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Investigation of vibrations of a main centrifugal fan used in mine ventilation

100%

Rusiński E. , Moczko P. , Odyjas P. , Pietrusiak D.

Archives of Civil and Mechanical Engineering

2014

tom Vol. 14, no. 4

569--579

Operation of machines in resonance ranges is a great challenge for design engineers. The paper focuses on the analysis of centrifugal fan casing vibrations which during machine operation, particularly in unsteady states, are very strong. Within a series of investigations performed according to the experimental modal analysis natural frequencies of fan casing vibrations were specified. Additional numerical simulations helped to define theoretical values of the natural vibrations frequency and its mode shapes. The results were analyzed and the numerical model was adjusted. The information was later used in the analysis of vibration measurements in real operating conditions. The results achieved for a nine-blade impeller (new type) were compared to results of an old construction eight-blade fan impeller. New solutions, which shall facilitate casing operation beyond resonance frequencies vibrations areas, were proposed.

On parallel operation of fans

100%

Krawczyk J.

2000

tom Vol. 48, nr 1

61-73

The paper presents a method for distinguishing unstable operating points in ventilation networks with fans operating in parallel. Several concepts of ventilation systems and their characteristics were applied. The analysis of local stability of equilibrium points of the system of ordinary differential equations describing unsteady incompressible flow in a simplified network ventilated by 2 fans in parallel, leads to formulation of a simple condition of stability. Some graphic examples of construction of ventilation systems characteristics are presented. Results of calculations were graphed to show time variations of flow quantities and pressure during transients caused by the loss of stability.

Zastosowanie reakcji impulsowej i skokowej w analizie działania ochrony odgromowej zwodu aktywnego typu ESE w stanie niestacjonarnego narostu potencjału elektrycznego chmury

84%

Skopec A. , Smycz E. , Stec C.

2011

tom R. 79, nr 10

40-44

Przedstawiono podstawy teoretyczne analizy w układzie zastępczym modelu zwodu aktywnego piorunochronu w sytuacji niestacjonarnego wzrostu potencjału oraz określono wyprzedzenie czasowe tworzenia się warunków wczesnego wyładowania (ESE).

The paper presents theoretical bases of analysis - in equivalent circuit - of active air terminal of lightning arrester in unsteady state of inerease of potential. Time lead of arising conditions for ESE are determined.