{ "metadata": { "name": "", "signature": "sha256:9f892b4a818165ad52b348800d0ffa60b6a3224f73f3dcda15a72be66b12ba9f" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "CHAPTER12:LINEARIZED SUPERSONIC FLOW" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E01 : Pg 395" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "import math \n", "from math import pi,sqrt\n", "alpha = 5*pi/180; # angle of attack\n", "M_inf = 3; # freestream mach number\n", "\n", "# from eq.(12.23)\n", "c_l = 4*alpha/sqrt(M_inf**2 - 1);\n", "\n", "# from eq.(12.24)\n", "c_d = 4*alpha**2/sqrt(M_inf**2 - 1);\n", "\n", "print\"The cl and cd according to the linearized theory are:cl =\", round(c_l,2)\n", "print\"The cl and cd according to the linearized theory are:cd =\",round(c_d,2)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The cl and cd according to the linearized theory are:cl = 0.12\n", "The cl and cd according to the linearized theory are:cd = 0.01\n" ] } ], "prompt_number": 1 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E02 : Pg 395" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "import math \n", "from math import sqrt,pi\n", "M_inf = 2.; # freestream mach number\n", "rho_inf = 0.3648; # freestream density at 11 km altitude\n", "T_inf = 216.78; # freestream temperature at 11 km altitude\n", "gam = 1.4; # ratio of specific heats\n", "R = 287.; # specific gas constant\n", "m = 9400.; # mass of the aircraft\n", "g = 9.8; # acceleratio due to gravity\n", "W = m*g; # weight of the aircraft\n", "S = 18.21; # wing planform area\n", "# thus\n", "a_inf = sqrt(gam*R*T_inf);\n", "V_inf = M_inf*a_inf;\n", "q_inf = 1./2.*rho_inf*V_inf**2.;\n", "\n", "# thus the aircraft lift coefficient is given as\n", "C_l = W/q_inf/S;\n", "\n", "alpha = 180./pi*C_l/4.*sqrt(M_inf**2. - 1.);\n", "\n", "print\"The angle of attack of the wing is:\",alpha,\"degrees\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The angle of attack of the wing is: 1.97493716351 degrees\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E03 : Pg 400" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "# All the quantities are expressed in SI units\n", "import math \n", "from math import sqrt,pi\n", "# (a)\n", "M_inf = 2.; # freestream mach number\n", "rho_inf = 0.3648; # freestream density at 11 km altitude\n", "T_inf = 216.78; # freestream temperature at 11 km altitude\n", "gam = 1.4; # ratio of specific heats\n", "R = 287.; # specific gas constant\n", "m = 9400.; # mass of the aircraft\n", "g = 9.8; # acceleratio due to gravity\n", "W = m*g; # weight of the aircraft\n", "S = 18.21; # wing planform area\n", "c = 2.2; # chord length of the airfoil\n", "alpha = 0.035; # angle of attack as calculated in ex. 12.2\n", "T0 = 288.16; # ambient temperature at sea level\n", "mue0 = 1.7894e-5; # reference viscosity at sea level\n", "\n", "# thus\n", "a_inf = sqrt(gam*R*T_inf);\n", "V_inf = M_inf*a_inf;\n", "\n", "# according to eq.(15.3), the viscosity at the given temperature is\n", "mue_inf = mue0*(T_inf/T0)**1.5*(T0+110.)/(T_inf+110.);\n", "\n", "# thus the Reynolds number can be given by\n", "Re = rho_inf*V_inf*c/mue_inf;\n", "\n", "# from fig.(19.1), for these values of Re and M, the skin friction coefficient is\n", "Cf = 2.15*10**-3;\n", "\n", "# thus, considering both sides of the flat plate\n", "net_Cf = 2.*Cf;\n", "\n", "# (b)\n", "c_d = 4.*alpha**2./sqrt(M_inf**2. - 1.);\n", "\n", "print\"(a) Net Cf = \",net_Cf*1e3\n", "print\"(b) cd =\",c_d*1e3" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "(a) Net Cf = 4.3\n", "(b) cd = 2.82901631903\n" ] } ], "prompt_number": 3 } ], "metadata": {} } ] }