Study on water hammer effects in tethered UAV vertical pipe cable systems using Bentley Hammer

doi:10.16265/j.cnki.issn1003-3033.2025.07.0942

Abstract

Abstract:

In order to address the issue of sudden changes in pressure and flow on the stability of the tethered UAV during high-rise firefighting, the water hammer effect in the vertical pipe cable during the start pump and pump stop was simulated using Bentley Hammer software. The vertical height of the pipe cable was controlled from 160 to 220 m, and the transportation flow was set from 260 to 320 L/min. The variation laws of pressure, flow and water hammer force at the locations of the pump and tethered UAV were analyzed. The results show that the water hammer phenomenon during the start pump and pump stops can be divided into the static/steady state stage, the sudden rise/drop stage, and the steady state/oscillation weakening stage. When starting the pump, the water hammer force at the ground pump end is proportional to the pipe cable height, with the maximum water hammer force increasing from 7 176.502 N to 8 413.785 N, indicating a stronger impact and a delayed response. The water hammer force of the UAV end is minimally affected by the pipe cable height. When the pump is stopped, the maximum water hammer force at the ground pump end increases with the pipe cable height, from 4 316.401 N to 7 219.388 N, increasing the risk of pipeline rupture. The reverse water hammer force at the UAV end is inversely proportional to the pipe cable height, decreasing from 10 616 N to 8 158.870 N, indicating that a lower pipe cable height is more likely to induce the UAV attitude instability. Regarding the transport flow, during pump start-up, the transport flow has a small impact on the peak water hammer force. When the pump is stopped, the peak water hammer force at the ground pump end is proportional to flow, increasing from 6 693.8 N to 7 541.606 N, increasing the risk of damage. The peak reverse water hammer force at the UAV end decreases with the increase of flow, from 9 866.063 N to 8 471.582 N. The smaller the flow rate, the more likely it is to cause damage to the tethering system.

Key words: Bentley Hammer, tethered unmanned aerial vehicle (UAV), vertical pipe cable, water hammer effect, water hammer of pump stop, water hammer force

CLC Number:

X949

LI Cong, HOU Lele, JIN Yanke, WU Zhuoqi, ZHOU Rui, YAO Yina. Study on water hammer effects in tethered UAV vertical pipe cable systems using Bentley Hammer[J]. China Safety Science Journal, 2025, 35(7): 122-132.

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对象	参数	数值
熟铁管	内径d/m	0.065
	壁厚e/m	0.01
	库特粗糙度κ	0.012
	曼宁系数n	0.012
	海森-威廉系数C	130
	修正的海森-威廉系数C_m	0.878
	杨氏模量E_v/kPa	1.72×10⁸
	粗糙度高度ε/m	0.000 3
	泊松比μ	28%
水	运动黏度ν/(m²·s^-1)	1.566×10^-6
	相对密度γ	1.000
	温度 $\theta $/℃	4
	蒸汽压力P_v/kPa	-101
	体积弹性模量E/kPa	2188128

工况	输运流量/(L·min^-1)	管缆高度/m
启泵	300	220
		200
		180
		160
	320	200
	300
	280
	200
停泵	300	220
		200
		180
		160
	320	200
	300
	280
	200