The energy release from an aluminum dust explosion is related to the degree of turbulence and the local concentration distribution at a given nominal concentration. In the present work, the combined ...effects of turbulence and concentration on aluminum dust/air explosions in a 20 L spherical test vessel were examined using ultrasonic sensors. The relationship between the dust concentration and the ultrasonic attenuation coefficient was established, and real-time online measurements of aluminum dust concentrations were performed. The data show that the turbulent kinetic energy increases sharply during the initial stage of injection and then decreases gradually over time, while the concentration and uniformity of suspended dust gradually increase as the turbulence decreases. Explosion energy data were obtained at various dust concentrations and demonstrate that concentrations from 700 to 900 g/m3 are optimal.
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•The ultrasonic signal spectrum had been obtained based on the Hilbert-Huang Transform.•The aluminum dust concentration had been calculated based on the amplitude attenuation of the pulsed ultrasonic frequency.•The results of calculations about turbulence been compared with experimental data.•The concentration distribution and uniformity of aluminum dust diffusion had been analyzed.•Explosion energy data were obtained at different aluminum dust concentrations.
An appropriate concentration of micro/nano aluminum powder (MNAP) cloud is necessary for fuel air explosive (FAE) detonation. However, because of the fast dynamics, uncertainty interference, and ...transient characteristics of MNAP diffusion, experimental research on the measurement of MNAP cloud concentration is still lacking. Here, a pair of ultrasonic transducers were developed based on pulse drive, to measure the dynamic MNAP cloud concentration during MNAP diffusion in a standard 20-L explosion vessel. The measurement method was based on Lloyd-Berry ultrasonic attenuation theory. The experimental results showed that the ultrasonic pulse had a strong anti-interference ability, high precision, and real-time response to enable the characterization of MNAP diffusion concentration. The diffusion concentration gradients of MNAP were established and agreed well with the trend predicted by computational fluid dynamics simulations. The results also indicated that aluminum nanoparticles have better distribution characteristics than those of aluminum microparticles. These analyses provide technical support to improve FAE detonation energy.
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•Thecalculation modelis establishedofMNAP concentrationbased on Lloyd and Berry ultrasonic scattering model.•The restrictions and approximations of the used attenuation model has been detailed stated.•A CFD simulation model isestablished to analysisthe distributioncharacteristics of MNAPconcentrationcomparatively.•A dynamic concentration measurement systemof MNAPisestablishedin the 20-L spherical vessel.•The results shown thatthe feasibility and noveltyof the dynamic concentration detection system.
Polypyrrole (PP)/adenosine triphosphate (ATP) was chosen as a conducting polymer/anionic drug model to serve as a bioactive releasing material for ATP. The process of ATP release from PP/ATP films ...was investigated for the first time by electrochemical electrospray ionization mass spectrometry (EC/ESMS). This technique allowed the simultaneous and direct detection of ATP and its related species during electrochemical release. In the experiments, suitable solvent conditions were found for both the electrochemical release and the electrospray mechanisms. EC/ESMS results showed that continuous potential cycles allowed a higher ATP release rate than potential steps. It was also found that the film thickness is an important factor affecting the rate and the amount of electrochemical ATP release.
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