{ "metadata": { "name": "", "signature": "sha256:6ab6ca7ec50b12b4ad5664b1412855d8b1bafd30fee8faf6c1773c772ff215d4" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Chapter13-Fluid Machines" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex1-pg618" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "#calculate Hydraulic Efficiency and Overall Efficiency and Outlet angles of the guide vanes and Rotor blade angle at inlet and oulet\n", "\n", "## Maximum hydraulic efficiency occurs for minimum pressure loss, that is, when\n", "\n", "## dp1/dQ=2.38Q-1.43=0\n", "\n", "Q_opt=1.43/2.38;\n", "\n", "p1_min=1.19*Q_opt**2-1.43*Q_opt+0.47; ## MPa\n", "\n", "rho=1000.; ## kg/m**3\n", "g=9.81; ## m/s**2\n", "w=69.1; ## rad/s\n", "P=200.*10.**3.; ## W\n", "Ohm_P=0.565; ## rad\n", "d=0.5; ## m\n", "h=0.06; ## m\n", "\n", "p1=p1_min*10.**6./(rho*g); ## mH2O, coversion of units\n", "\n", "H=(w*P**(1/2.)/(rho**(1/2.)*Ohm_P))**(4/5.)/g;\n", "\n", "Hydraulic_efficiency=(H-p1)/H;\n", "print'%s %.3f %s'%(\"Hydraulic Efficiency =\",Hydraulic_efficiency,\"\")\n", "\n", "\n", "Overall_efficiency=P/(Q_opt*rho*g*H);\n", "print'%s %.3f %s'%(\"Overall Efficiency =\",Overall_efficiency,\"\")\n", "\n", "\n", "H_Euler=H-p1;\n", "\n", "u1=w*0.25;\n", "v_w1=g*H_Euler/u1;\n", "A=math.pi*d*h*0.95; \n", "v_r=Q_opt/A;\n", "\n", "alpha1=math.atan(v_r/v_w1);\n", "print'%s %.3f %s'%(\"Outlet angles of the guide vanes =\",alpha1,\"degrees\")\n", "\n", "beta1=math.atan(v_r/(v_w1-u1));\n", "print'%s %.2f %s'%(\"Rotor blade angle at inlet =\",beta1,\"degrees\")\n", "\n", "u2=w*0.325/2;\n", "beta2=math.atan(v_r/u2);\n", "print'%s %.3f %s'%(\"Rotor blade angle at outlet =\",beta2,\"degrees\")\n", "\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Hydraulic Efficiency = 0.896 \n", "Overall Efficiency = 0.855 \n", "Outlet angles of the guide vanes = 0.321 degrees\n", "Rotor blade angle at inlet = 1.16 degrees\n", "Rotor blade angle at outlet = 0.539 degrees\n" ] } ], "prompt_number": 1 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex2-pg622" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "#calculate Overall efficiency and Limiting value for the height of the draft tube above\n", "w=6.25;\n", "D=0.75; ## m\n", "gv_angle=15; ## guide vane angle in degrees\n", "g=9.81; ## m/s^2\n", "H=27.5; ## m\n", "A1=0.2; ## m^2\n", "rho=1000.; ## kg/m^3\n", "p_atm=101.3*10**3.;\n", "p_min=35.*10.**3.;\n", "\n", "u1=math.pi*w*D;\n", "v1=u1*math.sin(105.)/math.sin(60.);\n", "v_r1=v1*math.sin(gv_angle);\n", "v_w1=v1*math.cos(gv_angle);\n", "v_w2=0.;\n", "\n", "n_hydraulic=u1*v_w1/g/H;\n", "\n", "n_overall=0.97*n_hydraulic;\n", "print'%s %.1f %s'%(\"Overall efficiency =\",n_overall,\"\")\n", "\n", "\n", "Q=A1*v_r1;\n", "\n", "P=n_overall*Q*rho*g*H;\n", "Ohm_P=w*2.*math.pi/(g*H)**(5/4)*(P/rho)**(1/2);\n", "\n", "## sigma > 0.119*(0.5)^(1.84) = 0.0331\n", "\n", "sigma=0.0331;\n", "\n", "##((p_atm-p_min)/(rho*g)-z0)/H > 0.0331\n", "\n", "z0=((p_atm-p_min)/(rho*g))-sigma*H;\n", "print'%s %.2f %s'%(\"Limiting value for the height of the draft tube above =\",z0,\"m\")\n", "\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Overall efficiency = -1.9 \n", "Limiting value for the height of the draft tube above = 5.85 m\n" ] } ], "prompt_number": 2 } ], "metadata": {} } ] }