A numerical simulation-based method for investigating Reynolds scaling effects of semi-confined impinging jets

Taking a semi-confined circular orifice impinging jet (m/b = 2) with a geometric scale ratio of 1:60 as the case study, this paper proposes a computational fluid dynamics-based method for investigating the Reynolds scaling effects of branch orifice impinging jets. The results show that scaling effects lead to remarkable flow discrepancies: due to its relatively low Reynolds number (Remodel = 2.31 × 104), the momentum attenuation of the model-scale jet dominated by the near-wall viscous effect is significantly greater than that of the prototype (RePrototype ≈ 1.07 × 107). The radial velocity of the model is 10%–40% lower than that of the prototype, and there is an obvious deviation in the flow regime between the two. After adjusting the Reynolds number of the model to be close to that of the prototype (ReCorrect model ≈ RePrototype ≈ 1.07 × 107), the scaling effects are significantly reduced, and the radial velocity distributions become nearly consistent (discrepancy narrowed to 10%–20%). The flow characteristics of both the recirculation zone and potential core zone of the correct model were basically consistent with those of the prototype, which verified that the error was attributable to the scaling effect rather than significant grid error.