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

Experimental study of the effects of a viscous liquid layer on the cavity dynamics of vertical entry by a sphere into water at low Froude number

Numerical study of vertical water entry of cylinder under the influence of wind and current

Relatively few studies have examined the effects of pulsating unsteadiness in turbine cooling blades. This unsteadiness can be a result of compressor blades and vane interaction. In addition, there is a particular lack of data of full turbine blades at various angles of attack. The effects of pulsation frequency (f = 2 Hz, 50 Hz, and 100 Hz) and the angle of attack (α = 0°, 15°, and 30°) on the film cooling effectiveness of a row film jet at the leading edge of a modified NASA C3X blade for two blowing ratios (M = 0.5 and 1.0) in comparison with the steady state experimentally investigated on pressure and suction sides of the blade and the flow field are obtained by simulation. Three-dimensional transient Reynolds-averaged Navier–Stokes equations coupled with the shear stress transport turbulence model (SST k − ω) are used in this research. Square waves are considered to pulse the injection air. Results show that the distribution of the instantaneous film cooling effectiveness is affected by frequency, angle of attack, blowing ratio, and curvature of the blade. With an increase in the angle of attack and the pulsing frequency, the averaged film cooling effectiveness increased. Pulsation and angle of attack have different effects on the performance of the injection jet toward the pressure and suction sides of the blade. Mixing of injection air with the mainstream at the pressure side is more than that at the suction side. Under certain conditions, the averaged film cooling effectiveness of pulsation flow is greater than the steady jet.

Effect of pulsating injection and mainstream attack angle on film cooling performance of a gas turbine blade

Numerical study of wave effect on water entry of a three-dimensional symmetric wedge

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.

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

The water entry process associated with complicated unsteady structures, with consideration of the influence of the waves, is not well studied. In the present work, the oblique water entry of a cylinder under different regular waves is numerically investigated. The volume of fluid (VOF) method and the sub-grid scale (SGS) stress model based on the large eddy simulation (LES) method are adopted for the 3-D simulation with six degrees of freedom. The present numerical model is based on a wave model, and as shown by the previous work that the predicted cavity evolution in the calm water agrees well with the experimental results. The present model is validated and it is shown that it could be used to predict the correct wave periods and fluctuations. The cavity evolution mechanism, the dynamic characteristics and the vortex structures are analyzed. The cavity of the water entry with waves closes more quickly than in the calm water case. Finally, several parametric studies of the water entry with different wave heights and water entry locations are carried out. The results provide insights into the effects of the waves on the cavity dynamics for oblique water entry problems.

Ning Li

Papers

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

Numerical simulation of the effect of waves on cavity dynamics for oblique water entry of a cylinder

Sensitization of the modified SST model to the swirling and curvature for turbulent impinging jet heat transfer