NUMERICAL SIMULATION OF A FLUID FLOW IN THE CYLINDRICAL DUCT CONTAINING TWO DIAPHRAGMS WITH ORIFICES OF DIFFERENT DIAMETERS

The flow of a viscous incompressible fluid in cylindrical duct with two serial diaphragms orifices different diameters was studied based on the numerical solution unsteady Navier-Stokes equations. algorithm finite volume method using second-order accurate difference schemes both space and time. TVD (Total-Variation Diminishing) form central-difference scheme flux limiter used for interpolation convective terms. combined evaluation velocity pressure fields carried out PISO (Pressure Implicit Split Operator) procedure. problem solved OpenFOAM (Open-source Field Operation And Manipulation) open-source toolkit libraries computing power cluster supercomputer V.M. Glushkov Institute Cybernetics National Academy Sciences Ukraine. It shown that within certain range diameter ratio diaphragms, circulation movement is established cavity between diaphragms. boundary layer breaks off from surface first diaphragm forms an annular shear layer. When approaching second diaphragm, sequence ring vortices formed it, which interact lead to emergence tonal sound. orifice decreases, share jet’s kinetic energy, participates middle increases. As result, amplitude fluctuations decreases. increases, energy involved when value reached, interaction does not occur. excitation sound stops. Strouhal number self-oscillations practically change changes. During calculations, modes self-oscillation were obtained, consistent previous works.