Nozzle work

The specific stub work is the difference in the (bulk) specific work skills of a fluid between the suction and discharge ports (inlet and outlet housing ) of a turbomachine in . The nozzle work thus corresponds to the total isentropic enthalpy difference: ${\displaystyle Y}$ ${\displaystyle \mathrm {\frac {m^{2}}{s^{2}}} }$

${\displaystyle {\begin{aligned}Y&=\Delta h_{ts}\\&=\Delta h_{p}+{\frac {c_{D}^{2}-c_{S}^{2}}{2}}+g(z_{D}-z_{S})\end{aligned}}}$

With

• the specific enthalpy difference due to the pressure difference ${\displaystyle \Delta h_{p}={\frac {p_{D}-p_{S}}{\rho }}}$ ${\displaystyle p_{D}-p_{S}}$
  • the indices for the pressure side and for the suction side ${\displaystyle _{D}}$ ${\displaystyle _{S}}$
  • the density of the fluid ${\displaystyle \rho }$
• the specific enthalpy difference due to the different flow velocities , cf. kinetic energy ${\displaystyle {\frac {c_{D}^{2}-c_{S}^{2}}{2}}}$ ${\displaystyle c}$
• the specific enthalpy difference , which is negligible for gases, due to the altitude difference , cf. potential energy ${\displaystyle g(z_{D}-z_{S})}$ ${\displaystyle z_{D}-z_{S}}$
  • the acceleration of gravity . ${\displaystyle g}$

The fall or delivery head  H can be defined with the specific nozzle work

${\displaystyle H={\frac {Y}{g}}}$

literature

• Fister, Werner: Fluid energy machines. Volume 1: Physical requirements, parameters, elementary levels of flow and displacement machines, Springer-Verlag, 1984 , ISBN 3-540-12864-6