Engine diagnostic practices are as old as the gas turbine itself. Monitoring and analysis methods have progressed in sophistication over the past 6 decades as the gas turbine evolved in form and complexity. While much of what will be presented here may equally apply to both stationary power plants and aero-engines, the emphasis will be on aero propulsion.Beginning with primarily empirical methods centering around monitoring the mechanical integrity of the machine, the evolution of engine diagnostics has benefited from advances in sensing, electronic monitoring devices, increased fidelity in engine modeling and analytical methods. The primary motivation in this development is, not surprisingly, cost. The ever increasing cost of fuel, engine prices, spare parts, maintenance and overhaul, all contribute to the cost of an engine over its entire life cycle. Diagnostics can be viewed as a means to mitigate risk in decisions that impact operational integrity. This can have a profound impact on safety, such as In-Flight Shut Downs (IFSD) for aero applications, (outages for land based applications) and economic impact caused by Unscheduled Engine Removals (UERs), part life, maintenance and overhaul and the overall logistics of maintaining an aircraft fleet or power generation plants.This paper will review some of the methods used in the preceding decades to address these issues, their evolution to current practices and some future trends. While several different monitoring and diagnostic systems will be addressed, the emphasis in this paper will be centered on those dealing with the aero-thermodynamic performance of the engine.© 2013 ASME

Gas Turbine Engine Health Management: Past, Present and Future Trends

A high throughput inductive pulse sensor for online oil debris monitoring

Microfluidic particle counters are important tools in biomedical diagnostic applications such as flow cytometry analysis. Major methods of counting particles in microfluidic devices are reviewed in this paper. The microfluidic resistive pulse sensor advances in sensitivity over the traditional Coulter counter by improving signal amplification and noise reduction techniques. Nanopore-based methods are used for single DNA molecule analysis and the capacitance counter is useful in liquids of low electrical conductivity and in sensing the changes of cell contents. Light-scattering and light-blocking counters are better for detecting larger particles or concentrated particles. Methods of using fluorescence detection have the capability for differentiating particles of similar sizes but different types that are labeled with different fluorescent dyes. The micro particle image velocimetry method has also been used for detecting and analyzing particles in a flow field. The general limitation of microfluidic particle counters is the low throughput which needs to be improved in the future. The integration of two or more existing microfluidic particle counting techniques is required for many practical on-chip applications.

/pdf/methods-for-counting-particles-in-microfluidic-applications-21xvd9k9wl.pdf

Methods for counting particles in microfluidic applications

A rolling bearing is an essential component of a rotating mechanical transmission system Its performance and quality directly affects the life and reliability of machinery Bearings’ performance and reliability need high requirements because of a more complex and poor working conditions of bearings A bearing with high reliability reduces equipment operation accidents and equipment maintenance costs and achieves condition-based maintenance First in this paper, the development of technology of the main individual physical condition monitoring and fault diagnosis of rolling bearings are introduced, then the fault diagnosis technology of multi-sensors information fusion is introduced, and finally, the advantages, disadvantages, and trends developed in the future of the detection main individual physics technology and multi-sensors information fusion technology are summarized This paper is expected to provide the necessary basis for the follow-up study of the fault diagnosis of rolling bearings and a foundational knowledge for researchers about rolling bearings

/pdf/development-and-trend-of-condition-monitoring-and-fault-sbh0e2r1gs.pdf

Development and trend of condition monitoring and fault diagnosis of multi-sensors information fusion for rolling bearings: a review

In this paper, prognostic tools are developed to detect the onset of electrical failures in an aircraft power generator, and to predict the generator's remaining useful life (RUL). Focus is on the rotor circuit since failure mode, effects, and criticality analysis (FMECA) studies indicate that it is a high priority candidate for condition monitoring. A signature feature is developed and tested by seeded fault experiments to verify that the initial stages of rotor faults are observable under diverse generator load conditions. A tracking filter is used to assess the damage state and predict generator RUL. This information helps to avoid unexpected failures while reducing the overall life-cycle cost of the system.

Prognostic Health Management of Aircraft Power Generators

The development of an in-line, full flow oil debris sensor for aircraft engine condition assessment is described. First used on the F22 fighter, this sensor is the only "all-metals" debris detector in production. The sensor is based on an inductive measurement technique which enables the system to detect, count and classify wear metal particles by size and type (ferromagnetic and nonferromagnetic) above a minimum particle size threshold. In flight, the measured count values are compared to preset levels to provide prognostic health information on the oil-wetted components of the engine. This paper describes the sensor design requirements, principle of operation, electronic design and mechanical design features. The results of a test program established to correlate the oil borne debris measurements to component degradation characteristics and data from actual engine bearing failures, are also presented.

D. Kitaljevich

Papers

In-line oil debris monitor for aircraft engine condition assessment