No abstract

This numerical study investigates the flow through a cylindrically shaped critical flow Venturi nozzle regarding the transitional behavior of the boundary layer inside the nozzle throat region. For the flow simulations, two different turbulence modeling approaches were used, and the simulation results were validated by comparison with experimental data. Characteristic quantities for describing the boundary layer development, namely the displacement and momentum thickness, were analyzed within the cylindrical part of the nozzle and compared with theoretical predictions based on integral methods for solving the boundary layer equations. Typical laminar and turbulent boundary layer flows could be classified depending on the Reynolds number, where the boundary layer curves show a self-similarity when multiplied by √ and ., respectively. The shape factor, defined as the ratio of displacement to momentum thickness, was identified to indicate the transitional region of the nozzle flow. Thus, this parameter can help improving transitional turbulence models based on experimental data.