Turbulent heat transfer in Helically Corrugated Tubes (HCT) was numerically investigated for pure water and SiO2 nanofluid using Computational Fluid Dynamics (CFD). This study was carried out for different corrugating pitches (5, 7, 8 mm) and heights (0.5, 0.75, 1.25 mm) at various Reynolds numbers ranging from 5000 to 13300. The effect of nanoparticles on heat transfer augmentation for plain t...

Helically corrugated waveguides have recently been studied for use in various applications such as interaction regions in gyrotron traveling-wave tubes and gyrotron backward-wave oscillators and as a dispersive medium for passive microwave pulse compression. The paper presents a summary of various methods that can be used for analysis of the wave dispersion of such waveguides. The results obtai...

this paper presents a three-dimensional numerical investigation carried out in turbulent forced convection in a tube with helical ribs. enhancement of heat transfer using helically corrugated tubes has beenstudied experimentally by many researchers but there exist a few published numerical analyses results. the paper also introduces the results of heat transfer and friction factor data for inco...

Chiral spoof surface plasmon polaritons in the terahertz region, resulting from a coherent superposition of TM and HE modes, can be generated by normally exciting helically corrugated metal wire with a linearly polarized Gaussian light. The handedness of the chiral SPP depends on the handedness of the helical groove. The chirality of the surface wave causes a spiral spatial extent of average po...

Application of nanofluid and coiled tubes are two passive methods for increasing the heat transfer. In the present study, the turbulent flows of water and nanofluid in coiled tubes heat exchanger were numerically studied. CuO-water nanofluid containing 1 vol% copper oxide nanoparticles was used and single-phase approach was considered for nanofluid flow. The effect of different geometrical para...

In the present article, a numerical study is performed to investigate the crushing behavior of cylindrical and conical corrugated composite tubes. Different aluminum foams are applied to the proposed structures in order to offer an excellent energy absorption capacity. The crushing behavior of tubes are evaluated in terms of two parameters: SEA (specific energy absorption) and CFE (crush force ...

A new method to generate ultrahigh-power microwave pulses compatible with mildly relativistic electron sources is proposed. This method involves a novel microwave compressor in the form of a metal helically corrugated waveguide, which can enhance the power of frequency-modulated nanosecond pulses up to the multigigawatt level. The results of the proof-of-principle experiments at kilowatt power ...