pressure coeffcient of a wing/blade

software: CFD POST ANSYS

menu bar, select Tools > Macro Calculator.

correction:

Ref pressure is relative pressure = abs pressure - reference pressure (in Fluent)

definitions;

Cp expression can be defined

as:

(Pressure - $pref [Pa])/dynHead

Pressure: static pressure

- $pref ： the Ref. Pressure set in the macro calculator

- dynHead ： a reference dynamic head (evaluated at the inlet) that can be defined as:

0.5 * areaAve(Density)@inlet * areaAve(Velocity)@inlet^2

- dynHead is a reference dynamic head

The
following information must be specified:

•
Boundary List: A list of boundaries
used in the simulation (blade).

•
Slice Normal: The axis that will be
normal to the slice plane.

•
Slice Position: The offset of the
slice plane in the direction specified by the normal axis.

•
Inlet Region: The locator used to
calculate inlet
quantities.

•
Ref. Pressure: The reference
pressure for the simulation.

•
Plot Axis: The axis on which the
results will be plotted.

Note for moving reference frame

use pressure as y variable, if moving reference frame is used,

cause the 'velocity' is 'relative velocity'

Code for ' pressure coefficient vs. x/c' in matlab

- Cpr.m

% plot and save 'pressure coefficient vs. x/c'

load pressure_9r_7.1m.out;

pressure=pressure_9r_7_1m(:,2);

x=pressure_9r_7_1m(:,1);

x=x+0.0139;

x_nor=x/0.0276;

cp=pressure_coeff(pressure);  % user defined function

plot(x_nor,cp);

cp_x = [x_nor cp];

save -ascii presure_coeff_7.1m.txt cp_x

- pressure_coeff.m code is as below

function cp= pressure_coeff(p)

% v : velocity

% p :  pressure

% p0 :   reference pressure

% rho : density

% omega: angular velocity, rad/s

% r : radius

  r=0.207;

v = 0.6;

p0=0;

omega = 13.043;

rho = 998.2;

U = v^2 + (omega*r)^2;

cp=2*(p-p0)/(rho*U)

gnuplot script

#set terminal jpeg

#set output 'coeff_epp_gci.jpg'

#set terminal png

#set output 'pressure_tsr5.png'

set terminal postscript eps font 24

set out 'pressure_coeff_tsr5.eps'

#set terminal x11

set autoscale

unset log

unset label

unset pm3d

set key at graph .7, .4

set key spacing 1

set xtic auto

set ytic auto

set xlabel "x/c - Normalized chord length"

set xrange [*:*]

# r0 initial pulse

set yrange [*:*] 

set ylabel "C_{pr} - Pressure coefficient"

set style line 1 lt 1 lc rgb "black" lw 4 pointtype 6

set style line 2 lt 2 lc rgb "black" lw 4 pointtype 2

set style line 3 lt 3 lc rgb "black" lw 4

set style line 4 lt 4 lc rgb "red" lw 4

set style line 5 lt 5 lc rgb "black" lw 4

set style line 6 lt 6 lc rgb "brown" lw 4

set pointsize 2

set bars 3

plot "presure_coeff_3.3m.txt" using 1:2  t  "3.5M" ls 1 with lines,\

"presure_coeff_5.4m.txt" using 1:2  t  "5.4M" ls 2 with lines,\

"presure_coeff_7.1m.txt" using 1:2  t  "7.1M" ls 3 with lines

巴特西

pressure coeffcient of a wing/blade

Code for ' pressure coefficient vs. x/c' in matlab

gnuplot script

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