An Accounting Mechanism of the Protrusion Effect in the Annular Channel When Calculating the Leontiev Tube

The paper analyses a technique to calculate the Leontiev tube and shows that there are several ways to increase operating efficiency of this device of gas-dynamic energy separation. Application of regular relief (dimples and protrusions) on the wall between supersonic and subsonic channels is one of them.Analyses the results available in publications of experimentally numerically investigated influence of semi-spherical protrusions in the slot channels on the enhancement of heat transfer and drag coefficients at various Reynolds numbers.Shows that at the laminar flow owing to semi-spherical protrusions in the slot channel a heat transfer coefficient can be 1.1‑2.6 times increased with simultaneous 1.7‑4.8 times growth of drag coefficient (as compared to the smooth channel).At transition and turbulent flows the heat transfer enhancement, because of shallow dimples (depth-to-print diameter ratio is from 0.1 to 0.25), can reach 1.1‑2.4 times, with simultaneous 1.2‑7.9 times growth of the drag coefficient (as compared to smooth channel).Using the higher protrusions can provide up to 3.0‑3.5 times heat transfer intensification, but in this case there is an outrunning growth of the drag coefficient.It is shown that the staggered array of the shallow spherical protrusions is advisable to use for heat transfer enhancement in the subsonic channel of the Leontiev tube. The shallow spherical dimples correspond to them and operate as heat transfer intensifiers in the supersonic channel.The paper proposes a mechanism that enables taking into consideration an impact of the protrusions in the slot channel on the intensification of the heat transfer and momentum processes when calculating the gas-dynamic energy separation device (Leontiev tube) using the known (earlier published) technique.The study has been implemented under supporting Grant no. 15-08-08428 of the Russian Foundation for Basic Research.