Evaluation method of riblets effects and application on a missile surface

To overcome the difficulties of numerical simulation for riblets drag reduction effects on large-scale aircraft model, a riblet-equivalent boundary condition is introduced by modifying wall ω value, which makes the riblets effects can be calculated with a conventional smooth wall by RANS computation. Firstly, an empirical formula is deduced by analyzing various experiment results, and the function relationship between nondimensional geometry factor h⁺ and wall ω value is established. Secondly, the verifications for riblet-equivalent boundary condition are conducted on both zero and adverse pressure flow, by comparing the numerical simulation results with experimental data, which indicates a good reliability of this new method. Finally, an application of riblet-equivalent boundary condition is conducted on a typical configuration missile. Three riblets surface cases are introduced, with various riblets geometry factors. Flow parameters are analyzed for presenting the flow structure and performance of riblets surface. The positive conclusions are obtained that a 2.4% total drag reduction and a 4.6% skin friction reduction are gained.