From: dudleydevices@aol.com
Sent: Monday, January 04, 2021 2:35 PM
To: dudleydevices@aol.com
Cc: dudleydevices@aol.com
Subject: Conversation with Peter Rodrigue about Hatch Inc Index Test
Comparison to ATECo Index Test Box results
This is validation of the ITB analysis for Dorena Dam’s Kaplan turbine at 102 feet head in the form of a conversation with Peter Rodrigue at Hatch about comparing their conventional, manual index test results to the ITB PostProcessing index test analysis. The project plan was to index test the turbine 4 times at 4 different water levels with heads spread out across the entire operating envelope. It took over 2-years to get the full spread. The financiers that owned the dam were selling it to another financier company and needed index tested prior to sale.
We were representing the owners, and Hatch Inc was representing the buyers. The water didn’t get high enough the first year so we had to wait another year to get a water level high enough for the index test. The sale went through while we waited for the water level to get high-enough the next year.
When the 4th test was getting near, I had been in contact with Hydro-Tech, Northbrook Power Management about the upcoming index test. All said I would get the data for the 4th test. I watched the water-level on Dorena Lake get up to 102 feet (level for the index test) but nobody called. A few pestering phone calls later I learned that Hatch had already run the index test and we need not bother about it anymore.
I protested to the financier that this was the 4th of 4 tests, all of which were intended to be combined to get a complete new 3-D Cam surface for the machine. Hatch did not reduce the data to a new smooth-curve best cam line so their data was incompatible with the other 3 index tests. This made all of the index testing we had done a waste and the Kaplan turbine 3-D Cam still needed to be tuned-up.
A call to the dam to verify the powerplant data logger had been running, and if so, could I have the data. The data was received and analysis normally just like the other 3 tests, completing the new cam profile. Next a copy of Hatch’s test report and data reduction spreadsheet were requested and received. The spreadsheet was dissected to get precisely the calculations in every cell to compare with the calculations in the ITB. When all of the discrepancies in the computations were resolved, the two answers agreed to the last digit.
A remaining issue is that Hatch’s results were 0.4% higher than the ITB after “splitting hairs” in both data sets. The question was, “Why?” In the final analysis Peter surmises it was just a typo.
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From: Rodrigue, Peter <peter.rodrigue@hatch.com>
Sent: Wednesday, January 03, 2018 9:37 AM
To: DudleyDevices@aol.com
Subject: RE: Dorena Index Test
Happy New Year Doug
In analyzing the test results we used IEC 60041 and ASME PTC-18 as a guide. Both standards now define turbine net head and turbine efficiency the same.
The energy level at the end of the draft tube should be as you have indicated with the illustration from the IEC standard. The problem we had was that tailwater level was measured a distance downstream of the draft tube exit, not right at the exit. There is likely some conversion of velocity head to pressure head between the end of the draft tube and the location of tailwater measurement. If you just simply determined the energy level by adding velocity head to the measured tailwater level the result would be:
- an overestimate of head loss (i.e. an underestimate of turbine net head) if velocity head is calculated from the area of the draft tube exit.
- an underestimate of head loss (i.e. an overestimate of turbine net head) if velocity head is calculated from the area of the flume at the location of tailwater level gage.
Therefore, we used a coefficient of 0.6 applied to the sum of the two velocity heads. The coefficient was based on textbook type hydraulics. Admittedly the coefficient is subject to judgement and could be considered “splitting hairs” a bit, as the effect on turbine net head and efficiency is small.
Regards
Peter Rodrigue
From: DudleyDevices@aol.com
[mailto:DudleyDevices@aol.com]
Sent: Tuesday, January 02, 2018 11:33 AM
To: Rodrigue, Peter <peter.rodrigue@hatch.com>
Subject: Re: Dorena Index Test
Hello Peter,
Happy New Year.
Things are looking better here.
I've got another question, please?
The string of conversions and calculations in the spreadsheet were worked through to sort out how the answers were derived, now the objective is to see where they fit into the industry accepted methods. The report does not state which industry standards (IEC, ASME, IEEE CSA etc) were relied on - or am I missing it? The question is about how the draft tube is modeled in the spreadsheet calculations. A copy of the original spreadsheet (unchanged from as-received) is attached for reference.
My purpose is to clarify this for ITB sales pitches and publication of the Dorena test results to show how the ITB functions. A preliminary demonstration of compliance with IEC or ASME recommended practices will lend credibility to the explanations and provide a clear understanding of where the numbers are coming from for the reader. The objective is to show how the math and modeling work; tying them to accepted industry practices and standards will make it an easy-read for non-technical folks. They'll get the same warm, fuzzy feeling from compliance with accepted industry standards that my wife gets from the "Good Housekeeping seal of approval."
It is unclear where the 0.6 coefficient used on the open-flume energy calculation to get the final efficiency value come from. Does it ever change to a different value?
Here’s where the math happens; open the "Index Test Data" page of the attached spreadsheet.
The question is: How does NetHead in cell V17 on the "Index Test Data" page get computed?
V17 = O17+Q17-R17-U17.
Where:
O17 is the pressure transducer elevation above sea-level plus the pressure it's measuring in meters of water column.
Q17 is the kinetic energy, or velocity head also in meters of water.
R17 is tailwater level above sea level in meters.
and U17 accounts for the kinetic energy in the water flowing through the unit.
U17 contains the sum of the velocity heads at the draft-tube exit plus 60% of the open-flume velocity head in the tailrace. This is where the system modeling becomes unclear.
Velocity Head = U17 = (S17^2) / (2*M$10) + (T17^2)/(2*M$10) * M$17.
= VHead in DraftTube +Vhead in open flume*0.6 Coefficient.
Which then becomes a factor in V17 where Net Head is computed.
The first time I tried to introduce the ITB into the market for Woodward, the peer-review process demanded that I show my work at every stage of the analysis. I'm anticipatingthe same degree of rigor this time.
This
is the modeling in the IEC manual:
The constructs use in IEC's model are emulated by the ITB model as much as possible without infringing on anyone's copyright to make the data display page.
This page is the computation page programmed to show the method used in your spreadsheet.
During operation the ITB program recomputes and fills this page every few seconds for an on-the-spot and timely indication of how well the machine is running.
The data plugged into the form as inputs for this image are the highest-power point in the index test data set.
Cheers,
Doug Albright
Actuation Test Equipment
In a message dated 11/13/2017 10:27:36 P.M. Central Standard Time, peter.rodrigue@hatch.com writes:
Doug, I do not know where the 92.4% comes from. Looking at the spreadsheet the number should be 92% as you have noted. When analyzing the data we were adjusting some of the numbers for generator efficiency (to allow for testing at unity power factor) and also modifying the draft tube exit loss slightly. Perhaps it is an earlier number that didn’t get updated, or is simply a typo.
Regards
Peter Rodrigue
From: DudleyDevices@aol.com [mailto:DudleyDevices@aol.com]
Sent: Monday, November 13, 2017 3:54 PM
To: Rodrigue, Peter <peter.rodrigue@hatch.com>
Cc: dudleydevices@aol.com
Subject: Re: Dorena Index Test
Hi Peter,
I'm still working through the details. I can follow the math in the spreadsheet cells OK, but here's a spot where I'm stumped. The report says in paragraph 6.2 on Index Testing that efficiency is 92.4% at max power with a reference to the turbine efficiency vs MW chart stashed in Appendix B at the back of the report.
It's difficult to split hairs on this picture of the graph to see 0.4% but it was easy to find the same chart in the spreadsheet where some graph manipulation tools are available. When the cursor is hovered over the highest power point, the efficiency in the popup flag is 92.0%, not 92.4%.
To make it handier to see what's happening the chart was moved from its own sheet to being an insert into the index test data sheet so that the column's highlights when the data series line on the graph is clicked on, and when the cursor is hovered over the highest power point a popup flag shows the exact values for the point to correlate with the data in the highlighted column. Increasing the resolution by adding digits to the right of the decimal point shows that the efficiency value is actually slightly less than 92% and was properly rounded up to 92.0. How did it get up to 92.4% as reported in the text of paragraph 6.2?
*
Background
My background is analog and digital electronic circuitry design and manufacturing and writing test automation software. I'm not a turbine guy - I'm a sparky and software guy...
The Index Test Box project was a temporary assignment in 1984 when I was working at Woodward Governor.
My normal job there was writing automation software for testing aircraft fuel system components. At that time I was writing software for mapping the dual 3-D Cams in gas turbine engine fuel controls. The fuel controls were operated in a simulated test environment on a motorized test stand supplied with 600 psi air and 1,600 psi jet fuel to simulate operating conditions on a jet engine. Fuel temperatures were cycles from -65 Deg F for a few hours up to 250 Deg-F for a few days and then run at room temperature for a week or more.
A special destructive test like this is run only once on a new fuel control design by adding dirt and salt water getting dribbled into the fuel stream to simulate the contaminants the fuel control will likely be exposed to in what is called a "dirt test." Actually it's a test of the $1 fuel filter on the engine that uses a $250,000 fuel control as the measuring stick. If the $1/4-million fuel control survives the $1 filter is approved.
The 1-year ITB project in 1984 was supposed to repackage the 3-D Cam mapping program into a test accessory for a Kaplan turbine governor and 3-D Cam under the tutelage of George Mittendorf. George was a leading engineer at Newport News, having worked on the design team for the Grand Coulee Dam runners.
.Objective
The ITB is first a diagnostic tool for viewing, recording and analyzing the behavior of Kaplan turbine gates and blades, along with the water levels, pressures, flow and power to evaluate accuracy and robustness of the control system.
Secondly, the ITB is a relative efficiency Kaplan turbine optimizer an accessory to a modern digital Kaplan governor and blade control system. Working in conjunction with a SCADA system and datalogger that provide the necessary front-end instrumentation, signal conditioning and subsequent data storage utility, the ITB will collect, analyze and display governor diagnostic information and turbine efficiency performance data.
This current ITB is intended for relative testing only, but for a better handle on the unit's behavior utilizes the same mathematical modeling tools of absolute value testing - but without the fuss and bother of maintaining NIST traceability and ASME, IEEE or IEC code compliance. The primary goal is simply 3-D Cam optimization by the least laborious and costly methods possible. By breaking the legwork at the facility down to tasks simple enough to be routine assignments for the personnel normally there, the minimal cost is enhanced by the increased knowledge gained by the personnel about turbine optimization.
I'm going to be making some big claims so a rigorous peer review is anticipated for my article,
this conversation has been very helpful towards that end.
Thanks again.
Doug Albright
In a message dated 11/11/2017 7:31:11 P.M. Central Standard Time, peter.rodrigue@hatch.com writes:
Doug, I have looked over the data and agree that if you use the data from the ITB display there is an offset error of about 5.5 ft in the net head, and if a correction is made to the test results the efficiency will be reduced. However, I am uncertain where the net head value on the ITB display comes from.
Our analysis calculated net head from the pressure transducer at the turbine minus TWL with correction for velocity head and the two measuring locations. The elevation of the pressure transducer was 223.78 m or 734.19 ft. Looking at the static check (zero flow data) Cells C7, D7 and E7 on the Index Test data sheet on our spreadsheet, the numbers are:
- HWL = 831.96
- TWL = 728.98
- Turbine pressure = 42.4 psi
Turbine pressure translates to 734.19 + 42.4/0.433 = 832.11. This is only 0.15 ft different from the HWL value.
Also
- Gross head = 831.96 – 728.98 = 102.98, which is consistent with the raw data “screenshot” that you added to the spreadsheet
- Net head = 832.11 – 728.98 = 103.13, which is different from the “screenshot”.
You can also look at the 1st on-cam test and 23% flow (Row 12 of the spreadsheet). At this point the flow is low and therefore the head. loss, while not zero, is quite low. The gross head is 831.96 – 729.39 = 102.57 ft (cell e12 – cell f12). The net head (ignoring velocity head correction, which is very low at low flow) is 31.2007 m (cell V12) = 31.2007/.3048 = 102.36 ft. This is quite close to the gross head. If we added a 5.5 ft correction to net head it would be higher than gross head.
If you used the ITB net head value and made a 5.5 ft offset correction you should, in theory, calculate similar efficiency values as calculated on our spreadsheet. However, this will not happen, particularly at the higher flows, because of a discrepancy in head losses. Looking at the charts in the file you sent me on demonstration of offset error, it appears that the head loss at maximum flow (810 cfs) is just under 3 ft. However if you calculate head loss for Row 17 on our spreadsheet, it comes out to 6.85 ft. I unsure of the reason. We had no information on the slope calibration of the pressure transducer we used for the inlet pressure readings. Also there could be an issue with the net head reading from the ITB.
Regards
Peter Rodrigue
From: DudleyDevices@aol.com [mailto:DudleyDevices@aol.com]
Sent: Friday, November 03, 2017 3:52 PM
To: Rodrigue, Peter <peter.rodrigue@hatch.com>
Subject: Dorena Index Test
Hi Peter,
Here is the information on the Dorena Test.
This first file is my analysis of the effect of increasing flow on losses that are the difference between grosshead and nethead. At zero flow, they should be equal, but for this test there was a 5.8 foot difference which works out to a 5.5% unit efficiency difference in the calculations.
Comparison of GrossHead to Nethead
Here is the final report from your guys:
Hatch Dorena Kaplan Index Test Report.pdf
Here is the data spreadsheet for your guy's test:
There are some differences between my and your guys' analises that I'd like to speak with you about.
Please give me a call.
Cheers,
Doug Albright
Actuation Test Equipment Company
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