The Experts below are selected from a list of 2814 Experts worldwide ranked by ideXlab platform
Tokio Kasai - One of the best experts on this subject based on the ideXlab platform.
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vibration monitoring of a helicopter Blade Model using the optical fiber distributed strain sensing technique
Applied Optics, 2016Co-Authors: Daichi Wada, Hirotaka Igawa, Tokio KasaiAbstract:We demonstrate a dynamic distributed monitoring technique using a long-length fiber Bragg grating (FBG) interrogated by optical frequency domain reflectometry (OFDR) that measures strain at a speed of 150 Hz, spatial resolution of 1 mm, and measurement range of 20 m. A 5 m FBG is bonded to a 5.5 m helicopter Blade Model, and vibration is applied by the step relaxation method. The time domain responses of the strain distributions are measured, and the Blade deflections are calculated based on the strain distributions. Frequency response functions are obtained using the time domain responses of the calculated deflection induced by the preload release, and the modal parameters are retrieved. Experimental results demonstrated the dynamic monitoring performances and the applicability to the modal analysis of the OFDR-FBG technique.
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Vibration monitoring of a helicopter Blade Model using the optical fiber distributed strain sensing technique
Applied Optics, 2016Co-Authors: Daichi Wada, Hirotaka Igawa, Tokio KasaiAbstract:? 2016 Optical Society of America.We demonstrate a dynamic distributed monitoring technique using a long-length fiber Bragg grating (FBG) interrogated by optical frequency domain reflectometry (OFDR) that measures strain at a speed of 150 Hz, spatial resolution of 1 mm, and measurement range of 20 m. A 5 m FBG is bonded to a 5.5 m helicopter Blade Model, and vibration is applied by the step relaxation method. The time domain responses of the strain distributions are measured, and the Blade deflections are calculated based on the strain distributions. Frequency response functions are obtained using the time domain responses of the calculated deflection induced by the preload release, and the modal parameters are retrieved. Experimental results demonstrated the dynamic monitoring performances and the applicability to the modal analysis of the OFDR-FBG technique.
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Long-gauge FBGs interrogated by DTR3 for dynamic distributed strain measurement of helicopter Blade Model
23rd International Conference on Optical Fibre Sensors, 2014Co-Authors: Michiko Nishiyama, Tokio Kasai, Hirotaka Igawa, Naoyuki WatanabeAbstract:ABSTRACT In this paper, we describe characteristics of distributed strain sensing based on a Delayed Transmission/Reflection Ratiometric Reflectometry (DTR 3 ) scheme with a long-gauge Fiber Bragg Grating (FBG), which is attractive to dynamic structural deformation monitori ng such as a helicopter Blade and an airplane wing. The DTR 3 interrogator using the long-gauge FBG has capability of detecting distributed strain with 50 cm spatial resolution in 100 Hz sampling rate. We evaluated distributed strain sensing characteristics of the long-gauge FBG attached on a 5.5 m helicopter Blade Model in static tests and free vibration dynamic tests. Keywords: structural health monitoring, deformation, helicopter Blade, DTR 3 , fiber Bragg grating 1. INTRODUCTION Aerospace systems have been employed stru ctural health monitoring (SHM) in order to detect load, stress and damage, as a result, prevent the fatal structural disorder. Especially, aerospace vehicle monitoring and control is trying to be created by the time-varying ma ss and inertia of the vehicle in flight, as well as the consequent in deformation and modal frequencies of the structures
David Volponi - One of the best experts on this subject based on the ideXlab platform.
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Effects of Fan Inflow Distortions on Heat Exchange in Air-Cooled Condensers: Unsteady Computations With Synthetic Blade Model
Volume 1: Aircraft Engine; Fans and Blowers; Marine, 2018Co-Authors: Gino Angelini, Tommaso Bonanni, Alessandro Corsini, Giovanni Delibra, Lorenzo Tieghi, David VolponiAbstract:Heat exchange in air-cooled condensers (ACC) is achieved by forced convection of fresh air on bundle of tubes by means of forced-draft axial-flow fans. These fans are characterized by low solidity and low hub ratio, large diameters, relatively low rotational velocity, high efficiencies. This combination usually leads to fans with non-stalling characteristics, with pressure rise continuously rising when reducing the flow rate, at least in standard (ISO or AMCA) test rigs. In real-life installations, in fact, it is quite difficult to characterize these fans, due to the practical difficulties arising in setting up a proper test rig and to control the boundary conditions of the system, in particular the fan inflow conditions. Here we focus on a real-life setting of ACC, numerically simulated with URANS. In this work the fan is simulated with a Synthetic Blade Model presented in [1]. This Model is derived from actuator disk theory, and allows to simulate the unsteady movement of the Blades and compute a non-constant azimuthal distribution of lift and drag forces, partially accounting for non-constant deviation in the Blade-to-Blade passage, while drastically reducing the mesh requirements. In this way it is possible to Model the shedding of wakes behind the Blades and their interaction with the heat exchanger. The flow will be assumed to be incompressible, due to the low Mach number and heat transfer will be treated assuming temperature to be a passive scalar convected by the flow. Duty point of the fan and heat exchange in the ACC will be studied while inflow conditions, in order to account for free inflow with a constant velocity distribution as well as distortions due to lateral wind. Computations will be carried out on the Virtual Test Rig of developed at Sapienza within the OpenFOAM 2.3.x library with a URANS approach and k-ε closure.
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Development and Validation of a Novel Synthetic Blade Model for Axial Flow Fans in Unsteady CFD
Volume 1: Aircraft Engine; Fans and Blowers; Marine; Honors and Awards, 2017Co-Authors: Tommaso Bonanni, Alessandro Corsini, Giovanni Delibra, David VolponiAbstract:Here we present a Synthetic Blade Model (SBM) for axial flow fans, derived from Actuator Disk and Actuator Line theories. This new approach is able to Model the momentum exchange between the fan and the fluid by adding source terms into momentum equation, like an actuator disk. However, the Model accounts for the position of the Blades, their rotation and the non-uniform distribution of deflection capability in the Blade-to-Blade passage, like in an actuator line Model. This approach is derived, described and validated against available data on a reversible tunnel and metro fan.
Hirotaka Igawa - One of the best experts on this subject based on the ideXlab platform.
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vibration monitoring of a helicopter Blade Model using the optical fiber distributed strain sensing technique
Applied Optics, 2016Co-Authors: Daichi Wada, Hirotaka Igawa, Tokio KasaiAbstract:We demonstrate a dynamic distributed monitoring technique using a long-length fiber Bragg grating (FBG) interrogated by optical frequency domain reflectometry (OFDR) that measures strain at a speed of 150 Hz, spatial resolution of 1 mm, and measurement range of 20 m. A 5 m FBG is bonded to a 5.5 m helicopter Blade Model, and vibration is applied by the step relaxation method. The time domain responses of the strain distributions are measured, and the Blade deflections are calculated based on the strain distributions. Frequency response functions are obtained using the time domain responses of the calculated deflection induced by the preload release, and the modal parameters are retrieved. Experimental results demonstrated the dynamic monitoring performances and the applicability to the modal analysis of the OFDR-FBG technique.
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Vibration monitoring of a helicopter Blade Model using the optical fiber distributed strain sensing technique
Applied Optics, 2016Co-Authors: Daichi Wada, Hirotaka Igawa, Tokio KasaiAbstract:? 2016 Optical Society of America.We demonstrate a dynamic distributed monitoring technique using a long-length fiber Bragg grating (FBG) interrogated by optical frequency domain reflectometry (OFDR) that measures strain at a speed of 150 Hz, spatial resolution of 1 mm, and measurement range of 20 m. A 5 m FBG is bonded to a 5.5 m helicopter Blade Model, and vibration is applied by the step relaxation method. The time domain responses of the strain distributions are measured, and the Blade deflections are calculated based on the strain distributions. Frequency response functions are obtained using the time domain responses of the calculated deflection induced by the preload release, and the modal parameters are retrieved. Experimental results demonstrated the dynamic monitoring performances and the applicability to the modal analysis of the OFDR-FBG technique.
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Long-gauge FBGs interrogated by DTR3 for dynamic distributed strain measurement of helicopter Blade Model
23rd International Conference on Optical Fibre Sensors, 2014Co-Authors: Michiko Nishiyama, Tokio Kasai, Hirotaka Igawa, Naoyuki WatanabeAbstract:ABSTRACT In this paper, we describe characteristics of distributed strain sensing based on a Delayed Transmission/Reflection Ratiometric Reflectometry (DTR 3 ) scheme with a long-gauge Fiber Bragg Grating (FBG), which is attractive to dynamic structural deformation monitori ng such as a helicopter Blade and an airplane wing. The DTR 3 interrogator using the long-gauge FBG has capability of detecting distributed strain with 50 cm spatial resolution in 100 Hz sampling rate. We evaluated distributed strain sensing characteristics of the long-gauge FBG attached on a 5.5 m helicopter Blade Model in static tests and free vibration dynamic tests. Keywords: structural health monitoring, deformation, helicopter Blade, DTR 3 , fiber Bragg grating 1. INTRODUCTION Aerospace systems have been employed stru ctural health monitoring (SHM) in order to detect load, stress and damage, as a result, prevent the fatal structural disorder. Especially, aerospace vehicle monitoring and control is trying to be created by the time-varying ma ss and inertia of the vehicle in flight, as well as the consequent in deformation and modal frequencies of the structures
Rafael Palacios - One of the best experts on this subject based on the ideXlab platform.
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a moderate deflection composite helicopter rotor Blade Model with an improved cross sectional analysis
International Journal of Solids and Structures, 2009Co-Authors: Peretz P Friedmann, Bryan Glaz, Rafael PalaciosAbstract:The compatibility between a composite beam cross-sectional analysis based on the variational asymptotic approach, and a helicopter rotor Blade Model which is part of a comprehensive rotorcraft analysis code is examined. It was found that the finite element cross-sectional analysis code VABS can be combined with a moderate deflection rotor Blade Model in spite of the differences between the formulations. The new YF/VABS rotor Blade Model accounts for arbitrary cross-sectional warping, in-plane stresses, and moderate deflections. The YF/VABS composite rotor Blade Model was validated against experimental data and various rotor Blade analyses by examining displacements and stresses under static loads, as well as aeroelastic stability of a composite rotor Blade in hover, and forward flight vibratory hubloads of a four Bladed composite rotor.
Wenwu Zhou - One of the best experts on this subject based on the ideXlab platform.
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an experimental study on the aerodynamic performance degradation of a wind turbine Blade Model induced by ice accretion process
Renewable Energy, 2019Co-Authors: Wenwu Zhou, Hui HuAbstract:Abstract An experimental study was conducted to characterize aerodynamic performance degradation of wind turbine Blades induced by dynamic ice accretion process. The experimental study was performed in an Icing Research Tunnel with a turbine Blade Model under a typical glaze icing condition. Ice structures were found to accrete rapidly over both the upper and lower surfaces of the Blade Model after starting the ice accretion experiment. Irregular-shaped ice structures were found to disturb the airflow around the Blade Model greatly, resulting in large-scale flow separations and shedding of unsteady vortex structures from the ice accreting surface. The aerodynamic performance of the Blade Model was found to degrade significantly. The performance degradation induced by the ice accretion was found to be a strong function of the angle of attack of the Blade Model with more significant degradations at lower angles of attack. For the test case at the angle of attack of 5.0°, while the lift decreases to only ∼12% of its original value after 600 s of the ice accretion experiment, the drag was found to increase 4.5 times correspondingly. The detailed flow field measurements were correlated with the aerodynamic force data to elucidate the underlying physics.
