Issue 10 Volume 41 May 16, 2003

and 0.65 plus or minus 0.04 MPa the square root of m. Hence, there was an insignificant difference in either K(sub Ic or K(sub
IIc) between 25 and 1316 C for the coating material, whereas there was a noticeable distinction between K(sub Ic) and K(sub
IIc), resulting in K(sub IIc) per K(sub Ic) = 0.65 at both temperatures. The empirical mixed-mode fracture criterion best
described the coatings’ mixed-mode fracture behavior among the four mixed-mode fracture theories considered. The angle of
crack propagation was in reasonable agreement with the minimum strain energy density criterion. The effect of the
directionality of the coating material in on K(sub Ic) was observed to be insignificant, while its sintering effect at 1316 C on
K(sub Ic) was significant.
Author
Thermal Control Coatings; Zirconium Oxides; Plasma Spraying; Ambient Temperature; High Temperature Tests; Fracture
Mechanics; Yttrium Oxides; Mechanical Properties
20030032975 QSS Group, Inc., Cleveland, OH, USA
Aircraft Engine Sensor/Actuator/Component Fault Diagnosis Using a Bank of Kalman Filters
Kobayashi, Takahisa; Simon, Donald L., Technical Monitor; March 2003; 40 pp.; In English; Original contains color
illustrations
Contract(s)/Grant(s): NAS3-00145; WBS-22-728-30-05
Report No.(s): NASA/CR-2003-212298; NAS 1.26:212298; E-13862; No Copyright; Avail: CASI; A03, Hardcopy
In this report, a fault detection and isolation (FDI) system which utilizes a bank of Kalman filters is developed for aircraft
engine sensor and actuator FDI in conjunction with the detection of component faults. This FDI approach uses multiple
Kalman filters, each of which is designed based on a specific hypothesis for detecting a specific sensor or actuator fault. In
the event that a fault does occur, all filters except the one using the correct hypothesis will produce large estimation errors,
from which a specific fault is isolated. In the meantime, a set of parameters that indicate engine component performance is
estimated for the detection of abrupt degradation. The performance of the FDI system is evaluated against a nonlinear engine
simulation for various engine faults at cruise operating conditions. In order to mimic the real engine environment, the
nonlinear simulation is executed not only at the nominal, or healthy, condition but also at aged conditions. When the FDI
system designed at the healthy condition is applied to an aged engine, the effectiveness of the FDI system is impacted by the
mismatch in the engine health condition. Depending on its severity, this mismatch can cause the FDI system to generate
incorrect diagnostic results, such as false alarms and missed detections. To partially recover the nominal performance, two
approaches, which incorporate information regarding the engine s aging condition in the FDI system, will be discussed and
evaluated. The results indicate that the proposed FDI system is promising for reliable diagnostics of aircraft engines.
Author
Aircraft Engines; Fault Detection; Kalman Filters; Systems Health Monitoring; Sensors; Actuators; Component Reliability
20030033034 Pennsylvania State Univ., University Park, PA, USA
Thrust Augmentation Measurements Using a Pulse Detonation Engine Ejector
Santoro, Robert J.; Pal, Sibtosh; March 2003; 20 pp.; In English; Original contains color illustrations
Contract(s)/Grant(s): NAG3-2657; WU-708-87-23
Report No.(s): NASA/CR-2003-212191; NAS 1.26:212191; E-13794; No Copyright; Avail: CASI; A03, Hardcopy
The present NASA GRC-funded three-year research project is focused on studying PDE driven ejectors applicable to a
hybrid Pulse Detonation/Turbofan Engine. The objective of the study is to characterize the PDE-ejector thrust augmentation.
A PDE-ejector system has been designed to provide critical experimental data for assessing the performance enhancements
possible with this technology. Completed tasks include demonstration of a thrust stand for measuring average thrust for
detonation tube multi-cycle operation, and design of a 72-in.-long, 2.25-in.-diameter (ID) detonation tube and modular ejector
assembly. This assembly will allow testing of both straight and contoured ejector geometries. Initial ejectors that have been
fabricated are 72-in.-long-constant-diameter tubes (4-, 5-, and 6-in.-diameter) instrumented with high-frequency pressure
transducers. The assembly has been designed such that the detonation tube exit can be positioned at various locations within
the ejector tube. PDE-ejector system experiments with gaseous ethylene/ nitrogen/oxygen propellants will commence in the
very near future. The program benefits from collaborations with Prof. Merkle of University of Tennessee whose PDE-ejector
analysis helps guide the experiments. The present research effort will increase the TRL of PDE-ejectors from its current level
of 2 to a level of 3.
Author
Pulse Detonation Engines; Ejectors; Thrust Augmentation; Thrust Measurement
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