{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# 7.14 Bernoulli's Theorem-Water" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "Water at 15 degrees Celsius is flowing through the piping system shown in Crane TP 410M's example at 1500 L/min.\n", "\n", "Calculate the velocity in both 4 and 5 inch sizes; and the pressure drop.\n", "\n", "Note: This problem suggests to handle the changing size elbow by adding on the result of a smooth expansion, which is also used here." ] }, { "cell_type": "code", "execution_count": 1, "metadata": {}, "outputs": [ { "data": { "text/html": [ "262809.7611610049 pascal" ], "text/latex": [ "$262809.7611610049\\ \\mathrm{pascal}$" ], "text/plain": [ "262809.7611610049 " ] }, "execution_count": 1, "metadata": {}, "output_type": "execute_result" } ], "source": [ "from math import *\n", "from fluids.units import *\n", "from thermo.units import Chemical\n", "\n", "water = Chemical('water', P=2*u.bar, T=15*u.degC)\n", "rho = water.rho\n", "mu = water.mu\n", "\n", "Q = 1500*u.L/u.min\n", "r_d = 1.5\n", "_, D1, _, _ = nearest_pipe(Di=100*u.mm)\n", "_, D2, _, _ = nearest_pipe(Di=125*u.mm)\n", "L1 = 34*u.m\n", "L2 = (22+45)*u.m\n", "dH = 22*u.m\n", "beta = D1/D2\n", "\n", "V1 = Q/(pi/4*D1**2)\n", "V2 = Q/(pi/4*D2**2)\n", "Re1 = Reynolds(rho=rho, mu=mu, V=V1, D=D1)\n", "Re2 = Reynolds(rho=rho, mu=mu, V=V2, D=D2)\n", "fd1 = friction_factor(Re=Re1, eD=0.0018*u.inch/D1)\n", "fd2 = friction_factor(Re=Re2, eD=0.0018*u.inch/D2)\n", "fd = (fd1+fd2)/2\n", "\n", "dP = rho*u.gravity*dH\n", "\n", "K_D1 = bend_rounded(Di=D1, angle=90*u.degrees, fd=fd, bend_diameters=r_d)\n", "K_D1 += diffuser_conical(D1, D2, angle=30*u.degrees, fd=fd)\n", "K_D1 += K_from_f(fd=fd1, L=L1, D=D1)\n", "\n", "K_D2 = bend_rounded(Di=D2, angle=90*u.degrees, fd=fd, bend_diameters=r_d)\n", "K_D2 += K_from_f(fd=fd2, L=L2, D=D2)\n", "\n", "dP += dP_from_K(K=K_D1, rho=rho, V=V1)\n", "dP += dP_from_K(K=K_D2, rho=rho, V=V2)\n", "dP.to(u.Pa)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "The result calculated in Crane's TP 410m is 26450 Pa. Their friction factor is 0.018. Again, it that value is used, the result calculated matches theirs - except this is off by an order of magnitude.\n", "\n", "In this edition, the gravitational term was forgotten. The prior 8th edition lists a value of 2.6 bar as the result for this problem. If their friction factor is used with this model, the following calculates a pressure drop of 2.62 bar." ] }, { "cell_type": "code", "execution_count": 2, "metadata": {}, "outputs": [ { "data": { "text/html": [ "262439.4308380222 pascal" ], "text/latex": [ "$262439.4308380222\\ \\mathrm{pascal}$" ], "text/plain": [ "262439.4308380222 " ] }, "execution_count": 2, "metadata": {}, "output_type": "execute_result" } ], "source": [ "fd = fd1 = fd2 = .018\n", "dP = rho*u.gravity*dH\n", "\n", "K_D1 = bend_rounded(Di=D1, angle=90*u.degrees, fd=fd, bend_diameters=r_d)\n", "K_D1 += contraction_round(D1, D2, r_d*D1)\n", "K_D1 += K_from_f(fd=fd1, L=L1, D=D1)\n", "\n", "K_D2 = bend_rounded(Di=D2, angle=90*u.degrees, fd=fd, bend_diameters=r_d)\n", "K_D2 += K_from_f(fd=fd2, L=L2, D=D2)\n", "\n", "dP += dP_from_K(K=K_D1, rho=rho, V=V1)\n", "dP += dP_from_K(K=K_D2, rho=rho, V=V2)\n", "dP.to(u.Pa)" ] } ], "metadata": { "language_info": { "name": "python" } }, "nbformat": 4, "nbformat_minor": 1 }