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author | prashantsinalkar | 2017-10-10 12:27:19 +0530 |
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committer | prashantsinalkar | 2017-10-10 12:27:19 +0530 |
commit | 7f60ea012dd2524dae921a2a35adbf7ef21f2bb6 (patch) | |
tree | dbb9e3ddb5fc829e7c5c7e6be99b2c4ba356132c /3720/CH14/EX14.3/Ex14_3.sce | |
parent | b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b (diff) | |
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diff --git a/3720/CH14/EX14.3/Ex14_3.sce b/3720/CH14/EX14.3/Ex14_3.sce new file mode 100644 index 000000000..587ff118c --- /dev/null +++ b/3720/CH14/EX14.3/Ex14_3.sce @@ -0,0 +1,56 @@ +//Example 14-3 +clc;clear; +// Given values +P_atm=101.3*1000; // Pa +g=9.81;// m/s^2 +alpha=1.05; +eps=0.02*0.0254;//Roughness in m +D=4*0.0254;// in 'm' converted from 'in' +L=10.5*0.3048;//in 'm' converted from 'ft' +gradz=1.219;// grad z=(z_1-z_2) in m + +// Calculation +A=((%pi*D^2)/4);//Area in m^2 +v=300:10:700;//Volume flow rate in gpm +T=[25 60];//Temperature matrix +for j=1:1:length(T) + //Water properties at T = 25°C and 60°C respectively + if T(j)==25 then + rho=997.0;// kg/m^3 + nu=8.91*10^-4;// Kinematic viscosity in kg/m.s + mu=nu/rho; + P_v=3.169*1000;// Pa + else + rho=983.3;// kg/m^3 + nu=4.67*10^-4;// Kinematic viscosity in kg/m.s + mu=nu/rho; + P_v=19.94*1000;// Pa + + end + +for i=1:1:length(v); + + v_(i)=(6.309*10^-5)*v(i); //Volume flow rate in m3^s converted from gpm + V(i)=v_(i)/A;//Velocity in m/s + Re=(4*v_(i))/(mu*%pi*D);//Reynolds number + + function [X]=fric(f) + X=-2.0*log10(((eps)/(3.7*D))+((2.51)/(Re*sqrt(f))))-1/sqrt(f); //Friction factor as a implicit function of Re using Colebrook equation + endfunction + + f=0.00001; //Initial guess to solve X + fr=fsolve(f,fric);//Calculating friction factor + + sigmaK_l=0.5+(3*0.3)+6.0;// Minor losses + H_l=((fr*L)/D+sigmaK_l)*(V(i)^2/(2*g));//The required net head of the fan at the minimum flow rate + + NPSH(j,i)=((P_atm-P_v)/(rho*g))+(gradz)-(H_l)-((alpha-1)*(V(i)^2)/(2*g)); +end +end +F=[300 400 500 600 680];//Flow rate in gpm +N=[3.8 4.44 5.06 6.13 7.0];//minimum NPSH required approximately taken from Fig.14-21 +plot(v',NPSH'*3.28,'r',F,N,'-o'); +xlabel('v,gpm'); +ylabel('NPSH,ft'); +legend('Available NPSH, 25°C','Available NPSH, 60°C','Required NPSH'); +printf('\nCavitation occurs at flow rates above approximately 600 gpm. \nThe maximum volume flow rate without cavitation decreases with temperature.') |