1、 _ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising ther
2、efrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2017 SAE International All rights reserved. No part of this
3、publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-49
4、70 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/standards.sae.org/AIR6202 AEROSPACE INFORMATION REPORT AIR6202 Issued 2012-04 Reaffirmed 2017-06 Test Cell Mass
5、Fuel Flow Measurement Using Coriolis Flow Meters RATIONALE AIR6202 has been reaffirmed to comply with the SAE Five-Year Review policy. TABLE OF CONTENTS 1. SCOPE 2 2. APPLICABLE DOCUMENTS 2 2.1 SAE Publications . 2 2.2 ASTM Publications 2 3. INTRODUCTION AND BENEFITS . 2 4. PRINCIPLE OF OPERATION .
6、3 5. BEST PRACTISE ADVICE FOR MECHANICAL CONFIGURATION/INSTALLATION SINGLE METER (LIQUID) 4 6. BEST PRACTISE ADVICE FOR MECHANICAL CONFIGURATION/INSTALLATION SINGLE METER (GAS) 6 7. BEST PRACTISE ADVICE FOR MECHANICAL CONFIGURATION/INSTALLATION TWIN METERS (LIQUID) . 7 8. MANAGEMENT OF “ZERO DRIFT“
7、. 8 9. INITIAL AND PERIODIC CALIBRATION REQUIREMENTS . 9 10. NOTES 9 1. SCOPE The scope of this information report applies to the steady state measurement of direct mass fuel flow in gas turbine engine test cells. A measurement accuracy, and hence uncertainty of between 0.1 to 0.2% of value is belie
8、ved to be achievable for liquid flow applications with some meter models/installations. Whilst capable of general transient measurement in 50 to 100 Hz region, this type of fuel meter is not capable of rapid transient measurement (in 100 to 250 Hz region). It is also not currently considered suitabl
9、e for “in flight“ fuel flow measurement. 2. APPLICABLE DOCUMENTS The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purcha
10、se order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1 SAE Publications Available fr
11、om SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AIR5026 Test Cell Instrumentation ARP4990 Turbine Flowmeter Fuel Flow Calculations AS5304 Standard Specification for Turbine Flowmeters 2.2 A
12、STM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM D1250 Standard Guide for Petroleum Measurement Tables 3. INTRODUCTION AND BENEFITS Traditionally, test cell mass fuel flow measurement for
13、 gas turbine engines has been calculated following the measurement of multiple parameters that include volumetric fuel flow, density and temperature(s). This includes measuring the temperature of fuel at both the meter during flow and a static sample of the fuel used, in order to correct “real time“
14、 meter density relative to the static sample in accordance with ASTM D1250. In some cases, “on line“ densimeters are used. Also, there are other elements to consider in the measurement uncertainty chain “stack up“ when using this traditional volumetric fuel flow measurement method, such as viscosity
15、 and pressure, particularly when using turbine flowmeters (see ARP4990). The total measurement uncertainty for the volumetric fuel flow measurment method is believed to be in the region of 0.25 to 0.5% of value depending on the meter choice, installation, range and method being used. This accuracy i
16、s only likely to be achieved over the top 80% (5/1 turn down ratio) of range of a single application flow meter. Below this range there is likely to be a significant increase in measurement uncertainty. Typically, turbine flow meters have been used in the US and positive displacement bulk meters use
17、d in the UK. SAE INTERNATIONAL AIR6202 Page 2 of 9_ The development of Coriolis fuel meters over the last 20 years has seen significant improvments in accuracy capability from 1.0 to 0.1% of value, by some manufacturers. When taking temperature compensation into account over a realistic working rang
18、e, a total uncertainty of approximately 0.2% of value is considered to be more realistic for liquid flow applications. This accuracy can be achieved over the top 95% of range (20/1 turn down ratio) of a single application flow meter. Below this range there is likely to be a significant increase in m
19、easurement uncertainty. The use of Coriolis fuel meters enables the direct measurement of mass fuel flow as a single parameter rather than multiple parameters and corrections that are described above, and is also likely to have additional cost benefits to the overall measurement system with the remo
20、val of these measurements/routines. Also, there are no moving parts to this design of meter requiring less overhaul maintenance throughout its life. These meters can also be used to measure gas flow, although it should be noted that the measurement accuracy capability is likely to be worse (typicall
21、y 0.3 to 0.4% of value). Some manufacturers also provide the ability for their meters to output density or volumetric flow if required. Two features of concern with this design are the management of the mechanical installation configuration (which is known to have sensitivity issues) and the risk of
22、 zero drift, particularly with ambient temperature variation. These issues and the principle of operation are covered in the following sections of this document. 4. PRINCIPLE OF OPERATION FIGURE 1 Drive Coil & Magnet Inlet Pickoff Outlet Pickoff No Flow Flow Flow Tubes SAE INTERNATIONAL AIR6202 Page
23、 3 of 9_ The illustration above highlights a curved double flow tube type configuration, a configuration that has been proven to be able to achieve the measurement accuracies/uncertainties that are quoted in the previous section. Other configurations, such as single and straight tubes can also be us
24、ed. The principle of operation of this configuration is decribed as follows: The flow tubes are driven to vibrate at their natural frequency by a magnet and drive coil, oscillating in opposing directions. This frequency output is measured by 2 pick off magnet and coil sensors positioned on the inlet
25、 and outlet bends of the flow tubes which will transmit the same coincident sine wave signal with no flow. The vibration motion combined with the momentum of the fluid flowing through the tubes induces a Coriolis force that twists the tubes. As one leg lags behind the other during twisting, a differ
26、ence in time can be seen between the pick off sine wave signals As this difference in time (t) is directly proportional to changing mass fuel flow, it can be used as a basis for metrology calibration. Fine tuning compensation is carried out with the use of an internal fuel tube temperature and calcu
27、lation, within the meter software structure. Density output is achieved by calculating the natural frequency of the illustrated sine wave, with increasing density being directly proportional to decreasing frequency and visa versa. Accuracy capability is similar to that quoted for mass flow output. T
28、hese devices can be used as Densitometers in their own right. Volumetric flow output is achieved by basic calculation using the mass flow and density outputs. Accuracy capability is similar to that quoted for mass flow output. 5. BEST PRACTISE ADVICE FOR MECHANICAL CONFIGURATION/INSTALLATION SINGLE
29、METER (LIQUID) FIGURE 2 Inlet Pick off Fuel Meter Location Skid Coriolis Fuel Meter ValvesLocation Clamps Support Pipe Work Transmitter Outlet Pick off SAE INTERNATIONAL AIR6202 Page 4 of 9_ The following highlights some best practise advise in regards to a single meter installation measuring liquid
30、 flow. This includes both Kerosine and Diesel (the latter for some marine gas turbine applications). Ensure that the test facility approach fuel flow supply has no unacceptable distortion, turbulence, or cavitation present. This can be achieved with the use of pressure controllers and regulators, fl
31、ow straighteners, filters, and acummulators. Select meter model with appropriate range and acceptable pressure loss characteristic to achieve the required specified accuracy. This may require ensuring use of “top of the range“ electronics, signal conditioning and transmitter. It is recommended that
32、the appropriate range to be covered (including any important low operating conditions) is within the top 80% range of the chosen meter model. Position the meter in the lowest part of the fuel system, preferably below engine centre line, in the gravity “ position. This is to try and ensure that there
33、 is no air in the system at the pick-offs, particularly when carrying out a static “zero datum checks“. Locate and secure the meter in an area of the test facility/ancillary area that is unlikely to be affected by any severe vibration or noise. Avoiding the main test cell and locating in an intrinsi
34、cally safe and self contained fire proof/bunded area is considered good practise. Position and locate the meter in a support frame or skid such that it is unlikely to be affected by any severe vibration or noise and that there is unlikely to be any undue stress or twist when connecting the flanges t
35、o the supporting pipe work. Connection of the meter using a less rigid bellows type flexible joint can be considered. Position the supporting pipe work such that it is reasonably straight and horizontal at the meter, with steady sloping runs on each side, thus avoiding any sudden steep drops or step
36、s. Suitably constructed flexible hoses can be considered and are less likely to introduce stress or twist at the joints. Position valves directly upstream and downstream of the meter such that they can be used to isolate the fuel content and thus, enable a good quality static “zero datum check“. SAE
37、 INTERNATIONAL AIR6202 Page 5 of 9_ 6. BEST PRACTISE ADVICE FOR MECHANICAL CONFIGURATION/INSTALLATION SINGLE METER (GAS) FIGURE 3 The following highlights some best practise advise in regards to a single meter installation measuring gas flow. This may be used for some industrial gas turbine applicat
38、ions in the energy business. Ensure that the test facility approach gas flow supply has no unacceptable distortion or turbulence present. This can be achieved with the use of pressure controllers and regulators, flow straighteners, filters, and acummulators. Select meter model with appropriate range
39、 and acceptable pressure loss characteristic to achieve the required specified accuracy. This may require ensuring use of “top of the range“ electronics, signal conditioning and transmitter. It is recommended that the appropriate range to be covered (including any important low operating conditions)
40、 is within the top 80% range of the chosen meter model. Position the meter in the the fuel system, preferably above engine centre line, in the “ position. This is to try and ensure that there is no liquid in the system at the pick-offs, particularly when carrying out a static “zero datum checks“. Lo
41、cate and secure the meter in an area of the test facility/ancillary area that is unlikely to be affected by any severe vibration or noise. Avoiding the main test cell and locating in an intrinsically safe and self contained fire proof area is considered good practise. Position and locate the meter i
42、n a support frame or skid such that it is unlikely to be affected by any severe vibration or noise and that there is unlikely to be any undue stress or twist when connecting the flanges to the supporting pipe work. Connection of the meter using a less rigid bellows type flexible joint can be conside
43、red. Inlet Pick off Fuel Meter Location Skid Coriolis Fuel Meter Valves Location Clamps Support Pipe Work Transmitter Outlet Pick off SAE INTERNATIONAL AIR6202 Page 6 of 9_ Position the supporting pipe work such that it is reasonably straight and horizontal at the meter, with, thus avoiding any sudd
44、en steep drops or steps. Suitably constructed flexible hoses can be considered and less likely to introduce stress or twist at the joints. Position valves directly upstream and downstream of the meter such that they can be used to isolate the fuel content and thus, enable a good quality static “zero
45、 datum check“. 7. BEST PRACTISE ADVICE FOR MECHANICAL CONFIGURATION/INSTALLATION TWIN METERS (LIQUID) FIGURE 4 The following highlights some best practise advise in regards to a twin meter installation measuring liquid flow. This includes both Kerosine and Diesel (the latter for some marine gas turb
46、ine applications). This is due to the fact that some OEMs prefer to use twin identical meter installations for improved measurement accuracy and enable cross-quality checking between the meters. The example above shows the meters fitted “in series“. The biggest risk with this configuration is the po
47、tential for unacceptable pressure loss that may require modification or alleviation. One method of alleviation is to consider fitting the meters “in parallel“ rather than “in series“. Ensure that the test facility approach fuel flow supply has no unacceptable distortion, turbulence or cavitation present. This can be achieved with the use of pressure controllers and regulators, flow straighteners, filters and acummulators. Select meter model with appropriate range and acceptable pressure loss chara
