Unsteady Aerodynamics and Forces Characteristics of Dual Row Control Stage with Partial Admission Condition

Abstract

Unsteady aerodynamic performance and forces on the rotor blades of dual row control stage with partial admission condition was numerically investigated using three-dimensional unsteady Reynolds-Averaged Navier-Stokes (URANS) and k-e turbulent model. The computational model includes four nozzle boxes, two full rotor blade rows and two guide vanes groups. The numerical steady aerodynamic performance of the partial admission dual row control stage is well agreement with the experimental data. The obtained unsteady results show that the periodic variations of mass flow rate and output power were correlated with the relative position between two admitted arcs of the nozzle box and guide vane group. The unsteady aerodynamic performance of nozzle cascades was influenced by the downstream rotor blade. The rotor blades were subject to large unsteady and periodic forces while traveling along the circumferential direction. The magnitude and direction of the unsteady forces on the rotor blades were significantly influenced by the rotor blades entered or left the admission arcs. The spectrum analysis of the excitation forces on the rotor blades show that the high amplitudes caused by partial admission were at low multiples of rotational frequency.