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SummaryThe goal of this paper is to develop mathematically less complex differential equations of motion of an elastic crankshaft and their solutions with acceptable accuracy in relation to the actual system. The instantaneous angular speed of the free end of the crankshaft consists of the nonuniform rigid body motion mode and elastic deformation mode. In general, the crankshaft, as well as other parts of the engine, could be considered as a structural component with distributed mass and elasticity. This will lead to a system with an infinite number of degrees of freedom, and require solving partial differential equations. Another approach is to discretize the continuous system into a finite set of rigid bodies interconnected with springs and dampers, which is the method chosen here. The lumped mass model of the crankshaft and the corresponding differential equations of motion for each mass simulate the actual dynamics of the crankshaft fairly accurately.

The aim of this paper is to numerically analyze the energy separation phenomenon in turbulent compressible swirling flow in a cylindrical tube. In that sense, the energy separation in a vortex tube with orifice at cold end closed completely is examined numerically using OpenFOAM software. Obtained results are validated with the experimental ones. For numerical calculations, both two-equation (standard k-ε) and full Reynolds stress turbulence models (LRR) are used. The computational domain is considered to be two-dimensional, and the working fluid-air is treated as calorically perfect gas. Mesh independence test is carried out for four different mesh sizes. Distributions of swirling flow intensity, average swirl and angular velocity clearly show the influence of the swirl presence in the flow. The values of these quantities point to the physics of this extremely complex flow-thermodynamic phenomenon, such is the energy separation. Based on values and distributions of these flow quantities a comparison between incompressible and compressible turbulent swirling flow is performed.