ENTRANCE HEAT TRANSFER FROM A PLASMA STREAM IN A CIRCULAR TUBE - ENGINEERING CORRELATIONS

Experimental values of the Nusselt number were measured and empirically correlated for entrance section heat transfer from a confined plasma jet of three gases—helium, argon, and nitrogen—flowing in a circular tube. The approximate upper limit of Reynolds number was 900 and temperature level was 7000° K. Heat transfer coefficients were higher than in previous investigations because the plasma enters the tube from a nozzle of smaller diameter causing recirculation near the tube wall. The present correlation is compared with empirical equations for warm gases at subplasma temperatures, boundary layer theory predictions, and the plasma correlation of Skrivan and von Jaskowsky. The “hot plasma core” model is discussed in respect to photographs of the plasma jet for each of the three gases. © 1968, American Chemical Society. All rights reserved.