You could reverse your x and y inputs. Use -x to make the triangle point up.
for w=0.5:0.1:1
l = w;
thet = 0:1:60;
theta = thet .*(pi/180);
c = cos(theta);
p = 4*(1-l^2).*(c.^2) + (2*l - 1)^2;
q = 2*(1-l*l).*c + (2*l-1)*sqrt(4*(1-l*l).*(c.^2) + 5 *l*l - 4*l);
r =(q./p);
thetaa = [0:60, 60:120, 120:180, 180:240, 240:300, 300:360].*(pi/180);
v = [r, fliplr(r(1:61)), r(1:61), fliplr(r(1:61)), r(1:61), fliplr(r(01:61))];
%polarplot(thetaa,v);
[x, y] = pol2cart(thetaa, v);
% ### plot y as x and -x as y ###
plot(y,-x);
hold on;
end
pbaspect([1 1 1]);
grid on;
xlabel('x-axis');
ylabel('y-axis');
