Indicators of Incipient Surge for Three Turbofan Engines Using Standard Equipment and Instrumentation

Abstract

Engine controller data have been interrogated for indications of incipient surge for three turbofan engines; a large Pratt and Whitney, a large General Electric, and a small Williams International. Versions of these engines are currently operating in the field and all have compression ratios of 18 or greater. The Pratt and Whitney engine was surged only at full power while the other two were surged at partial power and at full power. The interest in this work was in detecting the presence of warning signatures for a current inventory of engines. A constraint was imposed on the experiments to use only existing engine instrumentation. The frequency response of the controller and the engine instrumentation limited the high frequency detection capability to about 100 Hz for the large engines and about 200 Hz for the small engine, For the large engines, it was not possible to detect a surge warning but for the small engine a sufficient warning of incipient surge was detected.

Operation of Gas Turbine Engines in an Environment Contaminated With Volcanic Ash

“…The precursors of engine surge for all three of these engines is described in more detail in Ref. [30]. The YF112 compression system sustained erosion damage during dust exposure and during the subsequent surge events.…”

“…For a discussion of incipient surge, the reader is referred to Ref. [30], which provides significantly more detail related to the F100, YF101, and F112 engines.…”

Design and validation of an experiment for the detection and prediction of stall and surge in a PT6/T400 turboshaft engine

“…1) Detecting and counteracting stall cells as they form using fast response pressure transducers and air injection (e.g., Day 1993 2) Determining if it is possible to detect a consistent aerodynamic change in the engine (a precursor) early enough to take a corrective action (e.g., Baran and Dunn 1996) 3) Detecting deterioration of engine health that will cause loss of surge margin, such as blade damage (Dhingra et al 2003) 4) Using models to understand the response of an engine to destabilising conditions (e.g., Mazzawy 1977, Chue et al 1989, Colding-Jorgensen 1992 A health-monitoring technology of the type described in items two and three seemed more feasible for short-term implementation in aircraft engines, and fit well with the scope of the project to create a detection experiment.…”

“…there have been a limited number of studies on gas turbine engines (some good examples include Baran and Dunn 1996, Le et al1996, Freeman et al1998and Spakovsky et al 2000 Nelson et al (2000), and the large axi-centrifugal engine (12 kg/s airflow) tested by their group (1996 and. Most of the signal analysis by Owen and Le focused on the first axial stage of the engine, but Nelson and others that have studied centrifugal compressor rigs specifically (e.g., Chen et al 1994), have found that the stall inception behaviour of the centrifugal stage should be comparable.…”

“…This option is not easily available on the PT6, because the high-pressure turbine vanes provide the "throttle" behaviour, and they cannot be directly modified during testing. Baran and Dunn (1996) raised the operating line by exposing an engine to a dust-laden environment and completing a rapid acceleration and deceleration followed by a second acceleration. It was found that the dust clogged the turbine, which reduced the mass flow to the point that the repeated accelerations would push the compressor above the stall line.…”