Open AccessThis paper presents results of numerically investigated amplitudes and characteristic of unsteady loads on rotor blade, efficiency, and extra loss of kinetic energy in the model of a singlestaged turbine. The calculations performed in various regimes characterized by the ratio . Computational results were compared with experimental data obtained while studying a radial turbine model at SPbPU.
To perform the numerical experiment, steady (Stage) and unsteady (Transient StatorRotor) simulations were obtained using ANSYS CFX 14.5 in the cluster system at SPbPU Department of Computing Resources. The results have shown that amplitudes of time-averaged forces and torques decrease with increasing angular velocity, but their peak-to-peak amplitudes (max-min) increase. The peak-to-peak amplitude of unsteady force and torque at =0,55 with small axial gap Δz1=4 mm is 50-60% of time-averaged loads on rotor blade. The peak-to-peak amplitude of the dimensionless forces and torques in the range of = 0.4..0.75 increases from 20 to 90% of time-averaged values. The computational results were in agreement with experimental data of radial turbine model.
The maximum efficiency level has been found in steady and unsteady calculations with values 0.806 and 0.774, which corresponds to the efficiency level of this turbine stage type. A comparison of the "Stage" and "Transient Stator-Rotor" calculations indicates that the unsteady loss level in the nominal regime is 3.2%. This value is practically constant in entire range of from 0.4 to 0.75.