A comparative experimental study of turbulence reduction by porous honeycomb : a first look

The purpose of this experiment and study was to analyze the effectiveness of porous-cell honeycomb at reducing large-scale turbulence generated from a cylinder placed upstream of the honeycomb and compare its performance to standard honeycomb. Particle image velocimetry (PIV) and hot-film anemometry measurement techniques were used to acquire data for the experiment. The objective of the particle image velocimetry test was to measure the velocity of (individual) smoke particles (seed) in the flow from which the vorticity and turbulence intensity contours of the flow could be obtained. The PIV also provided a means for flow visualization in this study. The objective of the hot-film anemometry test was to measure certain aspects of the velocity field, and from this data calculate velocity, turbulence intensity, and frequency spectrum information to determine the effectiveness of each honeycomb model at reducing flow non-uniformity and turbulence. The measured effectiveness of each honeycomb was used in a comparative analysis to determine the relative effectiveness of each porous honeycomb at turbulence reduction. The experiment collected performance data from a regular (solid wall) honeycomb, and a 20 percent, a 30 percent, and a 40 percent porous honeycomb. All tests were performed in the UTSl Low-Speed Wind Tunnel. The experiments were conducted at unit Reynolds number of nearly 350,000 (348,040) per foot. Both sets of measurements reveal that porous honeycomb may be superior to regular honeycomb at turbulence reduction.