Gas turbine performance deterioration can be a major economic factor. An example is within offshore installations where a degradation of gas turbine performance can mean a reduction of oil and gas production. This paper describes the test results from a series of accelerated deterioration tests on a GE J85-13 jet engine. The axial compressor was deteriorated by spraying atomized droplets of saltwater into the engine intake. The paper also presents the overall engine performance deterioration as well as deteriorated stage characteristics. The results of laboratory analysis of the salt deposits are presented, providing insight into the increased surface roughness and the deposit thickness and distribution. The test data show good agreement with published stage characteristics and give valuable information regarding stage-by-stage performance deterioration.

Gas turbine performance deterioration can be a major economic factor. An example is within offshore installations where a degradation of gas turbine performance can mean a reduction of oil and gas production. This paper describes the test results from a series of accelerated deterioration tests on a General Electric J85-13 jet engine. The axial compressor was deteriorated by spraying atomized droplets of saltwater into the engine intake. The paper presents the overall engine performance deterioration as well as deteriorated stage characteristics. The results of laboratory analysis of the salt deposits are presented, providing insight into the increased surface roughness and the deposit thickness and distribution. The test data show good agreement with published stage characteristics and give valuable information regarding stage-by-stage performance deterioration.

Axial compressor deterioration due to removable deposits is a major concern in the operation of gas turbines. It is important to fully understand the flow mechanisms in order to successfully monitor and clean the engine. A test program on the GE J85-13 jet engine quantified the increased surface roughness and the distribution of salt deposits in an axial compressor. The test data showed good agreement with published data for stage performance deterioration. This paper compares the GE J85-13 test data on surface roughness to previously published work on surface roughness in compressors. The effect of surface roughness on the stage characteristics is modeled using theory for frictional losses, blockage and deviation. The results are compared to test data. The most significant effect of increased roughness is found to be the variation in the flow coefficient.

System integration testing in the defense and aerospace industry is becoming increasingly complex. The long lifetime of the system drives the need for sub‐system modifications throughout the system life cycle. The manufacturer must verify that these modifications do not negatively affect the system's behavior. Hence, an extensive test regime is required to ensure reliability and robustness of the system. System behaviors that emerge from the interaction of sub‐systems can be difficult to pre‐define and capture in a test setup using acceptance criteria. Typical challenges with current test practice include late detection of unwanted system behavior, high cost of repetitive manual processes, and risk of release delays because of late error detection. This paper reviews the state of practice at a case company in the defense and aerospace industry. We use an industry‐as‐laboratory approach to explore the situation in the company. The research identifies the challenges and attempts to quantify the potential gain from improving the current practice. We find that the current dependency on manual analysis generates resources ‐and scheduling constraints and communication issues that hinder efficient detection of system emergent behavior. We explore two approaches to automate anomaly detection of system behavior from test data. The first approach looks at anomaly detection in a top‐down approach to give an indication of the system integrity. The second approach uses anomaly detection on system parts, resulting in the ability to localize the root causes. The work lays the foundation for further research of automated anomaly detection in system testing.

This paper reports the results of a series of online water wash tests of a GE J85-13 jet engine at the test facilities of the Royal Norwegian Air Force. The engine performance was deteriorated by injecting atomized saltwater at the engine inlet. Then the engine was online washed with water injected at three different droplet sizes (25, 75 and 200 μm) and at water-to-air ratios ranging from 0.4% to 3% by mass. Engine performance was measured using standard on-engine instrumentation. Extra temperature and pressure sensors in the compressor section provided additional information of the propagation of deposits in the aft stages. The measurements were supported by visual observations. The overall engine performance improved rapidly with online wash. The build-up of deposits in the aft stages was influenced both by the droplet size and the water-to-air ratio. The water-to-air ratio was the most important parameter to achieve effective online washing.