Reynolds Number Calculator

Background

Reynolds Number is a dimensionless number that describes the fluid flow under given conditions. It is the ratio of inertial forces to viscous forces and is given by the following equation for fluid flow through a pipe.

Re = r.V_s.D / m

Where, Re = Reynolds Number

r = Density

V_s = Velocity of flow

D = Diameter of pipe

m = Dynamic viscosity

The equation can be rewritten as

Re = K.Q_f. r / D. m

Where, Q_f = Flow rate

K = constant value depending on units

Turbine meters need to be calibrated under field conditions for acceptable accuracy. The best calibration results are obtained by matching the field Reynolds Numbers and flow rates.

The field parameters are collected and entered into the application, along with the calibration test request data. The program then calculates the field Reynolds Number and meter calibration facility set up parameters for 2 types of tests:

1. Matching Reynolds Number and flow rates – calculate calibration pressures

2. Matching flow rates and density – calculate calibration pressures and Reynolds Numbers

Using the Program

Navigation

The calculator program comprises four input data screens and one results screen. To navigate among the input data screens, click on the screen number in the navigation panel on the left or click on the buttons in the bottom right hand corner.

Toolbar

The buttons on the toolbar in the top right hand corner provide the following functionality:

New calculation: The new page button resets all fields to their default value to start a new Reynolds Number calculation.

Edit test criteria: The pencil button allows you to return to the first screen, after viewing the results, to change any input data, and recalculate.

Save results:: This button allows you to save the results of the calculations in the form of a pdf file.

Help: View this User Guide.

Client Information

Fill in your identification and contact information and any additional comments. Click on to go to the next screen.

Field Conditions

Select either Metric or Imperial as the units you wish to enter the data. Any values that have already been entered will be converted. All fields on this page are required and must be within a specific range. Errors will be highlighted in red with an explanatory message.

Calibration Request

On this screen you select the number of points for meter calibration. Your options are the standard 5 Point, 2 Point or a custom number from 1 to 10 points. Click on the required option. If Other is selected, first enter the number of points, and then enter the desired flow rates in ascending order.

Select if the meter is to be calibrated additionally at a pressure other than the field pressure.

By default, the calibration temperature is the same as the field temperature. If the meter is to be calibrated at some other temperature, then enter the new temperature here.

Gas Properties

On this screen, the field natural gas properties need to be specified. There are 3 ways of doing this.

1) From the predefined list of gases, select the gas whose composition most closely matches the composition in the field.

2) If there is no gas whose composition matches closely, then select the nearest gas and modify the composition, ensuring that the sum of the fractions adds up to 100%

3) If the density and viscosity are known at the field pressure and calibration temperature, then select this option. Enter the density, and either dynamic viscosity or kinematic viscosity in the units of your choice. If units are changed, any entered values are automatically converted. If an additional calibration pressure was specified in the previous screen, then enter the second set of density and viscosity values at the additional calibration pressure and the calibration temperature.

Output Results

If the input data or the calibration facility setup parameters are out of range for the facility, then only the field Reynolds Numbers are calculated and no output is generated for the calibration setup.

The calibration test setup parameters are calculated using C0₂ as the reference gas. The first chart is a graph of the Reynolds Numbers and Flow Rate. There is one set of plots for Reynolds Number and Flow Rate matching and for Flow Rate and Density matching, for each calibration pressure.

Click on the Save Results button in the toolbar to save the file on your local computer. To return to the input screens click either the back button on your browser or the edit icon in the toolbar. To start from fresh form to enter in all new values, click the blank page icon.