Large vaned-voluted centrifugal pump is a general machine used for large-scale water diversion. As a vane-type hydraulic machinery, it also has the ability of reversible operation. With the introduction of policies to reduce carbon emissions, the proportion of unstable new energy use has increased. The existing large centrifugal pump unit can realize the function of reverse power transfer. For peak shaving and valley filling of power grid, it has high feasibility and economy. In this paper, a large vaned-voluted centrifugal pump is simulated numerically, it is external characteristics and flow state under positive and negative rotation are obtained, its performance is predicted by best efficiency point method, and it is found that pump reversal can run at the optimum efficiency point with higher flow rate and head. Error analysis is carried out for different formulas. The flow energy dissipation (FED) of different flow rates under positive and negative rotation is analyzed. It is found that the main energy loss locates on suction side of blade, inlet and outlet part of blade and tail part of guide blade head. By comparing the flow energy dissipation distribution under the same flow conditions with positive and reverse rotation, it is found that the high energy loss area of blade mainly exists in inlet and outlet part of blade in pump mode. The high energy loss area of the blades in turbine mode mainly exists in the inlet part of the blades. This study is of great significance to the operation of low-carbon power grid assisted by existing reservoirs and hydraulic machinery.
Large-scale vaned-voluted centrifugal pump is a key component in water conveyance engineering. Hydraulic performance and pressure pulsation are important assessment indicators for operation efficiency and stability. During the common operation, the impeller eccentricity is easy to occur due to installation error, radial force and other reasons, which results the changes of hydraulic performance and pressure pulsation. In this study, the hydraulic performance and pressure pulsation in the vaneless region are analyzed by computational fluid dynamics method. The influence of eccentric impeller on the hydraulic performance in each components and the pressure pulsation is studied. Results show that the eccentric impeller causes the increasing of hydraulic dissipation especially in the volute. However, decreasing of the hydraulic dissipation happens in the draft tube. Impeller eccentricity significantly enhances the amplitude of rotation frequency, but has no obvious effect on the blade passing frequency and its harmonics. The peak-peak value of pressure pulsation of eccentric impeller increases rapidly with the eccentricity ratio. The results of this study provide scientific support for solving the stability problem caused by eccentric impeller in engineering cases.
The pulsating characteristics in turbulent flow are very important physical quantities. There are many studies focused on the temporal characteristics of pulsation. However, the spatial distribution of temporal states with pulsations rarely receives attention. Therefore, the pulsation tracking network (PTN) method is proposed to track the pulsating characteristics of turbulence. Based on the computational fluid dynamics (CFD) simulation result, the PTN is arranged in a specific region of the flow domain. The fast Fourier Transform (FFT) method is used for time-frequency conversion. As shown in the example of trailing-edge vortex-shedding flow over NACA0009 hydrofoil, important pulsation quantities, including the total pulsation intensity, dominant frequencies, amplitude of frequencies, and the phase and phase difference, can be obtained with a high spatial resolution. The source, reason and attenuation of the vortex-shedding frequency fvs and the 2 fvs frequency caused by vortex-interaction are well indicated. The dominant regions of fvs and 2 fvs are shown and analysed. The propagation and attenuation of vortex-shedding induced pulsation are understood in detail. Based on the comparison against traditional analysis, PTN is found to function as a good supplement for the CFD post-processing by tracking unknown temporal and spatial characteristics. These findings represent a potential breakthrough in terms of solving actual pulsation-excited flow problems.
A large-scale, vaned-voluted centrifugal pump can be applied as the key component in water-transfer projects. Pressure pulsation will be an important factor in affecting the operation stability. This paper researches the propagation and spatial distribution law of blade passing frequency (BPF) and its harmonics on the design condition by numerical simulation. Experimental and numerical monitoring is conducted for pressure pulsation on four discrete points in the vaneless region, which shows that the BPF is dominant. The pulsation tracking network (PTN) is applied to research propagation law and spatial distribution law. It provides a reference for frequency domain information and visualization vaned diffuser. The amplitude of BPF and its harmonics decays rapidly in the vaneless region. BPF and BPF’s harmonics influence each other. BPF has local enhancement in the vaneless region when its harmonics attenuate. In the vaned diffuser, the pulsation amplitude of BPF attenuates rapidly, but the local high-pressure pulsation amplitude can be found on the vane blade concave side because of obstruction and accumulation of the vaned diffuser. In the volute, the pulsation amplitude of BPF is low with the decelerating attenuation. This study provides an effective method for understanding the pressure pulsation law in turbomachinery and other engineering flow cases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.