Calculation and designing of volutes of rotodynamic pumps

Abstract

Abstract. This work deals with improvements of the calculation and design methods of rotodynamic pump volutes taking into account viscous liquid flow. The research was performed with torque flow pump of "Turo" type. The analytical solution for the problem within the one-dimensional model of viscous liquid allowed to obtain a viscous liquid flow pattern in the volute. The law of velocity variation of viscous liquid flowing through the volute was obtained. There are numerical solutions of the problem concerning of viscous liquid flow in the pump with volute designed for traditional model of non viscous and viscous fluid. The research results are given by means of head-capacity and power input curves. To estimate the results of numerical study the tests were performed on the test stand. IntroductionRotodynamic pumps are energy machines. They are widely used in many branches of the industries and sectors of the national economy. Today's tendency of the development of rotodymanic pumps is connected with the increasing of their efficiency without any change in their mass and dimension. Following the energy balance the part of the hydraulic losses occurs in the volute chamber. The decrease of such losses within the total losses balance of a pump needs the improving of the calculation and design methods of pump volute especially in case of viscous liquid.One of the most effective methods with regard to minimum energy losses is a volute. It consists of a volute chamber casted integrally with a pump casing and a diffuser nozzle.Volute shall provide axially symmetric flow downstream of an impeller and thus producing steady flow in the impeller, convert part of the kinetic energy of the flow downstream of the impeller into the pressure energy and direct flow to the discharge nozzle or to the next pump stage.Volute designing is carried out for the rated conditions of the pump. Therefore, a relatively small circumferential non-uniformity of the flow is observed only within a rather short operating range, close to the optimum condition. Beyond the above mentioned range the non-uniformity of the flow around the impeller increases greatly. If this occurs the hydraulic losses as well as pressure pulsations and radial forces also increase in the volute and impeller. The usage of the volute is economically feasible only at the rated conditions.The existing methods for calculation of the volutes are based on a number of assumptions which simplify the physics of the liquid flow passing through the volutes. These assumptions include [1]: the liquid flow in the volute at the rated condition of the pump is assumed as steady flow;

Аналіз Перспектив Зменшення Енергоспоживання Вільновихрових Насосів Для Перекачування Рідин З Включеннями

“…Найменше значення коефіцієнта напору відповідає конструктивній схеми «Wemco». Вільновихрові насоси типу «Turo» займають проміжне положення [1,7]. Це дозволить мінімізувати загальну вартість життєвого циклу насосної установки [17].…”