The dissertation is devoted for researching the intensity of pressure pulsations in the flowing part of the pump type D and determination the influence of the main constructional and operating parameters of spiral type centrifugal pump on the amplitude of pressure pulsations in the outlet of impeller with aim to form the list of effective ways of reducing hydrodynamic vibration at the source of beginning and improving the operational characteristics of type D pumps.
Based on the results of the information-analytical review of the literature sources, was determine the main sources of hydrodynamic vibration and the dependence of its value on the pump supply. It is established that the hydrodynamic vibration of the pump is a consequence of pressure pulsations in its flowing part, and estimating the intensity of pressure pulsations is one of the real ways to obtain by an indirect method the information about the intensity of hydrodynamic vibration of the pump at the development stage.
Experimental research of the operating parameters of the pump D2000-100-2, as a typical representative of pumps type D and the class of spiral type centrifugal pumps , confirmed that the intensity of hydrodynamic vibration of the main units of pump depends on the intensity of pressure pulsations in its flowing part and allowed to determine the correlation coefficient that characterizing the relationship between the root mean square value (RMS) of the vibration velocity of the pump bearing shell at the blade frequency and the RMS value of the pressure pulsations amplitude at the blade frequency at the outlet of volute, and also allowed to determine the limiting RMS value of pressure pulsations amplitude at which the RMS value of the vibration velocity of the pump D2000-100-2 bearing shell is overrun. Based on the results of the experimental study of the operating process parameters (H, N, ɳ and ∆P) of the pump D2000-100-2, were confirmed the adequacy of the calculated grid of the flowing part of the pump and numerical simulation of non-stationary fluid flowing.
Numerical research of the parameters of the operational process of the pump type D confirmed the dependence of the amplitude of pressure pulsations on the pump supply, made it possible to establish the physical nature and the influence of recirculation of flow at the outlet of impeller on the pressure pulsation amplitude at the blade frequency and to determine the influence of the main constructional parameters of the flowing part of spiral type centrifugal pump and its operating parameters on the pressure pulsations amplitude and the integral parameters of the pump operational process. According to the results of the numerical study, a list of ways to reduce the intensity of pressure ripples depending on their efficiency (in terms of expanding the operating range of the pump) and determined the magnitude of the impact of relative changes in the constructional parameters of the spiral type centrifugal pump (z1, b1, b2, D3/D2, φ, ψ, z2) and its operating parameters (Q, n) on the relative change of the RMS value of pressure pulsations amplitude at the outlet of impeller.
Based on the scientific generalization of numerical modeling results and factorial experiment, were formed recommendations for adjusting the basic geometric parameters of the impeller with mutual displacement of its blades by 1/2 step relative to each other to improve the operational characteristics of type D pumps with quality and energy efficient water supply in the supply range 0,3Qopt...Qopt.
It is proposed to assess the feasibility of modernizing an existing pump by replacing its impeller, taking into account the actual operating modes of the pump unit on the supply and on the basis of the specific electricity consumption for pumping a unit volume of liquid. Based on the proposed method, depending on the supply of pumps type D (Q) and capital costs for its modernization (Cmod), the lower limit of the difference between the specific consumption of electricity (∆ρ1,2, kW•h/m3) for which the payback period the measure of modernization of the impeller will not exceed the average service life (for impellers of pumps type D - t = 5-8 years).
