Abstract
The results of numerical simulation and experimental study of the structure of unsteady flows in pipes with different cross sections are presented in the article. It is shown that the unsteady gas flow in a circular pipe is axisymmetric without secondary currents. Steady vortex structures (secondary flows) are observed in pipes with cross sections in the form of a square and an equilateral triangle. It was found that these secondary flows have a significant impact on gas flows in pipes of complex configuration. On the basis of experimental researches it is established that the strong oscillatory phenomena exist in the inlet pipe of the piston engine arising after the closing of the intake valve. The placement of the profiled plots (with a cross section of a square or an equilateral triangle) in the intake pipe leads to the damping of the oscillatory phenomena and a more rapid stabilization of pulsating flow. This is due to the stabilizing effect of the vortex structures formed in the corners of this configuration.
Highlights
It is known that the stagnation zone and reverse flow can be formed in the flowing parts of energy machines and plants
The structure of gas flows in pipes with different cross sections is investigated in a large number of scientific papers
In this study it was found that the cross-sectional shape of the pipe has a significant impact on the structure of the gas flow
Summary
It is known that the stagnation zone and reverse flow can be formed in the flowing parts of energy machines and plants (e.g., gas-turbine units or internal combustion engines). It has a negative influence on hydraulic resistance and on the flow characteristics of the system. It is shown that the gas flow in a long circular pipe is axisymmetric In such flows, sustainable large-scale turbulent structures (secondary flows) do not occur. Sustainable large-scale turbulent structures (secondary flows) do not occur Another picture is observed for gas flows in pipes with square or triangular cross plots (Fig. 1). It is determined that isotachs in appearance similar to the shape of the cross section are observed in cross-section of the pipe [1,2,3]
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