ASTM D5366-23

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Designation: D5366 − 96 (Reapproved 2017) D5366 − 23
Standard Test Method for
Determining the Dynamic Performance of a Wind Vane
This standard is issued under the fixed designation D5366; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of the starting threshold, delay distance, and overshoot ratio of a wind vane from
direct measurements in a wind tunnel. This test method is applicable only to wind vanes having measurable overshoot.
1.2 This test method provides for determination of the performance of a system consisting of a wind vane and its associated
position-to-output transducer in wind tunnel flow. Use of values determined by this test method to describe performance in
atmospheric flow of a wind direction measuring system incorporating the vane must be done with an understanding of the
differences between the two systems and the two environments.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
3. Terminology
3.1 For terms that areRefer to Terminology D1356 not defined herein, refer to Terminology for general terms and their
definitions.D1356.
3.2 Definitions:Definitions of Terms Specific to This Standard:
3.2.1 delay distance (D)—(D), n—the distance the air flows past a wind vane during the time it takes the vane to return to 50 %
of the initial displacement.
3.2.2 overshoot (θ )—), n—the amplitude of a deflection of a wind vane as it oscillates about θ after release from an initial
n B
displacement.
This test method is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Subcommittee D22.11 on Meteorology.
Current edition approved March 15, 2017Sept. 1, 2023. Published March 2017September 2023. Originally approved in 1993. Last previous edition approved in 20112017
as D5366D5366 – 96 (2017). – 96 (2011). DOI: 10.1520/D5366-96R17.DOI: 10.1520/D5366-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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D5366 − 23
3.2.3 overshoot ratio (Ω)—(Ω), n—the ratio of two successive overshoots, as expressed by the equation:
Ω5 θ /θ (1)
n11 n
~ !
where θ and θ are the n and n + 1 overshoots, respectively. In practice, since deflections after the first (toto the side
n (n+1)
opposite the release point are normally small, the initial release point (that is, the n = 0 deflection) and the first deflection after
release (n = 1) are used in determining the overshoot ratio.
3.2.4 starting threshold (U )—), n—the lowest speed at which the vane can be observed or measured moving from a 10° offset
o
in a wind tunnel.
3.3 Symbols:
D (m) delay distance
U (m/s) starting threshold
o
Ω (none) overshoot ratio
η (none) damping ratio
λ (m) damped natural wavelength
d
θ (degrees) overshoot; maximum angular excursion
n
θ (degrees) reference direction
o
θ (degrees) vane equilibrium position
B
θ − θ (degrees) dynamic vane bias
B o
3.4 Calculated or Estimated Values:
3.4.1 damping ratio (η)—(η), n—calculated from the overshoot ratio (1, 2).
ln 1/Ω
~ !
η5 (2)
2 2 0.5
π 1@ln 1/Ω #
~ ~ ! !
3.4.2 damped natural wavelength (λ )—), n—at sea level in the U.S. Standard Atmosphere, damped natural wavelength is related
d
to delay distance and damping ratio by the empirical expression (1, 2).
D 6.022.4η
~ !
λ 5 (3)
d 2 0.5
~12 η !
4. Summary of Test Method
4.1 Reference Direction (θ , degrees) is the indicated angular position of the vane when aligned along the centerline of thea wind
o
tunnel.
4.2 Vane Equilibrium Position (θ , degrees) is the final resting position of the vane after motion in response to an initial
B
displacement. Ideally, θ = θ .
B o
4.3 Dynamic Vane Bias (θ − θ , degrees) is the displacement of the vane from the wind tunnel centerline at 5 m/s. This
B o
measurement will identify wind vanes with unbalanced aerodynamic response because of damage (for example, bent tail) or poor
design.
4.4 Starting Threshold (U , m/s) is determined by observing or measuring the lowest speed at which the vane, released from a 10°
o
offset position in a wind tunnel, moves toward θ . Movement must be distinguishable from vibration.
B
4.5 Delay Distance (D, m) may be determined at a number of wind speeds but shall include 5 m/s and 10 m/s. It is computed from
the time required for the vane to reach 50 % of the initial displacement from 10° off θ . This time in seconds is converted to delay
B
distance by multiplying by the wind tunnel speed in metres per second. Tests shall include an equal number of displacements to
each side of θ .
B
The boldface numbers in parentheses refer to the list of references at the end of this standard.
D5366 − 23
4.6 Overshoot Ratio (Ω) may be determined at the same time as the delay distance. The maximum angular excursion on the
opposite side of θ from the initial 10° displacement fromθfrom θ is measured. This value is divided by the initial displacement
B B
to obtain Ω.
5. Significance and Use
5.1 This test method will provide provides a standard for comparison of wind vanes of different types. Specifications by regulatory
agencies and industrial societies (3-5) have stipulated performance values. This test method provides an unambiguous method for
measuring starting threshold, delay distance, and overshoot ratio.
6. Apparatus
6.1 Wind Tunnel (6):
6.1.1 Size—The wind tunnel shall be large enough so that the total projected area of supports, sensor apparatus, and the vane in
its displaced position is less than 5 % of the cross-sectional area of its test section.
6.1.2 Speed Range—The wind tunnel shall have a speed control that will allow the flow rate to be varied from 0 to at least 10 m/s.
The speed control shall maintain the flow rate within 60.2 m/s.
6.1.3 Turbulence and Swirl—Across the volume to be occupied by the vane, the flow profile shall vary by no more than 1 % about
the mean speed and shall exhibit a turbulence of less than 1 %. (Warning—Swirl in the wind tunnel may influence starting
threshold measurements. Variations in the measurement of θ a low speeds likelyat low speeds, likely, indicate the existence of
B
swirl.)
6.1.4 Calibration—The mean flow rate shall be verified at the mandatory speeds of 55 m ⁄s and 1010 m m/s ⁄s by use of transfer
standards that have been calibrated by the National Institute of Standards and Technology (formerly called the National Bureau
of Standards) or by a fundamental physical method.
6.1.4.1 Speeds below 2 m/s for threshold determination shall be verified by a sensitive anemometer or by some fundamental time
and distance technique, such as measuring the transition time of smoke puffs, soap bubbles, or heat puffs between two points
separated by a known distance.
6.1.5 Environment—The temperature and pressure of the environment within the wind tunnel test section shall be reported.
Differences of greater than 3 % in the density of air within the test environment may result in poor inter-comparability of
independent measurements of starting threshold, delay distance, and overshoot ratio since these values are density dependent.
6.2 Measuring System:
6.2.1 Direction—The resolution of the wind vane position–to–output transducer limits the resolution of the measurements. The
accuracy of the position–to–output conversion shall be within 60.1°. (Warning—Avoid potentiometer dead spots or crossover
positions while perfo
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