International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Traditional concept about the boundary layer structure, technique of the theoretical determination of a velocity profile in this layer, developed in first half of the 20th century, does not experienced, basically, any changes, although, on their close analysis a number of questions and even problems arises requiring their solution.

First of all, it is referred to physical causes of the occurrence of turbulence in the boundary layer, conservation of its near-wall region, conformance of a classical logarithmic velocity profile to experimental data, the appropriateness of introduction of such definition as “a laminar sublayer in the turbulent boundary layer”. All these outstanding problems are considered in the following materials.

The article deals with a problem of fatigue load calculations when designing the aircraft wing. Much of fatigue damage is done to the wing by occasional air gusts in turbulent atmosphere. Therefore, the author considers the pattern of continuous atmospheric turbulence that gives an idea of low-altitude gusts. It is at low altitudes that nonstandard flights are performed for which it is wrong to use the statistical data on fatigue damage available from the previously operated airplanes of the same class. The method is offered to determine the equivalent bending moments along the wing span in discrete flight modes and within the entire routine flight. The above method takes into account the profile parameters of routine flights, the dynamic vibrations of the wing and fatigue characteristics of the structural material. To prove the reliability of the method the calculation results have been compared to those of medium-range aircraft testing flights.

In this paper some results concerning the evolution of flame propagation through unburnt mixture of two different hydrocarbon fuels,such as CH4 and C8H18, in engines with strong macro flows were presented. Flame propagation was represented by the evolution of spatial distribution of temperature in various cutplanes within combustion chamber. Flame front location was determined in zones with maximum temperature gradient. All results were obtained by dint of multidimensional modeling of reactive flows in arbitrary geometry of IC engine combustion chamber with moving boundaries. In 4.-valve engines the fluid flow pattern during intake is characterized with organized tumble motion pursued by small but clearly legible deterioration in the vicinity of BDC. During compression the fluid flow pattern is entirely three-dimensional and fully controlled by vortex motion located in the central part of the chamber. For that reason these engines are designated as IC engines with strong macro flows (swirl, squish, tumble) yielding non-spherical flame shapes usually encountered in quiescent flows. Flame propagation results for both fuels were obtained with eddy-viscosity model i.e. with standard k-ε model of turbulence.
The interplay between fluid flow pattern and flame propagation is entirely invariant as regards fuel variationindicating that flame propagation through unburnet mixture of CH4 and C8H18 hydrocarbon fuels is not chemically controlled but controlled by dint of turbulent diffusion.