To flow velocity increases significantly as the inlet

To understand the causal conditions and
processes of negative pressure in the throat of Venturi injector?by measuring pressures at the inlet?outlet and throat for Venturi injector
respectively?the energy conversion relations
of water flow at different feature sections were studied?The results show that the inlet pressure
energy is translated into the throat kinetic energy when water flows through
the Venturi injector?As the
inlet pressure energy and the discharge increase?the kinetic energy in the throat increases?when the kinetic energy in the throat
reaches a certain value?the
pressure energy at the throat disappears completely and the negative pressure
occurs?When the negative pressure
reaches the minimum value and remains stable?the flow velocity increases significantly as the inlet pressure
increases?The kinetic energy and head loss
in the throat also increases very quickly as the flow rate increases?At the same flow rate?the differences between actual and
theoretical flow velocity could indicate the size of throat vacuum space?Compared with free outflow conditions?under nonĀ·flee outflow conditions?the starting pressure causing the negative
pressure in the throat increases?and the flow Volume is relatively great?To obtain the same negative pressure?the inlet pressures and flow rate under
non-free outflow conditions are significantly greater than those under free
outflow conditions?(Fan Xingkel
et al.,2013).

Optimum and efficient use of fertilizers is
one of the major advantages of drip irrigation systems. Success of micro
irrigation system lies in precise application of fertilizers. The investigation
was carried out to study the performance of venturi injector manufactured by
Jain Irrigation Systems Ltd. under normal field conditions, near Talsande
village of the Kolhapur district of Maharashtra state. The different pressure
combinations were maintained at upstream and downstream side of the venturi
injector. The different inlet pressures of 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0
kg/cm2 were selected with different outlet pressure combinations of 0.1, 0.3
and 0.5 at the outlet of the venturi injector. Injection rate and injection
efficiency were calculated for different varying inlet and outlet pressure
combinations using relationship suggested by manufacturer of the venturi
injector. The maximum injection rate in case of venturi (74 lps) was achieved
at inlet pressure of 1.8 kg/cm2 and outlet pressure of 0.1 kg/cm2 with pressure
differential of 1.7 kg/cm2. Injection efficiency of venturi was observed
maximum at 95 per cent at 2 kg/cm2 inlet pressure and 0.1 kg/cm2 outlet
pressure fallowed by 94.4 per cent at 1.8 kg/cm2 inlet pressure and 0.1 kg/cm2
outlet pressure and 94 per cent at 1.6 kg/cm2 inlet pressure and 0.1 kg/cm2
outlet pressure. (S.C. BHANGARE et al., 2015).