BABASKY UNICCON asked 6 days ago
I Carried out a simulation with exact same airplane with same T6 analysis setup for version 7.26.2 and version 7.52, but the T6 analysis results are very inconsistent when the analysis have a range of yaw and roll angle introduced into the analysis setup. I also noticed that whenever the range of yaw and roll angle is kept at Zero, the results on T6 analysis are very consistent. N/B. I didn’t introduce any wing flag angle (Aileron deflection angle).
this are the dropbox link to the image of the analysis. https://www.dropbox.com/scl/fi/43jinf3jz4aqq3ij64ts3/V7.26.2-CL-CD-ROLL-AND-YAW.PNG?rlkey=ywdk9353v4ixacosse96wcv2q&st=mrw0y3gi&dl=0
https://www.dropbox.com/scl/fi/je61g8ysu9eooj5354gqx/V7.26.2-CL-CD-STEADY-BANK-AND-YAW-NEUTRAL-AILERON.PNG?rlkey=j630e16lgptdw44d4wuuh07qd&st=ddnremjr&dl=0
https://www.dropbox.com/scl/fi/04ywj9m7yaexrldcgfi5l/V7.52-CL-CD-ROLL-AND-YAW.PNG?rlkey=od0ladgcyu6td66hy6pkgi0t6&st=5h0m9emj&dl=0
https://www.dropbox.com/scl/fi/y4l2un6znyubu4v9cm96e/V7.52-CL-CD-STEADY-BANK-AND-YAW-NEUTRAL-AILERON.PNG?rlkey=76pvleivlxuiywisb40h7nr2e&st=gqifbxvl&dl=0
Starting in v7.50, the calculation of the induced lift and drag has been modified to be compatible with the modified handling of flaps, which leads to minor deviations of both Cl and Cd. These deviations are then amplified when the ratio Cl/Cd is calculated. I would recommend comparing Cl and Cd separately.
André
Ok thanks. I checked for Lift force and Drag force separately (L/D) and found out it was consistent for previous versions and made more sense. but I tried another t6 analysis but this time I had range of just bank with constant minimum and max angle and another t6 analysis of bank angle ranging from 0 t0 6 degree, I noticed they all looked consistent with other analysis
so, do you recommend me using Lift force (L) and drag force (D) to compute actual lift to drag ratio before plotting it against AOA? the L/D i extracted from lift and drag force (looks more reliable) do not match the report CL/CD in the T6 analysis in some scenarios.
https://www.dropbox.com/scl/fi/gmegmu8ozeir8vvor9ecz/T6_1-TriUniform-ThinSurf-CONTROLS-DEFLECTION.xlsx?rlkey=94hx1xikklvskwo5kor04otjx&st=n87t3fq2&dl=0
https://www.dropbox.com/scl/fi/cg0fwa5detz7nx3hoxn0g/T6_1-TriUniform-ThinSurf-FIXED-ROLL_-YAW-CONTROLS.xlsx?rlkey=c8f2mxzo44kea1yg3rz4y9dkd&st=ueu3bexe&dl=0
https://www.dropbox.com/scl/fi/b879yjfcb14msg98uqb9a/CL-CD-PLOT-COMPARISON.PNG?rlkey=9npcmcylfrbzfaeiq53mu44sd&st=llbgh9ge&dl=0
L/D if calculated in the far-field plane will give the same result as Cl/Cd.
I think you are hitting the limits of what flow5 can reasonably calculate.
It’s also possible that it’s a flow5 bug, or a special case that flow5 does not handle very well. If you can share the project file, I’ll have a look.
André