Abstract In pump turbines, the observation in engineering field shows that pressure fluctuation has become one of most serious hydraulic instability phenomena. The pulsation will cause vibration and fatigue failure unit, even plant, which greatly affects safe operation power station. this paper, research on by domestic foreign researchers is introduced discussed. It includes characteristics var...

We study the one-point probability distribution functions (PDFs) of the peculiar velocity and the density fluctuation in a cosmological fluid. Within the perturbative approach to the structure formation scenario, the effect of “pressure” has recently been an area of research interest. The velocity dispersion of the cosmological fluid creates effective “pressure” or viscosity terms. From this vi...

Using bottom outlets for drain and regulation of water level in reservior has significant importance in performance mahagment of dam. Amount of service and emergency gates opening have important role in pressure, velocity and discharge coefficient variations and finally dam performance. In the present research, flow aeration between emergency and service gates was studied with different hydraul...

Effects of a generalized dark energy fluid is investigated on cosmic density fluctuations such as cosmic microwave background. As a general dark energy fluid, we take into consideration the possibility of the anisotropic stress for dark energy, which has not been discussed much in the literature. We comprehensively study its effects on the evolution of density fluctuations along with that of no...