This work examines the ability of small-scale, helium-air-mixture, coaxial jets to capture the acoustics of large-scale hot jets representing the exhaust of separate-flow turbofan engines. Experiments at University of California, Irvine (UCI) employed a one-eighth-scale model of a separate-flow nozzle being used at the Nozzle Acoustic Test Rig (NATR) of NASA Glenn Research Center. Comparisons w...

This work examines the ability of small-scale helium–air mixture coaxial jets to simulate the acoustics of largescale hot air jets representing the exhaust of separate-flow turbofan engines. Experiments employed a one-eighthscale model of a separate-flow nozzle used in hot tests at NASA John H. Glenn Research Center. Comparisons were conducted for two set points using the following methods: mat...

The development and upgrade of test installations, instrumentation and the data acquisition system of an existing turbofan engine test rig are described for an experimental program which was planned and initiated to investigate the transient unsteady operation of gas turbine engines with an emphasis on compressor operation. The objective of the program was to examine aerodynamic instabilities s...

The NASA Numerical Propulsion System Simulation (NPSS) project is exploring the use of computer simulation to facilitate the design of new jet engines. Several key issues raised in this research are being examined in an NPSSrelated research project: zooming, monitoring and control, and support for heterogeneity. The design of a simulation executive that addresses each of these issues is describ...

Complex engineering systems consist of many subsystems. Each of the subsystems is composed of a large number of components. While faults arise at component level, sensing capabilities are limited to subsystem level, and system operations and maintenance practices are scheduled based on system level paremeters. This paper presents a hierarchical architecture to analyze the effects of system leve...

Least-squares health parameter identification techniques, such as the Kalman filter, have been extensively used to solve diagnosis problems. Indeed, such methods give a good estimate provided that the discrepancies between the model prediction and the measurements are zero-mean, white, Gaussian random variables. In a turbine engine diagnosis, however, this assumption does not always hold due to...

In this paper, we present a unified framework for sensor validation, which is an extremely important module in the engine health management system. Our approach consists of several key ideas. First, we applied nonlinear minor component analysis (NLMCA) to capture the analytical redundancy between sensors. The obtained NLMCA model is data driven, does not require faulty data, and only utilizes s...

The effect of wedge-shaped fan flow deflectors on the mean and turbulent flow-fields of dual-stream jets is investigated. Several wedge-shaped deflector concepts were used to create asymmetry in the plume of a dual-stream jet issuing from a scaled down version of the NASA Glenn ‘5BB’ bypass-ratio 8 turbofan nozzle. The deflector configurations comprised internal and external wedges with and wit...

Due to a variety of technical problems encountered in advanced mechanical and aerospace industries, traditional reverse engineering in which only a copy of the old component using CAD/CAM systems is developed is less effective. As a matter of fact, re-engineering methodologies should be used to optimize the component/sub-system design concerning new materials and advanced manufacturing technolo...