Comparison of window, smoothedensemble, and cyclebycycle data reduction techniques for laser Doppler anemometer measurements of incylinder velocity
Abstract
The present study compares methods of data analysis for LDA measurements of incylinder velocity by using various methods to extract mean velocity and turbulence from the same data. Both the smoothedensemble and window methods use ensembled data to determine the mean velocity; hence these two methods are unable to distinguish cyclic variations in mean velocity from turbulence. The cyclebycycle method accounts for variations in mean velocity from one cycle to the next; the magnitude of the cyclic variations is largest when there is no strong welldirected mean flow, and can be several times as large as the turbulence in such cases. The window method also suffers from an error introduced by the finite window size; this is manifested as increased turbulence when large window sizes are used.
 Publication:

Fluid Mechanics of Combustion Systems
 Pub Date:
 1981
 Bibcode:
 1981fmcs.proc...11R
 Keywords:

 Combustion Chambers;
 Data Reduction;
 Engine Tests;
 Laser Doppler Velocimeters;
 Piston Engines;
 Velocity Measurement;
 Computational Fluid Dynamics;
 Computer Programs;
 Cylindrical Chambers;
 Flow Velocity;
 Fuel Flow;
 Turbulent Flow;
 Fluid Mechanics and Heat Transfer