To quantify the influence of the rotor speed on the particle dynamics, the average particle velocity is plotted in Fig. 18a as a function of time. As in previous investigations (Section 4.2.2), the mean particle velocity at the transient regime oscillates and reaches a constant value at steady state. However, the amplitude of the fluctuations at lower tip speed is also lower, caused by the reduced kinetic energy of the rotor disc. A comparison of the values at steady state shows a direct influence of the rotor movement on the average particle velocity, which increases with higher tip speed.