El campo de flujo con presencia de ondas de choque, turbulencia y separación de flujo se estudia mediante el empleo de equipos experimentales y puede reproducirse utilizando códigos computacionales. En el presente trabajo el objetivo es evaluar cinco modelos de turbulencia: SST k-ω, k-e estándar, k-ω estándar, k-kl-ω de transición y RSM, para el flujo de aire con presencia de ondas de choque en un difusor transónico. Se realizaron simulaciones numéricas 2D del campo de flujo aplicando el modelo RANS en el código ANSYS-Fluent, el cual aplica el método de volumen finito. Se emplearon las ecuaciones gobernantes: conservación de la masa, cantidad de movimiento, energía y de estado; para la viscosidad en función de la temperatura la ecuación de Sutherland. Además, se consideró el análisis basado en densidad para un fluido compresible. Se obtuvieron resultados numéricos de perfiles de presión estática en las paredes y de la velocidad en diferentes posiciones en el difusor, así como, del campo de densidad, número de Mach, presión estática, velocidad y temperatura estática, para las relaciones de presión rp=0,82 y rp=0,72, los cuales fueron comparados con datos experimentales publicados en la literatura. Se concluye que el modelo de turbulencia SST k-ω de Menter se ajusta más a los datos experimentales de presión y de velocidad para el flujo con presencia de ondas de choque

Computational fluid dynamics employs the Large Eddy Simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) models and combines both models to perform a hybrid RANS/LES simulation of the transient state flow field, within which there are the Detached Eddy Simulation (DES) and Scale-Adaptive Simulation (SAS) models. In the present work, the objective is to evaluate the DES and SAS turbulence models for flow (water) in a Venturi tube, for 2D computational domains. The domain was discretized for grids with quadrilateral cells, and the flow field was studied for four flow rates. The results of the pressure flow field simulations for the DES and SAS models were compared with experimental data reported in the literature, which fit the experiments. However, the DES k-ε model presented a negative pressure drop for a region of the flow adjacent to the wall, at the entrance of the throat section, the other models DES S-A, DES SST k-ω and SAS presented positive pressures. The discharge coefficients yielded values in the range of 0.94-0.951, which were lower than the experiments, for errors in the range of 1.57-2.76%.

In the present work for a quasi-one-dimensional isentropic compressible flow model, an empirical equation of the Mach number is constructed as a function of the stagnation pressure ratio for an analytical equation that algebraic procedures cannot invert. The Excel 2019 Solver tool was applied to calibrate the coefficients and exponents of the empirical equation during its construction for the Mach number range from 1 to 10 and 1 to 5. A specific heat ratio from 1.1 to 1.67 and the generalized reduced gradient iterative method were used to minimize the sum of squared error, which was set as the objective function. The results show that for Mach 1 to 10, an error of less than 0.063% is obtained, and for Mach 1 to 5, an error of less than 0.00988% is obtained. It is concluded that the empirical equation obtained is a mathematical model that reproduces the trajectories of the inverted curves of the analytical equation studied.

In the present work, the flow field is analysed for Mach number, pressure and temperature in 2D computational domains for a planar nozzle of symmetrical geometry as used in the experimental tests for cold (air) flow. The study has been considered for three mean angles of the divergent section: α = 9°, α = 11.01° and α = 13°, and for four pressure ratios: NPR = 2.412, NPR = 3.413, NPR = 5.423 and NPR = 8.78. For the numerical simulation of the turbulence in the presence of shock waves, the RANS model, the Sutherland equation and the Spalart-Allmaras turbulence model were used in the ANSYS-Fluent R16.2 code. The results obtained show fluctuations at the intersections of the internal shocks in the divergent, and the fluctuation decreases as the angle of the divergent increases. For NPR = 3.413, NPR = 5.423 and NPR = 8.78, the Mach number at the nozzle exit is the same, where for α = 11.01° Mach 2.00 was obtained, and based on this reference, for α = 13° there is an increase in velocity of 4.15% and for α = 9° a decrease in velocity of 3.78%. The lowest pressure and temperature drop occurs at the nozzle outlet for α = 13°.