The aim of this work was to investigate the resistance to hydraulic shock loads of flocculent versus granular sludge used in UASB reactors treating sewage with high solids content. Step-wise shock loads were conducted through decreasing HRT to examine the extent of reducing this parameter without significantly changing COD removal efficiency of the reactor. The lowest HRT of 4h resulted in only...

Stochastic groundwater modeling involves the propagation of probabilistic uncertainty from model input parameters to model estimates, usually via a Monte Carlo method. With the increasing reliance upon expert knowledge to define model inputs, and both fuzzy set and possibility theories to characterize this expert knowledge, alternative means of executing model equations are needed. While the fu...

The causes of resonance of a certain model pump-turbine unit during startup process were investigated in this article. A three-dimensional full flow path analysis model which contains spiral case, stay vanes, guide vanes, runner, gaps outside the runner crown and band, and draft tube was constructed. The transient hydraulic excitation force of full flow path was analyzed under five conditions n...

Competing linear, quasi-linear and non-linear hydraulic mount formulations of fixed and free decoupler types are comparatively evaluated for transient responses. First, features of the realistic excitation conditions are addressed. For instance, the mean load itself may vary with time, and several sinusoidal or transient excitations may be simultaneously present. Second, a multi-staged top cham...

Three-dimensional numerical simulations are carried out by commercial software STAR-CCM+ to investigate the hydraulic transient and flow behaviours of a prototype pump-turbine during the normal shutdown process. The global characteristics and pressure fluctuations are analysed as the pump-turbine runs through the turbine mode, into the turbine braking mode, and finally into the reversed pump mo...

5 Simple example problems 20 5.1 Cantilever beam . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 5.2 Frequency calculation of a beam loaded by compressive forces . . 27 5.3 Frequency calculation of a rotating disk on a slender shaft . . . . 29 5.4 Thermal calculation of a furnace . . . . . . . . . . . . . . . . . . 35 5.5 Seepage under a dam . . . . . . . . . . . . . . . . . . . . . . ...

Abstract The transient flow of a circular liquid jet impinging on horizontal disk, and the hydraulic jump formation, are examined theoretically numerically. interplay between inertia gravity is particularly emphasised. governed by thin-film equations, which solved along with force balance across jump. unsteadiness caused linearly accelerating from an initial to final steady state. To validate p...