A. Heltzel, PC Krause and Associates, Inc. Three-dimensional conjugate heat transfer models are built to predict the steady-state performance of microscale pin-fin and cross-flow heat exchangers with hydraulic diameters on the order of 100 μm. Modeling, meshing, and segmentation techniques are presented to allow for macroscale simulation of the microstructured devices. The effect of variation in geometric and flow parameters is investigated. Hydraulic and thermal predictions are compared to published experimental and extended beyond the limited range of test data to provide performance within a wide parametric range. A discussion of the dominating and relevant thermal transport mechanisms in both fluids and solid clarifies the routes to optimizing heat transfer in these small scale heat exchangers. Journal of Aerospace, in press...
Read MoreTools for Health Management of Aircraft Power Systems
T. Baudendistel, PC Krause and Associates, Inc; Steve Pekarek, Mario Rotea, Purdue University;E. A. Walters, Steve Peecher, Hao Huang, Smiths Aerospace; Sean A. Field, Nathan E. Kumbar, H. Huang, Naval Air Systems Command In this presentation, a pair of recently developed hardware and software tools for the prognostics and health-monitoring of electric generators, motors, power electronic components, and electric power systems will be presented. The first tool is a vibration sensor that is low cost, durable. This sensor has been used to detect torque-ripple-induced vibration created by electric machines. It provides a convenient means to detect faults of both electrical and mechanical components of electric drive systems and also facilitates feedback-based control to mitigate the vibration source through control of the excitation to a machine. The second tool is a thermal-observer based health monitor. This tool effectively predicts the thermal behavior of stator, rotor, and winding structures based upon input from a minimal number of thermocouples and stator current sensors. It is shown that through coupling of these two tools, a comprehensive prognostic and health management system (PHM) for aircraft generators and associated electrical systems can be developed. Using this multi-physics approach it is possible to effectively detect component degradation and aid in prediction of time-to-failure as well as provide information to feedback-based strategies for operation of generator electrical systems under component degradation or failure. This will improve the warfighting capabilities by extending the life of the generator electrical system. 2nd Annual Propulsion-Safety and Affordable Readiness Conference, March 2007, San Diego, CA. Contact information:...
Read MoreAdvanced Tools for Aircraft Power and Propulsion Simulation and Analysis
T. Baudendistel, M. Corbett, E. A. Walters, K. Miller, J. Williams, J. Wells, S. Pekarek, M. Rotea, S. Field, , S. Peecher, N. Kumbar, M. Wolff, J. Dalton, P. Lamm It will be shown that through coupling a set of multi-physics tools in a sensor suite, a comprehensive prognostics and health management system (PHM) for aircraft generators and associated electrical systems can be developed. Specifically, using DHS, component and system-level simulations, using Hardware-In-The-Loop (HIL), of aircraft generator systems under nominal and failure modes can be performed efficiently. Using the simulation results obtained, the vibration sensor, unique monitoring concepts and advanced signal conditioning are coupled to establish an approach that can effectively detect component degradation and predict time-to-failure, and to develop feedback-based strategies for operation of generator electrical systems under component degradation or failure. In addition, as aircraft power demands continue to increase with the increase in electrical subsystems. These subsystems directly affect the behavior of the power and propulsion systems and can no longer be neglected in system analyses. The performance of the whole aircraft must also be considered with the combined interactions between the power and propulsion systems. The larger loading demands placed on the power and propulsion subsystems result in thrust, speed, and altitude transients that affect the whole aircraft. This results in different operating parameters for the engine. The complex models designed to integrate new capabilities have a high computational cost. This paper investigates the possibility of using a hardware-in-the-loop (HIL) analysis with real time integration of the aircraft/propulsion system. Using this method, a significant reduction in computational runtime is observed, and the airframe/turbine engine model is usable in a HIL environment. This also allows for a more complete analysis of the interactions between engine loading and aircraft performance by including some real hardware components. The dynamic interactions between aircraft subsystems highlight the need for system-level modeling using a combination of high-fidelity computer models and hardware in a real-time environment. Hence, maintaining the war fighting capabilities by extending the life of the aircraft electrical systems. IAPG Mechanical Workgroup, May 2007, Alexandria, VA. Contact information:...
Read MoreUsing Hardware-in-the-Loop for Aircraft Prognostic Health Management
Michael W. Corbett, Peter T. Lamm, U.S. Air Force Research Laboratory; T. Baudendistel, J. Mitch Wolff, E. A. Walters, PC Krause and Associates, Inc. Aircraft power demands continue to increase with the increase in electrical subsystems. These subsystems directly affect the behavior of the power and propulsion subsystems and this interdependency can no longer be neglected in system analyses and prognostic health management (PHM) schemes. The performance of the whole aircraft must be considered with the combined interactions between the power, propulsion, and aeronautical subsystems. The larger loading demands placed on the power and propulsion subsystems result in thrust, speed, and altitude transients that affect the whole aircraft and result in different operating parameters. The complex models designed to integrate new capabilities have a high computational cost. This paper investigates the possibility of using a hardware-in-the-loop (HIL) analysis with real time integration of the aircraft/propulsion system and its possible application to PHM schemes. Using this method, a significant reduction in computational runtime is observed, and the airframe/turbine engine model is usable in an observer based PHM system. This would allow for a more complete analysis of the interactions between engine loading and aircraft performance by passing some real hardware component data to a real-time health observer. The possible implementation of a real-time, observer based PHM system is also discussed. 2007 ISHM Conference, August 2007. Contact information:...
Read MoreTools for Prognostics and Health-Monitoring of Aircraft Power Systems
T. Baudendistel, PC Krause and Associates, Inc; Steve Pekarek, Mario Rotea, Purdue University; E. A. Walters, PC Krause and Associates, Inc; Steve Peecher, Smiths Aerospace; Sean A. Field, Nathan E. Kumbar, Naval Air Systems Command In this presentation, a cadre of recently developed hardware and software tools for the prognostics and health-monitoring of electric generators, motors, power electronic components, and electric power systems will be presented. One of the tools is a vibration sensor that is low cost, durable, and relatively straightforward to implement in a drive system or power electronic module. This sensor has been used to detect torque-ripple-induced vibration created by electric machines. It provides a convenient means to detect faults of both electrical and mechanical components of electric drive systems and also facilitates feedback-based control to mitigate the vibration source through control of the excitation to a machine. In addition to providing vibration feedback, it has also been shown to be effective as a back-up position sensor. Specifically, in applications where fault tolerance is critical, the sensor has been used to determine the position of the rotor of the machine when in-line or Hall-effect sensors fail. A second tool is a thermal-based health monitor for electric machines that effectively predicts the thermal behavior of stator, rotor, and winding structures based upon input from a minimal number of thermocouples and stator current sensors. This observer has been tested on a 3.7 kW generator and is presently being used to evaluate the short- and long-term effects of pulsed loading of electric machines. A third tool is a method of Distributed Heterogeneous Simulation (DHS) that provides a means to simulate the healthy and faulted behavior of large-scale systems at a speed and level of detail heretofore unachievable. Specifically, DHS enables the synchronized interconnection of any number of dynamic subsystem simulations, developed using any combination of a variety of programs/languages, and implemented on a single computer/workstation/supercomputer, a local area network (Intranet), a distributed, and any combination thereof. Theoretically, using an M-computer network, DHS can approach an 3M gain in computational speed over single computer, single numerical algorithm implementation. It is shown that through coupling of these three tools, a comprehensive prognostic and health management system (PHM) for aircraft generators and associated electrical systems can be developed. Specifically, using DHS, component and system-level simulations of aircraft generator systems under nominal and failure modes can be performed efficiently. Using the simulation results obtained, the vibration sensor and thermal-condition monitor concepts are coupled to establish a multi-physics approach that can effectively detect component degradation and predict time-to-failure, and to develop feedback-based strategies for operation of generator electrical systems under component degradation or failure. Hence, maintaining the warfighting capabilities by extending the life of the generator electrical system. 2007 ISHM Conference, August 2007. Contact information:...
Read MoreNoninvasive Approach to Health Management of Aircraft Power Systems Using Torque Ripple
T. Baudendistel, PC Krause and Associates, inc; S. Pekarek, Purdue University; Steve Peecher, GE Aerospace; Sean Field, Nathan Kumbar, Naval Air Systems Command; E. A. Walters, PC Krause and Associates, inc. In this presentation, a recently developed hardware and software tool for the health management of electric generators, motors, power electronic components, and electric power systems will be presented. This tool enables higher fidelity health management prognostics. The hardware component of this tool is a vibration sensor that is low cost, durable, and relatively straightforward to implement in a drive system or power electronic module. The sensor has been used to detect torque-ripple-induced vibration created by electric machines. It provides a convenient means to detect faults of both electrical and mechanical components of electric drive systems and also facilitates feedback-based control to mitigate the vibration source through control of the excitation to a machine. The first software tool analyzes the raw data acquired by the vibration sensor. This software utilizes both signal processing and statistical algorithms to reduce the acquired data into a user friendly pareto chart format. This format allows vehicle level PHM systems to cost-effectively analyze and store pertinent data relating to the health of the power system. This format also allows ground maintenance teams to quickly assess the health changes between flights without adding to “information overload”. The second software tool is a method of Distributed Heterogeneous Simulation (DHS) that provides a means to simulate the healthy and faulted behavior of large-scale systems at a speed and level of detail heretofore unachievable. Specifically, DHS enables the synchronized interconnection of any number of dynamic subsystem simulations, developed using any combination of a variety of programs/languages, and implemented on a single computer/workstation/supercomputer, a local area network (Intranet), a distributed, and any combination thereof. Theoretically, using an -computer network, DHS can approach an gain in computational speed over single computer, single numerical algorithm implementation. It is shown that through coupling of these tools, a comprehensive prognostics and health management system (PHM) for aircraft generators and associated electrical systems can be developed. Specifically, using DHS, component and system-level simulations of aircraft generator systems under nominal and failure modes can be performed efficiently. Using the simulation results obtained, the vibration sensor, unique monitoring concepts and advanced signal conditioning are coupled to establish an approach that can effectively detect component degradation and predict time-to-failure, and to develop feedback-based strategies for operation of generator electrical systems under component degradation or failure. Hence, maintaining the war fighting capabilities by extending the life of the aircraft electrical systems. Contact information:...
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