[Physical flow aspects of pressure jet ventilation].
The decrease of the temperature of a gas at a process of throttling depends on the thermodynamic properties of the concerned gas, on the initial pressure, the initial temperature, and the final pressure. It is for oxygen nearly as big as for air, and it amounts to delta T = 2 degrees C at delta p = 10 bar pressure drop. With a gas temperature T1 = 290 K (17 degrees C) in the oxygen cylinder, the gas temperature in the tracheobronchial tree may fall to values of -3 degrees C to -20 degrees C. A gas jet impacting vertically on a wall produces the power F = m.v approximately to 0.5 N. This corresponds in average to a pressure at the stagnation point of P0 = 2 bar = 0.2 N/mm2 (respectively to the weight of a mass of 22 g/mm2). A good suction effect of the jet of injector can only be obtained with an injector tube adjusted in length and diameter. To obtain a good homogenization in mixtures by ultrasonic, a long mixing tube (L 20.D approximately 180 mm) is required. Gas injectors are to laid out according to the theory of a friction-loaded compressible flow. Test results are necessary for the control. In high frequency jet ventilation an acoustic resonant oscillation is used that, indeed, leads to a practically negligible gas exchange.
Iben
H
H
Technische Universität Magdeburg.
Christoph
B
B
D006611:High-Frequency Jet Ventilation; D006801:Humans; D008433:Mathematics; D010100:Oxygen / Q000502:physiology*; D011312:Pressure; D013696:Temperature; D013816:Thermodynamics
D010100:Oxygen
Strömungsphysikalische Aspekte der Druckstrahlbeatmung.