摘要：A better understanding of the flow field of thecross-flow turbine (CFT) will be useful in its design andoperation. As far as is known, no comprehensive study carriedout relating to the effect of Reynolds number to turbulentshear stress, shear wall, energy kinetic turbulent, dissipationrate and Reynolds stress, and the occurrence of vorticesaround the runners of the CFTs. This study was designed toinvestigate the flow field in the nozzle and runner of the CFTusing computational fluid dynamics (CFD) method. CFDmethods were chosen because they can visualize detailed flowpatterns that other methods cannot. The setups used in theCFD method such as two-dimensional unsteady simulations, sixdegrees of freedom features, shear stress transport k-ωturbulent model, and pressure-based solver. Based on results,for the nozzle, the shape of the velocity profile shows that thehighest momentum flux occurs at the end of the nozzle, nearthe runner. Distribution of shear wall was highest at the baseand tip of the nozzle; it was lowest at the centre. The turbulentkinetic energy profile at the nozzle was proportional to theturbulent boundary layer profile, Reynolds stress and eddyviscosity. This indicated that nozzle shape affects themomentum flux; therefore, good nozzle geometry can transferthe maximum water energy into the blade. The nozzle’soptimum geometry can be achieved by discharge and direction,optimizing velocity magnitude. This minimizes energy loss dueto friction between the stream, vortex and mass of wasted fluid.For the runner, the highest turbulent kinetic energy,dissipations rate and Reynolds stress were located at therunner. Not all the water’s energy converted into mechanicenergy because the part of that energy was used in mixingbetween water and air. The establishment of lift force on theactive blades was not caused by the flow field that crosses theupper part of the blade, but by the momentum of water that hitthe lower part of the blade. A vortex formed due to separationof the flow from the blade significantly affected the runner’sperformance rather than rotational flow (air phase) in theCFT.
