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Reddy K.R.,Iowa State University | Ryon J.A.,United Technologies Aerospace Systems | Durbin P.A.,Iowa State University
International Journal of Heat and Fluid Flow

The current work develops a variant of delayed detached eddy simulation (DDES) that could be characterized as limiting the production term. Previous formulations have been based on limiting the dissipation rate ( Spalart et al., 2006). A clipped length scale is applied directly to the eddy viscosity, yielding a Smagorinsky-like formulation when the model is on the eddy simulation branch. That clipped eddy viscosity limits the production rate. The length scale is modified in order to account for the log-layer mismatch (a well-known issue with DDES), without using additional blending functions. Another view of our approach is that the subgrid eddy-viscosity is represented by a mixing length formula l2ω in the eddy field ω acts like a filtered rate of strain. Our model is validated for channel flow as well as separated flows (backward-facing step, 2D periodic hills) and illustrated via an air-blast atomizer. © 2014 Elsevier Inc. Source

Dolan B.,University of Cincinnati | Gomez R.V.,University of Cincinnati | Munday D.,University of Cincinnati | Pack S.,United Technologies Aerospace Systems | And 2 more authors.
Journal of Propulsion and Power

Periodic behavior in the reaction zone of a multiple-nozzle combustor undergoing self-sustaining combustion oscillations is examined. Understanding of the thermoacoustic interactions among heterogeneous arrays of swirl cups is important to enable the implementation of this low NOx approach. This combustor has three stages: a high-swirl pilot stage, a low-swirl intermediate stage, and a low-swirl outer stage. Liquid jet A fuel is supplied to all three fuel stages, which is characteristic of the high-power operation mode. Four test conditions are examined in which thermoacoustic coupling is observed at a well-defined frequency. Phase-averaged images of the OH∗ chemiluminescence emission show dramatic changes in the OH∗ emission, which is dominated by recurrent weakening and reignition downstream of the low-stability intermediate and outer fuel stages. The pilot stage reaction zone also displays periodic variation in intensity that is 90 deg out of phase and precedes the intermediate and outer fuel stages. One operating condition results in pressure oscillation amplitude that is intermittently high and low. A new method using the proper orthogonal decomposition time coefficients is used to quantify the relative periodicity of the OH∗ images. The nozzle design and the interactions between nozzle stages combine to allow significant thermoacoustic coupling in this burner under certain conditions. © Copyright 2015 by Brian Dolan. Source

Luko S.N.,United Technologies Aerospace Systems | Neubauer D.V.,Corning Inc.
Standardization News

The article concerns prediction intervals for the next observation when users have a set of data and their data is of the attribute type. The intervals presented are approximate and are based on an approximating normal distribution. They should be useful for most cases where the initial sample observation is at least five events for the binomial case, and 10-15 or more for the Poisson case. A quality metric for a certain operation in a large firm is to measure the number of rejected material lots received by the firm's receiving inspection operation. This information is measured and reported to management on a monthly basis. For the Poisson distribution, observations are made on an inspection region that can be based on time, area, space, number of objects or some other region description. The number of events users observe can be any whole number at least zero. Source

Neubauer D.V.,Corning Inc. | Luko S.N.,United Technologies Aerospace Systems
Quality Engineering

In this first part of a two-part series, common attribute sampling standards are discussed and compared. Military standard 105 (MIL-STD-105) is the premier attribute sampling standard that has led to a number of derivative standards in recent decades that are discussed here. While these standards share a lot of common ground, there are some differences among them. While military standards, such as MIL-STD-105, are no longer supported by the U.S. Department of Defense, there are many comparable standards to use which are supported by various standards organizations. In this paper, the reader will be introduced to these derivative standards and how they compare to each other and to MIL-STD-105. In the second part of this series, MIL-STD-414 and its derivative standards will be discussed for the inspection of variables data. Their ties to MIL-STD-105E and its derivatives will also be used to tie together all the standards in this article as well. © 2013 Taylor & Francis Group, LLC. Source

Giannandrea A.M.,Rochester Institute of Technology | Raqueno N.,Rochester Institute of Technology | Messinger D.W.,Rochester Institute of Technology | Faulring J.,Rochester Institute of Technology | And 14 more authors.
Proceedings of SPIE - The International Society for Optical Engineering

A multi-modal (hyperspectral, multispectral, and LIDAR) imaging data collection campaign was conducted just south of Rochester New York in Avon, NY on September 20, 2012 by the Rochester Institute of Technology (RIT) in conjunction with SpecTIR, LLC, the Air Force Research Lab (AFRL), the Naval Research Lab (NRL), United Technologies Aerospace Systems (UTAS) and MITRE. The campaign was a follow on from the SpecTIR Hyperspectral Airborne Rochester Experiment (SHARE) from 2010. Data was collected in support of the eleven simultaneous experiments described here. The airborne imagery was collected over four different sites with hyperspectral, multispectral, and LIDAR sensors. The sites for data collection included Avon, NY, Conesus Lake, Hemlock Lake and forest, and a nearby quarry. Experiments included topics such as target unmixing, subpixel detection, material identification, impacts of illumination on materials, forest health, and in-water target detection. An extensive ground truthing effort was conducted in addition to collection of the airborne imagery. The ultimate goal of the data collection campaign is to provide the remote sensing community with a shareable resource to support future research. This paper details the experiments conducted and the data that was collected during this campaign. © 2013 SPIE. Source

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