Unsteady helicopter rotor aerodynamics are complicated. This paper reviews some of the fundamentals and newer developments of unsteady helicopter aerodynamics. Rotor flow is beautiful and complex. Visualizing rotor flow allows for an appreciation of the following theories and solution attempts as well as nature’s complexities. The flow through a helicopter rotor with forward motion is shown in ...

Abstract: This paper presents an exact input-output linearization control scheme for rotor speed and rotor flux control of induction motor drive. In this scheme the motor model, is described in the fixed stator frame, and it is linearized, using exact inputoutput linearization technique, allowing a decoupled control of rotor flux and torque. To avoid the use of mechanical sensor, the rotor spee...

Repetitive learning control was examined for active vibration control of rotor. A novel modification of a gradient-based repetitive learning control algorithm was developed. The stability of the algorithm was studied and the algorithm was tested on a rotor test rig. The experiments showed that repetitive learning control attenuated efficiently rotor vibrations excited by rotor unbalances. In ad...

this paper presents the aerodynamic design and economical evaluation of a 200 kw site specific wind turbine for the province of semnan in iran. by designing site specific wind turbines, the cost of energy which is calculated out of the annual energy production and also the cost of manufacturing the rotor are minimized. the aerodynamic design is based on the well-known blade element momentum the...

Rotor cage faults as broken rotor bars, increased bars resistance and end-ring faults can be caused by thermal stresses, due to overload, overheating and thus mechanical stresses, magnetic stresses and dynamic stresses due to shaft torques. Environmental stresses as contamination or abrasion also contributes to the rotor cage faults. The rotor cage faults can also lead to the shaft vibration an...

A rotor-router walk is a deterministic version of a random walk, in which the walker is routed to each of the neighbouring vertices in some fixed cyclic order. We consider here directed covers of graphs (called also periodic trees) and we study several quantities related to rotor-router walks on directed covers. The quantities under consideration are: order of the rotor-router group, order of t...

The problem of controlling a sensorless induction motor (i.e. without rotor speed measurements) is addressed. Smooth reference signals for rotor speed and rotor ‡ux modulus are required to be tracked exponentially and globally. Only semiglobal solutions have been recently obtained in the literature. A global solution is presented for current-fed induction motors which makes use of a novel rotor...

As a wind turbine extracts energy from the wind, induced wind velocities, lower than the freestream velocity, will be present both upstream and downstream of the rotor. In this study, the upstream induction zone of a 225 kW horizontal axis Vestas V27 wind turbine located at the Danish Technical University’s Risø campus is investigated using a scanning Light Detection and Ranging (lidar) system....

Title of Dissertation: Computational Investigation of Micro-Scale Coaxial Rotor Aerodynamics in Hover Vinod K. Lakshminarayan, Doctor of Philosophy, 2009 Dissertation directed by: Dr. James D. Baeder Department of Aerospace Engineering In this work, a compressible Reynolds-Averaged Navier Stokes (RANS) solver is extended to investigate the aerodynamics of a micro-scale coaxial rotor configurati...

Turbocharger is a high speed rotor system supported by a pair of floating ring bearings which comprise of double oil films. The stability of its rotor system is governed by not only the structure of the rotor but also by the nonlinear hydrodynamic force of two oil films. In this paper, a lumped dynamics model is developed for a turbocharger rotor system. In order to investigate the nonlinear be...