Labyrinth Seal Flow Measurement by Tracer Gas Injection

Abstract

A practical system for flow measurement in rotating seals using the injection and sampling of a tracer gas is presented. Carbon dioxide or helium is injected as a tracer into a labyrinth seal at a controlled rate and gas samples are extracted downstream for concentration measurement. Test results from a rotating labyrinth seal rig were obtained over a range of seal pressure ratios and rotor speeds in order to determine the conditions which assure optimum tracer gas mixing. Seal leakage rates calculated by tracer gas concentration are compared to venturi flow measurements.

A study of high speed flows in an aircraft transition duct

“…McGreehan et al [37] employed the trace gas technique to measure the rate at which airflow leaked through a labyrinth seal in a gas turbine engine. Joslyn and Dring [38] performed an experiment in a large scale low speed turbine where trace gas concentration was used as an analogy to temperature to study the radial redistribution of temperature in the turbine.…”

“…n Ethylene was used for the trace gas in References 28-35. Other gases that have been used as a trace gas are helium [27,37,39,40], carbon dioxide [37,38], and natural gas [36]. The instruments used for trace gas detection were largely determined by the choice of trace gas.…”

“…The instruments used for trace gas detection were largely determined by the choice of trace gas. A flame ionization detector provides a very accurate measurement of ethylene concentration and was used in Researchers that use helium have frequently used a thermal conductivity cell for trace gas detection [27,37,39,40]. Carbon dioxide concentration was commonly measured with a nondispersive infmred detector [37,38].…”

“…The instrument used for is largely determined by the choice of trace gas. Re searchers that use helium frequently use a thermal conductivity cell [27,39,40,37].…”

“…Carbon dioxide concentration is commonly measured with an nondispersive infriu^ed detector [57,38,37]. A flame ionization detector provides a very accurate measure-ment of ethylene concentration and has been used extensively for trace gas studies [28-35, 43, 58, 42], and was used for this investigation.…”