scholarly journals Effect of Enhanced Squeezing Needle Structure on the Jetting Performance of a Piezostack-Driven Dispenser

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 850 ◽  
Author(s):  
Xiang Huang ◽  
Xiaolong Lin ◽  
Hang Jin ◽  
Siying Lin ◽  
Zhenxiang Bu ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Droplet Diameter ◽  
Cavity Pressure ◽  
Ethanol Mixture ◽  
Product Integration ◽  
Theoretical Simulation ◽  
Variation Range ◽  
Stable Performance ◽  
Needle Structure ◽  
Jet Velocity

Advanced dispensing technology is urgently needed to improve the jetting performance of fluid to meet the requirements of electronic product integration and miniaturization. In this work, an on–off valve piezostack-driven dispenser was used as a study object to investigate the effect of needle structure on jetting performance. Based on fluid dynamics, we investigated nozzle cavity pressure and jet velocity during the dispensing process using theoretical simulation for needles with and without a side cap. The results showed that the needle with a side cap had larger jet velocity and was capable of generating 8.27 MPa of pressure in the nozzle cavity, which was 2.39 times larger than the needle without a side cap. Further research on the influence of the nozzle and needle structural parameters showed that a nozzle conic angle of 85°–105°, needle conic angle of 10°–35°, and side clearance of 0.1–0.3 mm produced a dispenser with a large jet velocity and stable performance, capable of dispensing microscale droplets. Finally, a smaller droplet diameter of 0.42 mm was achieved in experiments using a glycerol/ethanol mixture, with a variation range of ± 4.61%.

scholarly journals Exploring the Structure–Performance Relationship of Sulfonated Polysulfone Proton Exchange Membrane by a Combined Computational and Experimental Approach

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 959
Author(s):  
Cataldo Simari ◽  
Mario Prejanò ◽  
Ernestino Lufrano ◽  
Emilia Sicilia ◽  
Isabella Nicotera
Keyword(s):  
High Performance ◽  
Mechanical Stability ◽  
Structural Parameters ◽  
Hydration Number ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Water Dynamics ◽  
Mechanical Resistance ◽  
Theoretical Simulation ◽  
Sulfonated Polysulfone

Sulfonated Polysulfone (sPSU) is emerging as a concrete alternative to Nafion ionomer for the development of proton exchange electrolytic membranes for low cost, environmentally friendly and high-performance PEM fuel cells. This ionomer has recently gained great consideration since it can effectively combine large availability on the market, excellent film-forming ability and remarkable thermo-mechanical resistance with interesting proton conductive properties. Despite the great potential, however, the morphological architecture of hydrated sPSU is still unknown. In this study, computational and experimental advanced tools are combined to preliminary describe the relationship between the microstructure of highly sulfonated sPSU (DS = 80%) and its physico-chemical, mechanical and electrochemical features. Computer simulations allowed for describing the architecture and to estimate the structural parameters of the sPSU membrane. Molecular dynamics revealed an interconnected lamellar-like structure for hydrated sPSU, with ionic clusters of about 14–18 Å in diameter corresponding to the hydrophilic sulfonic-acid-containing phase. Water dynamics were investigated by 1H Pulsed Field Gradient (PFG) NMR spectroscopy in a wide temperature range (20–120 °C) and the self-diffusion coefficients data were analyzed by a “two-sites” model. It allows to estimate the hydration number in excellent agreement with the theoretical simulation (e.g., about 8 mol H2O/mol SO3− @ 80 °C). The PEM performance was assessed in terms of dimensional, thermo-mechanical and electrochemical properties by swelling tests, DMA and EIS, respectively. The peculiar microstructure of sPSU provides a wider thermo-mechanical stability in comparison to Nafion, but lower dimensional and conductive features. Nonetheless, the single H2/O2 fuel cell assembled with sPSU exhibited better features than any earlier published hydrocarbon ionomers, thus opening interesting perspectives toward the design and preparation of high-performing sPSU-based PEMs.

Yhe Compression Meso-Mechanics Theoretical Model and Experimental Verification of Polyurethane-Based Warp-Knit Spacer Fabric Composites

2021 ◽  
Vol 8 (5) ◽  
pp. 30-38
Author(s):  
Si Chen
Keyword(s):  
Theoretical Model ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Beam Theory ◽  
Theoretical Research ◽  
Dimensional Structure ◽  
Static Compression ◽  
Theoretical Simulation ◽  
Winkler Elastic Foundation ◽  
Spacer Fabric

In this research, a new type of binary material, a polyurethane-based warp-knitted spacer fabric composite (PWSF), having a unique three-dimensional structure, high strength, and a variety of surface structures was prepared. The compression meso-mechanics theoretical model based on the Winkler elastic foundation beam theory and structural parameters of PWSF were used to predict the compression performance of PWSF. To verify the validity of compression model, the compression stress-strain curves of theoretical simulation were compared with the quasi-static compression test results. The deviation between these two compression moduli was less than 7%. The compression meso-mechanics model established in this study can effectively simulate the actual compression behaviors for different PWSF specimens. A regular pattern of compression properties of this novel composite from the theoretical research on meso-mechanics perspectives can be proposed.

A Study on the Evaporation of Water–Ethanol Mixture Using Rainbow Refractometry

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Jantarat Promvongsa ◽  
Bundit Fungtammasan ◽  
Grehan Gerard ◽  
Sawitree Saengkaew ◽  
Pumyos Vallikul
Keyword(s):  
Refractive Index ◽  
Volume Fraction ◽  
Liquid Droplet ◽  
Droplet Diameter ◽  
Pure Water ◽  
Volatile Component ◽  
Ethanol Mixture ◽  
Steady Stage ◽  
Composition Gradients ◽  
Rainbow Refractometry

Evaporation of droplets of liquid mixture is a subject of interest in combustion studies, e.g., combustion of bioethanol blends. In this paper, experimental investigation, using rainbow refractometry, on the variations of droplet diameter and composition during the evaporation of water–ethanol droplet in quiescent atmosphere is studied. The droplet is suspended on the tip of 125 μm-diameter fiberglass rod. The initial diameter is around 1000–1100 μm, and the initial composition is varied from 0% to 100% of ethanol by volume. The scattered rainbow signal from the evaporating droplet is fitted to the Airy theory to extract information on the diameter and refractive index of the liquid droplet against evolution time. To determine the accuracy of droplet diameter measurements using this technique, the diameter is also measured from the shadow image of droplet simultaneously. At 0–60% of ethanol by volume, the diameter and volume fraction accuracies are within ±30 μm and 10%, respectively, even though the temperature and composition gradients inside a droplet are neglected. The results show that the water–ethanol mixture evaporates faster at the beginning due to the higher amount of the volatile component, i.e., ethanol. The D2–t curve appears as a series of two straight lines of different slopes: a steep one initially and a moderate one at later stage. The slope at the initial or the transition stage increases with the ethanol composition, while the slope at later stage (steady stage) is equivalent to that of pure water. Likewise, the refractive index decreases rapidly at the beginning and becomes steady reaching a final value of 1.333, which is close to the refractive index of pure water.

scholarly journals Validating a Reduced-Order Model for Synthetic Jet Actuators Using CFD and Experimental Data

Actuators ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 67 ◽  
Author(s):  
Tim Persoons ◽  
Rick Cressall ◽  
Sajad Alimohammadi
Keyword(s):  
Synthetic Jet ◽  
Operating Conditions ◽  
Reduced Order Model ◽  
Driving Voltage ◽  
Cavity Pressure ◽  
Order Model ◽  
Reduced Order ◽  
Synthetic Jet Actuators ◽  
Jet Actuators ◽  
Jet Velocity

Synthetic jet actuators (SJA) are emerging in various engineering applications, from flow separation and noise control in aviation to thermal management of electronics. A SJA oscillates a flexible membrane inside a cavity connected to a nozzle producing vortices. A complex interaction between the cavity pressure field and the driving electronics can make it difficult to predict performance. A reduced-order model (ROM) has been developed to predict the performance of SJAs. This paper applies this model to a canonical configuration with applications in flow control and electronics cooling, consisting of a single SJA with a rectangular orifice, emanating perpendicular to the surface. The practical implementation of the ROM to estimate the relationship between cavity pressure and jet velocity, jet velocity and diaphragm deflection and applied driving voltage is explained in detail. Unsteady Reynolds-averaged Navier Stokes computational fluid dynamics (CFD) simulations are used to assess the reliability of the reduced-order model. The CFD model itself has been validated with experimental measurements. The effect of orifice aspect ratio on the ROM parameters has been discussed. Findings indicate that the ROM is capable of predicting the SJA performance for a wide range of operating conditions (in terms of frequency and amplitude).

scholarly journals LEM Characterization of Synthetic Jet Actuators Driven by Piezoelectric Element: A Review

2017 ◽  
Author(s):  
Matteo Chiatto ◽  
Francesco Capuano ◽  
Gennaro Coppola ◽  
Luigi de Luca
Keyword(s):  
Piezoelectric Element ◽  
Synthetic Jet ◽  
Orifice Diameter ◽  
Cavity Pressure ◽  
Synthetic Jet Actuators ◽  
Lumped Element ◽  
Air Jet ◽  
Jet Actuators ◽  
Jet Velocity ◽  
Design And Manufacture

In the last decades synthetic jet actuators have gained much interest among the flow control techniques due to their short response time, high jet velocity and absence of traditional piping, that matches the requirements of reduced size and low weight. A synthetic jet is generated by the diaphragm oscillation (generally driven by a piezoelectric element) in a relatively small cavity, producing periodic cavity pressure variations associated with cavity volume changes. The pressured air exhausts through an orifice, converting diaphragm electrodynamic energy into jet kinetic energy. This review paper faces the development of various lumped-element models (LEMs) as practical tools to design and manufacture the actuators. LEMs can quickly predict device performances such as the frequency response in terms of diaphragm displacement, cavity pressure and jet velocity, as well as the efficiency of energy conversion of input Joule power into useful kinetic power of air jet. The actuator performance is analyzed also by varying typical geometric parameters such as cavity height and orifice diameter and length, through a suited dimensionless form of the governing equations. A comprehensive and detailed physical modeling aimed to evaluate the device efficiency is introduced, shedding light on the different stages involved in the process. Overall, the influence of the coupling degree of the two oscillators, the diaphragm and the Helmholtz’s one, on the device performance is discussed throughout the paper.

Experimental Study on Acoustic Characteristics of Particle Breakage Under Combined Shear and Extrusion Load

2021 ◽  
Vol 13 (5) ◽  
pp. 846-856
Author(s):  
Yu Luo Jian ◽  
Tong Xin ◽  
Wu Huang Yi
Keyword(s):  
Structural Parameters ◽  
Sound Intensity ◽  
Test Method ◽  
Motor Speed ◽  
Particle Crushing ◽  
Acoustic Parameters ◽  
Angle Variation ◽  
Acoustic Characteristics ◽  
Loading Process ◽  
Variation Range

The jaw crushing loading process is a typical loading process of combined shearing and extrusion. In this paper, by establishing a complete jaw crushing loading process, the sonic test method is used to determine and analyze the particle crushing law to explore acoustic characteristics of particle crushing under the combined action of shear and extrusion. A jaw crushing tester is used to simulate the jaw crushing process of sand aggregate specimens. A rock-soil sound wave detector is used to measure the sound speed, sound amplitude, and sound intensity during the simulated jaw crushing process. It is found that when the jaw angle variation range is 2.6°, the inlet-outlet ratio is 0.332 and the motor speed is 15 r/min, the sound velocity and the sound amplitude curves fluctuate more drastically and the sound intensity is higher. The crushing evaluation of the sand aggregate specimens, which have experienced crushing simulation, shows that when the jaw angle variation range is 3.0°, the inlet-outlet ratio is 0.332 and the motor speed is 33 r/min, higher crushing energy rate and crushing rate are achieved. Through the comparative analysis of each group’s acoustic parameters and crushing evaluations, it is found that both the acoustic parameters and the crushing evaluations reflect the crushing process, but they have similarities and differences. Therefore, to some extent, the acoustic parameters in the crushing process can be regarded as significant indicators for evaluating the crushing effect. This conclusion may be a reference for optimizing working parameters and structural parameters of crushing equipment.

Optimal design of a high homogeneous and small-size shim coil for atomic spin gyroscope based on 0-1 linear programming

2020 ◽  
Vol 64 (1-4) ◽  
pp. 165-172
Author(s):  
Dongge Deng ◽  
Mingzhi Zhu ◽  
Qiang Shu ◽  
Baoxu Wang ◽  
Fei Yang
Keyword(s):  
Linear Programming ◽  
Power Consumption ◽  
Low Power ◽  
Optimization Design ◽  
Structural Parameters ◽  
Axial Position ◽  
Low Power Consumption ◽  
Optimal Method ◽  
Atomic Spin ◽  
Shim Coil

It is necessary to develop a high homogeneous, low power consumption, high frequency and small-size shim coil for high precision and low-cost atomic spin gyroscope (ASG). To provide the shim coil, a multi-objective optimization design method is proposed. All structural parameters including the wire diameter are optimized. In addition to the homogeneity, the size of optimized coil, especially the axial position and winding number, is restricted to develop the small-size shim coil with low power consumption. The 0-1 linear programming is adopted in the optimal model to conveniently describe winding distributions. The branch and bound algorithm is used to solve this model. Theoretical optimization results show that the homogeneity of the optimized shim coil is several orders of magnitudes better than the same-size solenoid. A simulation experiment is also conducted. Experimental results show that optimization results are verified, and power consumption of the optimized coil is about half of the solenoid when providing the same uniform magnetic field. This indicates that the proposed optimal method is feasible to develop shim coil for ASG.

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