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{
"metadata": {
"name": ""
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 13: Engine friction and lubrication"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 13.1 Page No 423"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Input data\n",
"d=0.08\t\t #The diameter of bore in m\n",
"L=0.075\t\t #The length of the stroke in m\n",
"l=0.152\t\t #The connecting rod length in m\n",
"h=0.062\t\t #Skirt length of the piston in m\n",
"Fr=8000\t\t #Compressive force in the connecting rod in N\n",
"p=3000\t\t #The pressure in the cylinder kPa\n",
"y=0.004*10**-3\t #The clearence between piston and cylinder wall in m\n",
"U=0.006\t\t #The dynamic viscosity of the lubricating oil in pa.s\n",
"u=8.2\t\t #The piston speed in m/s\n",
"\n",
"#Calculations\n",
"import math\n",
"ts=(U*u)/y\t #The shear stress in N/m**2\n",
"A=pi*d*h\t #Contact area between the piston and the cylinder in m**2\n",
"Ff=ts*A\t\t #Friction force on the piston inN\n",
"r=L/2.0\t\t #Crank length in m\n",
"A=math.atan(r/l)\t #The angle made by the crank in radians\n",
"Ft=Fr*sin(A)\t#The side thrust in N\n",
"\n",
"#Output \n",
"print\"The friction force on the piston \",round(Ff,0),\"N\"\n",
"print\"The thrust force on the cylinder wall is\",round(Ft,0),\"N\"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The friction force on the piston 192.0 N\n",
"The thrust force on the cylinder wall is 1916.0 N\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 13.2 Page No 424"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Input data\n",
"d=0.065\t\t#The cylinder bore diameter in m\n",
"L=6.0\t\t#The length of the stroke in cm\n",
"l=12.0\t\t#The length of the connecting rod in cm\n",
"p=50.0\t\t#The pressure in the cylinder in bar\n",
"q=90.0\t\t#The crank position in power stroke of the cycle for one cylinder in degrees\n",
"Ff=900.0\t\t#Friction force in N\n",
"o=0.2\t\t#Wrist pin off set in cm\n",
"\n",
"#Calculations\n",
"r=L/2.0\t\t#The crank length in cm\n",
"sineA=r/l\t \n",
"cosA=(1-(sineA)**2)**(1/2.0)\t\n",
"Fr=(((p*10**5*(pi/4.0)*d**2)-Ff)/cosA)/1000.0 \n",
"Ft=Fr*sineA\t #The side thrust on the piston in kN\n",
"sineA1=(r-o)/l\t#The value of sine\n",
"cosA1=(1-(sineA1)**2)**(1/2.0)\t\t\t\n",
"Fr1=(((p*10**5*(pi/4.0)*d**2)-Ff)/cosA1)/1000.0\t\n",
"Ft1=Fr1*sineA1 #The side thrust in kN\n",
"\n",
"#Output \n",
"print\"(a) The force in the connecting rod \",round(Fr,3),\" kN\"\n",
"print\"The side thrust on the piston =\",round(Ft,2),\"kN\"\n",
"print\"(b) The side thrust on the piston =\",round(Ft1,3),\" kN\"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(a) The force in the connecting rod 16.206 kN\n",
"The side thrust on the piston = 4.05 kN\n",
"(b) The side thrust on the piston = 3.765 kN\n"
]
}
],
"prompt_number": 3
}
],
"metadata": {}
}
]
}
|
