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S. Upnere

Abstract

The paper presents the numerical study of vibrating multiple flexibly-mounted cylinders in a triangular rod bundle. Behavioural trends of six different clusters of oscillating rods have been analysed. The influence of neighbour cylinders on the central cylinder oscillation characteristics is analysed. Finite volume solver of open source computational fluid dynamics is used to calculate the fluid flow in the channel with the cylinder array. Built-in six degree-of-freedoms solver is utilised to simulate cylinder movement. Oscillating cylinders have two degrees-of-freedom. The obtained results are compared with numerical results available in the literature.

Open access

S. Upnere, N. Jekabsons and U. Locans

Abstract

The current paper presents an engineering approach for studies of the control algorithm designed for a mechanically robust large antenna. Feed-forward control methods with the 3rd-order polynomial tracking algorithm are supplemented to the original feed-back PID control system. Dynamical model of the existing servo system of 32m radio telescope has been developed to widen a case analysis of observation sessions and efficiency of the control algorithms due to limited access to an antenna. Algorithms along with the results from the system implemented on a real antenna as well as model results are presented.

Open access

R. Joffe, N. Jēkabsons, A. Bērziņš, M. Klapers and S. Upnere

Abstract

The main objective of the work was to analyze the operation of the large radio telescope RT-32 at the Ventspils International Radio Astronomy Centre (VIRAC). The analysis has been performed in order to evaluate dimensional changes in the RT- 32 structural base due to reorientation of the antenna mirror. Three different orientations of the dish were considered, and the dimensional changes in the load carrying substructure were measured. The measurements were made to estimate possible effect of the geometrical changes of the antenna due to gravitational loads on the overall performance of the radio telescope with respect to the obtained astronomical results, their accuracy and validity. Comprehensive mapping and classification of the corrosive damage of steel elements in the antenna have been done. A preliminary numerical analysis by the finite element method was carried out to demonstrate the overall effect of the damaged steel beams on the geometrical distortion of the antenna surface.

Open access

S. Upnere, N. Jekabsons and R. Joffe

Abstract

Comprehensive numerical studies, involving structural and Computational Fluid Dynamics (CFD) analysis, have been carried out at the Engineering Research Institute “Ventspils International Radio Astron- omy Center” (VIRAC) of the Ventspils University College to investigate the gravitational and wind load effects on large, ground-based radio tele- scopes RT-32 performance. Gravitational distortions appear to be the main limiting factor for the reflector performance in everyday operation. Random loads caused by wind gusts (unavoidable at zenith) contribute to the fatigue accumulation.