A fundamental physical mechanism whereby sprays are formed is formulated. A model of nonaxial sequence of superimposed disturbances, propagating one on top of the other, is used to describe the evolution of liquid jets into sprays. It is postulated that every consecutive superimposed disturbance travels tangent to the surface that supports its propagation. Model outputs show highly nonlinear profiles of the jet surface. Fourier analysis, of the derived superimposed disturbance functions, is performed in conjunction with the basic building blocks of the classical instability theory. Starting from the first superimposed disturbance, the sum of these linear building blocks results in nonlinear intricate profiles of the jet. These profiles are shown to be the source of drops from which a spray is made.
A linear model of three layers plane wall exposed to oscillating temperatures with different amplitudes and frequencies was built by using a physical superposition. A physical superposition of two states was performed, one state is a wall which one surface is exposed to oscillating temperature and the other surface is exposed to zero relative temperature and a second state is a wall which one surface is exposed to relative zero temperature while the other surface is exposed to oscillating temperature with different amplitudes and frequencies. Temperature distributions were introduced for different amplitudes, frequencies and thermal conductivities. It was shown that increasing the frequency value decreases the temperature penetration length, high frequency value leads to extremum temperature values changes on the surface while low frequency value allows gradually temperature changes during the time period. Temperature distribution lines where there are at the same time heat flux entry and heat flux exit were not received for the same constraint frequencies. Energy and Power Engineering appear causing a matter failure. Racopoulos et al. [1] [2] investigated the temperature oscillations in the combustion chamber walls of a diesel engine. Based on theoretical model and experimental measurements, the penetration of the oscillating temperature part of the temperature full value into the inner cylinder wall was shown for few matters. It was observed that when increasing the degree of insulation, the wall temperature swings highly increase, while at the same time the corresponding depth inside which they disappear, decreases. Investigation of the efficiency of a thermoelectric power generator (TPG) was performed by Yan and Malen [3]. Thermoelectric power generator converts heat directly into electricity without moving parts. It was shown that the use of a periodic heat source can increase the efficiency of a TPG. Temperature oscillations may be also formed by a periodic heating. Two methods of periodic heating implementation are an induction heating and a direct resistance heating. Surface hardening, welding and melting are some applications of induction heating. Direct resistance heating has major metal working applications as heating prior to forming and heat treating. Major nonmetals application is a glass melting. Sahin and Yilbas [4] analyzed the temperature rise in an insulated slab which is subjected to a direct resistance heating and to a conduction heating. It was found that for both heating methods, the thermal penetration depth for high frequencies is small.Additional area related to temperature oscillations is the controlling temperature in buildings. Ma and Wang [5] investigated the dynamic heat transfer performance of an exterior Planar Thermal Mass (ePTM) subject to sinusoidal heating and cooling. Analytical solution was performed when the mean value of outdoor air temperature was equal to indoor air temperature. The analytical solution showed that the time lag and the decrement factor are independent of ...
This paper deals with a periodic heat transfer along straight fins. The heat transfer is due to temperature fluctuations at the base of the fin. The paper introduces a general physical model for any constraint configuration using Fourier series when it is needed. Beyond the basic example, the cosine constraint, the paper presents two examples: absolute cosine constraint and square wave. All constraints show that the oscillations ability to penetrate the fin decreases with increasing frequency. It has been found that for a symmetrical time constraint such as the base cosine constraint, increasing the frequency leads to a convergence of the relative temperature to a zero value. For asymmetric constraint such as the absolute cosine constraint and the square wave, the convergence is to a positive value other than zero. Increasing the Biot number leads to a convergence to zero value in all constraints types.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.