The effect of injection angle and jet flow velocity into an isothermal channel on the heat transfer and fluid-induced vibrations: unilateral versus bilateral injection

The jet injection efficacy on the vibrational and heat transfer behavior of a circular cylinder placed on an elastic bed and inside an isothermal channel is investigated in this article. The cylinder, which is subject to the flow deployed in the channel, experiences free vibrations in the longitudinal and transverse directions of flow owing to the oscillating drag and lift forces. In the single-jet mode, there is a slot at the bottom of the channel, while in the double-jet mode, two slots on either side of the channel are implemented. The distance from the slot to the center of the cylinder is 1.5 times the diameter of the cylinder. In this research, the effect of injection angle and jet velocity on the vibrational and thermal behavior of the cylinder is investigated. Numerical simulation is based on the finite volume method. To link the movement of circular cylinder with flow field, the dynamic mesh method is used. The results of fluid–structure interaction simulations show that the complete suppression of vortex shedding perfectly attenuates cylinder vibrations with two degrees of freedom. The region wherein full vortex-induced vibration suppression occurs is much wider in the double-jet mode. In single-jet and double-jet mode, 99.9% reductions in VIV are obtained for $${U}_{j}=3 \, and\, \alpha =50$$ °and $${U}_{j}=2.5\, and \, \alpha =50^\circ ,$$ , respectively. Moreover, at a constant angle, the use of two jets can completely mitigate the cylinder transverse displacement at lower injection velocities. However, this greater efficiency requires a higher cost and more energy consumption. The use of jets on the channel wall lessens the thickness of hydrodynamic and thermal boundary layers and augments heat transfer. Heat transfer in single-jet mode increases by about 8% and 11% with increase in jet injection angle and injection velocity, respectively. Heat transfer in double-jet mode increases by about 14% and 37% with increase in jet injection angle and injection velocity, respectively. The maximum of mean heat transfer coefficient happens at a certain angle of injection, which is observed in the range $$50\le \alpha \le 100$$ and depends on the injection velocity and single/double-jet mode.