Introduction to Rotating Blades

The results under initial cavitating conditions show that the high frequency implosions of vapour bubbles interact with the low frequency passing of the rotating blades and compose part of the vibration signal.

Nevertheless, most studies of VGs are conducted on flat plates and airfoils rather than rotating blades.

Crack is one of the most fatal faults of rotating blades.

The present work investigates the effect of sweep on the free-field noise emission from the trailing edge of an isolated airfoil analytically, as a first step towards a more complete approach dedicated to rotating blades.

However, during running, severe interactions may occur between the rotating blades and the coating of the casing leading to these parts getting damaged.

Numerical simulations with two unsteady rotating point forces and experiments with the rotating blades of an unmanned aerial vehicle examine the validity of the proposed method.

The use of a lidar-based system is either in the detection of the object itself or of the wingtip vortices generated by rotating blades.

The Actuator Line Method (ALM), combining a lumped-parameter representation of the rotating blades with the CFD resolution of the turbine flow field, stands out among the modern simulation methods for wind turbines as probably the most interesting compromise between accuracy and computational cost.

The paper analysis the impact of airfoil flow by centrifugal force and the Coriolis force which generated by the rotating blades and defines the airfoil performance at separated changing flow region by numerical simulation.

The drone noise mainly comes from its rotating blades, providing plentiful information of the status of the drone.

During run ups and run downs, the rotating blades are subjected to fluctuating forces with time dependent frequencies and the dynamic response of the blades around the resonance crossings deviates from the stationary response.

PSP measurements on rotating blades can be made using the single-shot two-gate lifetime method, as demonstrated in several examples here.

The propeller was modeled both as an actuator disk and as rotating blades.

In order to study ice protection systems for rotating blades, a new experimental setup has been developed at the Anti-Icing Materials International Laboratory (AMIL).

Aiming at the problem of low resources utilization of rotating blades in the selection process of aeroengine fan rotor blades, this paper takes the first-order bending dispersion, first-order torque dispersion, and gravitational moment difference of rotor blades as the selection criteria and takes the minimum remaining blades as the optimization goal.

This canonical problem is an analytical-asymptotic approach that reveals the parametric dependence of interference of electromagnetic waves with rotating blades, a subject which is known as rotor blade modulation.

For the considered test cases, it seems that the size of the radial clearances of the rotating blades does not a play a significant role on the ventilation phenomenon.

The model is derived after a discussion about the aerodynamics of rotating blades.

However, increasing wind turbine size (mainly blade size) implies expanding the blade swivel range (rotor sweep zone), and concerns have been raised about a possible increase in the number of bird collisions with the rotating blades.

Results show that attitude angles of the bird produce a significant impact on the effect of the bird strike on rotating blades and would increase the possibility of blade failures, especially for the yaw angle of -45° and the pitch angle of − 60°.

In the recent technology over the Unmanned Aerial Vehicle (UAV), the implication of propeller contributes a principal part in the production of thrust by pushing the air with the rotating blades.

Blade tip timing (BTT) technology is one of the most effective methods for vibration monitoring and health management of rotating blades.

In this framework, turbulence interaction, flow non-uniformities, trailing-edge boundary layer fluctuations and blade-tip leakages are different mechanisms generating aeroacoustic sources on the rotating blades and contributing to the overall emitted sound.

This paper describes the mathematical model representing the signal reflected from rotating blades of propeller-driven aerial targets in the bistatic radar.

However, as the wind turbines grow, the aerodynamic noise generated from the rotating blades is becoming a major concern that limits the use of wind turbines, especially near residential housing areas.

The work in this paper can improve the reliability of BTT measurements, and is of great significance to the comprehensive perception of operation state and accurate evaluation of dynamic stress of rotating blades.

The abradable coatings had significantly enhanced turbomachinery performance by acting as a sacrificial seal between rotating blades and stationary casing.

Firstly, we develop a computational fluid dynamics- (CFD-) based method of simulation of the blade airfoil under natural rain scenario and different angles of attack in order to obtain a data-driven basis relating to multiple working conditions of the rotating blades for further analysis.

By considering the dynamics of vortex lines shed from the rotating blades, the tilted wake was connected to the geometry of the helical blades.

Flow effects caused by rotating blades are modelled based on both simplified approach and truly 3D simulations.

The study demonstrated a theoretical model of extracting the m-Doppler signature due to rotating blades of a quadcopter drone, in forward scattering radar (FSR) geometry.

The low-frequency in-plane thickness noise generating from the displacement of air by rotating blades has an important influence on helicopter detection.

It is well known that 90 percent or more of direct lightning strikes to wind turbines hit the rotating blades and these direct strikes result in the most costly damages to turbines.

A Blisk is the integrated part of rotating blades and a disk, which is recently being adopted for fan and compressor modules of jet engines for the purpose of the weight reduction and the performance improvement.

The experiments of the multi-MW scale wind turbine were performed at the top of the hill, near the sea and the FBG sensors were mounted at various locations on the internal surfaces of the rotating blades.

The performance characteristics of vertical axis wind turbines are considerably influenced by dynamic stall phenomenon which is the processes of delayed flow separation caused by a rapid excursion in the angle of attack of rotating blades.

The present contribution reports a comparison of results for the rotating blades of an RC helicopter obtained using fluid-structure interaction in a computer fluid dynamics (CFD) model with measurements performed in the physical object using a digital image correlation (DIC) methodology.

Flow effects caused by rotating blades of main or tail rotor are modelled by application of the developed Virtual Blade Model (VBM).

Wind turbines will not only attack flying creatures through rotating blades, but also the flying organisms will affect the habitat of ground creatures because of the reduction of flying height.

This paper proposes a dynamic model for measuring the 3D tip clearance of rotating blades using an isosceles-right-triangle sensing structure consisting of three identical two-circle coaxial optical fiber bundles and a demodulation approach using the ratios of difference signals between any two bundles based on the Taylor expansion principle.

This would reduce the weight of the rotating blades.

Air is drawn in through an intake and passes through a series of stages of stationary and rotating blades that guide and add rotational energy to Author Version Childs, P.

This study examined the nucleate pool boiling characteristics of distilled water attached to a heating surface with a horizontal circular plate above which the rotating blades were installed.

It is shown that the surge motion and the pitch motion of the floating platform both significantly alter the local attack angle, while only the platform pitch motion have significant impacts on the local relative wind speed experienced by the rotating blades.

Frequency modulation characteristic induced by rotating blades is extracted as a unique micro-Doppler signature to discriminate between the hovering UAV and ground clutter.

Each stage consists of rotating blades and stationary vanes.

The results on a single rotating airfoil allowed the analysis to highlight the physical phenomena taking place past the rotating blades, including the delay of stall and the modifications induced on the surrounding flow field; power enhancements higher than 20% were shown for some configurations.

Physical modelling of wind turbine systems is usually based on the average values of the aerodynamic parameters in the design process which would eliminate some important physical phenomena associated with the unsteady flows over the rotating blades.

Clutter filtering according to distinct Doppler echoes is a major measure to deal with the interference in radar signals caused by the rotating blades of nearby wind turbines.

A so-called rotational beamforming algorithm allows for the detection of sound sources on the rotating blades by using a virtual rotation of the microphones.

SB1 Defiant is a technology demonstrator with Future Lift technology, built around the Sikorsky X2 platform, using two counter-rotating blades at the top of the plane to eliminate the problem of a 150 km/h traction rotor (~ 240 km/h).

Their calculation can overwhelm the numerical scattering process when the incident sound has high-frequency content, such as that produced by the rotating blades of various propulsion devices.

The wind turbine clutter (WTC) caused by the rotating blades has become a main factor that limits the detection performance of weather radar.

In order to achieve the wind-induced vibration response analysis and fatigue analysis, this study conducts the wind field simulations around tubular tower and rotating blades of typical pitch-controlled 1.

We propose a novel track-before-detect algorithm which simultaneously estimates complex reflection coefficients, micro-Doppler features in the form of additional frequency shifts generated by rotating blades and the motion trajectory before the decision on object existence is made.

In this paper, we provide detailed theoretical analysis and establish the mathematical model of the interferometric frequency shifts of rotating blades.

Experimental results showed that the proposed method could identify all vibration events in rotating blades, even small events which may be wrongly identified by skillful operators.

Bezier surface is adopted as parameterization method to control the suction surface of the blades, which brings the following advantages: (A) significantly reducing design variables; (B) easy to ensure the mechanical strength of rotating blades; (C) better physical understanding; (D) easy to achieve smooth surface.

In this paper, the coupled bending–bending–axial–torsional free vibrations of rotating blades are investigated based on the Euler–Bernoulli beam model.

Moreover, the rotating blades are subjected to the Coriolis effect and the influence of the Coriolis force on the natural frequencies of high-speed rotational bladed disks such as those of an aero-engine become more apparent.

Bubbles were injected underneath the rotating blades.

The stiffening effects of the rotating blades are considered using a hybrid set of deformations, which consist of the stretch and chordwise deformations.

This paper describes model testing of a Tension Leg Platform Wind Turbine (TLPWT) with non-rotating blades to better understand its motion and tendon responses when subjected to combined wind and unidirectional regular wave conditions.