Gas Turbine Engine Flow-Field Diagnostics: Needs, Capabilities, and Proposed Development

Abstract

Over the past two decades, the interest in improved gas turbine engine performance and environmental emissions has illustrated the need for more robust flow-field diagnostics. Traditional diagnostic techniques, which include primarily exit plane flow-field probes and nonintrusive optical systems, have demonstrated limitations where high-temporal resolution is desired or optical access is limited. Recent efforts at the Arnold Engineering Development Center (AEDC), Arnold Air Force Base, Tennessee, have focused on measurement techniques for use in the high-temperature combustion streams typically encountered in gas turbine engine combustors and in the exit plane of augmentor nozzles. Building on previous development of exit plane flow-field probes, AEDC personnel currently are evaluating advanced probe fabrication techniques and instrumentation. Concurrent AEDC efforts in nonintrusive optical techniques have included the development of compact, fiber-coupled laser diode absorption systems for measurement of species number densities and inferred static temperature of various chemical components in AEDC test facility and combustion flows. A number of optical techniques are under consideration for embedding within flowfield probes to improve probe measurement temporal resolution, among other benefits. These and other advanced flow-field diagnostics are discussed in this paper.