• Title/Summary/Keyword: Impeller

Search Result 1,005, Processing Time 0.02 seconds

The Optimum Design of Flow Characteristics in Fermentation (발효조 내의 유동특성 최적화 설계)

  • 박상규;김기성;양희천
    • Proceedings of the Korean Society of Marine Engineers Conference
    • /
    • 2001.05a
    • /
    • pp.117-121
    • /
    • 2001
  • A numerical simulation was conducted to investigate the effect of height position of Rushton type Impeller in the fermentation. The computational method was based on the CFX code. The simulation was performed for 3 height differences(25, 30, 35mm) between Rushton type impeller and bottom of fermentation. The instantaneous flow fields showed that the bulk flow consisted of large scale vortices. However the main flow results showed that the formation of ring vortices above and below the impeller depended on the height of the impeller.

  • PDF

A Study on Reverse Engineering and 5-axis NC Machining of Impeller (임펠러의 역공학과 5축가공에 관한 연구)

  • 장동규;신재광;홍성균;이희관;양균의
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.21 no.6
    • /
    • pp.60-68
    • /
    • 2004
  • This paper presents a method fur impeller modeling and 5-axis machining by the reverse engineering. The impeller is composed of pressure surface, suction surface and leading edge, and so on. The surfaces can be modeled by using the characteristic curves such as hub curves, shroud curves and fillet curves. The characteristic curves are extracted from the scanned data and the inspection is performed between the surfaces generated by using the characteristic curves and the scanned data. Then, An impeller is machined by 5-axis mainlining and post-processing with inverse kinematic solution.

Design of Centrifugal Impeller for Passenger Car by Flow Field Analysis (유동장 해석을 통한 승용차 원심 회전차의 형상 설계)

  • Lee, Dong-Ryul
    • Journal of the Korean Society of Mechanical Technology
    • /
    • v.13 no.3
    • /
    • pp.49-55
    • /
    • 2011
  • For the purpose of the enhancement of the air conditioner performance and fuel effciency, several cases of centrifugal impeller for passenger car air conditioner have been numerically analyzed by changing central angle of blades and length of outlet for shape optimization of the impeller. Commercial CFD program Fluent 6.3.26 has been used to compute velocity, temperature, pressure and turbulence intensity that can lead numerous results. The central angles of two blades and three cases of outlet length led 4~12% and 3.5~6.4% differences of velocity and flow rate, respectively. The velocity distribution near the blade surface was axisymmetric and had a maximum value of 22.19 m/s and velocity of the vertical direction of the impeller showed linear increase with horizontal direction. At case 3 of oultet length, there existed a a minimum pressure value of -133320 Pa.

Effects of axial distance between inducer and impeller on the performance of the turbopump (인듀서와 임펠러 축방향 간극이 터보펌프 성능에 미치는 영향)

  • Choi, Chang-Ho;Kim, Dae-Jin;Hong, Soon-Sam;Kim, Jin-Han
    • The KSFM Journal of Fluid Machinery
    • /
    • v.11 no.5
    • /
    • pp.37-43
    • /
    • 2008
  • An inducer is employed in a modern rocket feed system because it allows a turbopump system to operate at a high speed with low inlet pressures so as to minimize the weight and the size of the system. Cavitation performance can be improved by installing an inducer to the pump, enabling to increase the operational speed of the pump. The main purpose of an inducer is to increase the static pressure prior to an impeller to enable the impeller to operate satisfactorily under cavitation environments. In the present study the effects of axial distance between the inducer and the impeller on the performance of the pump were studied using both experimental and computational methods. Two inducers with different axial length were used for the experiments and the pump performances were measured. The experimental results show that the suction performance decreases as the axial gap between the inducer and impeller is increased.

Analysis of Flow Phenomena in a Centrifugal Compressor Impeller Operating near Stall (스톨 근처에서 원심압축기 임펠러의 내부 유동현상에 관한 연구)

  • Eum, Hark-Jin;Kang, Shin-Hyoung
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.28 no.3
    • /
    • pp.330-337
    • /
    • 2004
  • Analysis of flow phenomena in a centrifugal compressor impeller has been carried out with numerical simulation to understand the physics of flow near stall. Near stall point, tip leakage flow spills ahead of the leading edge of adjacent blade and other leakage flow passes over the clearance of the adjacent blade instead of rolling up into vortex within the passage. The tip leakage flow at the mid chord of impeller blade impinges against the pressure surface of the adjacent blade and then rolls up into vortex within the passage, which blocks the flow passage and generates viscous loss. The spillage of leakage flow ahead of the adjacent blade generates the recirculation of flow entering the impeller, which causes the power transferred into the flow by the impeller to decrease and blocks the flow passage. Near diffuser hub wall, flow recirculation occurs. As operating point goes to stall point, the core of recirculation approaches the impeller exit The length rises to peak point and then drops with mass flow reduction, while the height steadily rises.

A Numerical Analysis on Mixing Performance for Various Types of Turbine Impeller in a Stirred Vessel (교반기 내 터빈 임펠러 형태에 따른 교반성능에 대한 수치해석적 연구)

  • Choi, Younguk;Choi, Jongrak;Kim, Daejoong;Hur, Nahmkeon
    • The KSFM Journal of Fluid Machinery
    • /
    • v.16 no.1
    • /
    • pp.47-55
    • /
    • 2013
  • In the present study, a numerical simulation to analyze mixing performance inside an industrial mixer was investigated for various geometry of turbine impellers. Various pitching angles and various types of turbine blades were considered in the simulation. In order to model the rotation of impeller, the Multiple Reference Frames (MRF) technique was used. For evaluation of the effect of various shapes on the mixing performance, dimensionless coefficient such as flow coefficient, circulation coefficient, power coefficient, pumping effectiveness and circulation effectiveness were used. From the results, the effect of pitching angle of a pitched turbine impeller was to give best pumping effectiveness around $30^{\circ}$ pitching angle, whereas best circulation effectiveness around $65^{\circ}$ pitching angle. Dual pitched turbine impeller showed best performance in both pumping effectiveness and circulation effectiveness among impeller types considered in the present study.

Reduction of the Axial Force of Water Pump Using CFD (전산유체역학을 이용한 워터펌프 축력 저감)

  • Jo, Sok-Hyun;Shin, Dong-Sung
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.20 no.3
    • /
    • pp.83-87
    • /
    • 2012
  • Computational Fluid Dynamics (CFD) method has been used to investigate the axial force of automotive water pump. As the excessive axial force can make some unexpected problems like impeller interference and coolant leakage we have focused on finding the cause of axial force and its reduction in this paper. First, we have tested the closed type water pump with and without balance hole by the calculation methods. By examining the pressure contour around the impeller, we have found that the axial force arises not only from the pressure difference around shroud but also from the pressure difference around hub. So we have tested two impellers - one is normal open type impeller and the other is open type impeller with modified hub. The results show that the axial force reduction is about 150~200N for normal one and 700N@3000RPM for modified impeller. And the hydraulic efficiency which is important in aspect of engine fuel efficiency is reduced about 6.5% for normal one but increased 4%@3000RPM for modified impeller.

An Experimental Study on the Effect of heat exchanger on turbo fan for air conditioning (열교환기가 공기조화용 터보팬의 성능에 미치는 영향에 대한 실험적 연구)

  • Chang Seung-Yong;Nam Leem-Woo;Joo Won-Gu;Cho Kang-Rae
    • Proceedings of the KSME Conference
    • /
    • 2002.08a
    • /
    • pp.615-618
    • /
    • 2002
  • Turbo-fan for ceiling cassette type air conditioner doesn't operate in general volute. It is operated by porous material, heat exchanger. Heat exchanger increases resistance of air conditioning system and disturbs exit-flow of impeller. Therefore it has some influences on impeller capacity. In this study, we want to how that influence of exchanger on impeller capacity for ceiling cassette type air conditioner. To research, we made circular case that didn't have asymmetric part unlike rectangular case. With and without heat exchanger we measured total pressure and static pressure of impeller and three-dimensional rear flow field From the result, a turbo fan , installed in the 35mm back of fan and operated in heat exchanger, experienced $2{\%}{\~}5{\%}$% total pressure loss over all flow rate. With heat exchanger impeller efficiency decrease as flow rate decrease when flow rate coefficient was below 0.18. Especially when flow rate coefficient was below 0.12, there was $20{\%}{\~}30{\%}$ decrease of impeller efficiency.

  • PDF

Performance Prediction and Flow Field Calculation for Airfoil Fan with Impeller Inlet Clearance

  • Kang, Shin-Hyoung;Cao, Renjing;Zhang, Yangjun
    • Journal of Mechanical Science and Technology
    • /
    • v.14 no.2
    • /
    • pp.226-235
    • /
    • 2000
  • The performance prediction of an airfoil fan using a commerical code, STAR/CD, is verified by comparing the calculated results with measured performance data and velocity fields of an airfoil fan. The effects of inlet tip clearance on performance are investigated. The calculations overestimate the pressure rise performance by about 10-25 percent. However, the performance reduction due to tip clearance is well predicted by numerical simulations. Main source of performance decrease is not only the slip factor but also impeller efficiency. The reduction in performance is 12-16 percent for 1 percent gap of the diameter. The calculated reductions in impeller efficiency and slip factor are also linearly proportional to the gap size. The span-wise distributions of phase averaged velocity and pressure at the impeller exit are strongly influenced by the radial gap size. The radial component of velocity and the flow angle increase over the passsage as the gap increases. The slip factor decreases and the loss increases with the gap size. The high velocity of leakage jet affects the impeller inlet and passage flows. With a larger clearance, the main stream moves to the impeller hub side and high loss region extends from the shroud to the hub.

  • PDF

Experimental Study on Stall Inception in a High-Speed Centrifugal Compressor ( II )- Stall Warning Method - (원심압축기 스톨 발단에 판한 실험적 연구 (II) - 스톨 경고 방법 -)

  • Gang, Jeong-Sik;Gang, Sin-Hyeong
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.25 no.10
    • /
    • pp.1445-1450
    • /
    • 2001
  • Stall inception in a high-speed centrifugal compressor has been examined. The main objective was to find stall precursor and to develop a reliable stall warning method. For stall warning, a method which uses the spectrum at impeller frequency is suggested. The use of the spectrum at impeller frequency as a stall warning method showed a warning time of about two hundreds impeller revolutions. This method uses only one sensor that it has made the stall warning method more useful. And the well-known traveling wave energy method proved to be a good method for stall warning also in a high-speed centrifugal compressor. The warning time was about one hundred impeller revolutions at lower speeds, and about one thousand impeller revolutions at higher speeds. The stall warning methods used here were found to be robust and reliable. Therefore, it seems to be promising to set up a reliable stall avoidance control based on this analysis.