The Application Of Adjoint Solver On Drag Reduction Based On Field Synergy Principle

Energy conservation and emission reduction is an important way to achieve sustainable development at the growing shortage of global energy context. Configuration optimization of mechanical equipment like vehicles and water conservancy equipment is a research priority:on the one hand, energy dissipation and flow resistance during flow would be reduced; on the other side, mechanical properties would be further improvement in performance. Therefore, drag reduction and optimization has an important significance to people’s daily lives. However, most traditional methods of drag reduction derived from life experience and experimental measurement, there is no reliable guiding theory up to now; besides, long-computation period and numerous variables make traditional methods low-efficiency. To cure the above problems, this dissertation proposed a new shape optimization theory which is based on field synergy principle and adjoint solver to realize purposeful and efficient shape optimization procedures.1.Based on field synergy principle,the field synergy equation for incompressible turbulent flow was derived from N-S equations by using Reynolds averaging method; meanwhile the field synergy drag reduction model of incompressible turbulent flow was established by seeking extreme of Lagrangian function; the relationship between velocity gradient and synergy angle、force and synergy angle were studied according to evaluation criteria of field synergy principle for heat transfer.2.The backward-facing step flow was simulated on the basis of the field synergy drag reduction model of incompressible turbulent flow, then the flow pattern of fully coordinated flow field and majorizing region were acquired; the backward-facing step was optimized by using discrete adjoint method so the consistency between field synergy principle and drag reduction was verified.3.Based on adjoint solver and Navier-Stokes equations, taking flow uniformity of elbow’s outlet and pressure drop of breeches pipe’s inlet and outlet as objective function, the corresponding adjoint equations and boundary conditions were derived, which were the guiding ideology to the optimization of the speed distributor.