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{
"metadata": {
"name": "",
"signature": "sha256:a61692019b8140a36f6ac02790d0dad90729cb0b28691dad1652c231a1bf0a41"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter7-Centrifugal Pumps,Fans and Compressors\n"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex1-pg216"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate the\n",
"\n",
"##function to calculate blade cavitation coefficient\n",
"\n",
"##given data\n",
"Q = 25;##flow rate in dm^3/s\n",
"omega = 1450;##rotational speed in rev/min\n",
"omega_ss = 3;##max. suction specific speed in rad/sec\n",
"r = 0.3;##inlet eye radius ratio\n",
"g = 9.81;##in m/s^2\n",
"\n",
"##Calculations\n",
"k = 1.-(r**2);\n",
"sigmab = 0.3;##initial guess\n",
"d = (sigmab**2)*(1. + sigmab)- (((3.42*k)**2)/(omega_ss**4));\n",
"i = 0;\n",
"if sigmab>0:\n",
"\tsigmab = sigmab - 0.0001;\n",
"elif sigmab<0:\n",
"\tsigmab = sigmab + 0.0001;\n",
"\n",
"phi = (sigmab/(2.*(1.+sigmab)))**0.5;\n",
"rs1 = ((Q*10**-3.)/(math.pi*k*(omega*math.pi/30.)*phi))**(1./3.);\n",
"ds1 = 2.*rs1;\n",
"cx1 = phi*(omega*math.pi/30.)*rs1;\n",
"Hs = (0.75*sigmab*cx1**2)/(g*phi**2);\n",
"\n",
"##Results\n",
"print'%s %.2f %s'%('(i)The blade cavitation coefficient = ',sigmab,'');\n",
"print'%s %.2f %s %.2f %s '%('\\n (ii)The shroud radius at the eye = ',rs1,' m' and '\\n The required diameter of the eye = ',ds1*10**3,'mm');\n",
"print'%s %.2f %s'%('\\n (iii)The eye axial velocity = ',cx1,' m/s');\n",
"print'%s %.2f %s'%('\\n (iv)The NPSH = ',Hs,' m');\n",
"\n",
"#asnwer is wrong due to round off error"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(i)The blade cavitation coefficient = 0.30 \n",
"\n",
" (ii)The shroud radius at the eye = 0.06 \n",
" The required diameter of the eye = 110.70 mm \n",
"\n",
" (iii)The eye axial velocity = 2.85 m/s\n",
"\n",
" (iv)The NPSH = 1.62 m\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex2-pg220"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate the\n",
"\n",
"##given data\n",
"alpha1 = 30.;##prewhirl in deg\n",
"hs = 0.4;##inlet hub-shrub radius ratio\n",
"Mmax = 0.9;##max Mach number\n",
"Q = 1;##air mass flow in kg/s\n",
"p01 = 101.3;##stagnation pressure in kPa\n",
"T01 = 288.;##stagnation temperature in K\n",
"gamma = 1.4;\n",
"Rg = 287.;##in J/(kgK)\n",
"\n",
"##Calculationsasza\n",
"beta1 = 49.4;##in deg\n",
"f = 0.4307;\n",
"a01 = math.sqrt(gamma*Rg*T01);\n",
"rho01 = p01*1000./(Rg*T01);\n",
"k = 1-(hs**2);\n",
"omega = (math.pi*f*k*rho01*a01**3)**0.5;\n",
"N = (omega*60./(2.*math.pi));\n",
"rho1 = rho01/(1. + 0.2*(Mmax*math.cos(beta1*math.pi/180.))**2)**2.5;\n",
"cx = ((omega**2.)/(math.pi*k*rho1*(math.tan(beta1*math.pi/180.) + math.tan(alpha1*math.pi/180.))**2.))**(1/3.);\n",
"rs1 = (1./(math.pi*rho1*cx*k))**0.5;\n",
"\n",
"ds1 = 2.*rs1;\n",
"U = omega*rs1;\n",
"\n",
"##Results\n",
"print'%s %.2f %s %.2f %s '%('(i)The rotational speed of the impeller = ',omega,' rad/s'and 'N = ',N,' rev/min.');\n",
"print'%s %.2f %s %.2f %s '%('\\n (ii)The inlet static density downstream of the guide vanes at the shroud = ',rho1,' kg/m^3.'and'\\n The axial velocity = ',cx,' m/s.');\n",
"print'%s %.2f %s %.2f %s '%('\\n (iii)The inducer tip diameter = ',ds1*100,' cm'and '\\n U = ',U,' m/s.');\n",
"\n",
"##there are small errors in the answers given in textbook\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(i)The rotational speed of the impeller = 7404.94 N = 70711.94 rev/min. \n",
"\n",
" (ii)The inlet static density downstream of the guide vanes at the shroud = 1.04 \n",
" The axial velocity = 187.38 m/s. \n",
"\n",
" (iii)The inducer tip diameter = 8.83 \n",
" U = 326.81 m/s. \n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex3-pg228"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate the\n",
"\n",
"##given data\n",
"Q = 0.1;##in m^3/s\n",
"N = 1200.;##rotational speed in rev/min\n",
"beta2_ = 50.;##in deg\n",
"D = 0.4;##impeller external diameter in m\n",
"d = 0.2;##impeller internal diameter in m\n",
"b2 = 31.7;##axial width in mm\n",
"eff = 0.515;##diffuser efficiency\n",
"H = 0.1;##head losses\n",
"De = 0.15;##diffuser exit diameter\n",
"A = 0.77;\n",
"B = 1.;\n",
"g = 9.81;\n",
"\n",
"##Calculations\n",
"U2 = math.pi*N*D/60.;\n",
"cr2 = Q/(math.pi*D*b2/1000.);\n",
"sigmaB = (A - H*math.tan(beta2_*math.pi/180.))/(B - H*math.tan(beta2_*math.pi/180.));\n",
"ctheta2 = sigmaB*U2*(1.-H*math.tan(beta2_*math.pi/180.));\n",
"Hi = U2*ctheta2/g;\n",
"c2 = math.sqrt(cr2**2 + ctheta2**2);\n",
"c3 = 4.*Q/(math.pi*De**2);\n",
"HL = 0.1*Hi + 0.485*((c2**2)-(c3**2))/(2.*g) + (c3**2.)/(2.*g);\n",
"H = Hi - HL;\n",
"eff_hyd = H/Hi;\n",
"\n",
"##Results\n",
"print'%s %.2f %s'%('The slip factor = ',sigmaB,'');\n",
"print'%s %.2f %s'%('\\n The manometric head = ',H,' m.');\n",
"print'%s %.2f %s'%('\\n The hydraulic efficiency = ',eff_hyd*100,' percentage.');\n",
"\n",
"##there is a very small error in the answer given in textbook\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The slip factor = 0.74 \n",
"\n",
" The manometric head = 30.11 m.\n",
"\n",
" The hydraulic efficiency = 71.84 percentage.\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex4-pg235"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math\n",
"#calculate the\n",
"\n",
"##given data\n",
"T01 = 22.;##stagnation temperature in degC\n",
"Z = 17.;##number of vanes\n",
"N = 15000.;##rotational speed in rev/min\n",
"r = 4.2;##stagnation pressure ratio between diffuser and impeller\n",
"eff_ov = 0.83;##overall efficiency\n",
"mdot = 2;##mass flow rate in kg/s\n",
"eff_m = 0.97;##mechanical efficiency\n",
"rho2 = 2.;##air density at impeller outle in kg/m^3\n",
"gamma = 1.4;\n",
"R = 0.287;##in kJ/(kg.K)\n",
"b2 = 11.;##axial width at the entrance to the diffuser in mm\n",
"\n",
"##Calculations\n",
"Cp = gamma*R*1000./(gamma-1.);\n",
"sigmaS = 1 - 2./Z;\n",
"U2 = math.sqrt(Cp*(T01+273.)*((r)**((gamma-1.)/gamma) -1.)/(sigmaS*eff_ov));\n",
"omega = N*math.pi/30.;\n",
"rt = U2/omega;\n",
"Wdot_act = mdot*sigmaS*(U2**2)/(eff_m);\n",
"cr2 = mdot/(rho2*2.*math.pi*rt*b2/1000.);\n",
"ctheta2 = sigmaS*U2;\n",
"c2 = math.sqrt(ctheta2**2 +cr2**2);\n",
"delW = sigmaS*U2**2;\n",
"T2 = T01+273.+(delW - 0.5*c2**2)/Cp;\n",
"M2 = c2/math.sqrt(gamma*R*1000.*T2);\n",
"\n",
"##Results\n",
"print'%s %.2f %s'%('Absolute mach number, M2 = ',M2,'');\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Absolute mach number, M2 = 1.01 \n"
]
}
],
"prompt_number": 5
}
],
"metadata": {}
}
]
}
|
