Calculating Flow Rate in a Pipe

Pipe Flow Rate Calculator

Result:

Understanding Pipe Flow Rate

The flow rate in a pipe, often referred to as volumetric flow rate (Q), is a crucial parameter in fluid dynamics and engineering. It represents the volume of fluid that passes through a given cross-sectional area per unit of time. Calculating flow rate helps in designing and managing various systems, including water supply networks, industrial pipelines, and HVAC systems.

The fundamental formula for calculating volumetric flow rate (Q) is:

Q = A * v

Where:

  • Q is the volumetric flow rate (typically measured in cubic meters per second, m³/s).
  • A is the cross-sectional area of the pipe (typically measured in square meters, m²).
  • v is the average velocity of the fluid flowing through the pipe (typically measured in meters per second, m/s).

To find the cross-sectional area (A) of a circular pipe, we use the formula for the area of a circle:

A = π * r²

Where:

  • π (pi) is a mathematical constant, approximately 3.14159.
  • r is the radius of the pipe (half of the diameter), measured in meters.

Therefore, the flow rate can also be calculated as:

Q = π * r² * v

If the diameter (d) is given, the radius (r) is d/2. So the formula becomes:

Q = π * (d/2)² * v

This calculator takes the pipe diameter and the fluid velocity as inputs and calculates the volumetric flow rate.

Example:

Let's say you have a pipe with a diameter of 0.1 meters (10 cm) and the fluid is flowing at an average velocity of 2.5 meters per second.

  • Pipe Diameter (d) = 0.1 m
  • Fluid Velocity (v) = 2.5 m/s
  • Radius (r) = d / 2 = 0.1 m / 2 = 0.05 m
  • Area (A) = π * r² = 3.14159 * (0.05 m)² = 3.14159 * 0.0025 m² ≈ 0.00785 m²
  • Flow Rate (Q) = A * v = 0.00785 m² * 2.5 m/s ≈ 0.01963 m³/s

So, the flow rate would be approximately 0.01963 cubic meters per second.

function calculateFlowRate() { var pipeDiameter = parseFloat(document.getElementById("pipeDiameter").value); var fluidVelocity = parseFloat(document.getElementById("fluidVelocity").value); var resultDisplay = document.getElementById("flowRateResult"); if (isNaN(pipeDiameter) || isNaN(fluidVelocity) || pipeDiameter <= 0 || fluidVelocity < 0) { resultDisplay.innerHTML = "Please enter valid positive numbers for diameter and non-negative for velocity."; return; } var pipeRadius = pipeDiameter / 2; var pipeArea = Math.PI * Math.pow(pipeRadius, 2); var flowRate = pipeArea * fluidVelocity; resultDisplay.innerHTML = flowRate.toFixed(5) + " m³/s"; }

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