Abstract: The cross flow and attack angle are the two main influencing factors in the process of expendable probe releasing and sinking. The numerical simulation model is developed based on the hybrid grid and $k-\varepsilon$ turbulent model, and the hydrodynamic characteristics of five cross flows and five attack angles are analyzed. The results show that the drag coefficient of the probe in the horizontal direction increases gradually, while the drag coefficient of the probe in the vertical direction increases slowly with the increase of the cross flow. The drag coefficient in the horizontal direction increases gradually with the increase of attack angle and turns to decrease nearby 45°, while the drag coefficient in the vertical direction increases continuously. The drag interpolation between probe head and tail is related with the larger attack angle, with 2m/s falling speed, which makes the attack angle change, and the probe sinking at a constant speed in a fixed attack angle ultimately. The results can provide evidences to improve the depth measurement accuracy of probe.

Key words: expendable probe, multi cross flow, multi attack angle, hydrodynamic characteristics