IMPACT ASSESSMENT OF NONSTATIONARY VISCOUS FLOW IN A CYCLE OF A HYBRID RECIPROCATING POWER MACHINE ON FLUID CONSUMPTION IN A SLOT SEAL

摘要

The paper considers the influence of the nonstationary flow of a viscous fluid in a slot seal on the instantaneous and average flow rate of a fluid over the power cycle. Boundary and initial conditions are set according to the schematization of indicator diagrams in the compressor and pump sections. To calculate laminar and turbulent flows, the "Laminar" and SST models were used. A numerical experiment was carried out to establish the tendencies of the nonstationary fluid flow in the slot seal and identify discrepancies in the determination of the instantaneous and integral flow rate per cycle in comparison with the quasi-stationary problem. The maximum divergence is observed near dead points, with the delay in changing the flow direction when changing the sign of the pressure gradient reaching 9 degrees (of shaft turning). As the concentric gap increases, the influence of inertia forces increases, leading to an increase in the discrepancy in determining mass flow rates in quasi-stationary and non-stationary formulations, which can reach 10% per cycle for a concentric gap of 100 microns.