CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Main CFD Forum (http://www.cfd-online.com/Forums/main/)
-   -   Highly aerodynamic design (http://www.cfd-online.com/Forums/main/72276-highly-aerodynamic-design.html)

dijinj January 31, 2010 23:17

Highly aerodynamic design
 
I have invented a new aerodynamic shape with low drag. I am looking for your esteemed feedback on the concept. Technical details are given in site http://sites.google.com/site/highlyaerodynamicdesign/
:)

dominic February 1, 2010 02:10

Diji,

Nice work and documentation... I have a few questions/comments:

1. The one thing that is very intriguing to me is when you mention " In animations you can clearly see turbulence is higher for aerofoil wing." How can you conclude from that simulation ? Just by seeing the vortex shedding alone ? One must be very careful in making concrete judgments like this. What is your Reynolds number ? How many volumes have you used ? Any details on the mesh quality ?/ Turbulence models etc...

2. You have mentioned : "Below is the animation of Cycloid wing and Aerofoil wing with same length to width ratio" .. Probably thickness/chord ratio would ring a bell to many of us. (Or was it Aspect ratio ? - not clear)... you say they are the same for the cycloid and the airfoil, what is it exactly ? (the value ?) what airfoil is it ?

3. It would be more meaningful if you gave us plots of Cd Vs Re in comparison with other airfoils. This can actually tell us whether the drag is less at a given Reynolds number.

4. Another statement you have mentioned:
"You can see below that at aerofoilís trailing end velocity vectors are not horizontal that means vertical component of velocity is not zero this causes turbulence.". Honestly, you have to look into this point seriously. So what if they are not horizontal ? How does that influence turbulence ?

5. You say you want to avoid separation, and at the same time, you want to avoid turbulence. Does this make sense for high Reynolds number flows ?

dijinj February 1, 2010 03:31

the animations are done in Maya fluid there is a pre-built wind tunnel in Maya and I placed a cycloid and airfoil with same aspect ratio(length: width).

in airfoil at trailing edge crossing of top and bottom flow lines might occur because vertical velocity is not zero. Also you will get the energy used to initiate vertical velocity in air at leading edge back to cycloid body if vertical velocity is zero at trailing edge

requirement of cycloid system is that there should not be any seperation this can be achieved by plasma flow control. I am working on a new cfd analysis including this

Lysistrata February 1, 2010 04:34

Quote:

Originally Posted by dijinj (Post 244396)
I have invented a new aerodynamic shape with low drag. I am looking for your esteemed feedback on the concept. Technical details are given in site http://sites.google.com/site/highlyaerodynamicdesign/
:)

ROFL. You refer to turbulence as though you know how to model it.

dijinj February 1, 2010 09:39

there are different turbulent models to choose from in CFD software like Fluent. so I can choose one from them

dominic February 1, 2010 09:53

What turbulence model did you choose, and what was the Reynolds number ?. Note that, both of the above are related. It's hard to narrow down to a selective turbulence model to handle a wide range of Reynolds numbers.

dijinj February 1, 2010 10:23

i used K-epsilon model and
for comparison NACA 4412 airfoil is used.
The freestream velocity is 50 m/s
Pressure = 101,325 Pa
Density = 1.2250 kg/m3
Temperature = 288.16 K
Kinematic viscosity v = 1.4607e-5 m2/s


All times are GMT -4. The time now is 21:43.