DETECTION OF THE TURBULENT-NON-TURBULENT INTERFACE.
Abstract
A new method was developed to form an intermittency function I(t) (ON for turbulent, OFF for non-turbulent flow) using an analog circuit. The detection process is based on a signal proportional to a spatial derivative of velocity; two adjustable detection parameters are used, namely, a threshold and a 'memory' or 'hold-time.' Methods are given for determining the optimum values of the detection parameters for a given flow using a two step procedure. First the detector cirucit performance is calibrated using a synthetic signal of known properties, and then measurements in the particular flow are related to the calibration tests to determine optimum settings. Detailed description is given of the detector circuit and of a circuit for generating a 'synthetic turbulence' signal. Methods of determining detection errors and difficulties met in using the detection method in particular flows are discussed. An analytic model of the detection process is presented. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1970
- Accession Number
- AD0712375
Entities
People
- Leslie S. G. Kovasznay
- Valdis Kibens
Organizations
- Johns Hopkins University