At the most fundamental level, main rotor loading noise is caused by the harmonically-varying aerodynamic loads (acoustic pressures) exerted by the rotating blades on the air. Rotorcraft main rotor noise is therefore, in principle, a function of rotor control inputs, and thus the forces and moments required to achieve steady, or “trim”, flight equilibrium. In certain flight conditions, the ensu...

We investigated temperature distribution in a solid state nuclear magnetic resonance (NMR) sample rotor under magic angle spinning (MAS) experiments by analyzing the (207)Pb chemical shift of solid lead nitrate (Pb(NO3)2). The analysis corrected a mismatch of the temperature dependence of (1)H spin-lattice relaxation time (T1(H)) obtained from different sample positions in the rotor. We prepare...

The paper proposes a mechanical model of SFD-sliding bearing flexible rotor system, employing RungeKutta method to tackle nonlinear differential equation, thus acquiring the dynamic response and the unbalanced response curve. Results obtained show the route of flexible rotor system from stable periodic motion to chaos state is: periodic motion—quasi-periodic motion—chaos —period doubling bifurc...

Five-phase synchronous reluctance machines (SynRM’s) have a higher torque density over conventional three-phase SynRM’s due to the utilization of the third harmonics in the magnetic field interacting with appropriate armature current. However, for effective utilization of the third harmonics, it is critical that the rotor of the SynRM creates sufficient coupling between the fundamental and thir...

Rotor aerodynamics is known to be significant in quadrotor flight [1]. We extend a previously proposed aerodynamic model which relates rotor thrust to rotor angular speed, relative velocity between the rotor plane of motion and the air, and proximity of both the ground and the ceiling. Our model adds the rotor angle of attack to this framework. We develop a simulation to demonstrate the effect ...

In this study, a novel control scheme including a proportional–integral–harmonic resonant (PI–R) controller is presented to eliminate the produced harmonics resulting from the quasi-sine rotor voltage injection in a doubly fed induction generator (DFIG) connected to power electric networks. The control scheme is implemented in the rotor reference frame ðarbrÞ under quasi-sine rotor injection by...

In this paper, one presents a transient state performance optimization of vectorcontrolled induction motor (IM) drives operating in the field-weakening region. The vector control scheme, based on the rotor flux field-orientation (RFOC), is considered to ensure maximum torque motor operation regime. Although in the high speed region, the measure of rotor speed and the sensitivity to parameters e...

The rotor power losses in magnetic bearings are due to eddy currents, hysteresis, and windage. The influence of air gap magnetic flux density and air gap thickness is not well understood at this time. This paper presents measured results in two magnetic bearing radial configurations with a laminated rotor. The rotor power losses were evaluated by measuring the rundown speed of the rotor, in air...

Problem statement: The Rotor reactance control by inclusion of external capacitance in the rotor circuit has been in recent research for improving the performances of Wound Rotor Induction Motor (WRIM). The rotor capacitive reactance is adjusted such that for any desired load torque the efficiency of the WRIM is maximized. The rotor external capacitance can be controlled using a dynamic capacit...

Current trends in micro-turbomachinery stress the need for adequate rotordynamic models. These models should allow accurate prediction of critical speeds, imbalance response and stable operation range of microturbomachinery rotor-bearing systems. This paper gives an overview of the total rotordynamic modelling process of a micro-turbine rotor supported on aerostatic bearings. A both accurate an...