What happens when you add a vortex generator (not trip strip) to a high lift or laminar wing, operating say at 500k to 1,000k Re?

I understand vortex generators add a little less lift than a slat on a classic naca wing, about 0.6cL. I understand that vortex generators are very different than trip strips, as they actually add energy to the boundary layer. I understand that both vortex generators and trip strips change the flow from laminar to turbulent, but trip strips don't add cl like a vortex generator does.

So ... what happens when you add a vg to a high lift wing like the selig 1233 or the eppler or Wortmann series of reflex or non-reflex laminar wings.

Do vortex generators still add about 0.6Cl or is it actually detrimental as these wings are designed to operate in laminar flow, not turbulent flow?

  • $\begingroup$ I did a lot of research on VGs some years ago when scratch building bits of a homebuilt project that never went anywhere. On thick wings with blunt leading edges, the Cl improvement is somewhat less than when you add them to a wing with sharp leading edges. Anyway, my plan was to build a Pegazair, which has automatic slats, without the slats and just drooping the LE and adding radius to the Peg's NACA 2415, and adding an array of VGs. I only took credit for a VG Cl improvement of about .4, and based on that I calculated the minimum flying speed as only about 4 mph faster than with slats. $\endgroup$ – John K Jul 2 '19 at 15:01
  • $\begingroup$ I have them on my 1973 Cessna 177B, the plane has the same control feel well below the stall speed and I can land in a shorter distance. The plane's "wing airfoil was obtained by fairing the front half of the cambered NACA 2415 shape onto the previous NACA 65A015 airfoil. This eliminated the laminar flow benefit of the 65-series airfoil (whose low-drag "bucket" at a low angle of attack had not been properly exploited in actual use), but gave a better lift-to-drag ratio at high angles of attack (i.e. during the climb), and softened the break at the stall." www.skytamer.com/Cessna_177B.html $\endgroup$ – CrossRoads Jul 2 '19 at 15:40
  • $\begingroup$ @CrossRoads unrelated question: does your Cardinal's nose oleo make little thumping/tapping noises while taxiing? My '67 did that and I was told it was because it was a floating piston oleo and the thump was the piston. $\endgroup$ – John K Jul 2 '19 at 20:12
  • $\begingroup$ No mine doesn't. Are you a member of Cardinal Flyers Online (CFO)? cardinalflyers.com There are several articles about fixing things like that. Sometimes it can be adding a simple shim to the top of the strut, other times the strut needs a rebuild with new O-rings. Join up, do some reading, ask a question via the digest that goes out nearly daily. $\endgroup$ – CrossRoads Jul 3 '19 at 12:07
  • $\begingroup$ Thanks for the answers. I'm a total fan of Vg's too, Put them on my Zenith Ch601. I fiqure, they'll probably save my life one day- lower landing speed, delayed stall, but the answers above are based on the Naca2415 which is not a LAMINAR foil. Still wondering what would happen on a laminar high camber foil, like a Selling 1233. $\endgroup$ – Fred Jul 3 '19 at 13:21

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