{ "metadata": { "name": "", "signature": "sha256:673810cabac48e32fa28182f2f2ca38e3fabfd4e716ae55b274dc47aad093ef0" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "CHAPTER03 : FUNDAMENTALS OF INVISCID INCOMPRESSIBLE FLOW" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E01 : Pg 63" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "import math \n", "from math import sqrt\n", "rho_inf = 1.23; # freestream density of air at sea level\n", "p_inf = 101000.; # freestream static pressure\n", "v_inf = 50.; # freestream velocity\n", "p = 90000.; # pressure at given point\n", "\n", "# The velocity at the given point can be expressed as\n", "v = sqrt((2.*(p_inf-p)/rho_inf) + (v_inf**2.));\n", "\n", "print\"The velocity at the given point is V =\",v,\"m/s\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The velocity at the given point is V = 142.780176712 m/s\n" ] } ], "prompt_number": 1 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E02 : Pg 64" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "rho = 1.225; # freestream density of air along the streamline\n", "p_1 = 101314.1; # pressure at point 1\n", "v_1 = 3.05; # velocity at point 1\n", "v_2 = 57.91; # velocity at point 2\n", "# The pressure at point 2 on the given streamline can be given as\n", "p_2 = p_1 + 1/2*rho*((v_1**2) - (v_2**2));\n", "print\"The pressure at point 2 is p2 =\",p_2,\"Pa\\n\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The pressure at point 2 is p2 = 101314.1 Pa\n", "\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E03 : Pg 69" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "import math \n", "rho = 1.225; # freestream density of air along the streamline\n", "delta_p = 335.16; # pressure difference between inlet and throat\n", "ratio = 0.8; # throat-to-inlet area ratio\n", "# The velocity at the inlet can be given as\n", "v_1 = math.sqrt(2*delta_p/rho/(((1/ratio)**2)-1));\n", "print\"The value of velocity at the inlet is V1 =\",v_1,\"m/s\\n\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The value of velocity at the inlet is V1 = 31.1897419034 m/s\n", "\n" ] } ], "prompt_number": 3 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E04 : Pg 72" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "import math \n", "rho=1.23; # freestream density of air along the streamline\n", "v=50.; # operating velocity inside wind tunnel\n", "rho_hg = 13600.; # density of mercury\n", "ratio = 12.; # contraction ratio of the nozzle\n", "g = 9.8; # acceleration due to gravity\n", "w = rho_hg*g; # weight per unit volume of mercury\n", "# The pressure difference delta_p between the inlet and the test section is given as\n", "delta_p = 1./2.*rho*v*v*(1.-(1./ratio**2.));\n", "# Thus the height difference in a U-tube mercury manometer would be\n", "delta_h = delta_p/w;\n", "print\"The height difference in a U-tube mercury manometer is delta_h =\",delta_h,\"m\\n\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The height difference in a U-tube mercury manometer is delta_h = 0.0114557541767 m\n", "\n" ] } ], "prompt_number": 4 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E05 : Pg 73" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# all the quantities are expressed in SI units\n", "import math \n", "from math import sqrt \n", "ratio = 12.; # contraction ratio of wind tunnel nozzle\n", "Cl_max = 1.3; # maximum lift coefficient of the model\n", "S = 0.56; # wing planform area of the model\n", "L_max = 4448.22; # maximum lift force that can be measured by the mechanical balance\n", "rho_inf = 1.225; # free-stream density of air\n", "# the maximum allowable freestream velocity can be given as\n", "V_inf = sqrt(2.*L_max/rho_inf/S/Cl_max);\n", "# thus the maximum allowable pressure difference is given by\n", "delta_p = 1./2.*rho_inf*(V_inf**2.)*(1.-(ratio**-2.));\n", "print\"The maximum allowable pressure difference between the wind tunnel setling chamber and the test section is delta_p =\",delta_p,\"Pa\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The maximum allowable pressure difference between the wind tunnel setling chamber and the test section is delta_p = 6067.76041667 Pa\n" ] } ], "prompt_number": 5 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E06 : Pg 75" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# all the quantities are expressed in SI units\n", "\n", "V2 = 100.*1609./3600.; # test section flow velocity converted from miles per hour to meters per second\n", "p_atm = 101000.; # atmospheric pressure\n", "p2 = p_atm; # pressure of the test section which is vented to atmosphere\n", "rho = 1.23; # air density at sea level\n", "ratio = 10.; # contraction ratio of the nozzle\n", "\n", "# the pressure difference in the wind tunnel can be calculated as\n", "delta_p = rho/2.*(V2**2.)*(1.-(1./ratio**2.));\n", "\n", "# thus the reservoir pressure can be given as\n", "p1 = p2 + delta_p;\n", "\n", "p1_atm = p1/p_atm; # reservoir pressure expressed in units of atm\n", "\n", "print\"The reservoir pressure is p1 =\",p1_atm,\"atm\"\n", "\n", "#Ex3_6b\n", "# all the quantities are expressed in SI units\n", "\n", "V2 = 89.4; # test section flow velocity converted from miles per hour to meters per second\n", "p_atm = 101000; # atmospheric pressure\n", "p2 = p_atm; # pressure of the test section which is vented to atmosphere\n", "rho = 1.23; # air density at sea level\n", "ratio = 10; # contraction ratio of the nozzle\n", "\n", "# the pressure difference in the wind tunnel can be calculated as\n", "delta_p = rho/2*(V2**2)*(1-(1/ratio**2));\n", "\n", "# thus the reservoir pressure can be given as\n", "p1 = p2 + delta_p;\n", "\n", "p1_atm = p1/p_atm; # reservoir pressure expressed in units of atm\n", "\n", "print\"The new reservoir pressure is p1 =\",p1_atm,\"atm\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The reservoir pressure is p1 = 1.01204192792 atm\n", "The new reservoir pressure is p1 = 1.0486663505 atm\n" ] } ], "prompt_number": 6 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E07 : Pg 80" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# all the quantities are expressed in SI units\n", "import math \n", "p0 = 104857.2; # total pressure as measured by the pitot tube\n", "p1 = 101314.1; # standard sea level pressure\n", "rho = 1.225; # density of air at sea level\n", "\n", "# thus the velocity of the airplane can be given as\n", "V1 = math.sqrt(2*(p0-p1)/rho);\n", "\n", "print\"The velocity of the airplane is V1 =\",V1,\"atm\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The velocity of the airplane is V1 = 76.0569067293 atm\n" ] } ], "prompt_number": 7 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E08 : Pg 82" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# all the quantities are expressed in SI units\n", "\n", "V_inf = 100.1; # freestream velocity\n", "p_inf = 101314.1; # standard sea level pressure\n", "rho_inf = 1.225; # density of air at sea level\n", "\n", "# the dynamic pressure can be calculated as\n", "q_inf = 1/2*rho_inf*(V_inf**2);\n", "\n", "# thus the total pressure is given as\n", "p0 = p_inf + q_inf;\n", "\n", "print\"The total pressure measured by pitot tube is p0 =\",p0,\"Pa\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The total pressure measured by pitot tube is p0 = 101314.1 Pa\n" ] } ], "prompt_number": 8 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E09 : Pg 85" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# all the quantities are expressed in SI units\n", "import math \n", "p0 = 6.7e4; # total pressure as measured by the pitot tube\n", "p1 = 6.166e4; # ambient pressure at 4km altitude\n", "rho = 0.81935; # density of air at 4km altitude\n", "\n", "# thus the velocity of the airplane can be given as\n", "V1 = math.sqrt(2*(p0-p1)/rho);\n", "\n", "print\"The velocity of the airplane is V1 =\",V1,\"m/s =\",V1/0.447,\"mph\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The velocity of the airplane is V1 = 114.169709845 m/s = 255.413221129 mph\n" ] } ], "prompt_number": 9 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E10 : Pg 88" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# all the quantities are expressed in SI units\n", "import math \n", "from math import sqrt\n", "V1 =114.2; # velocity of airplane at 4km altitude\n", "rho = 0.81935; # density of air at 4km altitude\n", "q1 = 1./2.*rho*(V1**2.) # dynamic pressure experienced by the aircraft at 4km altitude\n", "rho_sl = 1.23; # density of air at sea level\n", "# according to the question\n", "q_sl = q1; # sealevel dynamic pressure\n", "# thus the equivallent air speed at sea level is given by\n", "Ve = sqrt(2*q_sl/rho_sl);\n", "print\"The equivallent airspeed of the airplane is Ve =\",Ve,\"m/s\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The equivallent airspeed of the airplane is Ve = 93.2069457878 m/s\n" ] } ], "prompt_number": 10 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E11 : Pg 89" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# all the quantities are expressed in SI units\n", "V_inf = 45.72; # freestream velocity\n", "V = 68.58; # velocity at the given point\n", "# the coeeficient of pressure at the given point is given as\n", "Cp = 1. - (V/V_inf)**2.;\n", "print\"The coefficient of pressure at the given point is Cp =\",Cp" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The coefficient of pressure at the given point is Cp = -1.25\n" ] } ], "prompt_number": 11 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E12 : Pg 91" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# all the quantities are expressed in SI units\n", "import math \n", "from math import sqrt,pi\n", "Cp = -5.3; # peak negative pressure coefficient\n", "V_inf = 24.38; # freestream velocity\n", "\n", "# the velocity at the given point can be calculated as\n", "V = sqrt(V_inf**2*(1-Cp));\n", "\n", "print\"The velocity at the given point is V =\",V,\"m/s\"\n", "\n", "#Ex3_12b\n", "# all the quantities are expressed in SI units\n", "import math \n", "Cp = -5.3; # peak negative pressure coefficient\n", "V_inf = 91.44; # freestream velocity\n", "# the velocity at the given point can be calculated as\n", "V = math.sqrt(V_inf**2*(1-Cp));\n", "\n", "print\"The velocity at the given point is V =\",V,\"m/s\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The velocity at the given point is V = 61.1933143407 m/s\n", "The velocity at the given point is V = 229.512578479 m/s\n" ] } ], "prompt_number": 13 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E13 : Pg 100" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# all the quantities are expressed in SI units\n", "# When p = p_inf, Cp = 0, thus\n", "# 1-4*(sin(theta)**2) = 0\n", "# thus theta can be given as\n", "#theta = (asind(1/2), 180-asind(1/2), 180-asind(-1/2), 360+asind(-1/2)); # sine inverse of 1/2 and -1/2 where theta varies from 0 to 360 degrees\n", "theta1=30.;#\n", "theta2=150.;#\n", "theta3=210.;#\n", "theta4=330.;#\n", "print\"The angular locations where surface pressure equals freestream pressure are theta=\",theta1,theta2,theta3,theta4,\"degrees\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The angular locations where surface pressure equals freestream pressure are theta= 30.0 150.0 210.0 330.0 degrees\n" ] } ], "prompt_number": 14 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E14 : Pg 103" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "import math \n", "Cl = 5; # lift coefficient of the cylinder\n", "V_by_Vinf = -2 - Cl/2/math.pi; # ratio of maximum to freestream velocity\n", "\n", "# thus the pressure coefficient can be calculated as\n", "Cp = 1 - (V_by_Vinf**2);\n", "\n", "print\"The peak negative pressure coefficient is Cp =\",Cp" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The peak negative pressure coefficient is Cp = -5.95176382404\n" ] } ], "prompt_number": 15 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E15 : Pg 106" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "#theta = (180-asind(-5/4/math.pi) 360+asind(-5/4/math.pi)); # location of the stagnation points\n", "theta1=203.4;#\n", "theta2=336.6;#\n", "print\"The angular location of the stagnation points are theta =\",theta1, theta2,\"degrees\"\n", "#function temp = Cp(thet)\n", "# temp = 0.367 -3.183*sind(thet) - 4*(sind(thet)**2); # Cp written as a function of theta\n", "#endfunction\n", "Cp90=-6.82;#\n", "print \"\\nCp =\",Cp90\n", "#[k] = roots([-4 -3.183 0.367]);\n", "#theta_2 = 180/math.pi*(math.pi-asin(k(1)), 2*math.pi+asin(k(1)), asin(k(2)), math.pi-asin(k(2)));\n", "theta_2_1=243.9;#\n", "theta_2_2=296.11;#\n", "theta_2_3=5.86;#\n", "theta_2_4=174.1;#\n", "Cp270=-0.45;#\n", "print\"\\nThe angular location of points on the cylinder where p = p_inf is theta =\",theta_2_1,theta_2_2,theta_2_3,theta_2_4\n", "print\"\\nThe value of Cp at the bottom of the cylinder is Cp = \",Cp270" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The angular location of the stagnation points are theta = 203.4 336.6 degrees\n", "\n", "Cp = -6.82\n", "\n", "The angular location of points on the cylinder where p = p_inf is theta = 243.9 296.11 5.86 174.1\n", "\n", "The value of Cp at the bottom of the cylinder is Cp = -0.45\n" ] } ], "prompt_number": 16 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example E16 : Pg 110" ] }, { "cell_type": "code", "collapsed": false, "input": [ "# All the quantities are expressed in SI units\n", "import math \n", "rho_inf = 0.90926; # density of air at 3km altitude\n", "V_theta = -75; # maximum velocity on the surface of the cylinder\n", "V_inf = 25; # freestream velocity\n", "R = 0.25; # radius of the cylinder\n", "\n", "# thus the circulation can be calculated as\n", "tow = -2*math.pi*R*(V_theta+2*V_inf);\n", "\n", "# and the lift per unit span is given as\n", "L = rho_inf*V_inf*tow;\n", "\n", "print\"The Lift per unit span for the given cylinder is L=\",L,\"N\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "The Lift per unit span for the given cylinder is L= 892.663917563 N\n" ] } ], "prompt_number": 17 } ], "metadata": {} } ] }