Non-intrusive flowrate measurement and monitoring system of plant-protection unmanned aircraft systems based on pump voice analysis

Application of Unmanned Aircraft Systems(UAS)for plant protection is becoming a common tool in agricultural field management.To avoid shortcomings of intrusive flowrate sensors including poor measurement accuracy and poor anti-vibration ability,a non-intrusive flowrate measurement and monitoring system of plant-protection UAS was developed based on pump voice signal analysis.It is mainly composed of STM32 processor,microphone and signal-conditioning circuit.By collecting and analyzing the voice signal of the pump in the UAS,the monitoring system will output the real-time values of spraying flowrate and amount.An extraction model was developed to determine operation status and primary frequency of the pump based on voice signal analysis.Real-time spray flowrate can be determined from the real-time extracted primary frequency and the fitted correlation formulas of spraying flowrate under outlet area and pump primary frequency.The flowrate correlation equation of one certain pump from 4-rotor UAS 3WQFTX-1011S was obtained,the max deviation rate of fitted spray flowrate was only 2.8%.In primary frequency extraction test,the error rate of primary frequency extraction was less than 1%.In the 4-rotor UAS flight tests:the max deviation of operating starting/end point was only 0.7 s and the max deviation of extracted total operating time was only 0.8 s;the deviation of extracted spray flowrate was less than 2%,and the max deviation rate of total spray amount was 3.2%.This research could be used as a guidance for plant-protection UAS non-intrusive flowrate measurement and monitoring.

Flowrate Measurement in Turbulent Liquid Metal Channel Flow Using Time-of-Flight Lorentz Force Velocimetry:Experimental Investigations and Numerical Modeling

Lorentz force velocimetry(LFV)is a suitable non-contact technique to measure flow velocity and flowrates in electrically conducting high-temperature melts.LFV is based on the principles of magnetohydrodynamics:when an electrically conducting fluid passes the field lines produced by a magnet system,eddy currents are induced within the fluid.The interactions of the eddy currents with the magnetic field generate Lorentz forces.Using LFV the counterforce acting on the magnet system is measured.Such a flowmeter consists of a permanent magnet system and an attached digital force sensor.The force recorded by the flowmeter is proportional to the flowrate Q and depends on both the electrical conductivity σ of the fluid and the spatial distribution of the applied magnet field B.However,in metallurgical applications,σ is often unknown or fluctuates in time as it strongly depends on both temperature and composition of the melt.In the present paper we investigate a technique called Time-of-Flight Lorentz force velocimetry ToF LFV.In this technique,the flowrate can be determined by just cross-correlating the two force signals recorded by two flowmeters which are arranged one behind the other separated by a certain distance D.Sensing the passage of the triggered vortices, this ToF LFV measures the transit time τ of these vortices.Then we recalculate the velocity V according to the relation V = D/τ.We experimentally and numerically study turbulent liquid metal flow in the test facility EFCO(electromagnetic flow control channel)using the eutectic alloy GainSn as a test fluid.Our experiments show that this electromagnetic ToF LFV is well suited to determine the flow velocity and flowrate.The experiments are accompanied by numerical simulations using the commercial program package FLUENT.

INFLUENCE OF CAPILLARITY ON NANO-LITER FLOWRATE MEASUREMET WITH DISPLACEMET METHOD

Nanoqiter flowrate measurements in micro-tubes with displacement method were performed and the effect of capillarity force on the accuracy was investigated through lab experiments and theoretical analysis in this article. The experiments were conducted under the pressure drops ranging from 1 kPa to 10 kPa in a circular pipe with a diameter of 50 pm, to give the pressure-flowrate （P-Q） relation and verify the applicability of the classical Hagen-Poiseuille （HP） formula. The experimental results showed that there existed a discrepancy between the experimental data and the theoretical values predicted by the HP formula if the capillary effect was not considered, which exceeded obviously the limit of the system error. And hence a modified formula for the relation, taking the capillary effect into account, was presented through theoretical deduction, and after the HP formula had been modified the error was proved to be less than 3%, which was permitted in comparison with the system error. It was also concluded that only by eliminating the effect of the capillary force in experiments could the original HP formula be employed to predict the pressure-flowrate relation in the Hagen-Poiseuille flow in the micro-tube.

Applications of active acoustics in particle technology

Earlier work by the authors in which active sound pressure signals and impulsive pressure disturbances were used to measure flow rates in gas solid systems was briefly reviewed. Work in progress with an emerging technology in which Helmholtz resonance is applied to the measurement of volume is outlined.