Flow Nozzle Principle
Nozzles are commonly used to control flow rate, speed, direction, and mass. The velocity of fluid increases in a nozzle at the price of its pressure energy. Gas jets can be found in gas stoves, ovens, and grills. Before the invention of electric light, gas jets were a common source of illumination. Other sorts of fluid jets can be found in carburetors, which use smooth calibrated orifices to control the flow of gasoline into a combustion chamber. The laminar jet is another specialized jet.
This is a water jet with devices that smooth the pressure and flow, resulting in laminar flow, as the name implies. Fountains will perform better as a result of this. Another sort of jet is the foam jet, which uses foam instead of gas or fluid. Tyeres are nozzles used to feed hot blast into a blast furnace or forge. In big rooms where air dispersion via ceiling diffusers is neither possible or practical, jet nozzles are also used. Jet diffusers are air diffusers that use jet nozzles and are installed on the side walls of buildings to distribute air. The supply air stream is diverted upwards to supply warm air when the temperature differential between the supply air and the room air changes.
Nozzles can be convergent (narrowing down from a large diameter to a smaller diameter in the flow direction) or divergent (narrowing down from a big diameter to a smaller diameter in the flow direction) (expanding from a smaller diameter to a larger one). A de Laval nozzle has a convergent section and a divergent section. Subsonic fluids are accelerated by convergent nozzles.
The energy obtained from combusting fuel added to the inducted air provides a net thrust in a jet exhaust. This hot air goes through a propelling nozzle with a high speed nozzle, greatly increasing its kinetic energy.
For a given mass flow, increasing exhaust velocity improves thrust, while matching the exhaust velocity to the air speed maximizes energy efficiency. Convergent-divergent nozzles with enormous area ratios and thus extremely high pressure ratios are used in rocket engines to maximize thrust and exhaust velocity. Because all of the propulsive mass is carried by the vehicle, mass flow is at a premium, and very high exhaust speeds are preferred, mass flow is at a premium.
When a flow nozzle is inserted into a pipe conveying the flow rate to be measured, it generates a pressure drop that varies with the flow rate.
A differential pressure sensor is used to measure the pressure drop, and once calibrated, the pressure becomes a measure of flow rate.
Description of Flow Nozzle
A flow nozzle that is held between the flanges of the pipe carrying the fluid being measured. The throat of the flow nozzle has the smallest area.
As shown in the diagram, openings are provided at two locations 1 and 2 for attaching a differential pressure sensor (u-tube manometer, differential pressure gauge, etc.).
Operation of flow Nozzle
- The fluid whose flow rate is to be measured enters the nozzle smoothly and travels to the throat region, which has the smallest surface area.
- The fluid pressure in the pipe is p1 before it enters the nozzle. As the fluid enters the nozzle, it converges, lowering the pressure until it reaches the throat, which is the smallest cross section region. This p2 pressure at the throat is the absolute minimum.
- When calibrated, the differential pressure sensor connected between points 1 and 2 records the pressure difference (p1-p2) between these two positions, indicating the fluid flow rate through the pipe.
Applications of Flow Nozzle
- It is used to calculate liquid discharge rates into the atmosphere.
- It’s most commonly employed when suspended solids have the ability to settle.
- Is a popular choice for high-pressure, high-temperature steam flows.
Advantages of flow Nozzle
- When compared to a venturi meter, installation is simple and inexpensive.
- It is highly compact and has a high discharge coefficient.
Disadvantages of flow Nozzle
- The rate of pressure recovery is slow.
- When compared to an orifice flow meter, maintenance is expensive and installation is complicated.