COLLEGE OF AGRIL. ENGG. AND TECH., V.N.M.K.V.,PARBHANI

NAME : CHAVAN SUNIL KRISHNAJI

REG. NO. : 2012AE/11B

SEMINAR TOPIC :-

DROPLET SIZE AND VELOCITY

CHARACTERISTICS

INTRODUCTION

The spray quality generated by agricultural nozzles plays an important role in the application of plant protection .

The ideal nozzle‐pressure combination should maximize spray efficiency by increasing deposition and transfer of a lethal dose to the target.

Size and velocity of droplet also matters the area to be covered.

Within spray equipment systems, droplet SIZE and VELOCITY are one of the most influential factors.

The droplet size distribution near the orifice of a stationary nozzle depends on nozzle type, nozzle size, liquid properties and spray pressure.

For conventional boom sprayers, changing nozzle type is a relatively easy way to change droplet size

Increasing the spray liquid pressure with most nozzle designs not only results in a finer spray but also increases the velocity of droplets leaving the region of spray formation

SPRAY CHARACTERISTICS

Droplet size Droplet velocity distribution

Volume distribution pattern

Structure of individual droplet

INFLUENCING THE EFFICIENCY OF PESTICIDE APPLICATION

MATERIALS AND METHODS

NozzleOperatingPressure(bar)

Flow Rate(L min‐1)

ISO F 01 2.0 0.80ISO F 02 3.0 0.98ISO F 03 4.0 1.39ISO LD 01 2.0 0.80ISO LD 02 3.0 1.20ISO Injet 01 2.0 0.80ISO Injet 02 3.0 1.20

TESTED NOZZLE-PRESSURE COMBINATION

F-Flat fan nozzle LD-Low drift nozzle

PDPA MEASUREMENT :-

For the PDPA measurements, three nozzles were selected for each nozzle‐pressure combination to be tested.

Each nozzle was tested three times spraying vertically downward.

The nozzle was positioned 0.50 m above the measuring point.

All measurements were made while spraying water with a temperature of about 20°C at an ambient temperature of about 20°C and a relative humidity of 60% to 70%.

PDPA LASER‐BASED MEASUREMENT SETUP

RESULT AND DISCUSSION

DROPLET SIZE CHARACTERISTICS

1. Nozzle types2. Operating pressures

Investigate the effect of nozzle type were carried out at a constant operating pressure of 3.0 bar with water at a constant temperature of 20°C.

For the same nozzle size and operating pressure, standard flat‐fan nozzles produce the finest droplet size spectrum.

Found that low‐drift and air‐inclusion nozzles can provide similar performance to conventional sprays.

DIFFERENT SPRAYERS VOLUME AT DIFFERENT SIZES :-

PRESSURE – DIAMETER PROPORTION :-

We tested sprayers at operating pressures of 2.0, 3.0, and 4.0 bar.

From these results, it can be concluded that increasing the operating pressure from 3.0 to 4.0 bar significantly decreases the droplet size.

In increases the proportion of small droplets, but the effect is very limited compared to the effect of ISO nozzle size and type.

Remarkably, when the operating pressure was decreased from 3.0 to 2.0 bar, there was no significant effect on the droplet size characteristics and droplet sizes even tended to decrease.

RELATIONSHIP BETWEEN DROPLET SIZE AND DROPLET VELOCITY CHARACTERISTICS :-

From this graph, it is clear that there is a strong correlation between droplet sizes and velocities at a distance of 0.50 m below the nozzle.

In general, bigger droplet sizes correspond with higher droplet velocities and small droplets with lower droplet velocities.

For the bigger

droplet sizes , droplet velocities are relatively constant for the same nozzle‐pressure combination and vary from about 4.5 m s-1 up to 8.5 m s-1 depending on the nozzle type and size.

For very small droplets, velocities consistently decrease with decreasing droplet size.

Also for the smallest droplets, droplet velocities vary for the same droplet size interval from 0.5 to 2 m s-1 depending on ISO nozzle size and type.

Smaller droplets In diameter correspond with stopping distances smaller than 0.50 m.

A droplet released into stationary air accelerates until the aerodynamic drag and gravitational forces are in balance, at which stage the droplet will be falling at a uniform velocity.

DROPLET VELOCITY CHARACTERISTICS :-

V 10 V50 V90

In figure, droplet velocities below which slower droplets

constitute 10%, 50%, and 90% of the total volume.

With different nozzles at a constant operating pressure of 3.0 bar.

Considering standard flat‐fan nozzles and low‐drift flat‐fan nozzles

Big droplets correspond with high droplet velocities, small droplets with low droplet velocities.

Even when droplet size characteristics are equal, droplet velocities vary depending on the nozzle type.

VOLUME –DIAMETER RELATION :-

VELOCITY – DROPLET SIZE RELATIONSHIP :-

CONCLUSIONS :-

To measure the velocity and size of droplet, need accurate measurements.

]In general, bigger droplet sizes correspond with higher droplet velocities, and small droplets with lower droplet velocities.

For the larger droplet sizes , droplet velocities at 0.50 m from the nozzle exit were relatively constant for the same nozzle‐pressure combination and varied from about 4.5 up to 8.5 m s-1 depending on nozzle type and size.

Droplet velocities consistently decreased with decreasing droplet size.

Also for these smaller droplet sizes, droplet velocities were different for the same droplet size interval and varied from 0.5 to 2 m s-1 depending on ISO nozzle size and type.

For the same ISO nozzle size and operating pressure, standard flat‐fan nozzles produced the finest droplet size spectrum, followed by low‐drift flat‐fan nozzles and air inclusion nozzles.

For the same droplet size , droplet velocities were highest for flat‐fan nozzles, followed by low‐drift nozzles

The larger the nozzle size, the coarser is the droplet size spectrum at the same operating pressure.

Where an increase in operating pressure increased velocities.

All this information is very useful with regard to crop canopy penetration, the risk of spray drift, and the quantity and

distribution of the deposit on the target.

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