CA1322471C - Air flow measuring device - Google Patents
Air flow measuring deviceInfo
- Publication number
- CA1322471C CA1322471C CA000569664A CA569664A CA1322471C CA 1322471 C CA1322471 C CA 1322471C CA 000569664 A CA000569664 A CA 000569664A CA 569664 A CA569664 A CA 569664A CA 1322471 C CA1322471 C CA 1322471C
- Authority
- CA
- Canada
- Prior art keywords
- air flow
- pressure
- air
- measuring
- stator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 230000001939 inductive effect Effects 0.000 claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 7
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 6
- 230000001105 regulatory effect Effects 0.000 claims description 5
- 230000003068 static effect Effects 0.000 claims description 4
- 230000005465 channeling Effects 0.000 claims description 2
- 238000004891 communication Methods 0.000 claims description 2
- 239000012530 fluid Substances 0.000 claims description 2
- 238000005259 measurement Methods 0.000 description 6
- 238000001816 cooling Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000002674 ointment Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
- G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Volume Flow (AREA)
Abstract
Case 2992 IMPROVED AIR FLOW MEASURING DEVICE AND METHOD
ABSTRACT OF THE DISCLOSURE
There is disclosed an improved method and apparatus for measuring air flow through a stator duct of a dynamoelectric machine. The apparatus includes an inlet venturi connectable to the stator duct, a nozzle for producing a pressure drop related to the air flow rate. The pressure drop is measured by two pressure taps, one located upstream of the nozzle and the other located downstream of the nozzle. The improvement includes an adjustable fan located downstream of the nozzle for inducing an air flow through the apparatus that compensates for air leakage between the inlet venturi and the stator duct. The improvement further includes air leakage measuring sensors which compare air flow through the inlet means with an air flow reference in another part of the dynamoelectric machine. The air leakage measuring sensors register a predetermined pressure differential in air flow through the inlet means and the duct when the fan is adjusted to induce the predetermined compensating air flow through the apparatus.
ABSTRACT OF THE DISCLOSURE
There is disclosed an improved method and apparatus for measuring air flow through a stator duct of a dynamoelectric machine. The apparatus includes an inlet venturi connectable to the stator duct, a nozzle for producing a pressure drop related to the air flow rate. The pressure drop is measured by two pressure taps, one located upstream of the nozzle and the other located downstream of the nozzle. The improvement includes an adjustable fan located downstream of the nozzle for inducing an air flow through the apparatus that compensates for air leakage between the inlet venturi and the stator duct. The improvement further includes air leakage measuring sensors which compare air flow through the inlet means with an air flow reference in another part of the dynamoelectric machine. The air leakage measuring sensors register a predetermined pressure differential in air flow through the inlet means and the duct when the fan is adjusted to induce the predetermined compensating air flow through the apparatus.
Description
~322'~
Case 2992 IMPROVED AIK FLOW MEASURING DEVICE
FIELD OF THE INVENTION
The present invention relates to a method o~
measuring air flow through the stator ducts of a dynamoelectric machine and an apparatus adapted to measures the stator duct air ~low.
BACKGROUND OF THE INVENTION
Measuring air flow through the stator ducts of a dynamoelectric machine provides an evaluation of the various characteristics, including the cooling efficiency, of the dynamoelectric machine while running the dynamoelectric machine under various operating conditions. It will be apparent that the reliance that can be placed on the air flow measurements is related to exactness of the measurement.
Previously, measuring air flow through the stator ducts of a dynamoalectric machine has involved connecting an inlet of an air flow measuring device across the stator duct to capture the air passing from the stator duct. The measuring device further includes a restricted air flow path whereby the air ~low through the restriction could be monitored. This restriction usually involves some form of nozzle that creates a pressure drop across the nozzle which pressure drop varies in proportion to the air flow through the device.
-, '' . . ' ' ' ' .
~ .
' 13~2~7~ Case 2992 While an air flow monitoring or measuring device, as described above, is able to precisely measure the air flow through the device, such devices do not necessarily reflect variations in air flow through the stator duct due to the ~act that the measuring device cannot be readily attached to each stator duct in a manner which would prevent air leakage at the connection. As a consequence variations in the air flow through the measuring device may not vary in proportion to the variations in air flow through the stator ducts. Thus, the measurement of air flow by these devices is not a true measurement of air flow throu~h the stator ducts and the measured data is typically accurate to within 20 to 30 percent of the measured values. Clearly, the error of 20 to 30 percent, introduced by the connection of the measuring device to the stator duct, considerably diminishes the reliance that can be placed on the measured data.
OBJECT OF THE INVENTION
It is an object of the present invention to provide a measuring device that measures air flow through the stator ducts of a dynamoelectric machine with improved accuracy.
It is another object of the present invention to provide a measuring device that measures the air flow through the stator ducts of a dynamoelectric machine and compensates for air leakage at the connection o~ the air flow measuring means ts the stator ducts of the d~namoelectric machine.
It is another object of the present invention to provide method of a measuring air flow through the stator ducts o~ a d~namoelectric machine which compensates for air losses occurring at the connection of the air flow measuring means to the stator ducts of the dynamoelectric machine.
-~2~7~ Case 2g92 SUMMARY OF THE INVENTION
In accordance with one aspect of the presentinvention there is provided an apparatus for measuring air flow through stator ducts of a dynamoelectric machine. The apparatus includes an air inlet means connectable to at least one oE the stator ducts, and air flow measuring means connected downstream of the inlet means for measuring the air flow from the at least one stator duct. The apparatus further includes compensating means counteracting air flow losses between the at least one stator duct and inlet means.
The compensating means includes adjustable negative pressure inducing means, located downstream of the air flow measuring means, for inducing an air flow through the apparatus that counteracts air flow losses occurring where the inlet means is connectable to the one stator duct.
By providing an adjustable negative pressure inducing means located downstream of the air flow measuring means it is possible to re~adjust the air flow through the apparatus each time the apparatus is connected to a different stator slot of the dynamoelectric machine. As a result, the measured data associated with each stator slot will be more ~5 relational because the negative pressure inducing means will have effectively reduced or compensated for the losses at the connection of the inlet means of the apparatus to the stator duct of the dynamoelectric machine.
It is further envisaged that the compensating means of the air flow measuring means may include air leakage measuring means for measuring pressure associated with air flow through the inlet means and measuring static pressure associated with the core of dynamoelectric machine In this embodiment the adjusta~le negative pressure inducing means may be ~ ~3 2 2 ~ a ~
Case 2992 adjusted to provide the air flow by setting pressure drop to zero when the air leakage measuring means registers a predetermined pressure differential in air flow through the inlet means and the core of the dynamoelectric machine.
In the preferred embodiment oE the present invention the air flow measuring means comprises an ASME nozzle means in fluid flow communication with the inlet means. In this emhodiment the air pressure measuring means measures the air pressure drop across the nozzle where the pressure drop is related to the air flow through at least one stator duct. In the preferred embodiment the air pressure measuring means includes a first pressure sensor connected upstream of the nozzle and a second pressure sensor connected downstream of the nozzle. In tha preferred embodiment the adjustable negative pressure inducing means includes a fan for inducing the predetermined air flow through the apparatus.
In accordance with another aspect of the present invention there is provided a method of sensing air flow through stator ducts of a dynamoelectric machine. The method comprises the steps of:
a) capturing air flowing through one of the stator ducts and channeling the air through first and second flow restricting areas, b) sensing a first air flow pressure through the first flow restricting area, sensing a second referencing pressure in another section of the dynamoelectric machine, and comparing the first and second prassures, c) applying and regulating an adjustable negative pressure air flow through the first and second flow restricting areas whereby the negative pressure air flow is regulated when the comparison of the first and second pressures indicates a predetermined pressure 13~2,!~7~ Case 2992 drop therebetween, and d) sensing the pressure values upstream and downstream of the second flow restricting area to determine the air flowing through the one stator duct.
BRIEF DESCRIPTION OF_THE DRAWING
For a better understanding of the nature and objects of the present invention reference may be had to the sole figure of the drawing which diagrammatically illustrates the air flow measuring ~0 device of the present invention connected to a stator slot of a dynamoelectric machine.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawing there is shown a stator 10 of a dynamoelectric machine having a plurality of stator ducts 12. The air flow measuring apparatus is shown generally at 14.
The apparatus 14 includes an inlet means 16 which is shown connected to one to of the stator ducts. I'he inlet means can bs connected by suitable clamps ~not shown) so that the inlet means substantially covers the stator slot. The inlet means 16 comprises a venturi type o~ nozzle. A first pressure tap 18 is shown attached to the venturi nozzle and a second pressure tap 20 is shown diagrammatically taken at the back of the core. The pressures monitored by these taps 18 and 20 are measured and compared by a manometer 22.
The apparatus 14 further includes suitable flexible hosing 24 for communicating air flowing through the inlet nozzle 16 to a cylindrical chamber 26. The chamber 26, which obviously forms part of the apparatus 14, includes a nozzle 28 which is an ASME type nozzle. Two pressure taps 30 and 32 respectively located upstream and downstream of the nozzle 28 are shown connecked to a second manometer 34.
Case 2992 -- 6 ~
The apparatus further includes a compensating means 36 located downstream of the chamber 26 and nozzle 28. The compensating means includes a flexible hose 38 and a negative pressure inducing means or fan 40 which together control the flow of air out of the chamber 26 through the hose 38.
To improve the relational accuracy of the measurements of the stator ducts 12 and to compensate for air leakage losses, the compensating means 36 is regulated to compensate for losses at the connection of the inlet venturi 16 to the stator slot 12 of the dynamoelectric machine 10. The fan speed is re~ulated under a normal dynamoelectric operating condition so that the pressure differential measured between taps 18 and 20 by manometer 22 is zero. By setting the fan speed to compensate ~or the air leakages at the inlet means of the apparatus the accuracy of the measuring apparatus has improved from having errors in the range of 20 to 30 percent to having errors of less than 5 percent.
In operation, the inlet means is connected to each stator slot and the air flow through the stator slot is measuxed as a ~unction of the pressure drop across the nozæle 28. The pressure drop across nozzle 28 is monitored by taps 30 and 32 and measured by manometer 34. These measurements can be taken for various operating conditions of the dynamoelectric machine so as to determine the air flow cha~acteristics through the stator ducts of the dynamoelectric machine.
Case 2992 IMPROVED AIK FLOW MEASURING DEVICE
FIELD OF THE INVENTION
The present invention relates to a method o~
measuring air flow through the stator ducts of a dynamoelectric machine and an apparatus adapted to measures the stator duct air ~low.
BACKGROUND OF THE INVENTION
Measuring air flow through the stator ducts of a dynamoelectric machine provides an evaluation of the various characteristics, including the cooling efficiency, of the dynamoelectric machine while running the dynamoelectric machine under various operating conditions. It will be apparent that the reliance that can be placed on the air flow measurements is related to exactness of the measurement.
Previously, measuring air flow through the stator ducts of a dynamoalectric machine has involved connecting an inlet of an air flow measuring device across the stator duct to capture the air passing from the stator duct. The measuring device further includes a restricted air flow path whereby the air ~low through the restriction could be monitored. This restriction usually involves some form of nozzle that creates a pressure drop across the nozzle which pressure drop varies in proportion to the air flow through the device.
-, '' . . ' ' ' ' .
~ .
' 13~2~7~ Case 2992 While an air flow monitoring or measuring device, as described above, is able to precisely measure the air flow through the device, such devices do not necessarily reflect variations in air flow through the stator duct due to the ~act that the measuring device cannot be readily attached to each stator duct in a manner which would prevent air leakage at the connection. As a consequence variations in the air flow through the measuring device may not vary in proportion to the variations in air flow through the stator ducts. Thus, the measurement of air flow by these devices is not a true measurement of air flow throu~h the stator ducts and the measured data is typically accurate to within 20 to 30 percent of the measured values. Clearly, the error of 20 to 30 percent, introduced by the connection of the measuring device to the stator duct, considerably diminishes the reliance that can be placed on the measured data.
OBJECT OF THE INVENTION
It is an object of the present invention to provide a measuring device that measures air flow through the stator ducts of a dynamoelectric machine with improved accuracy.
It is another object of the present invention to provide a measuring device that measures the air flow through the stator ducts of a dynamoelectric machine and compensates for air leakage at the connection o~ the air flow measuring means ts the stator ducts of the d~namoelectric machine.
It is another object of the present invention to provide method of a measuring air flow through the stator ducts o~ a d~namoelectric machine which compensates for air losses occurring at the connection of the air flow measuring means to the stator ducts of the dynamoelectric machine.
-~2~7~ Case 2g92 SUMMARY OF THE INVENTION
In accordance with one aspect of the presentinvention there is provided an apparatus for measuring air flow through stator ducts of a dynamoelectric machine. The apparatus includes an air inlet means connectable to at least one oE the stator ducts, and air flow measuring means connected downstream of the inlet means for measuring the air flow from the at least one stator duct. The apparatus further includes compensating means counteracting air flow losses between the at least one stator duct and inlet means.
The compensating means includes adjustable negative pressure inducing means, located downstream of the air flow measuring means, for inducing an air flow through the apparatus that counteracts air flow losses occurring where the inlet means is connectable to the one stator duct.
By providing an adjustable negative pressure inducing means located downstream of the air flow measuring means it is possible to re~adjust the air flow through the apparatus each time the apparatus is connected to a different stator slot of the dynamoelectric machine. As a result, the measured data associated with each stator slot will be more ~5 relational because the negative pressure inducing means will have effectively reduced or compensated for the losses at the connection of the inlet means of the apparatus to the stator duct of the dynamoelectric machine.
It is further envisaged that the compensating means of the air flow measuring means may include air leakage measuring means for measuring pressure associated with air flow through the inlet means and measuring static pressure associated with the core of dynamoelectric machine In this embodiment the adjusta~le negative pressure inducing means may be ~ ~3 2 2 ~ a ~
Case 2992 adjusted to provide the air flow by setting pressure drop to zero when the air leakage measuring means registers a predetermined pressure differential in air flow through the inlet means and the core of the dynamoelectric machine.
In the preferred embodiment oE the present invention the air flow measuring means comprises an ASME nozzle means in fluid flow communication with the inlet means. In this emhodiment the air pressure measuring means measures the air pressure drop across the nozzle where the pressure drop is related to the air flow through at least one stator duct. In the preferred embodiment the air pressure measuring means includes a first pressure sensor connected upstream of the nozzle and a second pressure sensor connected downstream of the nozzle. In tha preferred embodiment the adjustable negative pressure inducing means includes a fan for inducing the predetermined air flow through the apparatus.
In accordance with another aspect of the present invention there is provided a method of sensing air flow through stator ducts of a dynamoelectric machine. The method comprises the steps of:
a) capturing air flowing through one of the stator ducts and channeling the air through first and second flow restricting areas, b) sensing a first air flow pressure through the first flow restricting area, sensing a second referencing pressure in another section of the dynamoelectric machine, and comparing the first and second prassures, c) applying and regulating an adjustable negative pressure air flow through the first and second flow restricting areas whereby the negative pressure air flow is regulated when the comparison of the first and second pressures indicates a predetermined pressure 13~2,!~7~ Case 2992 drop therebetween, and d) sensing the pressure values upstream and downstream of the second flow restricting area to determine the air flowing through the one stator duct.
BRIEF DESCRIPTION OF_THE DRAWING
For a better understanding of the nature and objects of the present invention reference may be had to the sole figure of the drawing which diagrammatically illustrates the air flow measuring ~0 device of the present invention connected to a stator slot of a dynamoelectric machine.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawing there is shown a stator 10 of a dynamoelectric machine having a plurality of stator ducts 12. The air flow measuring apparatus is shown generally at 14.
The apparatus 14 includes an inlet means 16 which is shown connected to one to of the stator ducts. I'he inlet means can bs connected by suitable clamps ~not shown) so that the inlet means substantially covers the stator slot. The inlet means 16 comprises a venturi type o~ nozzle. A first pressure tap 18 is shown attached to the venturi nozzle and a second pressure tap 20 is shown diagrammatically taken at the back of the core. The pressures monitored by these taps 18 and 20 are measured and compared by a manometer 22.
The apparatus 14 further includes suitable flexible hosing 24 for communicating air flowing through the inlet nozzle 16 to a cylindrical chamber 26. The chamber 26, which obviously forms part of the apparatus 14, includes a nozzle 28 which is an ASME type nozzle. Two pressure taps 30 and 32 respectively located upstream and downstream of the nozzle 28 are shown connecked to a second manometer 34.
Case 2992 -- 6 ~
The apparatus further includes a compensating means 36 located downstream of the chamber 26 and nozzle 28. The compensating means includes a flexible hose 38 and a negative pressure inducing means or fan 40 which together control the flow of air out of the chamber 26 through the hose 38.
To improve the relational accuracy of the measurements of the stator ducts 12 and to compensate for air leakage losses, the compensating means 36 is regulated to compensate for losses at the connection of the inlet venturi 16 to the stator slot 12 of the dynamoelectric machine 10. The fan speed is re~ulated under a normal dynamoelectric operating condition so that the pressure differential measured between taps 18 and 20 by manometer 22 is zero. By setting the fan speed to compensate ~or the air leakages at the inlet means of the apparatus the accuracy of the measuring apparatus has improved from having errors in the range of 20 to 30 percent to having errors of less than 5 percent.
In operation, the inlet means is connected to each stator slot and the air flow through the stator slot is measuxed as a ~unction of the pressure drop across the nozæle 28. The pressure drop across nozzle 28 is monitored by taps 30 and 32 and measured by manometer 34. These measurements can be taken for various operating conditions of the dynamoelectric machine so as to determine the air flow cha~acteristics through the stator ducts of the dynamoelectric machine.
Claims (8)
1. An apparatus for measuring air flow through stator ducts of a dynamoelectric machine, comprising:
air inlet means connectable to at least one of the stator ducts, air flow measuring means connected downstream of said inlet means for measuring the air flow from the at least one stator duct, and compensating means counteracting air flow losses between the at least one stator duct and inlet means comprising adjustable negative pressure inducing means, located downstream of the air flow measuring means, for inducing an air flow through the apparatus that counteracts air flow losses occurring where the inlet means is connected to the one stator duct.
air inlet means connectable to at least one of the stator ducts, air flow measuring means connected downstream of said inlet means for measuring the air flow from the at least one stator duct, and compensating means counteracting air flow losses between the at least one stator duct and inlet means comprising adjustable negative pressure inducing means, located downstream of the air flow measuring means, for inducing an air flow through the apparatus that counteracts air flow losses occurring where the inlet means is connected to the one stator duct.
2. The apparatus of claim 1 wherein the compensating means further includes air leakage measuring means for measuring pressure associated with air flow through the inlet means and for measuring static pressure associated with the core of the dynamoelectric machine, the adjustable negative pressure inducing means being adjusted to provide the predetermined air flow when the air leakage measuring means registers a predetermined pressure differential between the air flow pressure through the inlet means and the static pressure measured in the core of the dynamoelectric machine.
3. The apparatus of claim 1 wherein the air flow measuring means includes nozzle means in fluid flow communication with the inlet means, and the air pressure measuring means measuring the air pressure drop across the nozzle, the pressure drop being related to the air flow through at least one stator duct.
Case 2992
Case 2992
4. The apparatus of claim 3 wherein the air pressure measuring means includes a first pressure tap connected upstream of the nozzle and a second pressure tap connected downstream of the nozzle.
5. The apparatus of claim 1 wherein said air inlet means includes a venturi.
6. The apparatus of claim 1 wherein the adjustable negative pressure inducing means includes a fan for inducing the predetermined air flow through the apparatus.
7. The apparatus of claim 2 wherein the air leakage measuring means includes a first pressure tap sensing air flow pressure through the inlet means and a second air flow pressure tap connected to the core of the dynamoelectric machine for sensing static pressure, the air leakage measuring means further including an apparatus which compares the pressure sensed by the first and second pressure taps.
8. A method of sensing air flow through stator ducts of a dynamoelectric machine comprising the steps of:
a) capturing air flowing through one of the stator ducts and channeling the air through first and second flow restricting areas, c) sensing a first air flow pressure through the first flow restricting area, sensing a second referencing pressure in another section of the dynamoelectric machine, and comparing the first and second pressures, d) applying and regulating an adjustable negative pressure air flow through the first and second flow restricting areas whereby the negative pressure air flow is regulated when the comparison of the first and second pressures indicates a predetermined pressure drop therebetween, and e) sensing the pressure values upstream and - 9 - Case 2992 Claim 8 continued:
downstream of the second flow restricting area to determine the air flowing through the one stator duct.
a) capturing air flowing through one of the stator ducts and channeling the air through first and second flow restricting areas, c) sensing a first air flow pressure through the first flow restricting area, sensing a second referencing pressure in another section of the dynamoelectric machine, and comparing the first and second pressures, d) applying and regulating an adjustable negative pressure air flow through the first and second flow restricting areas whereby the negative pressure air flow is regulated when the comparison of the first and second pressures indicates a predetermined pressure drop therebetween, and e) sensing the pressure values upstream and - 9 - Case 2992 Claim 8 continued:
downstream of the second flow restricting area to determine the air flowing through the one stator duct.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000569664A CA1322471C (en) | 1988-06-16 | 1988-06-16 | Air flow measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000569664A CA1322471C (en) | 1988-06-16 | 1988-06-16 | Air flow measuring device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1322471C true CA1322471C (en) | 1993-09-28 |
Family
ID=4138219
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000569664A Expired - Fee Related CA1322471C (en) | 1988-06-16 | 1988-06-16 | Air flow measuring device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1322471C (en) |
-
1988
- 1988-06-16 CA CA000569664A patent/CA1322471C/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |