Prop

gpkitmodels/GP/aircraft/prop/prop_test.py

@@ -0,0 +1,31 @@
+" propelle tests "
+from propeller import Propeller
+from qprop import QProp
+from gpkitmodels.GP.aircraft.wing.wing_test import FlightState
+
+def eta_test():
+
+    fs = FlightState()
+    p = Propeller(fs)
+    p.substitutions[p.T] = 100
+    p.cost = 1/p.eta
+    sol = p.solve()
+    print sol.table()
+
+def qprop_test():
+
+    fs = FlightState()
+    p = QProp(fs)
+    p.substitutions[p.T] = 100
+    p.cost = 1/p.eta
+    sol = p.solve()
+    print sol.table()
+
+def test():
+    "tests"
+    eta_test()
+    #qprop_test()
+
+if __name__ == "__main__":
+    test()
+

gpkitmodels/GP/aircraft/prop/propeller.py

@@ -0,0 +1,60 @@
+" propeller model "
+from numpy import pi
+from gpkit import Model, parse_variables, SignomialsEnabled, SignomialEquality
+
+class Propeller(Model):
+    """ Propeller Model
+
+    Variables
+    ---------
+    R          10           [m]         prop radius
+    W          10           [lbf]        prop weight
+
+    """
+    def setup(self):
+        exec parse_variables(Propeller.__doc__)
+
+    def performance(self,state):
+        return Propeller_Performance(self, state)
+
+class Propeller_Performance(Model):
+    """ Propeller Model
+
+    Variables
+    ---------
+    T                       [N]         thrust
+    Tc                      [-]         coefficient of thrust
+    etaadd     0.7          [-]         swirl and nonuniformity losses
+    etav       0.85         [-]         viscous losses
+    etai                    [-]         inviscid losses
+    eta                     [-]         overall efficiency
+    z1         self.helper  [-]         efficiency helper 1
+    z2                      [-]         efficiency helper 2
+    lam                     [-]         advance ratio
+    CT                      [-]         thrust coefficient
+    CP                      [-]         power coefficient
+    Q                       [N*m]       torque
+    omega                   [RPM]       propeller rotation rate 
+
+    """
+
+    def helper(self, c):
+        return 2. - 1./c[self.etaadd]
+
+    def setup(self,parent,  state):
+        exec parse_variables(Propeller_Performance.__doc__)
+
+        V       = state.V
+        rho     = state.rho
+        R       = parent.R        
+
+        constraints = [eta <= etav*etai,
+                Tc == T/(0.5*rho*V**2*pi*R**2),
+                z2 >= Tc + 1,
+                etai*(z1 + z2**0.5/etaadd) <= 2,
+                lam == V/(omega*R),
+                CT == Tc*lam**2,
+                CP == Q*omega/(.5*rho*(omega*R)**3*math.pi*R**2),
+                eta == CT*lam/CP, #Is this the same eta? check 
+                ]
+        return constraints

gpkitmodels/GP/aircraft/prop/qprop.py

@@ -0,0 +1,58 @@
+" qprop model "
+from numpy import pi
+from gpkit import Model, parse_variables
+from gpkit.constraints.tight import Tight as TCS
+from gpfit.fit_constraintset import FitCS
+import pandas as pd
+from os.path import abspath
+
+class QProp(Model):
+    """ Propeller Model
+
+    Variables
+    ---------
+    T                       [N]         thrust
+    B          2            [-]         number of blades
+    r          0.5          [m]         local radius
+    R          1            [m]         propeller radius
+    dr         1            [m]         local delta radius
+    Q                       [N*m]       torque
+    G                       [m**2/s]    prop circulation
+    Omega     1000          [rpm]     rotation rate
+    eta                     [-]         prop efficiency
+    W                       [m/s]       local total velocity
+    Wa                      [m/s]       axial local total velocity
+    Wt                      [m/s]       tangential local total velocity
+    va                      [m/s]       axial local rotor-induced velocity
+    vt                      [m/s]       tangential local rotor-induced velocity
+    ep         0.1          [-]         inverse local lift to drag
+    cl         1.0          [-]         local coefficient of lift
+    c          0.1          [m]         local blade chord
+    F          0.5          [-]         Prandtl factor
+    lamw                    [-]         local wake advance ratio
+    f                       [-]         Prandtl exponent
+
+    """
+
+    def setup(self, state):
+        exec parse_variables(QProp.__doc__)
+
+        V = state.V
+        rho = state.rho
+
+        df = pd.read_csv(abspath("arccosfit.csv"))
+        fd = df.to_dict(orient="records")[0]
+
+        return [eta <= V*T/Omega/Q,
+                Q >= rho*B*G*(Wa + ep*Wt)*r*dr,
+                G >= 0.5*W*c*cl,
+                W**2 >= Wa**2 + Wt**2,
+                Wa >= V + va,
+                va >= vt*Wt/Wa,
+                Wt >= Omega*r,
+                # vt**2*(1 + (4*lamw*R/pi/B/r)**2) >= (B*G/4/pi/r/F)**2,
+                vt >= (B*G/4/pi/r/F),
+                # lamw >= r/R*(vt/va),
+                # f >= B/2*(0.5)*R/r*(va/vt),
+                # FitCS(fd, F, [f])
+               ]