Nozzle Efficiency Value

If the inlet velocity is small relatively to the exit velocity the energy balance of a nozzle is reduced to.

Misting nozzle 18 npt. This parameter reduces the overall efficiency and work output. These parameters describe how efficiently a turbine compressor or nozzle approximates a corresponding isentropic device. Mcgraw hill dictionary of scientific technical terms 6e copyright c 2003 by the mcgraw hill companies inc.

Ht8 h8 v8 2 2 nn an efficiency factor nn has been included here to account for all the losses in the nozzle but its value is normally very near 10. Since the objective is to increase the outlet fluid velocity we define the isentropic efficiency as the specific kinetic energy of the fluid leaving the actual or real nozzle divided by the specific kinetic energy of the fluid that would leave an isentropic nozzle. Efficiency of the nozzle is the ratio of the actual kinetic energy at the nozzle exit to the theoretical kinetic energy at the exit of the nozzle.

Then the isentropic efficiency of nozzles becomes h n h 1 h 2ah 1 h 2s. There was an optimum divergence angle for each pressure drop. Or it can also be defined as the actual enthalpy drop to the isentropic enthalpy drop for same inlet state and exit pressure.

Velocity coefficient is defined as the ratio of actual velocity of steam to an isentropic or theoretical velocity. Calculation of gross or stage efficiency of steam turbine is let h 1 enthalpy or total heat of steam before expansion through the nozzle in kjkg of steam h 2 enthalpy or total heat of steam after expansion through the nozzle in kjkg of steam enthalpy or heat drop in the nozzle ring of an impulse wheel total energy supplied per stage 1000 h d jkg of steam. Considering the energy equation for the nozzle the specific total enthalpy ht is equal to the static enthalpy plus the square of the exit velocity divided by two.

For turbines the value of h t is typically 07 to 09 7090. Ok next we can define the isentropic efficiency of a nozzle. The overall optimum divergence angle was 03060 in the range considered which had the highest efficiency of 70 at a pressure drop of 73 mpa.

There is no work interaction involved in nozzles and the potential energy change of the fluid is small. Velocity coefficient of nozzle. Naezel ifishense mechanical engineering the efficiency with which a nozzle converts potential energy into kinetic energy commonly expressed as the ratio of the actual change in kinetic energy to the ideal change at the given pressure ratio.