Fundamental approach to laminar flame propagation

The 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 thermal theory of constant-pressure deflagration for first-order global reactions

The one-dimensional thermal theory of constant-pressure deflagration has been discussed in a recent publication by the senior author and G. Millán. In this paper an explicit relation was given for the linear burning velocity in flames supported by first-order global reactions. It is the purpose of the present analysis to extend this work by dropping the assumptions (a) that the average molecular weight of the gas mixture remains constant, and (b) that the thermal conductivity is constant. As the result, the one-dimensional theory of constant-pressure deflagration described in this paper is complete except in so far as the following reasonable approximations are concerned: (a) a constant average specific heat equal to the ratio of heat release per gram of reactant to total temperature rise may be used; (b) the ideal gas law constitutes a satisfactory equation of state for reacting gas mixtures

Atomic Engineering?

It 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

Mechanical similitude and turbulence

This report deals with the theory of the vortex street which enables the reproduction of the mechanism of the form resistance with suitable approximation under stated conditions, although such a resistance is precluded in a fluid which is perfectly inviscid. Disregarding for the present the origination of the vortex, the stream attitude in the wake of the body may be described approximately correct by the representation of individual vortices, without transgressing the law governing the motion of such vortices in an ideal fluid. Another striking example is the theory of the induced drag of wings, which likewise shows the extent of applying the vortex equations without overstepping the bounds of the dynamics of ideal fluids

Analysis of the lamella roof horizontal forces

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The thermal theory of constant pressure deflagration

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Thermal theory of a laminar flame front near a cold wall

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The impact on seaplane floats during landing

In order to make a stress analysis of seaplane floats, and especially of the members connecting the floats with the fuselage, it is of great importance to determine the maximum pressure acting on the floats during landing. Here, the author gives a formula for maximum pressures during landing that permits one to apply experimental results to different bodies and different velocities. The author notes that the formula checks very well with experimental results

Recent European Developments in Helicopters

Descriptions are given of two captured helicopters, one driven by electric power, the other by a gasoline engine. An account is given of flight tests of the gasoline powered vehicle. After 15 successful flight tests, the gasoline powered vehicle crashed due to the insufficient thrust. Also discussed here are the applications of helicopters for military observations, for meteorological work, and for carrying radio antennas

B\'enard-von K\'arm\'an vortex street in an exciton-polariton superfluid

The dynamics of an exciton--polariton superfluid resonantly injected into a semiconductor microcavity are investigated numerically. The results reveal that a B\'enard--von K\'arm\'an vortex street is generated in the wake behind an obstacle potential, in addition to the generation of quantized vortex dipoles and dark solitons. The vortex street is shown to be robust against a disorder potential in a sample and it can be observed even in time-integrated measurements.Comment: 4 pages, 3 figure