• 제목/요약/키워드: Diffuser flow

검색결과 425건 처리시간 0.037초

소형 터보압축기 베인 디퓨저 확대각 변화에 따른 유동특성 고찰 (Effects of the Variation of Divergence Angle of Vaned Diffuser on the Flow Characteristics of a Small-size Turbo-compressor)

  • 김홍식;정조순;김윤제
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집E
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    • pp.813-818
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    • 2001
  • The flow characteristics of the vaned diffuser were complicated with geometric shapes. We have studied the effects of various vaned diffuser configurations, such as divergence angles and rectangular and conical cross-section shapes. Numerical analyses are carried out for the diffuser and casing. The pressure recovery coefficient was calculated to estimate the performance of the diffuser, and then compared with the measure data. Results show that the shapes and the divergence angles of the diffuser strongly influence on the performance of the small-size turbo-compressor.

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디퓨저를 갖는 수직펌프의 유동해석에 대한 연구 (A Study of Flow Analysis for a Vertical Pump with Diffuser)

  • 정경남;김세진;박편구;김하종
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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    • pp.216-220
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    • 2001
  • Flow analysis was carried out for two vertical pumps. The geometrical difference of two pumps is the adoption of vaned diffuser. Full pump models were used to simulate the velocity fields of the pumps. Pump head and velocity field were compared to obtain the features of diffuser flow. It was shown that the discontinuity of head curve was predicted and reverse flow could be generated at impeller exit even in the rated flow condition.

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실린더 후류를 이용한 2 차원 디퓨저 성능개선에 관한 수치해석적 연구 (A Computational Study of the Improvement of Two-Dimensional Subsonic Diffuser Performance Using the Turbulent Wake Caused by a Cylinder)

  • 김태호;윤복현;오대근;김희동
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 춘계학술대회
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    • pp.1720-1725
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    • 2004
  • The present study addresses a computational work to investigate the influence of a turbulent wake flow on the pressure recovery of a two-dimensional subsonic diffuser. The turbulent wake is generated by a cylinder with a small diameter, which is installed at the diffuser inlet. Computation is applied to two-dimensional steady Navier-Stokes equations. The computational results are qualitatively well compared to existing experimental data. The results show that the diffuser pressure recovery is strongly dependent on the diameter and location of the cylinder. It is found that there is a certain diameter and location of cylinder for the diffuser pressure recovery to be most enhanced. Compared with no cylinder case, the diffuser performance increases up 24%.

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디퓨저/노즐을 이용한 압전형 마이크로 펌프의 펌핑 특성에 미치는 입출구 위치의 영향 (Effect of Inlet and Outlet Position on the Pumping Characteristics of a Diffuser/Nozzle Based Piezoelectric Micropumps)

  • 장훈희;김창녕;정진
    • 설비공학논문집
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    • 제19권5호
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    • pp.411-417
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    • 2007
  • This study has been conducted to investigate pumping characteristics of diffuser/nozzle based piezoelectric micropumps. The micropumps include a piezo disk (an actuator), a chamber and a set of diffuser and nozzle. Flow in the current micropumps is controlled by a set of diffuser and nozzle, not by a nap valve. The diffuser/nozzle based micropumps are more reliable in operation and are easier in manufacturing than the flap valve based micropumps. The flow rates of the piezoelectric micropumps have been closely analyzed with a numerical calculation. It has been found that the positions of the inlet and outlet of the micropump can influence the performance of the diffuser/nozzle based piezoelectric micropumps. This study may provide fundamental understanding for the design and analysis of the piezoelectric micropumps.

진공 이젝터 시스템의 유동 컨트롤 (Flow Control in the Vacuum-Ejector System)

  • ;김희동
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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    • pp.321-325
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    • 2010
  • Supersonic ejectors are simple mechanical components, which generally perform mixing and/or recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for altitude testing of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser. This paper aims at the improvement of ejector-diffuser performance by focusing attention on reducing exhaust back flow into the test chamber, since alteration of the backflow or recirculation pattern appears as one of the potential means of significantly improving low supersonic ejector-diffuser performance. The simplest backflow-reduction device was an orifice plate at the duct inlet, which would pass the jet and entrained fluid but impede the movement of fluid upstream along the wall. Results clearly showed that the performance of ejector-diffuser system was improved for certain a range of system pressure ratios, whereas the orifice plate was detrimental to the ejector performance for higher pressure ratios. It is also found that there is no change in the performance of diffuser with orifice at its inlet, in terms of its pressure recovery. Hence an appropriately sized orifice system should produce considerable improvement in the ejector-diffuser performance in the intended range of pressure ratios.

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고고도 모사용 초음속 이차목 디퓨저의 유동 및 열전달 특성에 대한 수치적 연구 (A Numerical Study on Flow and Heat Transfer Characteristics of Supersonic Second Throat Exhaust Diffuser for High Altitude Simulation)

  • 임경진;김홍집;김승한
    • 한국추진공학회지
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    • 제18권5호
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    • pp.70-78
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    • 2014
  • 고고도 모사를 위한 초음속 이차목 디퓨저의 유동 및 열전달 특성에 대한 수치적 연구를 수행하였다. 디퓨저의 유동 특성에 영향을 주는 작동압력과 형상을 변화시켜 유동 특성과 냉각 특성을 파악하였다. 냉각이 없는 경우 디퓨저가 시동 된 후, 디퓨저 벽과 아음속 구간에서 3,000 K 이상의 고온 구간이 나타났다. 디퓨저에 냉각 시스템을 추가하면 벽면 근처가 냉각되면서 유속이 빨라져 유동 길이가 길어지고 유동 박리와 함께 압력 회복이 급격해진다. 디퓨저 내부에 압력 변화를 가져오는 유동 현상과 함께 heat flux의 경향도 유사하게 나타났다.

Optimization of Vane Diffuser in a Mixed-Flow Pump for High Efficiency Design

  • Kim, Jin-Hyuk;Kim, Kwang-Yong
    • International Journal of Fluid Machinery and Systems
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    • 제4권1호
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    • pp.172-178
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    • 2011
  • This paper presents an optimization procedure for high-efficiency design of a mixed-flow pump. Optimization techniques based on a weighted-average surrogate model are used to optimize a vane diffuser of a mixed-flow pump. Validation of the numerical results is performed through experimental data for head, power and efficiency. Three-level full factorial design is used to generate nine design points within the design space. Three-dimensional Reynoldsaveraged Navier-Stokes equations with the shear stress transport turbulence model are discretized by using finite volume approximation and solved on hexahedral grids to evaluate the efficiency as the objective function. In order to reduce pressure loss in the vane diffuser, two variables defining the straight vane length ratio and the diffusion area ratio are selected as design variables in the present optimization. As the results of the design optimization, the efficiency at the design flow coefficient is improved by 7.05% and the off-design efficiencies are also improved in comparison with the reference design.

거주공간에 대한 급·배기 일체형 디퓨저의 환기 및 온열환경 유지성능에 대한 연구 (A Study on The Performance of Ventilation and Thermal Environment for a Combined Type Diffuser in a Residential Space)

  • 임석영;장현재
    • 설비공학논문집
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    • 제29권2호
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    • pp.74-81
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    • 2017
  • In this study, the combined-type diffuser developed by the Authors, in a previous study, was applied to a residential space. The performance of a ventilation and thermal environment, created by the use of a combined-type diffuser was compared to the pan-type diffuser widely used in apartment houses. In cooling conditions, because of the relatively high air flow rate of ceiling cassette-type air conditioners, the characteristics of airflow distribution in a room were governed by the air conditioner's airflow. In heating conditions, because of the low air flow rate of the diffuser, the characteristics of airflow distribution were governed by the buoyancy effect created by cold external walls and a hot floor. In terms of the Air Diffusion Performance Index (ADPI), which is a thermal environmental index, the result of a combined-type diffuser was greater than a pan-type diffuser in both of cooling and heating conditions. Consequently, the combined-type diffuser showed equal or superior ventilation and thermal environment performance compared to a pan-type diffuser.

베인각도의 변화에 따른 디퓨저의 성능특성에 관한 실험적 연구 (Experimental study on the performance characteristics of the diffuser due to the variation of vane angle)

  • 조성국;강신형
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 1998년도 유체기계 연구개발 발표회 논문집
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    • pp.142-148
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    • 1998
  • Recently for the impressive gains of performance and efficiency over vaneless diffuser with apparently little or no loss in flow range, the use of LSVD(Low Solidity Vaned Diffuser) is well recommended. The experiments on the effect of the vane turning angle variation(positive, negative, zero) with other design parameters fixed on the performance and flow range were carried out. Diffuser with zero turning angle has the best characteristics in terms of performance and efficiency and The FFT results show the different frequency characteristics due to the vane turning angle in low flow range.

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역설계 방법을 적용한 사류펌프의 임펠러 및 디퓨저 설계 (Design of Impeller and Diffuser for Mixed Flow Pump with Inverse Design Method)

  • 이경용;최영석;김준호
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2009년도 하계학술발표대회 논문집
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    • pp.1322-1325
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    • 2009
  • The impeller and vane diffuser for the mixed flow pump(NS550) was designed by using meridional selection program and inverse design method. We decided the meridional shape of the impeller from the meridional design parameter, such as the specific speed and maximum diameter at the impeller exit. The meridional shape of vane diffuser was set from the impeller shape, distribution of cross sectional area and maximum diffuser diameter. The angle of impeller blade and diffuser vane was designed by using inverse design method. The predicted overall performance by using commercial CFD code(ANSYS CFX-11) shown good agreement with design goals.

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