Zonal Detached Eddy Simulations of a Dual-Stream Jet: Turbulence Rate Sensitivity

Abstract

This paper investigates the effect of turbulence injection using the random flow generation technique at the inlet boundaries of the core and fan channels of a dual-stream nozzle with an external plug. The objective is to reproduce the turbulence rate at the center of the nozzle ducts’ exhaust. The nozzle design and operating conditions are typically those of an aircraft engine at cruise, although the external flow is not simulated. The paper focuses on the effects of the nozzle exhaust turbulence characteristics, namely turbulent length scales and turbulent rate, on the jet flow prediction and the mixing-layer development. The results are discussed in terms of Reynolds-averaged data and spectral content. Turbulence injection over the whole height of the nozzle ducts accelerates the Reynolds-averaged Navier–Stokes to large-eddy simulation transition in both external and internal mixing layers, which is in better agreement with the experimental results. The transition length is further reduced when the injected turbulent ratio is higher but also when the injected turbulent length scale is smaller. Of interest, the shock-cell positioning in the fan jet is also improved using random flow generation, which emphasizes the importance of accounting for upstream turbulence for this type of simulation.