18 research outputs found
Atomic Engineering?
Get PDFIt has happened now for the third time in our lifetime (“our” referring to the elders of the engineering profession) that new avenues of engineering activities of tremendous importance have been opened by physicists and the engineering profession has found itself unprepared to challenge the task
Fundamental approach to laminar flame propagation
Get PDFThe complete system of equations for a theory of laminar flame equations is presented, taking into account both heat conduction and diffusion, for the case of an arbitrary number of simultaneous reactions. The eigenvalue problem determining the flame velocity is formulated. Two examples are given in order to show that explicit analytical expressions for the flame velocity can be obtained, which are in good agreement with the results obtained by numerical integration of the equations. In the first example (hydrazine decomposition) one reaction is considered as global, i.e., rate-controlling, reaction. In the second example (ozone decomposition) a hypothesis is introduced for the concentration of the free radical O, which corresponds to the steady-state approximation generally used in classical chemical kinetics. In both cases approximate explicit formulae are obtained for the flame velocity using legitimate approximation methods, without making drastic assumptions. The steady-state assumption used for the ozone flame has a bearing on a better understanding of the mechanism of chain reactions in general. The method indicated in the paper gives hope that the more complicated chain reactions, such as the combustion of hydrocarbons, will also be made accessible to theoretical computation
The Propagation of Plastic Deformation in Solids
Get PDFThe stress wave caused by a longitudinal impact at the end of a cylindrical bar has been analyzed in the case where the impact velocity is large enough to produce plastic strain. The theory gives a method for computing the stress distribution along the bar at any instant during impact. It is shown that for a given material, there is a critical impact velocity such that when subjected to a tension impact with a velocity higher than the critical, the material should break near the impacted end with negligible plastic strain.
An experimental investigation was made concurrently with the theoretical study. Some of the most significant experimental results are presented in this paper
On the Concept of Similiarity in the Theory of Isotropic Turbulence
Get PDFMuch recent work has been done in the study of isotropic turbulence, particularly from the point of view of its spectrum. But the underlying concept is still the assumption of the similarity of the spectrum during the process of decay, which is equivalent to the idea of self-preservation of the correlation functions introduced by the senior author. It is however generally recognized that the correlation function does change its shape during the process of decay, and hence the concept of self-preservation or similarity must be interpreted with suitable restrictions. Under the limitation to low Reynolds numbers of turbulence, the original idea of Kármán-Howarth has been confirmed. Then the decay consists essentially of viscous dissipation of energy separately in each individual frequency interval. However, when turbulent diffusion of energy, i.e., transfer of energy between frequency intervals, occurs at a significant rate, the interpretation of the decay process and the spectral distribution is quite varied. This an be seen by a comparison of Heisenberg, Batchelor, Frenkiel, and the present authors. The purpose of the present paper is an attempt to clarify this situation
The failure of the Tacoma Narrows Bridge
Get PDFThe Board of Engineers appointed by you to
report on the Failure of the Tacoma Narrows Bridge have
made a complete investigation of the design, the behaviour
after completion and the failure of the structure. Our
report covering this investigation follows
