function eta = effturbine_eps60(ns,ds,PR)
% File created by Violette Mounier (2017) - LAMD EPFL
% This function evaluates the performance of a radial inflow turbine, function of the following inputs:
% - ns [-] : specific speed
% - ds [-] : specific diameter
% - PR [-] : Pressure ratio [-]
% It is valid for a shroud to tip radius ratio  epsilon = 0.6
% For an isentropic efficiciency above 0.5 :
% 0.2 < ns < 0.85 
% 2.5 < ds < 8
% 1.5 < PR < 8.5

%% Inputs
x3=PR;
x2=ds;
x1=ns;

%% Model
eta=+2.91911.*x3+-0.833561.*x3.^2+0.106357.*x3.^3+-0.00609021.*x3.^4+-0.780679.*x2+-0.356543.*x2.*x3+0.0919244.*x2.*x3.^2+...
-0.00981018.*x2.*x3.^3+0.000402898.*x2.*x3.^4+0.273575.*x2.^2+0.00557772.*x2.^2.*x3+-0.00105467.*x2.^2.*x3.^2+2.09556e-05.*x2.^2.*x3.^3+...
-0.0275128.*x2.^3+0.000127351.*x2.^3.*x3+1.51829e-05.*x2.^3.*x3.^2+0.00109674.*x2.^4+-1.13957e-05.*x2.^4.*x3+-14.8438.*x1+...
-6.04.*x1.*x3+1.53933.*x1.*x3.^2+-0.139429.*x1.*x3.^3+0.00437482.*x1.*x3.^4+13.3663.*x1.*x2+0.394618.*x1.*x2.*x3+...
-0.0894802.*x1.*x2.*x3.^2+0.00370824.*x1.*x2.*x3.^3+-2.53803.*x1.*x2.^2+-0.0159173.*x1.*x2.^2.*x3+0.0026815.*x1.*x2.^2.*x3.^2+0.193253.*x1.*x2.^3+...
2.38141e-05.*x1.*x2.^3.*x3+-0.00522272.*x1.*x2.^4+62.7612.*x1.^2+2.0456.*x1.^2.*x3+-0.823485.*x1.^2.*x3.^2+0.0427109.*x1.^2.*x3.^3+-31.3479.*x1.^2.*x2+...
0.263808.*x1.^2.*x2.*x3+0.0220922.*x1.^2.*x2.*x3.^2+4.36918.*x1.^2.*x2.^2+-0.018999.*x1.^2.*x2.^2.*x3+-0.169594.*x1.^2.*x2.^3+-94.819.*x1.^3+...
3.10124.*x1.^3.*x3+0.0896069.*x1.^3.*x3.^2+34.0226.*x1.^3.*x2+-0.392335.*x1.^3.*x2.*x3+-3.22352.*x1.^3.*x2.^2+45.1157.*x1.^4+-1.84665.*x1.^4.*x3+...
-8.30698.*x1.^4.*x2+-1.68679.*1+-5.83341.*x1.^5+-1.00936e-05.*x2.^5+0.000115494.*x3.^5;
end
