax ≤ 0.3); (II) central shedding (0.3 ≤ xs/Lmax ≤0.7); and (III) tail shedding (0.7 ≤ xs/Lmax ≤1.0). xs/Lmax is the ratio of the initial shedding position of the cloud cavity to the maximal length of the attached cavity prior to shedding (Lmax)
Several conclusions were drawn: (1) The cavitation characteristics of Venturis with various divergence angles were investigated at cavitation numbers that ranged from 0.3 to 1.0 based on the synchronous analysis of the vapour–liquid interface and its corresponding wall static pressure
Summary
As a highly efficient and energy-saving cavitation method, Venturi cavitation is widely used in many industrial fields. This study synchronously investigated the cavity behavior and its corresponding wall static pressure characteristics in Venturi channels with various divergence angles to research the role of the divergence angle in cavity shape and the wall static pressure oscillation. Combined with the wall static pressure characteristics, as the divergence angle increased, the wall static pressure fluctuation in the Venturi became more intense. Cavitation has positive effects in the aerospace, biological, and chemical industries, among others It can be used for engine flow control, sewage purification and chemical reaction rate increase[6,7,8,9]. The cavity length and the flow field pressure are important indicators for characterizing cavitation processes, which mainly reflect cavitation regions and instability. By tuning the cavity length and the flow field pressure, it is possible to effectively suppress the adverse effects and promote the positive effects of cavitation
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