Title:
Investigation of the impact of turbine blade geometry on near-field microwave blade tip time of arrival measurements

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dc.contributor.advisor Jagoda, Jechiel I.
dc.contributor.advisor Jacobs, Laurence J.
dc.contributor.author Zimmer, Aline Katharina en_US
dc.contributor.committeeMember Seitzman, Jerry M.
dc.contributor.department Aerospace Engineering en_US
dc.date.accessioned 2009-01-22T15:45:49Z
dc.date.available 2009-01-22T15:45:49Z
dc.date.issued 2008-10-14 en_US
dc.description.abstract This study investigates the manifestation of geometric features of turbine blades in signatures of non-optical time of arrival (ToA) probes. The approach enables an evaluation of the various signal characteristics used for defining ToA for a range of airfoil geometries and provides knowledge about additional waveform characteristics. The objective of this research is to increase the accuracy of microwave ToA probes by gaining a better understanding of the microwave signals in five steps. Firstly, ToA definitions used in the past are compared. Considering accuracy, computational effort, and versatility, the constant fraction crossing definition is found to be the most accurate. Secondly, an experimental apparatus capable of measuring airfoil ToA with microwave probes and optical probes as a reference is designed and built. As a third step, a catalog of 16 turbine blade geometries is developed. Fourthly, the signatures of these turbine blades are acquired using both the optical and the microwave probes. Finally, the impact of the geometric effects on the signatures is evaluated. The quality of the microwave results is found to be highly dependent on the polarization of the microwaves. Analysis of the time domain signal shows that decreasing the blade width, increasing the chord angle, or incorporating a blade tip pocket or a varying cross-section leads to a decrease in the amplitude of the peak caused by the blade. Increasing the blade width and incorporating a chord angle leads to an increase in peak width. A frequency domain analysis is conducted on the microwave signals and verified using a synthetic signal. This analysis confirms the findings from the time domain analysis. The time domain analysis of the laser measurements shows that the spatial resolution of the laser is much higher than that of the microwave sensor. Consequently, the signal acquired with the optical setup provides a good means of defining the blade ToA. The knowledge gained in this study about the sensor and its interaction with passing blade tips of varying geometry can be used to enhance the understanding of microwave ToA measurements. This knowledge provides further insight into airfoil and engine health. en_US
dc.description.degree M.S. en_US
dc.identifier.uri http://hdl.handle.net/1853/26558
dc.publisher Georgia Institute of Technology en_US
dc.subject Phm en_US
dc.subject Nsms en_US
dc.subject Turbine blade en_US
dc.subject Time of arrival en_US
dc.subject Microwave sensor en_US
dc.subject.lcsh Blades
dc.subject.lcsh Microwave measurements
dc.subject.lcsh Aerofoils
dc.subject.lcsh Microwaves
dc.title Investigation of the impact of turbine blade geometry on near-field microwave blade tip time of arrival measurements en_US
dc.type Text
dc.type.genre Thesis
dspace.entity.type Publication
local.contributor.advisor Jacobs, Laurence J.
local.contributor.advisor Jagoda, Jechiel I.
local.contributor.corporatename College of Engineering
local.contributor.corporatename Daniel Guggenheim School of Aerospace Engineering
local.relation.ispartofseries Master of Science in Aerospace Engineering
relation.isAdvisorOfPublication 5af40958-ece2-4a76-b071-5ba4c6d99d80
relation.isAdvisorOfPublication 82d8814b-a147-40a3-908d-cb7a4766cdbe
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
relation.isOrgUnitOfPublication a348b767-ea7e-4789-af1f-1f1d5925fb65
relation.isSeriesOfPublication 09844fbb-b7d9-45e2-95de-849e434a6abc
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