Dynamic Behavior of Droplet Impact on Inclined Surfaces with Acoustic Waves

Yousefi

2020

MJMIE

Extensive activities have been carried out, including variable valve timing systems, smoke recovery systems and direct fuel injection engines to reduce engine emissions and increase engine efficiency. In four-stroke engines, the valves are moved using a cam, and the shape of the cam determines the timing of each valve. But using variable valve timing in the engine is an effective and big step to improve the resulting performance. The variable electromagnetic valve scheduling system allows the exhaust and fuel valves to operate in a completely variable manner and to react to the smallest changes in the cylinder heads. Today, it is used to control the valve timing by using a hydraulic motor and a cam. But the design and construction of the system studied in this research have more modern technology. In this study, magnetic magnets were used to remove the camshaft, camshaft, crankshaft, crankshaft and many mechanical parts instead of using a hydraulic motor to control variable timing and valve movement. Magnets in which existing coils acquire magnetic properties by applying current to them. For each valve, two magnets are used, one to open and the other to close the valve with a spring. Many dynamic and magnetic parameters have been used in the design of this system, and many geometric constraints are involved in its design. The electromagnetic force generated is proportional to the volume of the magnetic magnet, and this designed volume is limited by the space of the cylinder head block. The speed distribution of valves and armatures is Gaussian. The minimum valve speed in an electromagnetic motor depends on the natural frequency of the mass and spring system. It is constant regardless of the motor speed.

“…The amount of this force is considered as shear strength. Equation 14gives us the shear stress [22]. (14) By integrating along the valve stem, the friction force becomes equation 15.…”

Section:  Friction Forcementioning

confidence: 99%

“…In this study, a simple manifold type was considered to remove the exhaust gases, which eliminates about half of the generated force from the gas pressure. Table 2 shows the required parameters for using the mentioned forces [22].…”

Section:  Gas Forcementioning

confidence: 99%

An Analytical Investigation of Magnetic Variable Valve Timing System in Internal Combustion Engines

Yousefi

2020

MJMIE

“…[ 1 ] Mastering the bionic strategies could direct the core design in diverse industrial applications, such as anti‐icing, [ 2 ] self‐cleaning, [ 3 ] and microfluidics, [ 4 ] and challenge the upcoming intelligent techniques including energy generation, [ 5 ] green printing, [ 6 ] and liquid robots. [ 7 ] Recent manipulation strategies are mainly divided into active method, by applying external electric fields, [ 8 ] magnetic fields, [ 9 ] temperature fields, [ 10 ] light, [ 11 ] and acoustic waves, [ 12 ] and passive method, by designing macrostructures like ridges, [ 13 ] tips, [ 14 ] ratchets, [ 15 ] grooves, [ 16 ] lattice cells, [ 17 ] or integrating wettable and less wettable regions on a solid surface. [ 18 ] Owing to its advantages of spontaneity, facility, diversity, as well as the energy‐saving property, the passive liquid manipulation method has aroused large amounts of research interest.…”

Section: Introductionmentioning

confidence: 99%

Liquid Film Sculpture via Droplet Impacting on Microstructured Heterowettable Surfaces

Chu

Wen

et al. 2022

Adv Funct Materials

Liquid manipulation plays an increasingly critical role in daily life and future technological processes. Although intensive attention is paid on controlling droplets, how to manipulate the behavior of larger scale liquid film still remains mysterious. Here, a droplet-impact-induced liquid film sculpture strategy is demonstrated on a microstructured heterowettable surface that can precisely sculpt a liquid film into any graphic pattern. The fundamental principles of the liquid film sculpture are elucidate and a phase diagram is drawn to distinguish three liquid film states upon droplet impacting including dewetting, rupture, and nonrupture. To precisely guide the film sculpture, the microstructured heterowettable surface is designed so that water film will naturally rupture at the top of the microstructure after the droplet impact and subsequently dewet into desired pattern. Liquid film sculpture is accompanied by self-propulsion and high construction speed, both of which are preferred in no-spray printing, painting, cleaning, and drawing, inspiring future artistic and engineering applications.

“…The impact behavior of the drops on the solid substrate is a frequently studied phenomenon in fluid mechanics because of numerous industrial and daily applications ranging from spray coating, inkjet printing, , aeronautics, , to criminal forensics . During the impact process, there are two main stages, including spreading and retraction, and various outcomes of the drop, such as splash, deposition, and rebound, , which are highly determined by liquid properties (e.g., size, density, viscosity, surface tension), substrate properties (e.g., wettability, roughness, surface nano/microstructure, shape, elasticity, or porosity), and impact conditions (e.g., impact velocity, environment temperature and humidity, gas pressure, and so on). ,− Among these, the design of surface structures is the most commonly used method to tune the droplet dynamics . Generally speaking, the control of the drop impact dynamics for application has two aspects.…”

Section: Introductionmentioning

confidence: 99%

Impact Dynamics of Nanodroplets on V-Shaped Substrates: Asymmetrical Behavior and Fast-Rebound Dynamics

2021

Langmuir

Controlling the drop impact behaviors plays an important role in both designing surface functional materials and improving industrial techniques. Here, the impact dynamics of nanodroplets on “V-shaped” substrates is studied, which is manifested as asymmetrical spreading and retraction behaviors that could be weakened by increasing the angles of the “V” shape, accompanied by the evolution of the shape from leaf-like, stripe-like, to dumbbell-like at v = 20 Å/ps. When v increases to 40 Å/ps, the previously deposited nanodroplets could be transformed to a rebound one at α = 60 and 90°, which is ascribed to the combined effect of the confinement conditions and the extrusion force. Furthermore, an impact behavior map as a function of impact velocity and angle is depicted, which suggests that a decrease in angles or an increase in the impact velocity is likely to cause the nanodroplets to rebound. More importantly, the results give visible evidence that compared to the flat substrates, the V-shaped structure is advantageous for achieving a fast-rebound behavior even at a low speed of impact, which should be good news for practical applications in many multidisciplinary fields, such as self-cleaning, anti-icing/fogging, pollution prevention, energy storage, and so forth.