Pick a method and enter known values. Get velocity, discharge, and thrust in seconds accurately. Compare scenarios with the built‑in example data table below.
These scenarios show typical ranges for water-like fluids and common nozzle sizes.
| # | Method | Input | ρ (kg/m³) | Nozzle | Velocity (m/s) | Discharge (L/s) |
|---|---|---|---|---|---|---|
| 1 | Pressure | ΔP = 200 kPa, C = 0.98 | 1000 | d = 10 mm | ≈ 19.60 | ≈ 1.54 |
| 2 | Pressure | ΔP = 3 bar, C = 1.00 | 1000 | d = 6 mm | ≈ 24.49 | ≈ 0.69 |
| 3 | Head | H = 15 m, C = 0.97 | 998 | d = 12 mm | ≈ 16.68 | ≈ 1.89 |
| 4 | Head | H = 3 ft, C = 1.00 | 1000 | d = 8 mm | ≈ 4.24 | ≈ 0.21 |
| 5 | Flow | Q = 8 L/s, C = 1.00 | 1000 | d = 25 mm | ≈ 16.30 | 8.00 |
A jet velocity estimate connects pressure, elevation, and nozzle geometry to a measurable exit speed. This calculator supports three common inputs: pressure difference, head height, and volumetric flow. Each method reports velocity, estimated discharge, dynamic pressure, thrust, and an optional Reynolds number check for flow regime insight.
Jet velocity is the average exit speed at the nozzle. For an ideal nozzle, almost all available energy becomes kinetic energy. In practice, friction and contraction reduce speed, so the coefficient C (often 0.90–1.00) adjusts the ideal result to better match measurements.
For water near ρ ≈ 1000 kg/m³, ΔP = 100 kPa gives v ≈ √(2ΔP/ρ) ≈ 14.14 m/s (C = 1). ΔP = 200 kPa yields about 20.0 m/s. A 3 bar drop (300 kPa) gives about 24.5 m/s, consistent with many wash and spray systems.
Head is gravitational potential per unit weight. With standard gravity g = 9.80665 m/s², a 10 m head gives v ≈ √(2gH) ≈ 14.0 m/s (C = 1). A useful rule: 1 m of water head is about 9.81 kPa of pressure head equivalence.
When flow is measured, velocity is v = Q/A. Area for a circular nozzle is A = πd²/4. For d = 10 mm, A ≈ 7.85×10⁻⁵ m². If Q = 1.5 L/s (0.0015 m³/s), then v ≈ 19.1 m/s before applying C.
Once v is known, discharge is Q ≈ A·v (if area is provided). Thrust follows momentum flux: F = ρQv. Example: water, Q = 0.0015 m³/s, v = 19 m/s gives F ≈ 28.5 N. This helps compare nozzle options or estimate reaction loads.
Dynamic pressure q = ½ρv² is a compact “impact” metric. With water and v = 20 m/s, q ≈ 200 kPa. Higher q often means stronger cleaning, cutting, or erosion potential, but surface distance, spray breakup, and target angle still matter.
Re = ρvd/μ indicates whether the jet is laminar, transitional, or turbulent near the nozzle. With water μ ≈ 1 cP (0.001 Pa·s), d = 10 mm, v = 20 m/s gives Re ≈ 200,000, typically turbulent. Higher viscosity lowers Re significantly.
Use consistent units, and prefer measured density and viscosity when accuracy matters. If your nozzle has known losses, set C below 1. Compare results to measured flow at the nozzle, and ensure the selected method matches what you actually measured in the field.
Use pressure if you know the drop across the nozzle. Use head if you know elevation or tank level. Use flow if you measured Q and know the nozzle diameter or area.
Start with C = 1.00 for ideal estimates. For real nozzles, 0.90–0.99 is common depending on losses, contraction, and roughness. If you have test data, tune C to match measured velocity or flow.
Density links pressure energy to kinetic energy in the pressure method. Lower density fluids produce higher velocity for the same pressure drop. Density also affects thrust, dynamic pressure, and Reynolds number outputs.
Yes, for pressure and head methods you can compute velocity without diameter. However, discharge, thrust, and Reynolds number depend on nozzle size, so provide diameter or area for those extra outputs.
Thrust uses F = ρQv and assumes the jet exits cleanly and uniformly. Real jets can diverge or break up, reducing effective momentum at distance. Use it as a near‑nozzle estimate or comparative metric.
Near room temperature, water is about 1 cP. Warmer water is slightly lower, and colder water is higher. If you need better precision, use a temperature‑based viscosity value from a reliable table.
Each method reflects different measurements and assumptions. Pressure and head assume energy conversion, while flow is purely geometric. Losses, measurement location, and nozzle behavior can cause differences. The coefficient helps reconcile ideal estimates with reality.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.