Meanline

.gitignore

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+__pycache__

src/turborocket/meanline/lossmodels.py

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+"""
+
+This file contains a series of loss-model utilities functions for mean-line design of turbines
+
+Each Loss model is encapsulated into an object with a series of functions calculating loss contributions.
+
+Loss-Models currently implemented:
+
+    - craigcox: Loss Model by Craig and Cox
+    - kackerOkapuu: Loss Model by Kacker and Okapuu (1982)
+    - Aungier: Loss Modely by Aungier    
+
+"""
+
+import numpy as np
+
+class Aungier:
+    """
+
+    The Aungier Loss Model
+
+    Variables:
+        Y_p:    Profile Loss parameters
+        K_mod:  Experience factor (derived from the kackerOkapuu method)
+        K_inc:  Off-design incidence factor
+        K_m:    Mach Number Factor
+        K_p:    Compressibility Factor
+        K_RE:   Reynolds Number Factor
+
+        Y_p1:   Profile Loss coefficient for nozzle blades (beta_1 = 0)
+        Y_p2:   Profile Loss coefficent for rotor blades (beta_1 = alpha_2)
+
+        Y_s:    Secondary Flow Losses for low aspect ratio
+
+    """
+
+    def __init__():
+        # Intialising core parameters of the loss model
+        return
+
+    def Y(self):
+        """
+        Total Pressure Loss Coefficient (Y)
+
+        This function solves for the profile loss coefficient of the turbine stage, characterising the increase in total pressure of the turbine exit stage
+
+        Y = (P_t1 - P_t2) / (P_t2 - P_2)
+
+        Variables:
+            Y_p:    The Profile Loss Coefficient
+            Y_s:    The Secondary Flow loss coefficient
+            Y_tcl:  The blade clearnace loss coefficient
+            Y_te:   The trailing edge loss coefficient
+            Y_ex:   The supersonic expansion loss coefficient
+            Y_sh:   The shock loss coefficient
+            T_lw:   The lashing wire loss coefficient (rotors)
+        """
+
+        return Y_p + Y_s + Y_tcl + T_te + Y_ex + Y_sh + Y_lw
+
+    def delta_h_par(self):
+        """
+        Parasitic Losses (delta_h_par)
+
+        The parasitic losses accounts for waster work due to losses in disk friction, shear forces and partial admission.
+
+        These are reflected in an increase in total enthalph of the discharge flow
+        relative to the value produced when the flow passes through the blade row.
+
+        In contrast to the pressure loss coefficient, these losses do not affect total pressure, but do influence stage efficiency.
+
+        Variables:
+            delta_h_adm:    Partial admission losses (rotors)
+            delta_h_df:     Disk friction work (diaphragm-disk rotors)
+            delta_h_seal:   Leakage bypass loss (shourded rotors and rotor balance holes)
+            delta_h_gap:    Clearnace gap windage loss (shrouded blades and nozzles of diaphragm-disk rotors)
+            delta_h_q:      moisture work loss (rotors)
+        """
+
+        return delta_h_adm + delta_h_df + delta_h_seal + delta_h_gap + delta_h_q
+
+    def yp(self):
+        """
+        The Profile Loss Coefficient (Y_p)
+
+        This pressure loss coefficient characterises the profile losses of the turbine stage
+
+        Variables:
+            K_mod:  kackerOkapuu Experience factor
+            K_inc:  Correction for off-design incidence effects
+            K_m:    Correction for Mach Number effects
+            K_p:    correction for Compressibility effects
+            K_re:   correction for Reynolds Number effects
+            Y_p1:   profile loss coefficient for nozzle blades (beta_1 = 90)
+            Y_p2:   profile loss coefficients for impulse blades (alpha_2 = beta_1) 
+
+        Returns:
+            _type_: _description_
+        """
+
+        prt = (y_p1 + ((beta_1/alpha_2)**2 ) * (y_p2 - y_p1))*((5*t/c)**(beta_1/alpha_2)) - delta_y_te
+
+        y_p = k_mod * k_inc * k_m * k_p * k_re * prt;
+
+        return y_p
+
+    def F_ar(self):
+
+        if h_c < 2:
+            f_ar = 0.5 * (2*c/h)**(0.7)
+        else:
+            f_ar = (c/h)
+
+        return f_ar
+
+    def Y_s(self):
+        y_bar_s = 0.0334 * F_ar * (C_l / (s_c))**2 * (np.cos(alpha_2)/np.cos(beta_1))*(np.cos(alpha_2)**2/np.cos(alpha_m)***3)
+
+        y_s = k_s*k_re*(y_bar_s**2 / (1 + 7.5*y_bar_s))**(1/2)
+
+        return y_s
+
+    def Y_sh(self):
+
+        y_bar_sh = 0.8*x_1**2 + x_2**2
+
+        y_sh = (y_bar_sh**2 / (1 + y_bar_sh**2))**(1/2)
+
+        return y_sh
+
+    def Y_ex(self):
+
+        y_ex = ((M2 - 1)/M2)**2;
+
+        return y_ex
+
+    def Y_te(self):
+
+        y_te = ((t_2/s) * np.sin(beta_g) - t_2)**2
+
+        return y_te
+
+    def Y_tcl(self):
+
+        if TIP_TYPE = "shrouded":
+            B = 0.37
+        else:
+            B = 0.47
+
+        Y_tcl = B*(c/h)*(t_cl / c)**(0.78) * (C_l/(s/c))**2 * (np.cos(alpha_2)**2 /np.cos(alpha_m)**3)

src/turborocket/profiling/Supersonic/circular.py

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+"""
+Circular.py
+
+This source file encapsulates all the functions required for sizing the circular sections of the tubrine blade, following the free vortex assumption.
+
+The following equations follows the method for supersonic turbine design presented in NASA TN D-4421.
+
+Free vortex flow is assumed for the blade flow.
+
+# noqa: E501
+"""
+
+import numpy as np
+
+
+def M_star(gamma, M):
+    """
+    Critical Velocity Ratio
+
+    This function computes the critical velocity ratio of the flow as a function of Mach number and specific heat ratio.
+
+    Variables:
+        gamma:  Specific Heat Ratio
+        M:      Mach Number
+
+    # noqa: E501
+    """
+
+    crit_vel_rat = (
+        (((gamma + 1) / 2) * M**2) / (1 + ((gamma - 1) / 2) * M**2)
+    ) ** (1 / 2)
+
+    return crit_vel_rat
+
+
+def prandtl_meyer(gamma, crit_vel_rat):
+    """
+    Prandtl Meyer Angle (v)
+
+    This function computes the Prandtl-Meyer angle v based on the mach number of a flow.
+
+    # noqa: E501
+    """
+
+    v = np.pi / 4 * (((gamma + 1) / (gamma - 1)) ** (1 / 2) - 1) + (1 / 2) * (
+        (((gamma + 1) / (gamma - 1)) ** (1 / 2))
+        * np.arcsin((gamma - 1) * crit_vel_rat**2 - gamma)
+        + np.arcsin((gamma + 1) / crit_vel_rat**2 - gamma)
+    )
+
+    return v
+
+
+def arc_angles_upper(beta_o, beta_i, v_i, v_o, v_u):
+    """
+    Upper Circular Arc Angles Alpha
+
+    This function computes the circular arc angles based on the inlet and outlet angles,
+    coupled with their prantl-meyer angles
+
+    Variables:
+        alpha_l_i:  Lower Arc Inlet Angle
+        alpha_l_o:  Lower Arc Outlet Angle
+        alpha_u_i:  Upper Arc Inlet Angle
+        alpha_u_o:  Upper Arc Outlet Angle
+        beta_i:     Inlet relative flow angle
+        beta_o:     Exit relative
+
+    # noqa: E501
+    """
+
+    alpha_u_i = beta_i - (v_u - v_i)
+
+    alpha_u_o = beta_o + (v_u - v_o)
+
+    return [alpha_u_i, alpha_u_o]
+
+
+def arc_angles_lower(beta_o, beta_i, v_i, v_o, v_l):
+    """
+    Lower Circular Arc Angles Alpha
+
+    This function computes the arc angles based on the inlet and outlet angles, coupled with their prantl-meyer angles
+
+    Variables:
+        alpha_l_i:  Lower Arc Inlet Angle
+        alpha_l_o:  Lower Arc Outlet Angle
+        alpha_u_i:  Upper Arc Inlet Angle
+        alpha_u_o:  Upper Arc Outlet Angle
+        beta_i:     Inlet relative flow angle
+        beta_o:     Exit relative
+
+    # noqa: E501
+    """
+
+    alpha_l_i = beta_i - (v_i - v_l)
+
+    alpha_l_o = beta_o + (v_o - v_l)
+
+    return [alpha_l_i, alpha_l_o]
+
+
+def beta_o(M_i, M_o, gamma, beta_i):
+    """ """
+
+    exit_o = -np.arccos(
+        (
+            (M_i / M_o)
+            * ((1 + (gamma - 1) / 2 * M_o**2) / (1 + (gamma - 1) / 2 * M_i**2))
+            ** ((gamma + 1) / (2 * (gamma - 1)))
+        )
+        * np.cos(beta_i)
+    )
+
+    return exit_o
+
+
+def A_rat(beta_i, beta_o):
+    """
+    The Area Ratio (A_i / A_o)
+
+    This equation computes the area ratio of the supersonic turbine blade, assuming that the spacings are equal on the inlet and exit sides of the turbine (Axial turbine)
+
+    # noqa: E501
+    """
+
+    return np.cos(beta_i) / np.cos(beta_o)