■ 3. NUMBER OF PAGES 42 14. MONITORING AGENCY NAME » ADDRESS'/' d/Merenl /ram Controlling Olllea) IS. SECURITY CLASS, (ol thla report) UNCLASSIFIED 15«. DECLASSIFIC ATI ON/DOWN GRADING SCHEDULE .. N/A 16. DISTRIBUTION STATEMENT (ol thla Report) Approved for public release; distribution unlimited. 17. DISTRIBUTION STATEMENT (ol the abatrael entered In Block 30, II dlllerent Irom Report; IB. SUPPLEMENTARY NOTES Available in DDC. 19. KEY WOROS 'Continue on ravaraa aide II nacaaaaty and identify by block number) laser velocimetry turbulence measurements Doppler effect 20. ABSTRACT (Continue on reveree aide II noceaaary and Identity by block number) A dual beam laser velocimeter (LV) system has been applied to the measurements of mean velocity and turbulence intensity. The basic theory of the LV is described in terms of both Doppler and fringe models. A statistical analysis predicting the number of data points required to ensure a given accuracy is developed. It was found that for a given accuracy and confidence level, significantly larger numbers of data points are required for the turbulent J DD ,, FORM ya-ii AN 73 1473 EDITION OF I NOV 65 IS OBSOLETE UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered) UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGEfW"««! Data Bnlmrmd) 20, Continued intensity than for the mean velocity. Experimental verification of the analysis is given. A theoretical analysis of the LV counting process is proposed which predicts the biases to be found in velocity and turbulent intensity estimators. Of the two most common methods of averaging, the latter yielded, in general, lower biases in the estimators for a one-dimensional model. Finally, experimental LV data are presented, taken from a coaxial free-jet-mixing facility. The LV data are compared with similar pitot probe and hot-wire data with favorable agreement. However, a moderate systematic discrepancy was noted which may be attributed to the LV data reduction technique.
A newly developed signal processing and data handling system for use in laser velocimetry is described. The system provides for entry into lower signal-to-noise ratio environments for capture of data from smaller particles than was formerly practical. Experimental data from a two-component Bragg cell directional velocimeter is used in comparing the system with a conventional counter-type processor. Dramatic improvement in the ’’particle lag problem’’ is seen.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.