MODELING OF AN EXPERIMENTAL HYDRAULIC SYSTEM WITH TWO FLOW CONTROL PARAMETERS

This study suggests an innovative method for analyzing the behavior of hydraulic experimental systems that can be used as a tool for a system design. Design of experimental hydraulic systems can be a complicated challenge. Unlike industrial facilities, where the process is designated to work in a single or a limited narrow range of duty points and therefore classical design methods can be used, in experimental systems, where any selected duty point within a vast range may be needed, the system design may require much more advanced methods. Such an example is presented in this work where modeling of flow characteristics for an experimental hydraulic system is required. In this example, the system should provide any desired water flow rate in the wide range of 10-450 m(3)/h (an exceptional ratio in industrial facilities) with accuracy of +/- 2% while maintaining good stability. Review of former studies in this field didn't reveal any suggested methods for such a design. In addition, standard process and piping software were examined and found unsuitable for this challenge. Therefore, an independent hydraulic model was developed. The modeling method is based on conventional analytical correlations of hydraulic resistance for a fully developed turbulent flow, modeling of centrifugal pump's Pressure-Flow Curve (PFC) which depends on the frequency of the supplied voltage and by modeling the varying hydraulic resistance of a throttle control valve. This technique enables analytic evaluation of the possible flow rates in the system, to inspect the system stability and to perform a parametric study of the piping characteristics (diameter, valve type etc.) for two design alternatives. The code of the model was written in a free open-source Scilab platform. The results of the analytical model were illustrated on three dimensional plots displaying the system's flow-rate versus the pumps frequency and the degree of rotation of the throttle control valve. According to these results, the most prominent alternative was chosen for manufacture.