Evaluation of a developed SST k-ω turbulence model for the prediction of turbulent slot jet impingement heat transfer

A blackbox optimization of volumetric heating rate for reducing the wetness of the steam flow through turbine blades

The large eddy simulation model coupled with the modified Schnerr-Sauer cavitation model has been used to numerically simulate the unsteady cavitation and noncavitation flow of the three-dimensional NACA66 hydrofoil under different operating conditions. The resulted show that the magnitude of the cavitation number plays a decisive role in the hydrofoil cavitation quasiperiodic phenomenon. The cavitation number 1.25 is used as a typical working condition for analysis. Using the Ffowcs Williams-Hawkings acoustic analogy approach accompanied with the vorticity transport equation splitting, the growth and shedding of cavitation also lead to the growth and shedding of the vortex structure. The cavitation-vortex interaction is mainly influenced by the vortex stretching term and vortex dilatation term and amplitude of them are larger than 500. The baroclinic torque term may be responsible for generating vorticity during the cloud cavitation collapse and has a lower amplitude about 200. The cavity volume acceleration is the main influencing factor of the low-frequency pressure fluctuation around the cavitating hydrofoil. Moreover, the NACA66 hydrofoil surface-pressure data are collected for dynamic mode decomposition to locate the hydrofoil surface noise sources. The alternate high and low amplitude regions in the mode results overlap highly with the cavitation transformation regions. The cavity transformation and pressure fluctuations are the main reason for the generation of periodic low-frequency noise source regions on the hydrofoil surface. Moreover, the corresponding frequencies of each order mode are linearly correlated with the cavitation shedding frequency of 5.70 Hz. Combined with the results of the multiple mode comparisons.

Numerical study on cavitation-vortex-noise correlation mechanism and dynamic mode decomposition of a hydrofoil

Experimental study on the trajectory of projectile water entry with asymmetric nose shape

In this work, a developed Shear Stress Transport (SST) model has been used for numerically simulating the problem of turbulent round jet impingement heat transfer. Based on the cross-diffusion correction activated in the logarithmic and wake parts of a region by using a blending function in the destruction term of turbulent kinetic energy k, the developed SST model is capable of recovering the effect of the pressure gradient ignored by the standard SST model. Also, the Kato-Launder model is added in the production term of k to consider the stagnating flows. The developed model has been investigated for turbulent round jets with the nozzle-plate spacing of 2, 4, and 6. The model is verified by comparing with the measurements and the results of the standard SST model, the SST with low-Re model, the Launder and Sharma model with the Yap model, the k-ω model, and the Reynolds-averaged Navier-Stokes/large eddy simulation model. Comparing with other referred methods, the developed model obtains accurate prediction in terms of velocity and pressure. As for heat transfer, it also possesses appropriate performance. Moreover, the developed model is sensitive to the pressure gradient, which helps the model be capable of reproducing accurate flow structures. By using the present model, it has been found that the velocity profiles are dominated by the turbulent kinetic energy away from walls. Meanwhile, the results show that the inner peak of heat transfer is connected with the radial pressure gradient at the stagnation point.

Huakun Huang

Papers

Evaluation of a developed SST k-ω turbulence model for the prediction of turbulent slot jet impingement heat transfer

Modeling and computation of turbulent slot jet impingement heat transfer using RANS method with special emphasis on the developed SST turbulence model

Analysis of the performance of a new developed shear stress transport model in a turbulent impinging jet flow

Physical investigation of transient dynamic behaviors of cavitation-induced vibration over a flexible hydrofoil

The effects of rough surfaces on heat transfer and flow structures for turbulent round jet impingement