Computational analysis of nozzle geometry variations for subsonic turbulent jets. (10th September 2016)

• Record Type: Journal Article
• Authors: Cetin, Mehmet Onur; Pauz, Vitali; Meinke, Matthias; Schröder, Wolfgang
• Is Part Of: Computers & fluids. Volume 136(2016)
• Page Start: 467
• Page End: 484
• Publication Date: 2016-09-10
• Subjects: Large-eddy simulation -- Turbulent jet -- Multi-shear-layer flow -- Nozzle built-in components -- Cartesian mesh method; Fluid dynamics -- Data processing -- Periodicals; 532.050285
• DOI: 10.1016/j.compfluid.2016.05.033
• Languages: English
• ISSNs: 0045-7930

Abstract

Highlights: Effect of nozzle built-in components on the jet flow development is assessed. Numerical method is successfully validated against references from the literature. A Cartesian mesh method for three nozzle geometries with increasing complexity. Highly resolved large-eddy simulation for turbulent hot jets. The jet near field is dominated by flow structures induced by the geometry. Abstract: Large-eddy simulations (LES) of turbulent hot jets emanating from realistic helicopter engine nozzle configurations at a Reynolds number of Re = 7.5 × 10 5 and a Mach number of M = 0.341 are conducted. The numerical method is based on hierarchically refined Cartesian meshes. The nozzle wall boundaries are resolved by a conservative cut-cell method. Three nozzle geometries of increasing complexity are considered, i.e., the flow fields of a clean geometry without any built-in components, a nozzle with a centerbody, and a nozzle with a centerbody plus struts are computed. The numerical method is validated by solutions for a single, a coaxial, and a chevron nozzle jet problem. A grid convergence study shows that the essential flow characteristics due to the intricacy of the nozzle geometry are well resolved. The results evidence that the flow field in the region 35 nozzle radii downstream of the exit is dominated by flow structures induced by the geometry. Compared to the clean geometry, the other two configurations show enhanced turbulent mixing. The centerbody and centerbody-plus-strut nozzle configurations reveal a spectral peak in the near nozzle exit region at S t = 0.15 which is caused by the wake flow of the centerbody.