Fluid Rectification Research Articles

Development of a dual magnetostrictive material rods–based electro-hydrostatic actuator

Recently, the use of smart material–based electro-hydrostatic actuators is increasingly becoming more attractive to overcome the inherent disadvantages of conventional actuation systems and to offer new opportunities for performance improvement. A new type of a dual magnetostrictive material rods–based electro-hydrostatic actuator is presented in the current study. An active rotary rectification valve is utilized to convert small, high-frequency vibration displacements of the magnetostrictive material rods into continuous, smooth and bidirectional motion of a hydraulic cylinder by fluid rectification. Simulation and experiments were performed to confirm the feasibility of the new concept. The experimental results indicate that the dual magnetostrictive material rods–based electro-hydrostatic actuator exhibits a maximum flow rate that is approximately twice that of a single magnetostrictive material rod–based electro-hydrostatic actuator, and that the operating frequency increases from 110 to 150 Hz.

Development of a magnetostrictive material–based electro-hydrostatic actuator with an active rotary rectifying valve

A magnetostrictive material–based electro-hydrostatic actuator with an active rotary valve for fluid rectification is presented in this article, which consists of a magnetostrictive material–based pump, an active rotary valve and a hydraulic cylinder. First, the magnetostrictive material–based pump plunger motion model is established, and the factors that affect the phase lag between the magnetostrictive material–based pump plunger displacement and the input voltage are discussed. Second, the flow area model of the active rotary valve and the kinetic model of the cylinder are established. After that, the phase compensation for the input voltage that influences the synchronous motion between the magnetostrictive material–based pump plunger and the valve spool is investigated. Finally, the simulation model is built in MATLAB/Simulink, and the results are subsequently verified with experimental data. The results indicate that the phase lag of magnetostrictive material–based pump plunger output displacement is mostly influenced by magnetization with a low driving frequency and by an eddy current with a high driving frequency. The compensation angle for the input voltage affects the output flow of the magnetostrictive material–based electro-hydrostatic actuator and the moving direction of the cylinder piston rod. For a magnetostrictive material–based electro-hydrostatic actuator rectified by the active rotary valve, at the driving frequency of 200 Hz, the peak output flow can reach 2.4 L/min, which is much higher than 1.1 L/min of a magnetostrictive material–based electro-hydrostatic actuator rectified by the passive reed valve.

Supercritical fluid rectification of lignin pyrolysis oil methyl ether (LOME) and its use as a bio-derived aprotic solvent

Lignin can be converted by pyrolysis, supercritical rectification, and methylation, into an aromatic bio-derived solvent.

Supercritical fluid rectification of lignin microwave-pyrolysis oil

Supercritical fluid rectification selectively extracts single ring phenols from lignin microwave-pyrolysis oil.

Reliable, high-frequency miniature valves for smart material electrohydraulic actuators

A key element in developing high-performance smart material electrohydraulic actuators is the design of improved check valves for high-frequency fluid rectification. One method to create valves with fast frequency response is to replace the single-reed valves typically used in these systems with an array of miniature-reed valves. A robust miniature-reed design is presented to overcome the fatigue and fabrication limitations observed in previous approaches. The fluid–structure interaction between an individual valve and hydraulic fluid is modeled using the multiphysics software COMSOL; the results are validated with experimental testing on an array of miniature reeds. The performance of this array in a smart material actuator is compared with a larger, single-reed valve design. The miniature-reed array is shown to reliably rectify flow in the high-pressure and high-frequency environment of a smart material pump.

Lateral air cavities for microfluidic pumping with the use of acoustic energy

An acoustically activated micropump is fabricated and demonstrated using a single step lithography process and an off-chip acoustic energy source. Using angled lateral cavities with trapped air bubbles, acoustic energy is used to oscillate the liquid–air interface to create a fluidic driving force. The angled lateral cavity design allows for fluid rectification from the first-order pulsatile flow of the oscillating bubbles. The fluid rectification is achieved through the asymmetrical flow produced by the oscillating interface generating fluid flow away from the lateral cavity interface. Simulation and experimental results are used to develop a pumping mechanism that is capable of driving fluid at pressures of 350 Pa. This pumping system is then integrated into a stand-alone battery operated system to drive fluid from one chip to another.

The effect of flap parameters on fluid rectification in a microfluidic diode

We have studied the effect of flap parameters on fluid rectification in a microfluidic diode. We use Navier-Stokes equations and arbitrary Lagrangian-Eulerian formulation to obtain dynamics of fluid flow and motion of the flap. The flap opens during forward flow and seals against a stopper during reverse flow. This allows flow in the forward direction and prevents it in the reverse direction. The rectifier is fluidic analog to a semiconductor diode in function because it rectifies fluid flow. Velocity-pressure (V-P) curves analog to the current-voltage (I-V) curves of the electronic diode has been obtained. The effect of the flap parameters, such as length, thickness, and Young's modulus has been found out. The transient response of the flap and fluid flow under oscillating pressure driven flow has also been obtained.