Ice crystal accretion test rig development for a compressor transition duct

Ingestion of ice crystals into aircraft gas turbine engines have been shown to trigger partial or complete power loss. Although the ice crystal phenomenon has been recognized since the early 1950's, it was not until the mid-1990's that significant attention had been given to it with a key event being a flight campaign conducted with a small commuter aircraft which demonstrated ice crystals to be responsible for engine power loss. Although flight and engine testing have revealed ice crystals to be detrimental to gas turbine engine operation, these are not ideal test platforms to observe the ice crystal phenomenon due to limited access for instrumentation and visual observations. This paper discusses the development of an ice crystal test system used to simulate the ice crystal environment seen in a gas turbine compressor while maintaining visual accessibility and ease of instrumentation. This test system consists of a method to produce a range of ice crystal environments, the ability to vary airflow conditions in the rig and a static test section which simulates a gas turbine compressor transition duct. This system has been successful in producing a wide range of ice crystal test conditions and has shown significant ice accretion can occur on surfaces above 0\ub0C while allowing for visual observations and recording of temperature data during the accretion phenomenon. \ua9 2010 by Her Majesty the Queen in Right of Canada.Peer reviewed: YesNRC publication: Ye

Understanding ice crystal accretion and shedding phenomenon in jet engines using a rig test

The aviation industry has now connected a number of engine power-loss events to the ingestion of atmospheric ice crystals. Ice crystals are believed to penetrate to and eventually accrete on surfaces in the engine core where local air temperatures are warmer than freezing. Research aimed at understanding the accretion and shedding of ice crystals within the engine is being conducted industrywide. Although this specific icing condition is readily produced inside an operating engine, rig testing is the preferred research tool because it has the advantage of good visibility of the ice accretion process and easy access for video documentation. This paper presents one of the first efforts to simulate the warm air/cold ice conditions occurring inside the engine core using a test rig. The test section contains geometry simulating the transition duct between the low and high compressors in a typical jet engine and an airfoil simulating the engine strut connecting the inner and outer surfaces. Test results showed ice formed on the airfoil and other surfaces in the test section at air temperatures warmer than freezing. However, when both the air and surface temperatures were held below freezing, the injected ice did not melt and no ice accretion was observed. Ice only formed on the airfoil when mixed-phase conditions (liquid and ice) were produced, by introducing the ice into a warm airflow. This test concludes that a rig-level ice crystal icing test is feasible and capable of producing ice accretion in a simulated engine environment. As it was the first test of its kind, reporting of these preliminary test results are expected to benefit future experimenters. Copyright \ua9 2011 by ASME.Peer reviewed: YesNRC publication: Ye