openLaval.py 文件源码

def get_Kstar_max(self):
        """ value of K*(dimensionless vortex constant) for which weight flow in maximum
        See also:
            NASA TN D-4421 eq. 23-25
        """

        max_val = 0
        while(1):
            try:
                f = lambda Mstar: (1 - (max_val/self.Mlstar)**2 * Mstar**2) ** (1/(self.gamma - 1))
                integrate.quad(f,self.Mlstar,self.Mustar)
            except:
                max_val -= 0.1
                break
            max_val += 0.1

        def func(Kstar_max):
            a1 = (1 - Kstar_max**2)**(1/(self.gamma -1))
            a2 = (1 - (Kstar_max**2) * (self.Mustar/self.Mlstar)**2)
            a3 = (1/(self.gamma - 1))

            # This if is to avoid the bug in python3 it self
            if(a2<0):
                a2 = ((Kstar_max**2) * (self.Mustar/self.Mlstar)**2 - 1)
                a = a1 + a2**a3
            else :
                a = a1 - a2 ** a3

            f = lambda Mstar: (1 - (Kstar_max/self.Mlstar)**2 * Mstar**2) ** (1/(self.gamma - 1))
            b = integrate.quad(f,self.Mlstar,self.Mustar)
            return a - b[0]

        Kstar_max = optimize.brentq(func,0.1,max_val)

        return Kstar_max