ASTM D5096-24

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.
Designation: D5096 − 24
Standard Test Method for
Determining the Performance of a Cup Anemometer or
1
Propeller Anemometer
This standard is issued under the fixed designation D5096; 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 3. Terminology
1.1 This test method covers the determination of the starting 3.1 For definitions of terms used in this standard, refer to
threshold, distance constant, transfer function, and off-axis Terminology D1356.
response of a cup anemometer or propeller anemometer from
3.2 Definitions of Terms Specific to This Standard:
direct measurement in a wind tunnel.
3.2.1 starting threshold (U , m/s), n—the lowest wind speed
o
1.2 This test method provides for a measurement of cup at which a rotating anemometer starts and continues to turn and
anemometer or propeller anemometer performance in the produce a measurable signal when mounted in its normal
environment of wind tunnel airflow. Transference of values position; the normal position for cup anemometers is with the
determined by these methods to atmospheric flow must be done axis of rotation vertical, and the normal position for propeller
with an understanding that there is a difference between the anemometers is with the axis of rotation aligned with the
two flow systems. direction of flow; note that if the anemometer axis is not
aligned with the direction of flow, the calculated wind speed
1.3 The values stated in SI units are to be regarded as
component parallel to the anemometer axis is used to deter-
standard. The values given in parentheses after SI units are
mine starting threshold.
provided for information only and are not considered standard.
3.2.2 distance constant (L, m), n—the distance the air flows
1.4 This standard does not purport to address all of the
past a rotating anemometer during the time it takes the cup
safety concerns, if any, associated with its use. It is the
wheel or propeller to reach (1 − 1 ⁄e) or 63 % of the equilibrium
responsibility of the user of this standard to establish appro-
3
speed after a step change in wind speed (1). The response of
priate safety, health, and environmental practices and deter-
a rotating anemometer to a step change in which wind speed
mine the applicability of regulatory limitations prior to use.
increases instantaneously from U = 0 to U = U is (2):
f
1.5 This international standard was developed in accor-
2t/τ
~ !
dance with internationally recognized principles on standard- U 5 U 1 2 e (1)
~ !
t f
ization established in the Decision on Principles for the
where:
Development of International Standards, Guides and Recom-
U = is the instantaneous indicated wind speed at time t in
t
mendations issued by the World Trade Organization Technical
m/s,
Barriers to Trade (TBT) Committee.
U = is the final indicated wind speed, or wind tunnel speed,
f
in m/s,
2. Referenced Documents
t = is the elapsed time in seconds after the step change
2
2.1 ASTM Standards:
occurs, and
D1356 Terminology Relating to Sampling and Analysis of
τ = is the time constant of the instrument.
Atmospheres
Distance Constant is:L 5 U τ (2)
f
D3631 Test Methods for Measuring Surface Atmospheric
3.2.3 transfer function (Û = a + bR, m/s), n—the linear
f
Pressure
relationship between wind speed and the rate of rotation of the
anemometer throughout the specified working range. Û is the
f
predicted wind speed in m/s, a is a constant, commonly called
1
This test method is under the jurisdiction of ASTM Committee D22 on Air
zero offset, in m/s, b is a constant representing the wind
Quality and is the direct responsibility of Subcommittee D22.11 on Meteorology.
Current edition approved March 1, 2024. Published March 2024. Originally
passage in m/r for each revolution of the anemometer cup
approved in 1990. Last previous edition approved in 2023 as D5096 – 23. DOI:
wheel or propeller, and R is the rate of rotation in r/s.
10.1520/D5096-24.
2
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
3
Standards volume information, refer to the standard’s Document Summary page on The boldface numbers in parentheses refer to the list of references at the end of
the ASTM website. this standard.
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