High Temperature Gas-cooled Reactor usually adopts helical tube bundles for its heat transfer equipment (steam generator or intermediate heat exchanger). The geometrical arrangement of helical tube bundles determines its thermal hydraulic performances. The flow attack angles between the tube axes of helical tubes and the fluid flow directions are smaller than 90 degrees, which is introduced by the inclination of the helical tubes due to upward winding. Except for the parameters of tube diameter, helical diameter. longitudinal pitches, transverse pitches and inclination angles, the inclination direction (or winding direction) of neighboring layers of helical tubes also influences the thermal hydraulic performances. The opposite sense inclination effect is numerically investigated. A three dimensional model having 5 layers of straight tubes with opposite sense inclination of neighboring layers is established. Standard k-e model was used for the turbulence modeling. The velocity and temperature field were investigated. Special attention is paid on the opposite sense inclination effect on pressure drop and heat transfer coefficient. The results show that the opposite sense inclination will lower the heat transfer coefficient and pressure drop coefficient, which coincides with the measured results.
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