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"source": [
"## Chapter 12: Turbomachines"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Example 12.1 Page no 443"
]
},
{
"cell_type": "code",
"execution_count": 1,
"metadata": {
"collapsed": false
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{
"name": "stdout",
"output_type": "stream",
"text": [
"Efficiency of th pump = 74.0 %\n"
]
}
],
"source": [
"# Example 12.1\n",
"\n",
"from math import *\n",
"\n",
"from __future__ import division\n",
"\n",
"# Given\n",
"\n",
"Q = 0.25 # discharge from the pump in m**3/s\n",
"\n",
"gma= 0.8*9810 # specific weight in kg/m**3\n",
"\n",
"H=25 # elevation head in m\n",
"\n",
"T = 350 # Torque to drive the shaft in Nm\n",
"\n",
"N = 1800 # Speed in RPM\n",
"\n",
"w = 2*pi*N/60 # angular velocity\n",
"\n",
"# Solution\n",
"\n",
"Eff = gma*Q*H*100/(T*w) # efficiency\n",
"\n",
"print \"Efficiency of th pump =\",round(Eff,0),\"%\""
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Example 12.2 Page no 447"
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {
"collapsed": false
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"outputs": [
{
"name": "stdout",
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"text": [
" (a)\n",
"Radial velocity at exit = 10.6 m/s\n",
"Whirl velocity = 25.3 m/s\n",
"Relative velocity = 12.25 m/s\n",
"Actual velocity = 27.43 m/s\n",
"(b)\n",
"Head added for no inlet whirl = 81.0 m\n",
"(c)\n",
"Power required = 317.8 kW\n"
]
}
],
"source": [
"# Example 12.2\n",
"\n",
"from math import *\n",
"\n",
"from __future__ import division\n",
"\n",
"# Given\n",
"\n",
"d = 0.4 # diameter of the pump in m\n",
"\n",
"b = 0.03 # width in m\n",
"\n",
"theta = pi/3 # blade angle\n",
"\n",
"N = 1500 # speed in RPM\n",
"\n",
"Q = 0.4 # flow rate in m**3/s\n",
"\n",
"g = 9.81 # acceleration due to gravity in m/s**2\n",
"\n",
"# Solution\n",
"\n",
"w = 2*pi*N/60 # anggular velocity in rad/s\n",
"\n",
"u2 = (d/2)*w # blade velocity in m/s\n",
"\n",
"V2r = Q/(2*pi*(d/2)*b) # relative velocity in m/s\n",
"\n",
"print \"(a)\"\n",
"\n",
"print \"Radial velocity at exit =\",round(V2r,1),\"m/s\"\n",
"\n",
"V2t = u2 - V2r*(cos(theta)/sin(theta))\n",
"\n",
"print \"Whirl velocity = \",round(V2t,1),\"m/s\"\n",
"\n",
"v2 = V2r/sin(theta)\n",
"\n",
"print \"Relative velocity = \",round(v2,2),\"m/s\"\n",
"\n",
"V2 = sqrt(V2t**2+V2r**2)\n",
"\n",
"print \"Actual velocity =\",round(V2,2),\"m/s\"\n",
"\n",
"print \"(b)\"\n",
"\n",
"H = u2*V2t/g\n",
"\n",
"print\"Head added for no inlet whirl =\",round(H,0),\"m\"\n",
"\n",
"print \"(c)\"\n",
"\n",
"P = g*Q*H\n",
"\n",
"print \"Power required =\",round(P,1),\"kW\""
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Example 12.3 Page no 450"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Impeller size = 38.45 cm\n",
"Speed of the pump = 1500.0 RPM\n"
]
}
],
"source": [
"# Example 12.3\n",
"\n",
"from math import *\n",
"\n",
"from __future__ import division\n",
"\n",
"# Given\n",
"\n",
"d = 0.36 # diameter of the impeller of pump\n",
"\n",
"N = 1500 # Speed of impeller in RPM\n",
"\n",
"# Solution\n",
"\n",
"# For best efficiency\n",
"\n",
"Q1 = 82 # discharge in l/s\n",
"\n",
"H1 = 17.5 # Head in m\n",
"\n",
"Eta = 0.8 # efficiency \n",
"\n",
"Q2 = 100 # discharge in l/s\n",
"\n",
"H2 = 20 # head in m\n",
"\n",
"# Solving the simulataneous equation we get\n",
"\n",
"D2 = 38.45\n",
"\n",
"print \"Impeller size =\",round(D2,2),\"cm\"\n",
"\n",
"N2 = 1500 \n",
"\n",
"print \"Speed of the pump =\",round(N2,0),\"RPM\""
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Example 12.4 Page no 454 "
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Discharge, Q = 1.11 ft**3/s\n",
"Dynamic head of the pump, H = 122.1 m\n",
"Specific speed of the pump, Ns = 1096.0 RPM\n"
]
}
],
"source": [
"# Example 12.4\n",
"\n",
"from math import *\n",
"\n",
"from __future__ import division\n",
"\n",
"# Given\n",
"\n",
"q = 500 # discharge in cgm\n",
"\n",
"Q = 500/449 # discharge in ft**3/s\n",
"\n",
"D = 0.667 # diameter in ft\n",
"\n",
"A = pi*D**2/4\n",
"\n",
"V = Q/A # velocity in ft/s\n",
"\n",
"g = 32.2 # acceleration due to gravity in ft/s**2\n",
"\n",
"N = 1800 # speed in RPM\n",
"\n",
"# Solution\n",
"\n",
"# for water at 65 deg C\n",
"\n",
"nu = 1.134*10**-5 # viscosity in ft**2/s\n",
"\n",
"e = 0.00085 # epssilon in ft\n",
"\n",
"r = 0.001275 \n",
"\n",
"R = V*D/nu # reynolds no\n",
"\n",
"f = 0.022 # from moody's diagram\n",
"\n",
"Hl = V**2*(12.1+(f*224.9))/64.4\n",
"\n",
"hs = 119.4 + Hl\n",
"\n",
"print \"Discharge, Q = \",round(Q,2),\"ft**3/s\"\n",
"print \"Dynamic head of the pump, H =\",round(hs,1),\"m\"\n",
"\n",
"Ns = N*sqrt(q)/(hs)**(3/4)\n",
"\n",
"print \"Specific speed of the pump, Ns =\",round(Ns,0),\"RPM\""
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Example 12.5 Page no 457"
]
},
{
"cell_type": "code",
"execution_count": 6,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Minimum value of static suction lift = 4.02 m\n"
]
}
],
"source": [
"# Example 12.5 \n",
"\n",
"from math import *\n",
"\n",
"from __future__ import division\n",
"\n",
"# Given\n",
"\n",
"H = 60 # height in m\n",
"\n",
"Pb = 98*10**3 # barometric pressure in N/m**2\n",
"\n",
"Hl = 1 # head in m\n",
"\n",
"Pv = 1707 # vapour pressure \n",
"\n",
"sigma = 0.08\n",
"\n",
"w = 9810 # specific weight\n",
"\n",
"# Solution\n",
"\n",
"Npsh_m = sigma*60 # minimum NPSH\n",
"\n",
"Hsm = (Pb/w)-(Pv/w)-Npsh_m-Hl\n",
"\n",
"print \"Minimum value of static suction lift = \",round(Hsm,2),\"m\""
]
},
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