Microfluidic Inertial Switch Capable of Bidirectional Anti-High Overload

doi:10.16183/j.cnki.jsjtu.2020.279

Abstract

Abstract:

In order to realize the stable application of microfluidic inertial switch in the intelligent ammunition fuze system, a bidirectional anti-high overload microfluidic inertial switch is proposed to solve the problem of switch contact instability caused by the mercury droplet separation under high impact. The structures of snake-shaped buffer channel and three-stage capillary valve are designed based on the principle of capillary force applied to the mercury droplet in microchannel. The force state of the mercury droplets in the contraction type and the expansion type of capillary valves is analyzed. The static threshold model of the mercury droplet in the rectangular channel is established. The user defined function (UDF) is used to apply acceleration load to the finite element simulation of the switch. The simulation analysis suggests that under the action of typical forward service drop load and typical reverse service drop load, the mercury droplets can be restored to its initial state without droplet separation, indicating that the switch has a reliable anti-high overload ability. Two centrifugal experiments are conducted to complete the preparation and injection of tiny mercury droplets. The microfluidic switch prototype is used in the impact test of the Machete drop hammer. The results show that the mercury droplet separation does not occur in the switch under the action of typical forward impact load and typical reverse impact load, which are consistent with the simulation results.

Key words: microfluidic inertial switch, micro-acceleration switch, capillary force, anti-high overload

CLC Number:

ZHANG Runduo, NIE Weirong, QIU Weixiang. Microfluidic Inertial Switch Capable of Bidirectional Anti-High Overload[J]. Journal of Shanghai Jiao Tong University, 2021, 55(7): 826-833.

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参数	取值
参数	模型1	模型2	模型3	模型4	模型5	模型6
b₁/μm	20	20	20	20	20	20
b₂/μm	300	300	300	300	300	300
b₃/μm	150	150	150	60	150	150
b₄/μm	20	25	25	25	35	25
l/μm	250	250	50	250	250	250
h/μm	50	50	50	50	50	50
ΔH/μm	160	160	160	160	160	160
r/μm	-	-	-	-	-	60
α₁/(°)	-70	-70	-70	-70	-70	-70
α₂/(°)	70	70	70	70	70	70
α₃/(°)	-40	-40	-40	-40	-40	-40

参数	取值
ρ_m/(kg·m^-3)	13550
ρ_g/(kg·m^-3)	1.225
η_m/(Pa·s)	1.52×10^-3
η_g/(Pa·s)	2×10^-3
σ_m/(N·m^-1)	0.484
θ_f/(°)	140
θ_b/(°)	130

Z×10^-3/g	Δt/μs	Y
9.0	240	0
9.6	230	0
10.8	248	0
11.1	257	0
12.1	286	0
12.8	249	1