def test_huzel_43_a1_throat(self): """Test against Huzel and Huang example problem 4-3, for the A-1 engine at the throat.""" # Values given in the problem statement p_c = 6.9e6 # 1000 psi c_star = 1725. # 5660 ft second**-1 D_t = 0.633 # 24.9 inch c_p = 2031. # 0.485 BTU lbm**-1 rankine**-1 mu_e = 7.47e-5 # 4.18e-6 lbm inch**-1 second**-1 Pr = 0.816 # Prandtl number sigma = 1.0 # Correction factor # Answer given for the convection coefficient h_g_huzel = 7950. # 0.0027 BTU inch**-2 second**-1 fahrenheit**-1 h_g = convection.bartz(p_c, c_star, D_t, D_t, c_p, mu_e, Pr, sigma) self.assertTrue(abs(h_g - h_g_huzel) < 1e3)
def test_ssme(self): """Test agaisnt the SSME example from 16.512 Lecture 7.""" T_e = 3200. T_w = 1000. T_avg = (T_e + T_w) / 2 sigma = convection.bartz_sigma_sanchez(T_e, T_avg) p_c = 22e6 c_star = 2600. c_p = 2800. mu_e = 3e-5 Pr = 1 D_t = 0.25 # Not given in example, taken from another reference. # Note: the value for h_g given in the lecture notes, 160e3 W m**-2 K**-1 # appears to be incorrect. Kelly Mathesius and Matt Vernacchia re-did # the calculation, and instead got 22e3 W m**-2 K**-1. h_g_exp = 22e3 # Answer from the example h_g = convection.bartz(p_c, c_star, D_t, D_t, c_p, mu_e, Pr, sigma) self.assertTrue(abs(h_g - h_g_exp) < 0.1e3)