Net force on a control volume equals rate of change of momentum flux.
Linear momentum balance: ΣF=d(mV)/dt in control volumes: F=ṁ(V_out-V_in)+pressure terms. Gives forces on pipe bends, jets on vanes, thrust of rockets and propellers. Choose control volume surfaces perpendicular to flow.
A jet of 10 kg/s at 20 m/s hitting a flat plate exerts 200 N.
The momentum equation gives the forces on pipe bends, nozzles and jet impacts, which are needed for structural supports and thrust calculations.
Net force on a control volume equals rate of change of momentum flux.
The momentum equation gives the forces on pipe bends, nozzles and jet impacts, which are needed for structural supports and thrust calculations.
The net force on a control volume equals the rate of momentum leaving minus the rate entering, plus pressure forces on the boundary.
A change in flow direction changes momentum, so a force is needed to turn the fluid, and the pipe supports must carry it.
Typical applications include calculating the force on a pipe bend that holds water at high pressure, estimating the thrust of a jet engine nozzle and finding the force on a vane that deflects a water jet.
Study "Pitot tubes and Venturi meters" first (topic 54 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
Vector equation. Pressure forces plus body forces. Reaction on supports.
A jet of 10 kg/s at 20 m/s hitting a flat plate exerts 200 N.
The next topic is "Laminar and turbulent flow", which builds directly on this one.
It is classed as Intermediate in Thermodynamics & Fluids (topic 55 of 105). It is an intermediate topic. Work through the beginner topics in Thermodynamics & Fluids first.
Want to practise? Open the interactive course for quick checks, quizzes, simulations and progress tracking.