Coastdown/Wind Tunnel Drag Correlation and Uncertainty Analysis

2001 ◽  
Author(s):  
Joel A. Walter ◽  
David J. Pruess ◽  
Gary F. Romberg
Keyword(s):  
Wind Tunnel ◽  
Uncertainty Analysis

Uncertainty Analysis of Aerodynamic Coefficients in an Automotive Wind Tunnel

2005 ◽  
Author(s):  
Joel A. Walter ◽  
Victor Canacci ◽  
R. K. Rout ◽  
Wayne Koester ◽  
Jack Williams ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Uncertainty Analysis ◽  
Aerodynamic Coefficients

scholarly journals Demonstration and uncertainty analysis of synchronised scanning lidar measurements of 2-D velocity fields in a boundary-layer wind tunnel

2017 ◽  
Vol 2 (1) ◽  
pp. 329-341 ◽  
Author(s):  
Marijn Floris van Dooren ◽  
Filippo Campagnolo ◽  
Mikael Sjöholm ◽  
Nikolas Angelou ◽  
Torben Mikkelsen ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Uncertainty Analysis ◽  
Wind Turbine ◽  
Short Range ◽  
Goodness Of Fit ◽  
Wind Tunnels ◽  
Small Scale ◽  
Measurement Technology ◽  
Lidar Measurement ◽  
Hot Wire

Abstract. This paper combines the research methodologies of scaled wind turbine model experiments in wind tunnels with short-range WindScanner lidar measurement technology. The wind tunnel at the Politecnico di Milano was equipped with three wind turbine models and two short-range WindScanner lidars to demonstrate the benefits of synchronised scanning lidars in such experimental surroundings for the first time. The dual-lidar system can provide fully synchronised trajectory scans with sampling timescales ranging from seconds to minutes. First, staring mode measurements were compared to hot-wire probe measurements commonly used in wind tunnels. This yielded goodness of fit coefficients of 0.969 and 0.902 for the 1 Hz averaged u and v components of the wind speed, respectively, validating the 2-D measurement capability of the lidar scanners. Subsequently, the measurement of wake profiles on a line as well as wake area scans were executed to illustrate the applicability of lidar scanning to the measurement of small-scale wind flow effects. An extensive uncertainty analysis was executed to assess the accuracy of the method. The downsides of lidar with respect to the hot-wire probes are the larger measurement probe volume, which compromises the ability to measure turbulence, and the possible loss of a small part of the measurements due to hard target beam reflection. In contrast, the benefits are the high flexibility in conducting both point measurements and area scanning and the fact that remote sensing techniques do not disturb the flow during measuring. The research campaign revealed a high potential for using short-range synchronised scanning lidars to measure the flow around wind turbines in a wind tunnel and increased the knowledge about the corresponding uncertainties.

scholarly journals An Uncertainty Analysis of Inlet Dynamic Distortion Data Using an Analog/Digital Hybrid Editing System

1994 ◽  
Author(s):  
Maryann Zelenak
Keyword(s):  
Wind Tunnel ◽  
Uncertainty Analysis ◽  
Total Pressure ◽  
Wind Tunnel Test ◽  
Development Program ◽  
Test Facility ◽  
Data Sets ◽  
Precision Error ◽  
Wide Range ◽  
Test Points

The objectives of this analysis were to establish precision and bias errors for an analog-digital hybrid computer system (DYNADEC) used in the dynamic data editing phase of inlet wind tunnel testing. An uncertainty analysis was initiated to evaluate the system using inlet data from the Aeronautical Systems Center (ASC)/Arnold Engineering Development Center (AEDC) Aeropropulsion System Test Facility (ASTF) Freejet Development Program. Three test points from a subscale freejet test of the F-15 air induction system and three test points from a wind tunnel test of this same F-15 inlet model were selected to represent a wide range of test conditions and turbulence levels. Precision errors of the 40 total pressure probes at the location of the engine face were 1–2% of the 40 total pressure recovery magnitudes. Precision errors of the Pratt and Whitney Ka2 distortion index, the parameter used to edit the data on DYNADEC, were also investigated. These results indicated that Ka2 precision errors decreased with higher turbulence levels. Static bias errors were also computed by sending known signals through the DYNADEC system and measuring the output quantity. Static bias errors were much smaller in comparison to the precision error magnitudes and were considered negligible. This analysis also provided a foundation to evaluate future data sets using this editing system.

scholarly journals Demonstration and uncertainty analysis of synchronised scanning lidar measurements of 2D velocity fields in a boundary-layer wind tunnel

2017 ◽  
Author(s):  
Marijn F. van Dooren ◽  
Filippo Campagnolo ◽  
Mikael Sjöholm ◽  
Nikolas Angelou ◽  
Torben Mikkelsen ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Wind Tunnel ◽  
Uncertainty Analysis ◽  
Wind Turbine ◽  
Short Range ◽  
Goodness Of Fit ◽  
Wind Tunnels ◽  
Small Scale ◽  
Lidar Measurement ◽  
Hot Wire

Abstract. This paper combines the currently relevant research methodologies of scaled wind turbine model experiments in wind tunnels with remote-sensing short-range WindScanner lidar measurement technology. The wind tunnel of the Politecnico di Milano was equipped with three wind turbine models and two short-range WindScanner lidars to demonstrate the benefits of synchronised scanning lidars in such experimental surroundings for the first time. The dual-lidar system can provide fully synchronised trajectory scans with sampling time scales ranging from seconds to minutes. First, staring mode measurements were compared to hot-wire probe measurements commonly used in wind tunnels. This yielded goodness of fit coefficients of 0.969 and 0.902 for the 1 Hz averaged u- and v-components of the wind speed, respectively, validating the 2D measurement capability of the lidar scanners. Subsequently, the measurement of wake profiles on a line as well as wake area scans were executed to illustrate the applicability of lidar scanning to measuring small scale wind flow effects. An extensive uncertainty analysis was executed to assess the accuracy of the method. The downsides of lidar with respect to the hot-wire probes are the larger measurement probe volume and the loss of some measurements due to moving blades. In contrast, the benefits are the high flexibility in conducting both point measurements and area scanning, and the fact that remote sensing techniques do not disturb the flow while measuring. The research campaign revealed a high potential for using short-range synchronised scanning lidars to accurately measure small scale flow structures in a wind tunnel, and increased the knowledge about the corresponding uncertainties.

Uncertainty Analysis in a Scale Model Wind Turbine Array Boundary Layer

2017 ◽  
Author(s):  
John J. Turner ◽  
Martin Wosnik
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Turbulent Boundary Layer ◽  
Uncertainty Analysis ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Test Section ◽  
Scale Model ◽  
Acquisition Time ◽  
Flow Physics

Uncertainty estimates from an experimental investigation of a scale model wind turbine array, conducted with (on the order of) 100 0.25 meter diameter model wind turbines in a high Reynolds number turbulent boundary layer facility, are reported. An expanded uncertainty analysis using the Taylor series method is executed to predict uncertainty for the system of interest in the mean flow. A workable comprise has been found for data acquisition time mitigating changing initial conditions due to exposure to atmospheric conditions and temperature drift. The study was conducted in the University of New Hampshire (UNH) Flow Physics Facility (FPF) which is the worlds largest flow physics quality turbulent boundary layer wind tunnel, with test section dimensions of 6 m wide, 2.7 m tall and 72 m long. Naturally grown turbulent boundary layers with scale ratios of energy-containing to dissipative scales (Karman number) of up to 20,000 can be generated, and are on the order of 1 m thick near the downstream end of the test section. The long fetch of the facility offers unique opportunities to study the downstream evolution of the wake of single wind turbines, and the flow through model wind turbine arrays over long distances. Far downstream within a wind farm it is proposed that the farm reaches a fully developed state where the flow field becomes similar from one row to the next. The goal of this work is to accurately determine the uncertainty associated with open to atmosphere wind tunnel data for use in validation of numerical models regarding the fully developed wind turbine array boundary layer.

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