The Inverse Vortex Wake Model: A Measurement Analysis Tool

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Wouter Haans ◽  
Gijs van Kuik ◽  
Gerard van Bussel
Keyword(s):  
Wind Tunnel ◽  
Analysis Tool ◽  
Vortex Wake ◽  
Flow Conditions ◽  
Rotor Wake ◽  
Rotor Aerodynamics ◽  
Measurement Analysis ◽  
Wake Model ◽  
Induced Velocity ◽  
Blade Loads

To reduce the level of uncertainty associated with current rotor aerodynamics codes, improved understanding of rotor aerodynamics is required. Wind tunnel measurements on model rotors contribute to advancing our knowledge on rotor aerodynamics. The combined recording of blade loads and rotor wake is desired, because of the coupled blade and wake aerodynamics. In general, however, the small size of model rotors prohibits detailed blade load measurements; only the rotor wake is recorded. To estimate the experimental blade flow conditions, a measurement analysis tool is developed: the inverse vortex wake model. The rotor wake is approximated by a lifting line model, using rotor wake measurements to reconstruct the vortex wake. Conservation of circulation, combined with the Biot–Savart law, allows the induced velocity to be expressed in terms of the bound circulation. The unknown bound circulation can be solved for, since the velocity is known from rotor wake measurements. The inverse vortex wake model is subsequently applied to measurements on the near wake of a model rotor subject to both axial and yawed flow conditions, performed at a TUDelft open jet wind tunnel. The inverse vortex wake model estimates the unsteady experimental blade flow conditions and loads that otherwise would have remained obscured.

Dynamic Prescribed Vortex Wake Model for AERODYN/FAST

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Hugh D. Currin ◽  
Frank N. Coton ◽  
Byard Wood
Keyword(s):  
Vortex Wake ◽  
Flow Conditions ◽  
Dynamic Flow ◽  
Unsteady Aerodynamic ◽  
Horizontal Axis Wind Turbines ◽  
Wind Tunnel Data ◽  
Aerodynamic Experiment ◽  
Wake Model ◽  
The University ◽  
Blade Element

A new aerodynamic wake model has been developed for horizontal axis wind turbines. The aim is to develop an engineering tool for investigation and design of furling turbines. The prescribed vortex wake code HAWTDAWG, developed at the University of Glasgow, has been extended for dynamic flow conditions. This dynamic prescribed wake model is built into the aerodynamic code AERODYN and linked to the structural dynamics code FAST. The new model has been compared to unsteady aerodynamic experiment Phase VI wind tunnel data. Comparisons are also made to blade element momentum and generalized dynamic wake models built into AERODYN. Results are encouraging and justify further investigation.

scholarly journals Implementation of the BEM skewed-wake model within the multibody aero-elastic solver Cp-Lambda

2020 ◽  
Vol 173 ◽  
pp. 02004
Author(s):  
Igor Petrović ◽  
Filippo Campagnolo ◽  
Tadej Kosel ◽  
Carlo L. Bottasso
Keyword(s):  
Experimental Data ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Flow Conditions ◽  
Aerodynamic Loads ◽  
Model Predictions ◽  
Wind Tunnel Data ◽  
Wake Model ◽  
Nrel Phase Vi ◽  
Local Variability

To account for the problem of an azimuthally constant induction in the BEM method, which influences on incorrectly predicted aerodynamic loads in the yawed flow, a skewed-wake model implementation to the BEM method has been performed. The numerical aerodynamic loads have been compared with the wind tunnel data of the NREL Phase VI and against another numerical campaign. At first, the model predictions have been validated against experimental data performed with aligned flow conditions, showing a reasonable match. Successively, the model predictions are validated against experimental results obtained with the wind turbine yawed. Results show, a possible better prediction of loads at yawed flow with Skewed-Wake correction, however the method does not overall correlate better, compared to the BEM method with implemented local variability of the induction factor.

scholarly journals Surface Renewal as a Significant Mechanism for Dust Emission

2016 ◽  
Author(s):  
Jie Zhang ◽  
Zhenjiao Teng ◽  
Ning Huang ◽  
Lei Guo ◽  
Yaping Shao
Keyword(s):  
Wind Tunnel ◽  
Emission Rate ◽  
Dust Emission ◽  
Limit Surface ◽  
Soil Dust ◽  
Flow Conditions ◽  
Wind Tunnel Experiments ◽  
Surface Renewal ◽  
Surface Particle ◽  
Significant Mechanism

Abstract. Wind-tunnel experiments of dust emissions from different soil surfaces are carried out to better understand dust emission mechanisms. The effects of surface renewal on aerodynamic entrainment and saltation bombardment are analysed in detail, and the measurements are used to test published dust models. It is found that flow conditions, surface particle motions (saltation and creep), soil dust content and ground obstacles all strongly affect dust emission, causing dust emission rate to vary over orders of magnitude. Aerodynamic entrainment is highly effective, if dust supply is unlimited, as in the first 2–3 minutes of our wind-tunnel runs. While aerodynamic entrainment is suppressed by dust supply limit, surface renewal through the motion of surface particles is found to be an effective pathway to remove the supply limit. Surface renewal is also found to be important to the efficiency of saltation bombardment. We demonstrate that surface renewal is a significant mechanism affecting dust emission and recommend that this mechanism be included in future dust models.

A modified near wake dynamic model for rotor analysis

1999 ◽  
Vol 103 (1021) ◽  
pp. 143-146 ◽  
Author(s):  
T. Wang ◽  
F. N. Coton
Keyword(s):  
High Resolution ◽  
Dynamic Model ◽  
Numerical Evaluation ◽  
Helicopter Rotor ◽  
Vortex Interaction ◽  
Near Wake ◽  
Blade Vortex Interaction ◽  
Wake Model ◽  
Induced Velocity

Abstract The Beddoes near wake model, developed for high resolution blade vortex interaction computations, enables efficient numerical evaluation of the downwash due to trailed vorticity in the near wake of a helicopter rotor. The model is, however, limited by the assumption that the near wake lies in the plane of the rotor and, in some cases, by its inability to accurately evaluate the induced velocity contribution from vorticity trailed from inboard blade sections. In this paper, modifications to the method are proposed which address these issues and allow it to be used with confidence over a wider range of rotor flows.

scholarly journals Fabrication and Hypersonic Wind Tunnel Validation of a MEMS Skin Friction Sensor Based on Visual Alignment Technology

Sensors ◽  
2019 ◽  
Vol 19 (17) ◽  
pp. 3803
Author(s):  
Xiong Wang ◽  
Nantian Wang ◽  
Xiaobin Xu ◽  
Tao Zhu ◽  
Yang Gao
Keyword(s):  
Wind Tunnel ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Skin Friction ◽  
Flow Conditions ◽  
Friction Coefficients ◽  
Hypersonic Wind Tunnel ◽  
Laminar Flow Conditions ◽  
Turbulent Flow Conditions ◽  
Better Than

MEMS-based skin friction sensors are used to measure and validate skin friction and its distribution, and their advantages of small volume, high reliability, and low cost make them very important for vehicle design. Aiming at addressing the accuracy problem of skin friction measurements induced by existing errors of sensor fabrication and assembly, a novel fabrication technology based on visual alignment is presented. Sensor optimization, precise fabrication of key parts, micro-assembly based on visual alignment, prototype fabrication, static calibration and validation in a hypersonic wind tunnel are implemented. The fabrication and assembly precision of the sensor prototypes achieve the desired effect. The results indicate that the sensor prototypes have the characteristics of fast response, good stability and zero-return; the measurement ranges are 0–100 Pa, the resolution is 0.1 Pa, the repeatability accuracy and linearity are better than 1%, the repeatability accuracy in laminar flow conditions is better than 2% and it is almost 3% in turbulent flow conditions. The deviations between the measured skin friction coefficients and numerical solutions are almost 10% under turbulent flow conditions; whereas the deviations between the measured skin friction coefficients and the analytical values are large (even more than 100%) under laminar flow conditions. The error resources of direct skin friction measurement and their influence rules are systematically analyzed.

scholarly journals The Influence of an Upstream Pylon on Open Rotor Aerodynamics at Angle of Attack

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Nishad G. Sohoni ◽  
Cesare A. Hall ◽  
Anthony B. Parry
Keyword(s):  
Potential Field ◽  
Angle Of Attack ◽  
Separated Flow ◽  
Rotor Blades ◽  
Tip Vortex ◽  
Rotor Wake ◽  
Rotor Aerodynamics ◽  
Open Rotor ◽  
Urans Cfd ◽  
Work Done

The aerodynamic impact of installing a horizontal pylon in front of a contra-rotating open rotor engine, at take-off, was studied. The unsteady interactions of the pylon's wake and potential field with the rotor blades were predicted by full-annulus URANS CFD calculations at 0 deg and 12 deg angle of attack (AoA). Two pylon configurations were studied: one where the front rotor blades move down behind the pylon (DBP), and one where they move up behind the pylon (UBP). When operating at 12 deg AoA, the UBP orientation was shown to reduce the rear rotor tip vortex sizes and separated flow regions, whereas the front rotor wake and vortex sizes were increased. In contrast, the DBP orientation was found to reduce the incidence variations onto the front rotor, leading to smaller wakes and vortices. The engine flow was also time-averaged, and the variation in work done on average midspan streamlines was shown to depend strongly on variation in incidence, along with a smaller contribution related to change of radius.

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