final report on the apmp air speed key comparison …

Draft B Report on APMP.M.FF-K3

1

Final Report on the APMP Air Speed Key Comparison (APMP.M.FF-K3)

July, 2010 (Revised)

Yoshiya Terao1, Yong Moon Choi2, Mikhail Gutkin3, Wu Jian4, Iosif Shinder5

and Cheng-Tsair Yang6

1 NMIJ, AIST, Japan (Pilot) 2 KRISS, Korea 3 VNIIM, Russia

4 NMC, A*STAR, Singapore

5 NIST, USA 6 CMS/ITRI, Chinese Taipei


2

1. Introduction This key comparison, APMP.M.FF-K3 has been undertaken by APMP/TCFF, which is

Technical Committee for Fluid Flow, and was piloted by National Metrology Institute of Japan (NMIJ, AIST). The objective of this key comparison is to demonstrate the degree of equivalence of the air speed standards held at the participating laboratories to the CCM.FF-K3 key comparison reference value (KCRV) and to provide supporting evidence for the calibration and measurement capabilities (CMCs) claimed by the participating laboratories in the Asia-Pacific regions.

This Draft B report was prepared in accordance with the Guidelines for CIPM Key Comparisons(1) and The Guidelines on conducting comparisons (APMP-G2) (2).

2. Organization

(1) Participants and test speeds The participants and their actual testing dates are listed in Table 1. The comparison was

made at the air speeds of 2, 5, 10, 16 and 20 m/s. The test air speeds at each participant are also indicated in Table 1.

Table 1. Participants and test air speed.

Participant

(Economy) 2 5 10 16 20Cheng-Tsair Yang

CMS/ITRI [email protected], +886-3-5741206(ChineseTaipei)

Center for Measurement Standards,Industrial Technology Research Institute30, Da-Hsueh Rd.,Hsin-Chu city, 300 TaiwanYong Moon Choi

KRISS [email protected], +82-42-868-5317(Korea) Korea Research Institute of Standards and Science

Center for Fluid Flow and Acoustics1 Doryong-Dong, Yuseong-Gu, Daejeon 305-340, Rep.of KoreaIosif Shinder

NIST [email protected], +1- 301-975-2451(USA) National Institute of Standards and Technoloty

100 Bureau Drive, Stop 8361 Gaithersburg, MD 20899-8361, USAWu Jian

NMC A*STAR [email protected], +65-62791961(Singapore) National Metrology Centre, A*STAR,

#02-27, 1 Science Park Drive, Singapore 118221Abdul Rahamn Mohamed

NML-SIRIM [email protected], +603-87781666(Malaysia) National Metrology Laboratory, SIRIM BERHAD

LOT PT 4803, Bandar Baru Salak Tinggi,43900 Sepang, Selangor, Malaysia

Mikhail GutkinVNIIM [email protected], [email protected], +7-812-422-1273

(Russia) D.I.Mendeleyev Institute for MetrologyMoskovsky Prospect 19, St. Pertersburg 190005, Russia

Yoshiya TeraoNMIJ/AIST [email protected], +81-29-861-4375

(Japan)National Metrology Institute of Japan,National Institute of Advanced Industrial Science and TechnologyAIST Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan

* *

6 *

7Pilot * * *

* *

5 Withdrawn

* *

4 * * * * *

*

* *3

LinkLab

* * *

2 * * *

#Contact PersonE-mail Address and Phone NumberShipping Address

Test Air Speed(m/s)

1 * * * * *

Six NMIs from APMP planned to participate. Among these NMIJ was the only laboratory that had taken a part in the relevant global key comparison (CCM.FF-K3). NIST, USA, who


3

also participated in CCM.FF-K3, was invited to ensure the linkage to the global key comparison in accordance with the APMP-G2.

During the circulation of the transfer standard started, NML-SIRIM withdrew their participation. As a result, the final number of the participants was six.

(2) Test schedule

The actual testing dates at each participant are listed in Table 2.

Table 2. Participants and test schedule.

Participating Lab From To

NMIJ (#1) February 16, 2009 March 02

CMS March 16 April 02

NMIJ (#2) April 07 April 23

NIST May 04 May 27

KRISS June 22 July 08

A*STAR July 17 August 10

NMIJ (#3) August 31 September 13

VNIIM October 19 November 02

NMIJ (#4) December 07 December 21, 2009

3. Transfer Standard

The ultrasonic anemometer to be used in this KC is manufactured by KAIJO SONIC CORPORAITION. The probe has three pairs of ultrasonic transducers, and measures the three-dimensional velocity vector derived from the propagation time of the ultrasonic waves between each pair of transducers. The signal processing unit provides a scalar value of the air speed, Vm, which is given by,

2

z2

y2

xm VVVV (1)

where Vx, Vy and Vz denote the components of the three-dimensional velocity vector. This

signal processor also gives the time averaged air speed, mV .

Photo 1 shows the probe set to be calibrated in the test section of the wind tunnel at NMIJ.


4

Photo 1 Probe of the ultrasonic anemometer

4. Calibration results (1) Calibration result to be reported

At each participant, the ratios of the laboratory's reference air speed (Vref) to the time

averaged air speed mV were obtained at each test speed and reported along with their uncertainty. The averaging time was 60 s. In this report the calibration result is represented by

,i ref mx V V (2)

where subscript i denotes the participant.

(2) Reproducibility of the transfer standard observed at NMIJ

Fig.1 shows the calibration results of the transfer standard at NMIJ during the circulation. This figure shows that the anemometer was very stable both at 2 m/s and 20 m/s.


5

2 m/s

1.010

1.015

1.020

1.025

1.030

Feb-09 Apr-09 Aug-09 Nov-09

Test atCMS

Test at NIST,KRISS and

A*STAR

Test atVNIIM

x NMI

(a) 2 m/s

20 m/s

1.000

1.005

1.010

1.015

1.020

Feb-09 Apr-09 Aug-09 Nov-09

Test atCMS

Test at NIST,KRISS and

A*STAR

Test atVNIIM

x NMI

(b) 20 m/s

Fig. 1 Result of reproducibility test of the transfer standard

(3) Calibration results of the participants

The calibration results reported by the participants are listed in Table 3. For NMIJ, the

result obtained on April 26, 2009 is presented here.

Table 3 Calibration results reported by the participants. U(xi) is an expanded uncertainty with coverage factor (k) of 2.

CalibrationResult

x i

ExpandedUncertainty

U (x i)

CalibrationResult

x i

ExpandedUncertainty

U (x i)

CalibrationResult

x i

ExpandedUncertainty

U (x i)

CalibrationResult

x i

ExpandedUncertainty

U (x i)

CalibrationResult

x i

ExpandedUncertainty

U (x i)

NMIJ 1.0207 0.0067 1.0110 0.0038 1.0073 0.0035 1.0104 0.0035 1.0115 0.0035

CMS 1.0199 0.0056 1.0134 0.0052 1.0110 0.0050 1.0098 0.0050 1.0088 0.0056

NIST 1.0139 0.0083 1.0003 0.0080 1.0073 0.0095 1.0059 0.0071 1.0077 0.0087

KRISS 1.0179 0.0109 1.0060 0.0061 1.0065 0.0054 1.0090 0.0056 - -

A*STAR 1.0157 0.0055 1.0088 0.0055 1.0079 0.0050 1.0103 0.0035 1.0098 0.0035

VNIIM 1.0100 0.0061 1.0070 0.0060 1.0050 0.0060 1.0040 0.0061 0.9998 0.0060

20

Air Speed (m/s)

NMI2 5 10 16


6

5. Linkage to the global key comparison

At the air speeds of 2 m/s and 20 m/s, the two link laboratories have a result both from CCM.FF-K3 (CCM KC) (3) and APMP.M.FF-K3 (APMP KC). These results are plotted in Fig. 2 with the key comparison reference value (KCRV), derived from CCM KC. These KCRV is used as the reference value after the results from APMP KC are corrected by the procedure described by Delahaye and Witt(4).

A correction, which should be applied to the result from APMP KC, was obtained by equation (3):

i iD w D (3)

where iD is the difference between the results from CCM KC and APMP KC at a same link

laboratory (NMIJ or NIST) as presented by equation (4), and iw is the weighing coefficient

obtained from the uncertainty at each link lab as presented by equation (5).

i i, CCM i, APMPD x x (4)

2i

i

2 2NMIJ NIST

1

1 1u

w

u u

(5)

With this procedure, the correction was calculated as: 0.0024 at 2 m/s,

0.0012 at 20 m/s.

D

(6)

Finally, corrected value ix for each participant of APMP KC was calculated as:

i i, APMPx x D . (7)

This correction provides an estimate of what would have been the result from the APMP KC participants, if they had actually participated in CCM KC. Thus those result from APMP KC participants can be compared with KCRV and the participants results at CCM KC. For 2 m/s and 20 m/s, the corrected results are plotted in Fig. 3 and 7 along with KCRV and results from NMi-VSL and PTB, who participated only in CCM KC. The results at other air speed are plotted in Fig. 4 to 6.

(a) 2 m/s

0.99

1.00

1.01

1.02

1.03

1.04

0 1 2 3 4 5 6

CCM KC

NMIJ

NMIJ

NISTNIST

KCRV

APMP KC

xi

(b) 20 m/s

0.99

1.00

1.01

1.02

1.03

0 1 2 3 4 5 6

CCM KC

NMIJ

NMIJ

NIST NIST

KCRV

APMP KC

xi

Fig. 2 Results from the link laboratories at CCM KC and APMP KC


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0.990

0.995

1.000

1.005

1.010

1.015

1.020

1.025

1.030

1.035

NMIJ

CMS

NIST

KRISS

A*STAR

VNIIM

KCRVNM

iPTB

CCM KC

xi'

Fig. 3 Corrected calibration results at 2 m/s. Values of KCRV,

NMi and PTB are taken from Final report of CCM KC.

0.990

0.995

1.000

1.005

1.010

1.015

1.020

NMIJ

CMS

NIST

KRISS

A*STA

RVNIIM

xi

0.990

0.995

1.000

1.005

1.010

1.015

1.020

NMIJ

CMS

NIST

KRISS

A*STA

RVNIIM

xi

Fig. 4 Calibration results at 5 m/s. Fig. 5 Calibration results at 10 m/s.


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0.990

0.995

1.000

1.005

1.010

1.015

1.020

NMIJ

CMS

NIST

KRISS

A*STA

RVNIIM

xi

0.990

0.995

1.000

1.005

1.010

1.015

1.020

NMIJ

CMS

NIST

A*STAR

VNIIM

KCRVNM

iPTB

CCM KC

xi'

6. Degree of Equivalence

(1) Degree of Equivalence to KCRV For each participating laboratory, the degree of equivalence (DoE) was calculated using

i i refd x x (8)

where refx denotes KCRV. The results are listed in Table 4. Among the eleven DoEs shown

in Table 4, the ten DoEs, except that of VNIIM at 20 m/s, are within the expanded

uncertainty of the KCRV (U(xref)), which is 0.0024 at 20 m/s and 0.0154 at 2 m/s with k = 2.

Table 4. Degree of equivalence of each lab to KCRV

2　ｍ/ｓ 20 m/sNMIJ 0.0040 0.0014CMS 0.0032 -0.0013NIST -0.0028 -0.0024

KRISS 0.0012 -A*STAR -0.0011 -0.0003VNIIM -0.0067 -0.0103

(2) Degree of Equivalence between participants For each combination of two participating laboratories, the DoE was calculated using

,i j i jd x x at 2 m/s and 20 m/s (9)

,i j i jd x x at other air speeds (10)

The expanded uncertainty was obtained using

Fig. 6 Calibration results at 16 m/s.

Fig. 7 Corrected calibration results at 20 m/s. Values of KCRV, NMi and PTB are

taken from Final report of CCM KC.


9

, ,2i j i jU d u d (11)

and 2 2 2,i j i ju d u x u x (12)

The results are listed in Table 5 to 9. Table 5 Degree of equivalence between participants and its expanded uncertainty (k = 2) at 2 m/s

d i,j U (d i ,j) d i ,j U (d i,j) d i ,j U (d i,j) d i ,j U (d i,j) d i ,j U (d i,j) d i ,j U (d i,j)

NMIJ - - -0.0008 0.0088 -0.0068 0.0107 -0.0028 0.0128 -0.0050 0.0087 -0.0107 0.0091CMS 0.0008 0.0088 - - -0.0060 0.0100 -0.0020 0.0123 -0.0042 0.0079 -0.0099 0.0083NIST 0.0068 0.0107 0.0060 0.0100 - - 0.0040 0.0137 0.0018 0.0100 -0.0039 0.0103

KRISS 0.0028 0.0128 0.0020 0.0123 -0.0040 0.0137 - - -0.0022 0.0122 -0.0079 0.0125A*STAR 0.0050 0.0087 0.0042 0.0079 -0.0018 0.0100 0.0022 0.0122 - - -0.0057 0.0082

VNIIM 0.0107 0.0091 0.0099 0.0083 0.0039 0.0103 0.0079 0.0125 0.0057 0.0082 - -

NMIJ CMS NIST KRISS A*STAR VNIIM

Table 6 Degree of equivalence between participants and its expanded uncertainty (k = 2) at 5 m/s


NMIJ - - 0.0024 0.0065 -0.0107 0.0088 -0.0050 0.0072 -0.0022 0.0067 -0.0040 0.0071CMS -0.0024 0.0065 - - -0.0131 0.0095 -0.0074 0.0080 -0.0046 0.0076 -0.0064 0.0080NIST 0.0107 0.0088 0.0131 0.0095 - - 0.0056 0.0100 0.0084 0.0097 0.0067 0.0100

KRISS 0.0050 0.0072 0.0074 0.0080 -0.0056 0.0100 - - 0.0028 0.0082 0.0010 0.0086A*STAR 0.0022 0.0067 0.0046 0.0076 -0.0084 0.0097 -0.0028 0.0082 - - -0.0018 0.0081

VNIIM 0.0040 0.0071 0.0064 0.0080 -0.0067 0.0100 -0.0010 0.0086 0.0018 0.0081 - -

NMIJ CMS NIST KRISS A*STAR VNIIM

Table 7 Degree of equivalence between participants and its expanded uncertainty (k = 2)

at 10 m/s


NMIJ - - 0.0061 0.0063 -0.0070 0.0087 -0.0014 0.0071 0.0015 0.0065 -0.0003 0.0070CMS 0.0000 0.0063 - - -0.0107 0.0094 -0.0051 0.0079 -0.0023 0.0075 -0.0040 0.0078NIST 0.0037 0.0102 0.0061 0.0109 - - -0.0014 0.0113 0.0014 0.0110 -0.0003 0.0113

KRISS 0.0045 0.0066 0.0069 0.0075 -0.0062 0.0096 - - 0.0023 0.0077 0.0005 0.0081A*STAR 0.0031 0.0063 0.0055 0.0072 -0.0076 0.0094 -0.0019 0.0079 - - -0.0009 0.0078

VNIIM 0.0060 0.0071 0.0084 0.0080 -0.0047 0.0100 0.0010 0.0086 0.0038 0.0081 - -

A*STAR VNIIMKRISSNMIJ CMS NIST

Table 8 Degree of equivalence between participants and its expanded uncertainty (k = 2)

at 16 m/s

d i,j U (d i ,j) d i,j U (d i ,j) d i,j U (d i ,j) d i,j U (d i ,j) d i ,j U (d i,j) d i ,j U (d i,j)

NMIJ - - 0.0030 0.0063 -0.0101 0.0087 -0.0044 0.0070 -0.0016 0.0065 -0.0034 0.0069CMS 0.0013 0.0063 - - -0.0094 0.0094 -0.0038 0.0079 -0.0010 0.0074 -0.0028 0.0078NIST 0.0051 0.0080 0.0075 0.0088 - - 0.0000 0.0094 0.0029 0.0090 0.0011 0.0093

KRISS 0.0020 0.0068 0.0044 0.0077 -0.0087 0.0097 - - -0.0002 0.0078 -0.0020 0.0082A*STAR 0.0008 0.0052 0.0031 0.0063 -0.0099 0.0087 -0.0043 0.0070 - - -0.0033 0.0069

VNIIM 0.0070 0.0072 0.0094 0.0080 -0.0037 0.0100 0.0020 0.0086 0.0048 0.0082 - -

A*STAR VNIIMNMIJ CMS NIST KRISS


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Table 9 Degree of equivalence between participants and its expanded uncertainty (k = 2) at 20 m/s

d i,j U (d i ,j) d i ,j U (d i ,j) d i,j U (d i,j) d i ,j U (d i ,j) d i,j U (d i,j)

NMIJ - - -0.0027 0.0066 -0.0038 0.0093 -0.0017 0.0049 -0.0117 0.0069CMS 0.0027 0.0066 - - -0.0011 0.0103 0.0010 0.0066 -0.0090 0.0082NIST 0.0038 0.0093 0.0011 0.0103 - - 0.0021 0.0093 -0.0079 0.0105

A*STAR 0.0017 0.0049 -0.0010 0.0066 -0.0021 0.0093 - - -0.0100 0.0069VNIIM 0.0117 0.0069 0.0090 0.0082 0.0079 0.0105 0.0100 0.0069 - -

A*STAR VNIIMNMIJ CMS NIST

7. Summary and conclusion A selected transfer standard had been circulated among the six participants in eleven

months starting February 2009. The repeated calibration results at NMIJ demonstrated sufficient reproducibility of the transfer standards. At 2 m/s and 20 m/s, a linkage to the global key comparison (CCM.FF-K3) was established by applying correction to the participants results based on the results from the link laboratories.

8. References (1) Guidelines for CIPM key comparisons, March 1999 (Revised in October 2003). (2) APMP-G2: The Guidelines on conducting comparisons, 2003 (3) Final Report on the CIPM Air Speed Key Comparison (CCM.FF-K3), October, 2007 (4) Linking the Results of Key Comparison CCEM-K4 with the 10 pF Results of EUROMET

Project 345, François Delahaye and Thomas J. Witt, Metrologia 39(2002) Technical Supplement 01005.


11

Appendix - Uncertainty budget of participating laboratories

In this appendix, the uncertainty budget of each participating laboratory is presented. Each part is taken from the document submitted by a participant and has not been edited by the pilot lab.

Part 1 CMS The uncertainty budget of the CMS air speed standards The real air speed at the anemometry position can be expressed as = f (Vldv ,δ, ε) (1)

where

Vldv : air speed measured by using LDV

Vtunnel : real air speed at the position of anemometry

δ : correction factor for flow characteristic

ε : correction factor for wind-tunnel performance

According to equation (1), the uncertainty of air speed in the measurement zone can be expressed as

(2)

where

c1: sensitivity coefficient of the variable Vldv；

c2: sensitivity coefficient of the variable δ；

c3: sensitivity coefficient of the variable ε； The relative uncertainty (3) The uncertainty budget of the air speed measurement system is shown in Table 1

ldvtunnel VV

23

2

2

2

1

2 )()()()( ucucVucVu ldvtunnelc

2/1222 )))(

())(

())(

(()(

uu

V

Vu

V

Vu

ldv

ldv

tunnel

tunnelc

ldvVf

c

2

ldvVf

c

3

222

2)()()()(

uf

uf

VuV

fVu ldv

ldv

tunnelc

ldvV

fc 1


12

Table 1: Uncertainty summary

item

0.005 9.5

0.056 1067

1 particle lag 0.000 ∞

2 Velocity bias 0.010 ∞3 Turbulence int. 0.055 9994 Fring bias 0.000 ∞

0.230 8

1 along vertical direction 0.141 14

2 along horizonal direction 0.129 7

3 along flow direction0.128 9

0.242 23

k 2.07 23

0.500 23

Flow and particle influences ofLDV Measurement

LDV Facility

Sources

Flow velocity distribution inwind tunnel

Combined standard uncertainty

]

)([

ldvV

Vu ldv

u(xi)/x i % νX

])(

[u

]

)([

tunnelV

Vu tunnelc

]

)([u

]

)([

tunnelV

VU tunnel


13

Part 2 KRISS Combined uncertainty and Expanded uncertainty of KRISS The model equation of an air speed measurement using pitot tube as follows;

vtup

vs

21

2)1(

(1)

The meaning of symbols in Eq.(1) as follows, 1) Air speed measured by pitot tube: sv [m/s]

2) Calibration factor of the pitot tube: [-] 3) Compressibility factor: [-] 4) Differential pressure measurements: p [Pa]

-Differential pressure measured by gauge: mp [Pa]

-Blocking effect of the pitot tube: )( p [Pa] -Pressure loss due to pitot tube: [Pa]

-Installation angle of pitot tube: p [Pa] 5) Density of air: [kg/m3] 6) Turbulence intensity: tu [m/s] 7) Velocity difference caused by the location of measurement: v [m/s]

The uncertainty of the sv in Eq. (1) yields,

21

222222222222 )()()()()()()( vuctuucucpucucucvu vtupsc (2)

The sensitivity coefficients can be obtained by differentiating Eq. (2).

21

2)1(

pc [Pa1/2 (kg/m3)-1/2]

21

2

pc [Pa1/2 (kg/m3)-1/2]

21

2)1(

2

1

pc p [(Pa kg/m3)-1/2]

21

3

2)1(

2

1

pc [Pa1/2 (kg/m3)-3/2]

tuc = 1vc

For example, at 16.01 m/s, p is 152.9 Pa, air density is 1.1881 kg/m3, pitot coefficient is 1.0015 from ISO3966, and the compressibility correction factor )1( is 0.99973. Then, the sensitivity factors are as follows, in units given above:

60.1c , 61.1c , 525.0pc , 676.0c , 1 vtu cc (3)

The combined standard uncertainty of the velocity measurement using Pitot tube and the degrees of freedom are calculated with the root-sum-square method from the following standard uncertainties in Table 1 and the degrees of freedom. Table 1 Standard uncertainty of the parameters of KRISS air speed


14

)( ixu Parameter

Type A Type B Type A Type B ic

n/a 2.00E-03 n/a 55 1.60E+01

)1( 4.25E-07 1.01E-07 59 38 -1.61E+01

p (Pa) 2.84E-01 4.82E-02 100 1 5.25E-02

(kg/m3) 5.17E-05 2.72E-04 62 6 -6.76E+00

tu (m/s) 4.15E-05 N/A 10000 N/A 1

v (m/s) 2.67E-02 N/A 9 N/A 1

Therefore, the combined uncertainty of sv can be calculated, )( sc vu =8.910-2 m/s. The

effective degrees of freedom is eff =51. The coverage factor is 2.01 with 95% confidence level.

Final results for sv =16.01 m/s is sv =16.01 8.9210-2 m/s. The same kind of uncertainty

analysis is repeated from 2.0 to 16 m/s. Results are shown in Table 2 and these are the calibration measurement capability of the pitot tube measurement in the wind tunnel. Table 2 Expanded uncertainty of the pitot tube measurement

sv (m/s) 2.074 5.165 10.049 16.012

pitotU (m/s) 2.25E-02 3.11E-02 5.43E-02 8.92E-02

*pitotU (%) 1.08 0.60 0.54 0.56

k 2.09 2.00 2.02 2.01

eff 21 58 45 51


15

Part 3 NIST

The uncertainty of the NIST air speed standards

0.1~30 m/s, k=1Source of uncertainty Type u [m/s]

Misalignment of LDA with disk B 0.000027Disk radius B 0.000068Disk rotation rate B 0.000085LDA resolution A 0.003000LDA - Disk calibration factor A 0.22%

At 2 m/s for k=2Source of uncertainty Type u [m/s]

Misalignment of LDA with disk B 0.000054Disk radius B 0.000136Disk rotation rate B 0.000170LDA resolution A 0.006000LDA - Disk calibration factor A 0.008800Expanded Uncertainty, [m/s] 0.010653Expanded Uncertainty, [%] 0.5327

At 20 m/s for k=2Source of uncertainty Type u [m/s]

Misalignment of LDA with disk B 0.000054Disk radius B 0.000136Disk rotation rate B 0.000170LDA resolution A 0.006000LDA - Disk calibration factor A 0.088000Expanded Uncertainty, [m/s] 0.088205Expanded Uncertainty, [%] 0.4410

(This part has been taken from the final report of CCM Key comparison(3) . Detailed uncertainty analysis has been published as "NIST Special Publication 250-79". The original text can be found at http://ts.nist.gov/MeasurementServices/Calibrations/sp250_series.cfm. )


16

Part 4 NMC A*STAR

ESTIMATION OF MEASUREMENT UNCERTAINTY OF A*STAR FOR APMP.M.FF-K3

1. CALIBRATION EQUIPMENT

Features Examined

Equipment

Air velocity

2m/s;

5m/s;

10m/s;

16m/s;

20m/s.

1) Precision Wind-tunnel System

Expanded measurement uncertainty

Measurement Range

2). Laser Doppler Anemometer

Expanded measurement uncertainty

Measurement Range

Fig1. Precision Wind Tunnel Standard


17

Fig2. Laser Doppler Anemometer

2. COMPARISON SETUP

Fig 3. The setting up for APMP M.FF-K3 comparison

3. Environmental Condition

The calibration should be carried out under the ambient condition of Temperature : 23 ± 1 ºC Humidity : 55 ± 5 % rh


18

4. TRACEABILITIES 5. ESTIMATED MEASUREMENT UNCERTAINTY

5.1 Calculate applied air velocity.

Air velocity at the measurement point is given by:

V= Kwt·Kd· Kt· Kwl· Kb·Vwt (1)

Where:

V: Velocity at measurement position Vwt: Velocity set by wind tunnel Kwt: Calibration factor of wind tunnel Kd: Correction due to wind distribution Kt: Correction due to wind turbulence Kwl: Correction due to wind tunnel long term stability Kb: Correction due to wind blockage

5.2 Air velocity generated by wind tunnel via pressure and air density measurement (2)

β: nozzle compression ratio ΔP: the pressure drop across nozzle ρ: density of air

Kwt = VLDA/Vwtc (3) VLDA Measurement value of LDA (Laser Doppler anemometer)

Dimension (m) Time (s)

Speed calibration (m/s) Beam angle (o)

Temperature Deferential pressure Barometric pressure

Unit Under Test

Laser Doppler Anemometer

Wind Tunnel

P

Vwt

2

1

14


19

5.3 Calculate velocity calibration of air velocity meter.

VUUT=V-Error (4)

5.4 Estimate measurement uncertainty:

(V) = ( Kwt, Kd, Kt, Kwl, Kb, Vwt, Vuut)

= (Kwt, Kd, Kt, Kwl, Kb, ΔP, ρ, VLDA, Vuut) (5)

5.5 Combined measurement uncertainty: u2c = (cKwt·uKwt)2 + (cKd·uKd)2 + (cKt·uKt)2 + (cKwl·uKwl)2 + (cKb·uKb)2

+ (cΔP·uΔP)2 + (cρ ·uρ)2 + (cVLDA ·uVLDA)2 + (c Vuut·u Vuut )2 (6)

5.6 Expanded measurement uncertainty: U=k·uc (7)

5.7 The estimated measurement uncertainty is listed at table 1~3 in the following pages.


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Table 1. Summary of Measurement Uncertainty (2m/s and 5m/s)

Ref no: Source of uncertainty Symbol Unit Uncertainty

Degree of freedom Sensitivity Std uncertainty (ui)

Absolute Relative Coverage factor

1 Calibration factor of wind tunnel Kwt ‐ ‐ 0.400% 1 2 0.200%

2 Correction due to wind distribution Kd ‐ ‐ 0.010% 1 1 0.010%

3 Correction due to wind turbulence Kt ‐ ‐ 0.050% 1 1 0.050%

4 Correction due to wind tunnel long term stability Kwl ‐ ‐ 0.010% 1 1 0.010%

5 Correction due to wind blockage Kb ‐ ‐ 0.050% 1 1 0.050%

6 Density of air ρ Kg/m3 ‐ 0.010%

1 0.010%

7 Pressure drop across nozzle ΔP Pa 0.2 0.200%

2 0.100%

8 Measurement value of LDA VLDA m/s ‐ 0.070% 1 2 0.035%

9 Unit under test VUUT ‐

9.1 Repeatability urep m/s 0.00 0.0% 1 1 0.000%

9.2 Resolution ures m/s 0.01 0.5% 1 3.46410 0.144%

Combined Uncertainty uc(Density) 0.28%

Expanded Uncertainty(at a level of confidence of 95% with k=2) U 0.56%

pdp

2

1

d2

1


21

Table 2. Summary of Measurement Uncertainty (10m/s)










1 0.010%

7 Pressure drop across nozzle ΔP Pa 0.2 0.200% 2 0.100%



9.1 Repeatability urep m/s 0.00 0.00% 1 1 0.000%

9.2 Resolution ures m/s 0.01 0.10% 1 3.46410 0.029%



pdp

2

1

d2

1


22

Table 3. Summary of Measurement Uncertainty (16m/s and 20m/s)










1 0.010%

7 Pressure drop across nozzle ΔP Pa 0.2 0.008% 2 0.004%



9.1 Repeatability urep m/s 0.00 0.00 1 1 0.000%

9.2 Resolution ures m/s 0.01 0.0004 1 3.46410 0.012%



pdp

2

1

d2

1


23

Part 5 VNIIM Uncertainty budget of VNIIM

Calibration of transfer standard – ultrasonic anemometer – has been performed

by measuring the anemometer indicated speed and the VNIIM standard reading simultaneously. Measurements accomplished at aerodynamic facility: loop tube with open test section. Nozzle diameter is 700 mm, range 0,1 – 100 m/s. Means of air speed measuring:

0,1 – 30 m/s LDA 5 -100 m/s Pitot static tube with differential manometer Distance between nozzle exit plane and ultrasonic anemometer sensors was 70

mm. While using LDA air speed determined as V=Kl *Kb*Kd* Vl

Kl – LDA calibration factor Kb – correction factor due to duct blockage Kd – correction factor due to velocity distribution across the duct Vl– air speed indicated by LDA Expanded uncertainty sources and values 1. LDA calibration 0,0044 2. Duct blockage

0,0010 3. Velocity distribution across the duct 0,0040 ( 2 – 20 m/s )

KC calibration result (VNIIM) V 2 5 10 16

20 m/s Xi 1,010 1,007 1,005 1,004

0,9998 U(Xi) 0,006 0,006 0,006 0,006 0,006 Attached are photos of VNIIM standard facility.


24

Standard aerodynamic facility (1)


25

Standard aerodynamic facility (2)


26

LDA of aerodynamic tube


27

TC sensor at the test section


28

LDA, display panel


29

Part 6 NMIJ/AIST

Uncertainty budget at NMIJ

The anemometer calibration system at NMIJ consists of an LDV calibrator, an LDV transfer standard and a wind tunnel as shown in Fig. B-1. The schematic of the LVD calibrator and the wind tunnel is illustrated in Figs. B-2 and B-3.

The uncertainty budget is shown Table B-1 and B-2.

Fig. A-1 Anemometer Calibration System

A-2 LDV Calibrator

LDV probeScreenOptical power meter head

Optical length scale

Rotor assembly Electronic shutter

Fine adjustment carriageTraverse table

LDV probeScreenOptical power meter head

Optical length scale

Rotor assembly Electronic shutter

Fine adjustment carriageTraverse table

LDV calibrator (Primary standard)

LDV (Transfer standard)

Wind tunnel with ultrasonic anemometers (Working standard)

Customers' anemometer


30

A-3 Calibration Wind Tunnel

Settling section Contraction

Corner vanes

Fan

DC Motor

Honeycomb screens

7500

3300

Test section


31

Table A-1 Uncertainty sources and their sensitivity coefficient

Input quantity Symbol Uncertainty source Sensivity coefficient Type

Reference air speed refV | 1 |

USR Correction factor to output value of ultrasonic reference anemometer

| 1 | B(A)

meterS Frontal projected area of DUT

meterWT

meter

SS

S

A

WTS Cross-sectional area of calibration wind tunnel

meterWT

meter

SS

S

A

*USRU Output of ultrasonic

reference anemometer when DUT is installed at the test section

*corrctd

*USR

U

U A

*USR0U Output of ultrasonic

reference anemometer at zero air speed

*corrctd

*USR0

U

U A

Repeatability of DUT mV |-1 |

Table A-2 Uncertainty budget (Symbols are defined in Table A-1)

Air speed range Unit Uncertainty

sources 1.3 1.5

1.5 2

2 3

3 5

5 7

7 10

10 15

15 20

20 25

25 30

30 35

35 40

m/s

refV 0.304 0.23 0.169 0.148 0.144 0.147 0.147 0.143 0.145 0.145 0.169 0.169 %

USR 0.303 0.229 0.169 0.148 0.143 0.147 0.147 0.143 0.145 0.145 0.169 0.169 %

meterS 9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03 %

WTS 9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03

9.5 x10-03 %

*USRU

2.4 x10-04

2.4 x10-04

2.1 x10-04

2.8 x10-04

5.5 x10-04

7.5 x10-04 0.001 0.001 0.002 0.002 0.002 0.003 m/s

*USR0U

1.7 x10-04

1.7 x10-04

1.7 x10-04

1.7 x10-04

1.7 x10-04

1.7 x10-04

1.7 x10-04

1.7 x10-04

1.7 x10-04

1.7 x10-04

1.7 x10-04

1.7 x10-04 m/s

mV 0.145 0.124 0.104 0.073 0.043 0.031 0.03 0.03 0.029 0.033 0.035 0.035 %

x 1 1 1 1 1 1 1 1 1 1 1 1 —

xu 0.003 0.003 0.002 0.002 0.001 0.001 0.001 0.001 0.001 0.001 0.002 0.002 —

x

xu 0.336 0.261 0.198 0.165 0.15 0.15 0.15 0.146 0.147 0.149 0.173 0.173 %

x

xU 0.673 0.523 0.397 0.331 0.3 0.299 0.299 0.292 0.294 0.298 0.346 0.346 %

final report on the apmp air speed key comparison …

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