Nozzle Dynamics - Converging-Diverging Nozzles
In 1888, Swedish inventor Gustaf de Laval created the converging-diverging nozzle. This meant that following the reduction of flow area to a minimum, the nozzle then expanded back outward to ford an hourglass shape. This dramatically increased nozzle efficiency, allowing for far higher flow speeds at the exit.
It is entirely due to the invention of the converging-diverging nozzle that the jet engine was made possible, resulting in the ease and comfort of modern air travel. Additionally, and far more impressively, the converging-diverging nozzle enabled modern rocketry. In the early twentieth century, Robert Goddard made use of de Laval's converging-diverging design to increase nozzle efficiency to a point that would enable rockets to escape Earth's gravitational field. Goddard is widely considered the father of modern rocketry, and the man who began the Space Age.
It is entirely due to the invention of the converging-diverging nozzle that the jet engine was made possible, resulting in the ease and comfort of modern air travel. Additionally, and far more impressively, the converging-diverging nozzle enabled modern rocketry. In the early twentieth century, Robert Goddard made use of de Laval's converging-diverging design to increase nozzle efficiency to a point that would enable rockets to escape Earth's gravitational field. Goddard is widely considered the father of modern rocketry, and the man who began the Space Age.
JR
CDN designs are incredibly important because they can force a subsonic flow to become supersonic without adding any energy to the flow. Under design pressure ratio (DPR) conditions, there must be a throat area where the flow becomes sonic. If the DPR conditions are satisfied, there will be a supersonic flow at the exit of the CDN nozzle. If the flow is choked, the maximum mass-flow rate of the nozzle can be calculated through the following equation:
\[\frac{{d{m_{\max }}}}{{dt}} = {k^{.5}}{(\frac{2}{{k + 1}})^{.5(k + 1)/(k - 1)}}A*{\rho _0}{(R{T_0})^{.5}}\]
A consequence of supersonic flow in the diverging section of the nozzle is the possible appearance of shock waves within the nozzle, which can effect the flow dynamics.
\[\frac{{d{m_{\max }}}}{{dt}} = {k^{.5}}{(\frac{2}{{k + 1}})^{.5(k + 1)/(k - 1)}}A*{\rho _0}{(R{T_0})^{.5}}\]
A consequence of supersonic flow in the diverging section of the nozzle is the possible appearance of shock waves within the nozzle, which can effect the flow dynamics.
JL