10:30
Cavitation and cavitating flows III
Chair: Diego Villa
10:30
30 mins
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STUDIES ON PLANING AVOIDANCE CONTROL FOR A VENTILATED SUPERCAVITATNG VEHICLE
Seonhong Kim, Nakwan Kim
Abstract: In this paper, we focus on planing avoidance control for a ventilated supercavitating vehicle (VSV) considering stability. A VSV can control the size of cavity by blowing the gas into the cavity. By controlling the cavity size, the planing can be prevented in advance. However the vehicle lost its stability due to the growth of the cavity. Additional control input is determined to prevent “stability lost” based on linear stability analysis considering ventilation system dynamics. The proposed controllers are applied to the supercavitating vehicle model and numerical simulations were performed to analyse the physical feasibility and performed of designed controller. The results show that the proposed control methods can maintain vehicle stability in manoeuvring operation and can eliminate the planing phenomenon.
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11:00
30 mins
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NUMERICAL AND EXPERIMENTAL INVESTIGATIONS ON UNSTEADY CAVITATION OF A CP PROPELLER
Jian-qiang Wang, Ju Ding, Hai Yu, Yue-jin Cai
Abstract: This paper presents results of the numerical and experimental investigations of the cavitation characteristics of a high-skew CP propeller in the usual design and off-design conditions. The computations are carried out with RANS and LES solutions using a cavitation model based on a two-phase mixture formulation. The computations of unsteady non-uniform inflow conditions at two different pitch settings are carried out. Compared with experimental observations, the computational results of RANS solutions closely reproduce the main features of cavity patterns under the design pitch condition. The cavity pattern obtained by RANS model is a little smaller than the experimental result. LES model gives a better cavity pattern at the tip area. Under the off-design condition the face tip-vortex cavitation are observed in the experiment. The results obtained by RANS and LES model show an acceptable cavity pattern in comparison with the experiment.
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