Grains exiting an underwater silo exhibit an unexpected surge in discharge rate as they empty. This contrasts with the constant flow rate of dry granular hoppers and the decreasing flow rate of pure liquids. Here we find that this surge depends on hopper diameter and happens also in air. The surge can be turned off by fixing the rate of fluid flow through the granular packing. With no flow cont...

Control and Modeling for stall and surge phenomenon in axial flow compressors have received great importance in recent times. In power generation plant and aerospace propulsion compression system are prone to the aerodynamic instabilities of stall and surge. In aero engine compressors higher pressure ratio has always been a growing stipulates which has over involved by diverse rotating stall an...

surge and rotating stall phenomena are two dynamic instabilities that occur in both axial and centrifugal compressors. surge is the stream instability phenomenon in compressor that imposes severe damages to the compressors. nowadays, suppressing surge phenomenon is one of the most important issues in oil and gas industries, especially when flow reduction or gas reflux is considered. this resear...

conclusions in this study, some characteristics that had a positive impact on the success of a manager in a hospital surge situation were identified. these characteristics ought to be taken into account when appointing hospital administrators and designing training programs for hospital administrators with the aim of being better prepared to face disasters. background hospital administrators pl...

This paper introduces the indicators for surge arrester condition assessment based on the leakage current analysis. Maximum amplitude of fundamental harmonic of the resistive leakage current, maximum amplitude of third harmonic of the resistive leakage current and maximum amplitude of fundamental harmonic of the capacitive leakage current were used as indicators for surge arrester condition mon...

Computer modeling with the EMTP code has been applied to several configurations and earthing practices in use in various countries to show the effect of any differences in the dispersion (sharing) of a lightning stroke current among the available paths for the earth-seeking lightning current. Simplifying assumptions have been made to some details of the configurations to focus on the main diffe...

This paper presents computer-based design and analysis of control systems for centrifugal compressors when the operating fluid is supercritical CO2. It reports a non-linear dynamic model including a main forward compression line and two different configurations for the recycle antisurge line. Disturbance scenarios are proposed for testing the configurations and performance indicators are sugges...

sures experienced by a pipeline can be either beneficial or detrimental from an operational performance perspective, depending on the amount, the two phase regime of the mixture (whether homogeneous or slug) and the nature and cause of the transient. It is generally held that when free (undissolved) air, or gas, is present in a hydraulic system, it can greatly reduce the surge pressure levels b...

In a hydroelectric power plant or in a pumping station in order to avoid sudden large increase of pressure due to instantaneous valve closure sometimes a surge tank is installed. The height of surge tank is designed by the highest possible water level during the operation. The theoretical treatment of oscillation in a surge tank is difficult because of the non-linearity of friction term in the ...