Space-Time Correlations and Trailing Edge Flow Structure in Fan-Blade Wakes with Trailing Edge Blowing

Fundamentals and Applications of Modern Flow Control

“…Brookfi eld confi rmed these exact same effects on a model fan modifi ed to allow blowing through an array of holes drilled into the TEs of the fan blades. Borgoltz et al (2006) estimates that these combined effects could reduce broadband noise generated by a downstream stator by as much as 7 dB. Similar rates of blowing and reductions on unsteady forces on downstream stators were observed by Wo et al (2002) in a low-speed fan, who used injection through part-span slots located near the midspan of the blade TEs.…”

“…Using a linear cascade, Sell established that blowing through holes in the TEs of compressor blades could both "fi ll" the wake and lower the turbulence levels within it, producing a momentumless wake for a blowing rate equivalent to 1% of the total mass fl ux through the blade row. Borgoltz et al (2005Borgoltz et al ( , 2006 showed that blowing also has dramatic effects on the eddy structure of the wake downstream of compressor blades. Blowing rates equivalent to about 2% of the total mass fl ow through the fan not only fl attened the fan blade wake profi les and reduced turbulence levels within them, but also greatly reduced unsteady pressures on the downstream stators away from the hub.…”