2015 한국유체기계학회 하계 학술대회 논문, 2015년 6월 22일-24일, 원주 The KSFM Journal of Fluid Machinery: Vol. 18, No. 6, December, 2015, pp.76~80(Received 22 Jun. 2015; accepted for publication 05 Nov. 2015) 76 한국유체기계학회 논문집: 제18권, 제6호, pp. 76~80, 2015(논문접수일자: 2015.06.22, 심사완료일자: 2015.11.05) ◎ 논 문 ◎ Original Paper DOI: http://dx.doi.org/10.5293/kfma.2015.18.6.076 ISSN (Print): 2287-9706 Relationship between Cavitation Incipient and NPSH Characteristic for Inverter Drive Centrifugal Pumps Md Rakibuzzaman * ⋅Sang-Ho Suh ** † ⋅Hyoung-Ho Kim * ⋅Young-Hoon Jang * Key Words : Cavitation Model(캐비테이션 모델), Cavitation Incipient(캐비테이션 시작점), NPSH Characteristics(유효흡입수두특성), Numerical Study(수치적 연구) ABSTRACT The purpose of this study is to understand the cavitation phenomena in centrifugal pumps through computational fluid dynamics method. NPSH characteristic curve is measured from different flow operating conditions. Steady state, liquid-vapor homogeneous method with two equations transport turbulence model is employed to estimate the NPSH curve in centrifugal pumps. The Rayleigh-Plesset cavitation model is adapted as source term for inter-phase mass transfer in order to understand cavitation phenomena in centrifugal pumps. The cavitation incipient curve is clearly estimated at different flows operating conditions. A relationship is made between cavitation incipient and NPSH curve. Also the effects on water vapor volume fraction and pressure load distributions on the impeller blade are also described. 1. Introduction Cavitation phenomena plays an important role in the design and development of turbomachines such as pumps, turbines, hydrofoil etc.. Cavitation is a process of vapor formation and disappearance of the vapor phase of a liquid when it is subjected to reduce and subsequently increased pressure at constant temperatures. (1) The appearance and disappearance of regions with vapor is a major of noise, vibration, erosion and efficiency loss in hydraulic machinery. (2) In many technical applications cavitation is hardly avoidable at all operating conditions. When it occurs it needs to be controlled. in order to reduce these unfavorable effects, technology for accurate prediction and estimation of cavitation are very important in the development of high-speed fluid devices such as centrifugal pump. (3) Due to the importance of the cavitation phenomenon and the great process in the cavitation and turbulence models, numerical simulations have been widely used to investigate the cavitation flow field in the turbomachinery such as centrifugal pumps. (4,5) In order to clarify and understand the behavior of cavity flow, cavity flow models and analytical methods for numerical simulations have been proposed. (6,7) An extensive amount of literature exists on experimental studies of cavitation and most of are on hydrofoils. Arakeri and Acosta (1973) have studied the viscous effects in the inception of cavitation and development on two axisymmetric bodies using the flow visualization method. (8) They found cavitation inception occur in the laminar boundary layer separation region. Bakir et al. (2004) coupled the Rayleigh-Plesset equation to the flow solver and computed void fraction in pump inducer. (9) Medvitz et al. (2002) performed the cavitation analysis in centrifugal pump using multiphase CFD and pointed out the head inception and breakdown point. (10) Bruno et al. (2009) have studied on different NPSH characteristics in centrifugal * Graduate School, Soongsil University ** Dept. of Mechanical Engineering, Soongsil University † 교신저자, E-mail : suhsh@ssu.ac.kr