{ "metadata": { "name": "", "signature": "sha256:50af8d3cf8d660e7f072a797c56082a406513e091b4f2f4b68a912e6ceab549d" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "CHAPTER19:TURBULENT BOUNDARY LAYERS" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E01 : Pg 612" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "# (a)\n", "import math \n", "from math import sqrt\n", "Re_c = 1.36e7; # as obtained from ex. 18.1a\n", "rho_inf = 1.22; # freestream air denstiy\n", "S = 40.; # plate planform area\n", "# hence, from eq.(19.2)\n", "Cf = 0.074/Re_c**0.2;\n", "V_inf = 100.;\n", "# hence, for one side of the plate\n", "D_f = 1./2.*rho_inf*V_inf**2.*S*Cf;\n", "# the total drag on both the surfaces is\n", "D = 2.*D_f;\n", "print\"The total frictional drag is: (a)D =\",D,\"N\"\n", "# (b)\n", "Re_c = 1.36e8; # as obtained from ex. 18.1b\n", "# hence, from fig 19.1 we have\n", "Cf = 1.34*10.**-3.;\n", "V_inf = 1000.;\n", "# hence, for one side of the plate\n", "D_f = 1./2.*rho_inf*V_inf**2.*S*Cf;\n", "# the total drag on both the surfaces is\n", "D = 2.*D_f;\n", "print\"(b) D =\",D,\"N\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The total frictional drag is: (a)D = 1351.89748485 N\n", "(b) D = 65392.0 N\n" ] } ], "prompt_number": 1 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E02 : Pg 612" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "# from ex 18.2\n", "import math\n", "from math import sqrt\n", "Re_c_star = 3.754e7; # Reynolds number at the trailing edge of the plate\n", "rho_star = 0.574;\n", "ue = 1000.; # velocity of the upper plate\n", "S = 40.; # plate planform area\n", "# from eq.(19.3) we have\n", "Cf_star = 0.074/Re_c_star**0.2;\n", "# hence, for one side of the plate\n", "D_f = 1./2.*rho_star*ue**2.*S*Cf_star;\n", "# the total drag on both the surfaces is\n", "D = 2.*D_f;\n", "print\"The total frictional drag is:D =\",D,\"N\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The total frictional drag is:D = 51916.421508 N\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E03 : Pg 615" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "Me = 2.94; # mach number of the flow over the upper plate\n", "ue = 1000.;\n", "Te = 288.; # temperature of the upper plate\n", "ue = 1000.; # velocity of the upper plate\n", "S = 40.; # plate planform area\n", "Pr = 0.71; # Prandlt number of air at standard condition\n", "gam = 1.4; # ratio of specific heats\n", "\n", "# the recovery factor is given as\n", "r = Pr**(1./3.);\n", "\n", "# for M = 2.94\n", "T_aw = Te*(1.+r*(2.74-1.));\n", "T_w = T_aw; # since the flat plate has an adiabatic wall\n", "\n", "# from the Meador-Smart equation\n", "T_star = Te*(0.5*(1.+T_w/Te) + 0.16*r*(gam-1.)/2.*Me**2.);\n", "\n", "# from the equation of state\n", "p_star=1.\n", "R=1.\n", "rho_star = p_star/R/T_star;\n", "\n", "# from eq.(15.3)\n", "mue0=1.\n", "T0=1.\n", "c=1.\n", "mue_star = mue0*(T_star/T0)**1.5*(T0+110.)/(T_star+110.);\n", "\n", "# thus\n", "Re_c_star = rho_star*ue*c/mue_star;\n", "\n", "# from eq.(18.22)\n", "Cf_star = 0.02667/Re_c_star**0.139;\n", "\n", "# hence, the frictional drag on one surface of the plate is\n", "D_f = 1./2.*rho_star*ue**2.*S*Cf_star;\n", "\n", "# thus, the total frictional drag is given by\n", "D = 2.*D_f;\n", "\n", "print\"The total frictional drag is:D =\",D,\"N\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The total frictional drag is:D = 4967.70450221 N\n" ] } ], "prompt_number": 3 } ], "metadata": {} } ] }