ASTM D6011-96(2015)

Standard Test Method for Determining the Performance of a Sonic Anemometer/Thermometer

SIGNIFICANCE AND USE
5.1 This test method provides a standard method for evaluating the performance of sonic anemometer/thermometers that use inverse time solutions to measure wind velocity components and the speed of sound. It provides an unambiguous determination of instrument performance criteria. The test method is applicable to manufacturers for the purpose of describing the performance of their products, to instrumentation test facilities for the purpose of verifying instrument performance, and to users for specifying performance requirements. The acoustic pathlength procedure is also applicable for calibration purposes prior to data collection. Procedures for operating a sonic anemometer/thermometer are described in Practice D5527.  
5.2 The sonic anemometer/thermometer array is assumed to have a sufficiently high structural rigidity and a sufficiently low coefficient of thermal expansion to maintain an internal alignment to within the manufacturer's specifications over its designed operating range. Consult with the manufacturer for an internal alignment verification procedure and verify the alignment before proceeding with this test method.  
5.3 This test method is designed to characterize the performance of an array model or probe design. Transducer shadow data obtained from a single array is applicable for all instruments having the same array model or probe design. Some non-orthogonal arrays may not require specification of transducer shadow corrections or the velocity calibration range.
SCOPE
1.1 This test method covers the determination of the dynamic performance of a sonic anemometer/thermometer which employs the inverse time measurement technique for velocity or speed of sound, or both. Performance criteria include: (a) acceptance angle, (b) acoustic pathlength, (c) system delay, (d) system delay mismatch, (e) thermal stability range, (f) shadow correction, (g) velocity calibration range, and (h) velocity resolution.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 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 health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Mar-2015
• ICS: 17.200.10 - Heat. Calorimetry
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.11 - Meteorology

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D6011 − 96 (Reapproved 2015)
Standard Test Method for
Determining the Performance of a Sonic Anemometer/
1
Thermometer
This standard is issued under the fixed designation D6011; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2.1 axial attenuation coeffıcient—aratioofthefreestream
windvelocity(asdefinedinawindtunnel)tovelocityalongan
1.1 This test method covers the determination of the dy-
3
acoustic propagation path (v /v ) (1).
t d
namicperformanceofasonicanemometer/thermometerwhich
3.2.2 critical Reynolds number (R )—the Reynolds number
employs the inverse time measurement technique for velocity
c
at which an abrupt decrease in an object’s drag coefficient
or speed of sound, or both. Performance criteria include: (a)
occurs (2).
acceptanceangle,(b)acousticpathlength,(c)systemdelay,(d)
3.2.2.1 Discussion—The transducer shadow corrections are
system delay mismatch, (e) thermal stability range, (f) shadow
no longer valid above the critical Reynolds number due to a
correction, (g) velocity calibration range, and (h) velocity
discontinuity in the axial attenuation coefficient.
resolution.
3.2.3 Reynolds number (R )—the ratio of inertial to viscous
1.2 The values stated in SI units are to be regarded as
e
forces on an object immersed in a flowing fluid based on the
standard. No other units of measurement are included in this
object’s characteristic dimension, the fluid velocity, and vis-
standard.
cosity.
1.3 This standard does not purport to address all of the
3.2.4 shadow correction (v /v )—the ratio of the true
safety concerns, if any, associated with its use. It is the dm d
along-axis velocity v , as measured in a wind tunnel or by
responsibility of the user of this standard to establish appro- dm
another accepted method, to the instrument along-axis wind
priate safety and health practices and determine the applica-
measurement v .
bility of regulatory limitations prior to use. d
3.2.4.1 Discussion—This correction compensates for flow
2. Referenced Documents
shadowing effects of transducers and their supporting struc-
2
tures. The correction can take the form of an equation (3) or a
2.1 ASTM Standards:
lookup table (4).
C384Test Method for Impedance andAbsorption ofAcous-
tical Materials by Impedance Tube Method 3.2.5 speed of sound (c, (m/s))—the propagation rate of an
adiabatic compression wave:
D1356Terminology Relating to Sampling and Analysis of
Atmospheres
0.5
c 5 ~γ]P/]ρ! (1)
s
D5527Practices for Measuring Surface Wind and Tempera-
where:
ture by Acoustic Means
IEEE/ASTM SI 10American National Standard for Metric
P = pressure
ρ = density,
Practice
γ = specific heat ratio, and
3. Terminology
s = isentropic (adiabatic) process (5).
3.1 Definitions—For definitions of terms related to this test
3.2.5.1 Discussion—The velocity of the compression wave
method, refer to Terminology D1356.
defined along each axis of a Cartesian coordinate system is the
3.2 Definitions of Terms Specific to This Standard:
sum of propagation speed c plus the motion of the gas along
that axis. In a perfect gas (6):
1 0.5
This test method is under the jurisdiction of ASTM Committee D22 on Air
c 5 γR*T/M (2)
~ !
Quality and is the direct responsibility of Subcommittee D22.11 on Meteorology.
Current edition approved April 1, 2015. Published April 2015. Originally The approximation for propagation in air is:
approved in 1996. Last previous edition approved in 2008 as D6011–96 (2008).
0.5 0.5
c 5 403 T 110.32 e/P 5 403 T (3)
@ ~ !# ~ !
DOI: 10.1520/D6011-96R15. air s
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3
Standards volume information, refer to the standard’s Document Summary page on Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
the ASTM website. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D6011 − 96 (2015)
3.2.6 system clock—the clock used for timing acoustic 3.2.11.2 Discussion—Proceduresinthistestmethodinclude
wavefront travel between a transducer pair. a test to determine whether separate determinations of δ t and
1
δt are needed, or whether an average δt can be used. The
2
3.2.7 system delay (δt, µs)—the time delay through the
relationship of transit time to speed of sound is:
transducer and electronic circuitry (7).
2
d 1 1
3.2.7.1 Discussion—Each path through every sonic array
2 2
c 5 1 1v (10)
F S DG
n
axis can have unique delay cha
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6011 − 96 (Reapproved 2008) D6011 − 96 (Reapproved 2015)
Standard Test Method for
Determining the Performance of a Sonic Anemometer/
1
Thermometer
This standard is issued under the fixed designation D6011; 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 dynamic performance of a sonic anemometer/thermometer which employs
the inverse time measurement technique for velocity or speed of sound, or both. Performance criteria include: (a) acceptance angle,
(b) acoustic pathlength, (c) system delay, (d) system delay mismatch, (e) thermal stability range, (f) shadow correction, (g) velocity
calibration range, and (h) velocity resolution.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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 health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
C384 Test Method for Impedance and Absorption of Acoustical Materials by Impedance Tube Method
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
D5527 Practices for Measuring Surface Wind and Temperature by Acoustic Means
IEEE/ASTM SI-10SI 10 Use of the International System of Units (SI): The Modern Metric SystemAmerican National Standard
for Metric Practice
3. Terminology
3.1 Definitions—For definitions of terms related to this test method, refer to Terminology D1356.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 axial attenuation coeffıcient—a ratio of the free stream wind velocity (as defined in a wind tunnel) to velocity along an
3
acoustic propagation path (v /v ) (1).
t d
3.2.2 critical Reynolds number (R )—the Reynolds number at which an abrupt decrease in an object’s drag coefficient occurs
c
(2).
1
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 Oct. 1, 2008April 1, 2015. Published October 2008April 2015. Originally approved in 1996. Last previous edition approved in 20032008 as
D6011 - 96D6011 – 96 (2008).(2003). DOI: 10.1520/D6011-96R08.10.1520/D6011-96R15.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The boldface numbers in parentheses refer to the list of references at the end of this standard.
3.2.2.1 Discussion—
The transducer shadow corrections are no longer valid above the critical Reynolds number due to a discontinuity in the axial
attenuation coefficient.
3.2.3 Reynolds number (R )—the ratio of inertial to viscous forces on an object immersed in a flowing fluid based on the object’s
e
characteristic dimension, the fluid velocity, and viscosity.
3.2.4 shadow correction (v /v )—the ratio of the true along-axis velocity v , as measured in a wind tunnel or by another
dm d dm
accepted method, to the instrument along-axis wind measurement v .
d
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D6011 − 96 (2015)
3.2.4.1 Discussion—
This correction compensates for flow shadowing effects of transducers and their supporting structures. The correction can take the
form of an equation (3) or a lookup table (4).
3.2.5 speed of sound (c, (m/s))—the propagation rate of an adiabatic compression wave wave:
0.5
c 5 γ]P/]ρ (1)
~ !
s
where:
P = pressure
ρ = density,
γ = specific heat ratio, and
s = isentropic (adiabatic) process (5).
3.2.5.1 Discussion—
The velocity of the compression wave defined along each axis of a Cartesian coordinate system is the sum of propagation speed
c plus the motion of the gas along that axis. In a perfect gas (6):
0.5
c 5 ~γR*T/M! (2)
The approximation for propagation in air is:
0.5 0.5
c 5 @403 T 110.32 e/P # 5 403 T (3)
~ ! ~ !
air s
3.2.6 system clock—the clock used for timing
...