The film was created as a teaching aid for students of higher educational institutions. The first law of thermodynamics. Calculation of nozzle profiling. Types of nozzles and their efficiency under various conditions.
Footage from the year 1900. Southeast Asia, peasants turning a water wheel of an irrigation system with their feet.
A resident of Oceania climbs a palm tree to collect coconuts.
A rickshaw in China.
A peasant plowing with a horse-drawn plow in Russia.
An inventor wants to fly on a device with wings.
A stopped windmill.
Details of a steam mechanism.
Chronicle of the year 1900. The first automobile.
Competitions of the first automobiles.
A cartoon explaining the work of an internal combustion chamber.
Piston mechanism.
A car shows tricks at a stadium.
Turbine.
The first rocket.
The concept of the theory of gas and vapor outflow.
This theory is necessary for calculating the flow path of turbines, compressors, jet engines and rockets.
Spaceship.
The conversion of thermal energy into kinetic energy is subject to the first law of thermodynamics.
Formulas of the first law of thermodynamics.
A cartoon explaining the dependence of the gas outlet velocity from the nozzle on the gas pressure at the inlet and outlet.
Possible range of pressure drop.
Nozzle profiling law.
Continuity equation.
Profiling law equation for incompressible flow.
In this case, the acceleration of the working fluid always requires a decrease in the channel cross-section; the nozzle is always converging.
Gas flow formula in ordinary, differential form.
This formula shows that the nature of the cross-section change depends on which parameter will change more strongly: the speed or the specific volume.
In the first case, the profiling law will be the same as for an incompressible fluid, and in the second case, the channel must be expanded to accelerate the gas. L. Gumilevsky's book, which tells about the Swedish engineer Carl de Laval, who found that the speed and flow rate of steam through a converging nozzle, with a decrease in pressure drop, increase only to a certain value of the drop, and then remain constant.
Portrait of Carl de Laval.
Drawing of a combined nozzle, which made it possible to continuously increase the steam flow rate.
Laval nozzle.
Clarification of the general conditions of nozzle profiling during reversible, adiabatic outflow leads to a differential equation.
Equation.
During subsonic gas flow, the nozzle must be convergent.
During supersonic flow, it must be divergent.
For continuous transition through the speed of sound, the nozzle must be combined.
Thermal energy, Kinetic energy, Nozzle
1900
Stones falling into water.
Cartoon showing the disturbance of still and moving water caused by a stone falling.
The situation is similar with the propagation of small disturbances in gas passing at the speed of sound.
The signal about the pressure drop behind the nozzle, propagating in all directions at the speed of sound, is geometrically added to the flow velocity.
If a-c (where a is the speed of sound, c is the flow velocity) is greater than 0, then the signal enters the nozzle and the flow accelerates due to the decreased pressure drop.
Cartoon explaining this phenomenon.
When the pressure drop reaches a critical value, the signal does not pass through the narrow section of the nozzle and the velocity at the outlet remains constant, equal to the local speed of sound.
Graphic dependence of the flow velocity and mass flow rate of gas on the pressure drop.
Experiment on air flow from a converging nozzle.
To achieve a gas flow velocity greater than critical, it is necessary to begin to increase the nozzle cross-section.
Formulas confirming this effect.
Formula for maximum gas flow rate.
Cartoon considering the operation of a combined nozzle.
The operation of the Laval nozzle filmed in the Tepler device.
Nozzles of a spacecraft.
Rocket launch.
Combination nozzle, Gas pressure