Papers by Keyword: Ultrasonic Cavitation

Abstract: In this study, we conducted experiments to investigate the use of ultrasonic-assisted alkali-catalyzed transesterification for converting oil extracted from Roselle seed into biodiesel. Our goal was to evaluate how the production yield, and fluid properties of the biodiesel are affected by different operating conditions. Study scopes include the impact of mixing power, time, and volume of reactants. Our findings indicate that the ultrasonic-assisted process is consistently more effective than conventional mixing during the reaction stage. Our results show that the optimal power for ultrasonic production of biodiesel is 150 watts for 30 minutes, resulting in a production yield exceeding 95%. The viscosity and density of the product meet biodiesel standards. Additionally, when the ultrasonic-assisted process is used, glycerin can be removed more easily.

Abstract: Aluminium matrix composites (AMCs) have emerged as the substitute for the monolithic (unreinforced) materials over the past few decades. The applications of AMCs are common in automotive, aerospace, defence and biomedical sectors due to its lower weight, high strength, high resistance against corrosion and high thermal and electrical conductivity. In this work, it is aimed fabricate a new class Al 7075 based hybrid composites reinforcing with nanoparticulates suitable for automotive application. Al7075 reinforced with fixed quantity of boron carbide (B₄C) (1.5 wt.%) and varying wt % of flyash (0.5 wt.%, 1.0 wt.%, 1.5 wt.%) is fabricated using ultrasonic-assisted stir casting technique. Physical and mechanical characterization such as density, porosity, micro hardness, tensile strength and impact strength were estimated for three different compositions. The tensile strength and percentage increase in hardness value of the nanocomposite Al7075-B4C (1.5 wt. %)-flyash (0.5 wt. %): HNC3 found maximum as 294 MPa and 32.93%. In comparison with Al7075 alloy the impact strength of HNC3 shows the highest percentage of 9.31% respectively.

Abstract: Fabrication of nanocomposites is a highly challenging task because of the particles need to be disseminated across the molten liquid due to broad surface area, poor wettability. Homogeneous dispersion is tough in traditional stirring methods leads to cluster and agglomeration formation in high viscous molten metals. In such attempts, the ultrasonic vibration process exhibits the better dispersion and distribution of nanocomposites with enhanced material properties as compared to other fabrication processes. This paper deals with the fabrication process, probe design and effective process parameters of sonication process to the uniform dispersion of nanoparticles.

Abstract: In this work, AA6061/1.25 vol. % SiC_p metal matrix nanocomposites (MMNCs) were fabricated using the ultrasonic cavitation assisted casting process. To investigate the effect of ultrasonic amplitudes on processing the MMNCs, the MMNC samples were processed with 15 µm, 30 µm and 50 µm of ultrasonic amplitudes. The results indicate that the ultrasonic amplitudes play a significant role in dispersing the SiC nanoparticles uniformly in the AA6061 melt and it also affecting the mechanical properties of the fabricated MMNCs. The AA6061/1.25 vol. % SiC_p MMNC sample processed with 30 µm of ultrasonic amplitude possessed the good dispersion of SiC_p in the Al melt and hence better mechanical properties compared to the MMNCs processed with 15 µm and 50 µm amplitudes.

Abstract: The structure of cast iron specimen and the temperature control unit of the engine coolant ultrasonic cavitation apparatus were improved in this paper. The broken problem of cast iron specimen was solved by split-structure design, which also solved the loose binding problem between specimen and sonotrode. The temperature control unit included a beaker with water circulating jacket, water bath, circulating pump and connection hose. The temperature control unit overcame the difficulty of the temperature control of test coolant solution. More important, the temperature control inside the soundproof box was realized, which avoided the effect of ultrasonic vibration noise on the health of operator. The unit has the characteristics of simple, practical and easy to use.

Abstract: The pressure field induced by cavitaion bubble is responsible for the grinding mechanism and the cutting chatter of power ultrasonic honing. Based on the cavitation bubble dynamics model in the grinding area of power ultrasonic honing, the radiation pressure field of cavitation bubble was established. Experimental results show that the bubble is distributed in the grinding area like honeycomb and the size is about 10μm. Numerical simulation of dynamics and pressure field of cavitation bubble was performed. Numerical results show the dynamic behavior of cavitation bubble presents grow, expend and collapse under an acoustic cycle. However the expansion amplitude of bubble can be decreased and the collapse time can be extended and even collapse after several acoustic cycles with increasing ambient bubble radius. The bubble radiation pressure during collapsing bubble increases with increasing ultrasonic amplitude and ultrasonic frequency. And the pressure value of collapsing bubble is about 10Mpa which is more an order of magnitude than atmospheric pressure.

Abstract: Metal matrix nanocomposites (MMNCs) have emerged as an important class of materials for structural applications specifically in the automobile and aerospace sectors; however, development of cost effective mass production technique of MMNCs with requisite operational and geometrical flexibilities is still a great challenge. Focused research in the last decade has highlighted that ultrasonic cavitation based processing is the most promising method for manufacturing of MMNCs with nearly uniform distribution of nanoparticles, having added advantage of being a liquid-phase route. This article presents an overview on the basic principles and recent advances in the ultrasonic cavitation based processing of MMNCs with a particular emphasis on identifying relationships amongst processing variables, microstructural parameters and mechanical properties. Critical issues of MMNCs fabrication are discussed.

Abstract: Ultrasonic biological effects are reactions between ultrasonic energy and biological tissue. The reactions will promote the separation of medical materials from some herbs. The research contents: (1) the mechanism of medical-component extraction of CTM based on ultrasonic cavitations; (2) the experiment research on optimization of extraction technique of CTM. The research methods: (1) to explain the mechanism, the dynamics and interaction between ultrasound and plant tissues; (2) combining with the experiments, the extracting effect and energy saving are used for evaluating the technique. The research results: (1) the optimized ultrasonic frequency is 25±10kHz, the power density in the space in the device should be 0.5~1.2W/cm³, the medium temperature should be 30~60°C. (2)Comparing with the boiling technique, the extracting effect of the ultrasonic technique is increased by 15%~30%, energy is saved by 500%. The experiment results are good tally with the theories.

Abstract: The major problem associated with the fabrication of cast metal matrix composites is the agglomeration tendency of the particles in the metal matrix. The agglomeration of the particles in the metal matrix greatly reduces the mechanical properties of the fabricated composite materials. In this work, to reduce the agglomeration tendency of SiC particles in Al matrix, different weight percentages of SiC particles reinforced Al composites were fabricated by the conventional stir casting and the ultrasonic cavitation assisted casting routes. Results indicate that in both the methods, particle distribution was uniform upto certain weight percentage after that agglomeration of particles were observed. The mechanical properties of the as-cast composites were superior to that of the as-cast alloys. Composites fabricated by the ultrasonic cavitation method showed slightly better mechanical properties than the composites fabricated by the conventional stir casting route. From the consolidated results it was also observed that 10 weight % of SiC_p reinforced composite fabricated by the ultrasonic cavitation method yields the better mechanical properties when compared to the other composites fabricated in this study. Keywords: Metal Matrix Composites, Stir Casting, Ultrasonic Cavitation, Mechanical Properties, Microstructure, Comparative Study

Abstract: t can particularly generate abundant cavitation bubbles in the processing of the power ultrasonic honing. The dynamics of cavitation bubbles in the grinding area are very vital to study the machining mechanism and the cutting chatter of power ultrasonic honing. Based on the Rayleigh-Plesset equation, a new dynamics model of cavitation bubble is established, considering the velocity of ultrasonic honing and honing pressure. With the superposition principle of velocity potential, the dynamics of double cavitation bubble is also established. Moreover, the dynamic characteristics of cavitation bubble also can be simulated numerically. The results show that cavitation bubble in the grinding zone begins to grow extensively and then undergoes collapse, and even subsequent rebound and then. The variation trend of radius change of double cavitation bubble in the grinding area is more than that of single cavitation bubble by an order of magnitude.