Q3D Manual

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Guidelines for using Q3D AeroSolver

1. Wing planform geometry definition:
a. The coordinates of the apex points (x,y,z) should be defined in
meter.
b. The chord should be defined in meter.
c. The twist angle should be defined in degree (positive = nose up).
d. The axis (for defining x, y, and z) is illustrated in the following
figure:

e. Only the left wing (from front view) should be defined. The other
wing will be automatically created by mirroring the defined wing.

2. Airfoil geometry definition:
a. All the airfoils should be defined with the same number of CST
coefficients.
b. The number of CST coefficient for the upper and lower surfaces
must be the same.
3. Viscous vs inviscid analysis
a. The wing analysis can be switched between viscous and inviscid
analysis using AC.Visc variable. If the value of this variable is
chosen to be 1 the Q3D solver performs a viscous analysis and
reports the total wing viscous drag.
b. If the value of AC.Visc is chosen to be 0 the Q3D solver only
performs an inviscid analysis and the outputs contains lift, pitching

moment and only induced drag. This analysis is useful when only
the lift and pitching moment distribution are needed.
4. Flow condition:
a. Even if some of the input parameters are dependent variables (for
instance, V can be calculated when M and H are given), ALL of
them must be provided, hence it is user responsibility to provide a
consistent set.
b. The values of speed, altitude, density and viscosity must be
expressed in SI units (m, kg, s).

5. Tool installation and system requirement:
a. Q3D AeroSolver should be used in Matlab 2009 or higher.
b. The tool is only available for Windows (that is because, the
commercial software VGK used by Q3D AeroSolver is only
available for Windows).
c. When installing the tool on your PC, do NOT change file and folder
names and structure.
6. The Q3D AeroSolver is developed only for wing analysis. The effect
of fuselage and tail cannot be modelled in this tool.
7. The outputs (Res):
a. Res.Alpha is the 3D wing angle of attack. The angle of attack of
each wing spanwise section is the wing angle of attack plus the
wing incidence (if defined) plus the local twist angle.
b. Res.CLwing is the 3D wing total lift coefficient.
c. Res.CDwing is the 3D wing total drag coefficient (including profile,
induced and wave drag if AC.Visc =1 but only induced drag if
AC.Visc =0).
d. Res.Wing includes the results of VLM analysis:
i. Res.Wing.Yst is the spanwise location of each strips (where
the vortexes are placed).
ii. Res.Wing.chord is the wing chord at each strip.
iii. Res.Wing.cl is the local lift coefficient at each strip.

iv. Res.Wing.ccl is the local lift coefficient multiplied by the
local chord at each strip.
v. Res.Wing.cdi is the local induced drag coefficient at each
strip.
vi. Res.Wing.cm_c4 is the local pitching moment coefficient
about the quarter chord line at each strip. This pitching
moment includes the moment due to the wing sweep and the
moment due to the airfoils camber, but the effect of airfoil
thickness is not taken into account. It also does not contain
the effect of shock waves if they exist.
e. Res.Section includes the results of 2D sections analysis (only for
viscous analysis, for inviscid analysis section properties are not
reported):
i. Res.Section.Y is the spanwise locations of the analysed 2D
sections.
ii. Res.Section.Cl is the local lift coefficient of the analysed 2D
sections.
iii. Res.Section.Cd is the drag coefficient (profile + wave drag)
of the analysed 2D sections.
iv. Res.Section.Cm is the pitching moment coefficient of the
analysed 2D sections around the airfoil quarter chord. This
pitching includes the effect of airfoil shape (both camber and
thickness) and also includes the effects of compressibility
(shock waves if they exist).

Example of Matlab input file for Q3D
%% Aerodynamic solver setting
% Wing planform geometry
%
x
y
AC.Wing.Geom = [0
0
0.9 14.5

z
0
0

chord(m)
3.5
1.4

twist angle (deg)
0;
0];

% Wing incidence angle (degree)
AC.Wing.inc = 0;

% Airfoil coefficients input matrix
%
| ->
upper curve coeff.
<-| | ->
lower curve coeff.
<-|
AC.Wing.Airfoils =[0.2171 0.3450 0.2975 0.2685 0.2893 -0.1299 -0.2388 -0.1635 -0.0476 0.0797;
0.2171 0.3450 0.2975 0.2685 0.2893 -0.1299 -0.2388 -0.1635 -0.0476 0.0797];

AC.Wing.eta = [0;1];
% Viscous vs inviscid
AC.Visc = 1;

% Spanwise location of the airfoil sections

% 0 for inviscid and 1 for viscous analysis

% Flight Condition
AC.Aero.V
= 68;
AC.Aero.rho
= 1.225;
AC.Aero.alt
= 0;
AC.Aero.Re
= 1.14e7;
aerodynamic chord)
AC.Aero.M
= 0.2;
% AC.Aero.CL
= 0.4;
run the code for given alpha%
AC.Aero.Alpha = 2;
run the code for given cl

Res = Q3D_solver(AC);

%
%
%
%

flight speed (m/s)
air density (kg/m3)
flight altitude (m)
reynolds number (bqased on mean

% flight Mach number
% lift coefficient - comment this line to
% angle of attack -

comment this line to

Example of outputs of Q3D
Res =
Alpha: 2

% Wing total angle of attack

CLwing: 0.5967

% wing total CL

CDwing: 0.0143

% wing Total CD

CMwing: -0.3577

% Wing total CM

Wing: [1x1 struct]

% Results of VLM (see below)

Section: [1x1 struct]

% Results of airfoil analysis (see below)

>> Res.Wing
ans =
Yst: [14x1 double]
chord: [14x1 double]
cl: [14x1 double]
ccl: [14x1 double]
cdi: [14x1 double]
cm_c4: [14x1 double]

>> Res.Section
ans =
Y: [0 2.0714 4.1429 6.2143 8.2857 10.3571 12.4286 14.5000]
Cl: [0.5592 0.5861 0.6053 0.6183 0.6251 0.6214 0.5851 0.4255]
Cd: [0.0047 0.0048 0.0048 0.0049 0.0050 0.0051 0.0051 0.0051]
Cm: [-0.1119 -0.1120 -0.1120 -0.1119 -0.1117 -0.1113 -0.1107 -0.1089]



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