Particle tracer analysis for PIV experiments in a closed loop transonic wind tunnel
P. Manovski (1,2), P. Gulotta (1,3), C.M. de Silva (4), R. Brown (1), M. Giacobello (1), N. Hutchins (2), I. Marusic (2)
(1) Defence Science and Technology Group, Australia
(2) Dept. of Mechanical Engineering, The University of Melbourne, Australia
(3) United States Air Force, United States of America
(4) Schl. of Mechanical and Manufacturing Engineering, University of New South Wales, Australia
A performance study of several tracer particles for PIV has been conducted. The study included particle response time analysis of an oblique shock wave generated by a conical nose of a store model in a closed loop transonic wind tunnel, and in-situ measurements of the particle size distribution in a low-speed wind tunnel facility. From the oblique shock wave analysis, the estimated particle response time for different smoke materials and generator settings was of the order of 1.4 - 2.2 μs and the effective particle size was 0.58 - 0.85 μm, which was much larger than the measured geometric mean particle size. This larger size was mainly attributed to the correlation bias towards larger particles in PIV measurements. The effective particle size from the particle response time analysis accounts for the holistic performance of the PIV system. Additionally, particle response analysis was performed on ambient water droplets resident in the tunnel. The estimated particle response time for the water droplets was in the order of 3.4 μs and the effective particle size was 0.97 μm, revealing inferior performance compared to the smoke particles.