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Handbook of Turbomachinery Second Edition Revised - Ventech!

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TEST PROCEDURES AND DATA COLLECTION<br />

While preparing for a test program there are several recommended pretest<br />

activities that should be accomplished to help ensure a successful test<br />

program. Many times testing has been accomplished only to find out after<br />

the fact that critical instrumentation was not functioning or data were not<br />

recorded properly. Troubleshooting instrumentation and measurement<br />

problems and errors during the test can impact cost and schedules. The<br />

following, which is by no means comprehensive, includes several recommended<br />

activities that should be performed to minimize measurement<br />

problems during the test activity.<br />

Pretest<br />

Prior to test rig installation into the test cell, a careful inspection <strong>of</strong> the<br />

hardware should be made. During the inspection, the following types <strong>of</strong><br />

questions should be addressed: Are the flow ducts properly aligned to avoid<br />

steps in the flow path? Are the flow-path ducts free from oil and debris? Are<br />

the measurement sensors facing into the flow direction? Are the sensors free<br />

from machining burrs, dirt, and grime? Have protective caps been removed<br />

from the sensors? Are the lines running from the individual sensors labeled<br />

properly so that they will be hooked up to the correct data channels? Do<br />

survey actuators fit and traverse without obstructions? Are sensors that are<br />

located over the rotor blade row flush-mounted so that they will not get<br />

clipped by the rotor blade during testing? Has each <strong>of</strong> the instrumentation<br />

sensors been flow checked to ensure that calibration tolerances are satisfied?<br />

Daily Before Testing<br />

Simple checkout procedures before each day’s testing can also minimize<br />

instrumentation problems. Before testing starts, it is recommended that the<br />

test rig be leak checked. This can be done by sealing and pressurizing the test<br />

rig slightly above ambient. Once the test rig is pressurized, several data scans<br />

can be recorded. Pressure data channels with readings less than rig pressure<br />

indicate that a leak may be present. Sources <strong>of</strong> leaks can include poor<br />

connections and broken lines.<br />

A second recommended check is a ‘‘zero-data scan’’ to record ambient<br />

temperatures and pressures <strong>of</strong> all measurements prior to the start <strong>of</strong> testing.<br />

This is one <strong>of</strong> the best instrumentation diagnostics that can be performed.<br />

During the data scan all readings should indicate ambient conditions. When<br />

individual sensors do not read ambient values, it is a good indication that<br />

there is a potential problem with that sensor and/or data channel.<br />

Copyright © 2003 Marcel Dekker, Inc.

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