Turbulence

The graph to right is a plot of all the reading taken by the data acquisition system (Raw Readings/Data) plotted against the Reported Data after smoothing algorithm has done its job.

This is actual data taken during the preliminary testing at the initial installation on a Venturi type column without flow straighteners.

Sample Graph - Actual points

To the right is the graph of a 22kW fan (760mm dia, 525V).

These are the stored points with the 5 which appear on the report ticked.

In this case 19 points were stored.

The test was done on a Conical Inlet test column.

Sample Graph - Curve fit from table

The same test as above, except that it is based on the 5 points which appear on the test report.

This is the method that has been used all along and, possibly, the more acceptable presentation.

Comparative Test

We were to explain variations of a fan tested on the original installation (ABC on graph) compared to another repairers test (XYZ) of the same fan.

As the reports and graphs were presented different, the tabled readings were plotted on one sheet.

What immediately stood out is that XYZ did not adjust the absorbed power for the air density.  The second point of note is the stray peak pressure (above the peak of the curve fit) - a typical problem with turbulance and manual readings.