Bionic optimum design of straight cone nozzle and the effectiveness evaluation of reducing fluid resistance

Abstract

High-pressure water jet technology is a clean and effective approach to break, cut or clean solid materials. The nozzle's hydraulic performance determines the efficiency and quality of the high-pressure water jet technology implementation. The fluid resistance reduction technology of bionic non-smooth surface is applied to the structural design of the straight cone nozzle successfully. The circular groove is selected as the bionic unit. The selection results in the investigation and development of a bionic straight cone nozzle with the optimum hydraulic performance. Moreover, the separated nozzle machining method is successfully implemented. A comprehensive approach that implements the orthogonal experiment, high-pressure water jets' impact forces testing and range analysis results in the optimization of the bionic straight cone nozzle's structure. The optimal structural parameters of the nozzle as follows: the outlet diameter is 4 mm, length-to-diameter ratio is 2.5, contraction angle is 60°, the circular groove width is 3 mm, the circular groove depth is 2 mm and the circular groove number is 2. In addition, the circular grooves are uniformly arranged on the surface of the straight cone nozzle's internal chamber resulting in reduction of the fluid resistance effectively. Under the same experimental conditions, the impact forces of high-pressure water jets produced by the bionic straight cone nozzles are greater in comparison with the impact forces of high-pressure water jets produced by the ordinary straight cone nozzles. The average rate of fluid resistance reduction of bionic straight cone nozzles is up to 2.33%. Furthermore, the results of CFD numerical simulation show that the circular grooves at the contraction and the outlet sections can also reduce the high-pressure water flow resistance effectively. In the meantime, the opposite rotating vortexes in the circular grooves are the main reason for the reduction in fluid resistance of the bionic straight cone nozzle.

Optimization Design and Analysis of Bionic Friction Reducing Nozzle in Oil Shale High-Pressure Jet Mining

“…All the optimization work involves increasing rock breaking effect, saving hydraulic energy, and improving energy conversion efficiency [20,21]. Wen et al [22] chose a circular annular groove as a bionic unit and arranged the circular annular groove evenly on the inner cavity surface of a straight cone nozzle. The original smooth flow channel inside the nozzle became a bionic non-smooth surface structure, effectively improving the flow channelʹs hydraulic characteristics inside the nozzle.…”

Effect of Special-Shaped Nozzle Structure on Water Jet Performance

“…The results showed that the lateral deflection of peak pressure was affected by the combination of jet velocity, surface shape, and surface angle. Weng et al [14] designed circular grooves with different widths and numbers at the nozzle inlet. The liquid support effect produced by the circular grooves reduced the resistance between the water jet and the inner surface of the nozzle and improved the impact force of the water jet.…”