Abstract
To analyze the interrelations among impeller blade geometry, flow field fluctuation intensity and impeller-induced hydrodynamic noise of jet centrifugal pump (JCP), a Gappy proper orthogonal decomposition (POD) method combined with computational fluid dynamics/computational fluid acoustics (CFD/CFA) technique was proposed to reconstruct and predict the unsteady flow field fluctuation intensity and flow-induced noise in impeller region. The snapshot sets were composed of blade profile parameters, flow field fluctuation intensity data and the data of sound pressure level of hydrodynamic noise in the frequency domain. Similar mesh reconstruction and flow field interpolation were carried out to have the same number of flow field data. The snapshot sets were decomposed into a linear combination of orthogonal bases using the singular value decomposition (SVD) method. The orthogonal basis coefficients corresponding to the objective variables were fitted by the least square method. The results show that the proposed method has a good accuracy in predicting the flow field fluctuation intensity and flow-induced noise of the JCP impeller domain. The relative error of pressure fluctuation intensity field is less than 4.0%, relative velocity fluctuation intensity field is less than 3.0%, turbulent kinetic energy fluctuation intensity field is less than 4.5%, and impeller-induced hydrodynamic noise is less than 10%. Taking the method as a surrogate model to predict the flow field fluctuation intensity and the radiation level of hydrodynamic noise in the optimization process of centrifugal pump impeller, it could not only reduce the calculation amount and time significantly and improve optimization speed and efficiency greatly but could also provide a reference for vibration characteristics of the models.
Highlights
The proper orthogonal decomposition (POD) method is known as Karhunen-Loeve expansion and can discover the dominant features hidden in the data through a set of known data and repair of the missing data
(1) The example exampleshowed showed that it ahas a good accuracy the reconstruction offield the fluctuation flow field intensity andintensity impeller-induced hydrodynamic noise of the objective sample based onsample the mapping fluctuation and impeller-induced hydrodynamic noise of the objective based relationship between the geometry and flow field fluctuation intensity of the sample set, or on the mapping relationship between the geometry and flow field fluctuation intensity of the betweenset, theor geometry hydrodynamic noise of the sample set.ofThe sample betweenand theimpeller-induced geometry and impeller-induced hydrodynamic noise therelative sample set
The relative error of the pressure fluctuation intensity field was less than 4.0%, the relative velocity fluctuation intensity field was less than 3.0%, turbulent kinetic energy fluctuation intensity field was less than 4.5%, and impeller-induced hydrodynamic noise was less than 10%
Summary
The proper orthogonal decomposition (POD) method is known as Karhunen-Loeve expansion and can discover the dominant features hidden in the data through a set of known data and repair of the missing data. POD method is a deformable usage of the Snapshot POD method proposed by Sirvorch and Kirby [3], which addresses some defects in the original POD method, such as improving the efficiency and stability of eigenvalue solution and having better applicability in data prediction It has been widely employed in the optimization design of airfoil and turbomachinery [4,5,6,7], flow field. Between and the tongue of the or mechanism guide vane, and the resonance of the fluid, and ,the it impeller is very important to study the volute induced radiation characteristics of the structure, etc. Relationships predict the flowintensity field fluctuation intensity noise and flow-induced in the. The exploration aim is to make prediction method flow field and sound a centrifugal pump. New exploration forofa the prediction method of thefield flowoffield and sound field of a centrifugal pump
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