Influence of Disc Tip Geometry on the Aerodynamic Performance and Flow Characteristics of Multichannel Tesla Turbines

Abstract

As a competitive small-scale turbomachinery option, Tesla turbines have wide potential in various fields, such as renewable energy generation systems and small power equipment. This paper investigates the influence of disc tip geometry, including its profile and relative height, on the aerodynamic performance and flow characteristics of one-to-one and one-to-many multichannel Tesla turbines. The results indicate that compared to the turbine with blunt tips, the isentropic efficiency of the one-to-one turbine with sharp tips has a little decrease, which is because the relative tangential velocity gradient near the rotational disc walls decreases a little and additional vortices are generated at the rotor inlet, while that of the one-to-many turbine with sharp tips increases significantly, resulting from an increase in the relative tangential velocity in the disc channels and a decrease in the low Mach number and vortex area; for instance the turbine efficiency for the former relatively decreases by 3.6% and that for the latter increases by 13.5% at 30,000 r/min. In addition, the isentropic efficiency of the one-to-many turbine with sharp tips goes up with increasing relative height due to increasing improvement of flow status, and its increment rate slows down. A circular or elliptic tip performs better with lower relative height and a triangular tip behaves better with higher relative height. To sum up, a blunt disc tip is recommended for the one-to-one turbine, and a sharp disc tip is for the one-to-many turbine. The relative height and tip profile of the one-to-many turbine should be determined according to their effects on turbine performance, manufacturing difficulty and mechanical deformation.

An investigation on the forced convection heat transfer in the gap of two rotating disks with laminar inflow

“…It has been found that the tangential velocity in the core region is less for contrarotating disks than for corotating disks. 42 Accordingly, the core temperature is more for corotating disks than contrarotating disks.…”

“…Fluid flows between two heated concentric rotating disks 42 as shown in (Figure 1A and 1B). Figure 1C shows an axisymmetric computational domain where the angular speeds of the top disk and the bottom disk are ω 1 and ω 2 , respectively, and the gap between the disks is L. Fluid enters the peripheral gap and discharges at the inner radius r i .…”

“…Geometry and coordinate system: (A) isometric view of the rotor of a disk turbine,42 (B) sectional view of the rotor,42 and (C) axisymmetric computational domain [Color figure can be viewed at wileyonlinelibrary.com]…”

Analysis on Inlet Nozzle Design Geometry of Tesla Turbine

“…To get P01, Equation ( 4) from [10] can be used, and ¨P can be calculated as stated in this article [11]. Noted that the efficiency of the turbine decreases with the increase in rotational speed [12]. Where: P01 = H = total head P = pressure ȡ = density g = gravity V = velocity z = elevation (5) Where: ¨P = head loss ¨Pin = head loss at inlet ¨Pout = head loss at outlet ( 6 ) Where: ¨Pin = head loss at inlet ‫ܭ‬ = area ratio Vin = velocity at inlet g = gravity ( 7 ) Where: P01 = H = total head P = pressure ȡ = density g = gravity V = velocity z = elevation ( 8 ) Where: ‫ܭ‬ = area ratio An,i = cross-sectional area at nozzle inlet An,o = cross-sectional area at nozzle outlet…”

Performance Assessment of Bladeless Micro-Expanders Using 3D Numerical Simulation

“…The predicted efficiency of turbine oscillates around 50%. Rusin et al [8] compared the experimental results of Tesla turbine with numerical analysis by considering the surface roughness of the disks. The highest power and efficiency values obtained were: 55.6 W, 11.2% for inlet pressure 3 bar and 98.3 W, 11.8% for 4 bar.…”