Stagnation Point Releif 1

[CraigBEng]

I am currently doing a project to use the energy at the stagnation point by means of a slat that runs from the leading edge on top of an aerofoil, releasing it at the wake region.
this in theory should reduce drag, increase lift, greater stall angle, and reduce turbulent flow.

Please note I am a "Newbie" could anyone please point me in the direction of some research that has been done of a simular kind or offer any help? as it is difficult to find any?

 

[rb1957]

i before e

i'd look into boundary layer suction (Blackburn Buccaneer)
and automatic slats (Handley Page)

actually i have thought of applying this idea to trucks but the problem i thought (and this applies to your idea too) is that you've got to ship a large volume of air (rather than just a pressure tap).

as far as airfoils go, if yo mess with the pressure distribution like this, aren't you going to spoil the lift ? the other approaches (boundary layer suction) add energy (do work) to the airfoil.

good luck

 

[CraigBEng]

Except after C!

Thank you for your prompt reply, i dont think that it will effect the lift characteristics much i have wind tunnel tested the unmodified NACCA 23015 at low speeds the readings are all roughly the same this was due to a low Reunolds number and scale effect.

What the prototype basically is a naca 23015 with a super thin wing attached over the top of it with a small amount of clearance.

does anyone know how or where to find the stagnation point on an aerofoil?

Thank you

 

[rb1957]

actually i completely misread your OP; pretty much all i got was stagnation point (high pressure) releasing it into the wake (low pressure), and immediately visualised a duct and started typing ! (and hence my rable into trucks, still think there's an idea there)

now i see a very wide chord slat (conventional slats are narrow chord). early slats (and probably some today) were designed to be deployed by the suction pressures as the airfoil approaches stall, thereby delaying full stall and so were primarily a safety device. this is my reference to Handley Page slats, i think the first to implement the design.

as to the stagnation point, 23015 is symmetric so the stagnation point should start of being at CL and drift down the tip radius as the AoA increases. i've seen the stagnation stream line as hitting the airfoil perpendicular to the local profile tangent; but i can't think of how to define the contact point.

in any case, if you're shrouding the airfoil with wide chord slats, won't the stagnation streamline attach to the shroud ? also, if the slats have a very small nose radius, won't they stall out ? conventional slats have a very large tip radius and a bunch of camber, to keep the flow attached.

 

[CraigBEng]

I did not consider this,

What kind of energy if any does the stagnation point posses?

My mentour told me that this kind od experiment would reduce the wake region.

by comparing the modified aerofoil with the unmodified wake region i should have some sort of differential equation.

I am unsure how to obtain this?

I also now am unsure wheather the aerofoil is a NACCA 38015 is there a way by mearuring the cord and other characteristics to find out excactly what it is?