{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# 7.24 Laminar Flow" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Objective: Rate an orifice plate in laminar flow" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "Problem statement: calculate the Reynolds number to determine the type of fluid\n", " \n", "Given: S.A.E. 10W oil flows through a 3\" schedule 40 pipe. It has a measured delta P of 0.4 psi. The orifice plate has a 2.15\" diameter bore, and is a standard sharp-edged orifice. Find the flow rate through the orifice in gallons/minute." ] }, { "cell_type": "code", "execution_count": 1, "metadata": {}, "outputs": [], "source": [ "from fluids.units import *\n", "from math import pi\n", "\n", "NPS, Di, Do, t = nearest_pipe(NPS=3, schedule='40')\n", "A = 0.25*pi*Di*Di\n", "D2 = 2.15*u.inch\n", "mu = 40*u.cP # given\n", "rho = 53.6*u.lb/u.ft**3\n", "\n", "# Assume an absolute pressure of 5 bar.\n", "dP = 0.4*u.psi\n", "P1 = 5*u.bar\n", "P2 = P1-dP\n", "k = 1.3 # assumed\n" ] }, { "cell_type": "code", "execution_count": 2, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Flow rate is: 88.00974933637421 gallon / minute\n" ] }, { "data": { "text/html": [ "1947.5090707193106 dimensionless" ], "text/latex": [ "$1947.5090707193106\\ dimensionless$" ], "text/plain": [ "1947.5090707193106 " ] }, "execution_count": 2, "metadata": {}, "output_type": "execute_result" } ], "source": [ "# First calculate the orifice with the standard formula\n", "m = differential_pressure_meter_solver(D=Di, rho=rho, mu=mu, k=k, D2=D2, P1=P1, P2=P2, \n", " m=None, meter_type='ISO 5167 orifice', \n", " taps='corner')\n", "Q = (m/rho).to_base_units()\n", "print('Flow rate is: %s'% Q.to(u.gal/u.min))\n", "v = Q/A\n", "Re = rho*v*Di/mu\n", "Re.to_base_units()" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "Because the flow rate is laminar, outside the range of the ISO formula, we turn to another set of data - a set of CFD results developed for laminar flow by Hollingshead." ] }, { "cell_type": "code", "execution_count": 3, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Flow rate is: 77.16025233085325 gallon / minute\n" ] }, { "data": { "text/html": [ "1707.4277843809423 dimensionless" ], "text/latex": [ "$1707.4277843809423\\ dimensionless$" ], "text/plain": [ "1707.4277843809423 " ] }, "execution_count": 3, "metadata": {}, "output_type": "execute_result" } ], "source": [ "# First calculate the orifice with the standard formula\n", "m = differential_pressure_meter_solver(D=Di, rho=rho, mu=mu, k=k, D2=D2, P1=P1, P2=P2, \n", " m=None, meter_type='Hollingshead orifice')\n", "Q = (m/rho).to_base_units()\n", "print('Flow rate is: %s'% Q.to(u.gal/u.min))\n", "v = Q/A\n", "Re = rho*v*Di/mu\n", "Re.to_base_units()" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "The answer given in Crane is that a calibration for the meter must be provided. They assume a `C` of 0.75. The value of `C` according to Hollingshead is below." ] }, { "cell_type": "code", "execution_count": 4, "metadata": {}, "outputs": [ { "data": { "text/html": [ "0.7156763185721802 dimensionless" ], "text/latex": [ "$0.7156763185721802\\ dimensionless$" ], "text/plain": [ "0.7156763185721802 " ] }, "execution_count": 4, "metadata": {}, "output_type": "execute_result" } ], "source": [ "differential_pressure_meter_C_epsilon(D=Di, D2=D2, m=m, P1=P1, P2=P2, rho=rho, mu=mu, k=k, \n", " meter_type='Hollingshead orifice')[0]" ] } ], "metadata": { "language_info": { "name": "python" } }, "nbformat": 4, "nbformat_minor": 1 }