• Title/Summary/Keyword: diffuser

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Design and Prototyping Micro Centrifugal Compressor for Ultra Micro Gas Turbine

  • Hirano, Toshiyuki;Tsujita, Hoshio;Gu, Ronglei;Minorikawa, Gaku
    • International Journal of Fluid Machinery and Systems
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    • v.2 no.4
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    • pp.426-430
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    • 2009
  • In order to investigate the design method for a micro centrifugal compressor, which is the most important component of an ultra micro gas turbine, an impeller having the outer diameter of 20mm was designed, manufactured and tested. The designed rotational speed is 500,000 rpm and the impeller has a fully 3-dimensional shape. The impeller was rotated at 250,000 rpm in the present study. The experimental results of the tested compressor with the vaned and the vaneless diffusers were compared. It was found that the vaned diffuser attained the higher flow rate than the vaneless diffuser at the maximum pressure ratio. In addition the maximum pressure ratio was higher for the diffuser having a larger diffuser divergence angle at the high flow rate. These results were compared with those obtained by the prediction method used at the design stage.

A Design Improvement of the Vent Silencer of the Industrial Plants Using Acoustic Analysis (음향해석을 이용한 산업용 플랜트 배출 소음기의 설계 개선)

  • Lee, Jong-Wha;Lee, Boo-Youn;Nam, Kyoung-Hun;Kim, Baek-Young;Kim, Won-Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.2 s.179
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    • pp.122-128
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    • 2006
  • This study focuses on a performance improvement of the vent silencer using acoustic analysis. Since the vent silencer is generally used for a high level shock noise, it should be designed to reduce a wide frequency band noise. In the designing stage of the vent silencer, structural shapes of diffuser and splitter are the most significant design parameters. Effects of modifying the original structure of the diffuser and the splitter are analyzed and evaluated. From the results, It is found that the diffuser with two pipes and double-step structure more effectively reduces a wide frequency band noise but the increment of the number of splitters is not desirable.

Analysis of Physical Parameters for the Evaluation of HVAC Diffuser Noise (공기조화 취출구 소음 평가를 위한 물리지수 분석)

  • Park, Hyeon-Ku;Kim, Hang;Go, Seong-Seok;Kim, Sun-Woo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.402-405
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    • 2006
  • The diffuser noise of HVAC(heating ventilating and air-conditioning) uses dB(A) or NC as a indoor noise criteria that ASHRAE represents, and there is no specific guide line for application. According to the previous study, there are some problems like that even though the sound level of sound source is same, the NC shows different values, which makes the noise rating confused. This problem is caused by the frequency characteristics of sound source and its sound level. Therefore, appropriate evaluation method should be considered based on the subjective responses. This study aims to analyze the physical parameters appropriate for the evaluation of HVAC diffuser noise. To achieve this, recording of sound sources, calculation of physical parameters and psycho-acoustic experiment were carried out and the results were derived from the correlation analysis between physical parameters and subjective evaluatio

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On the Assessment of Compressibility Effects of Two-Equation Turbulence Models for Supersonic Transition Flow with Flow Separation

  • Sung, Hong-Gye;Kim, Seong-Jin;Yeom, Hyo-Won;Heo, Jun-Young
    • International Journal of Aeronautical and Space Sciences
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    • v.14 no.4
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    • pp.387-397
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    • 2013
  • An assessment of two-equation turbulence models, the low Reynolds k-${\varepsilon}$ and k-${\omega}$ SST models, with the compressibility corrections proposed by Sarkar and Wilcox, has been performed. The compressibility models are evaluated by investigating transonic or supersonic flows, including the arc-bump, transonic diffuser, supersonic jet impingement, and unsteady supersonic diffuser. A unified implicit finite volume scheme, consisting of mass, momentum, and energy conservation equations, is used, and the results are compared with experimental data. The model accuracy is found to depend strongly on the flow separation behavior. An MPI (Message Passing Interface) parallel computing scheme is implemented.

An Experimental Study on the Flow Characteristics of a Swirl-Jet Diffuser (공장환기용 선회 제트 디퓨저의 유동 특성에 관한 실험 연구)

  • Lee, C.S.;Jurng, J.;Jeong, S.Y.;Hong, K.H.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.6 no.2
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    • pp.103-109
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    • 1994
  • An experimental study is performed on the flow characteristics of a swirl-jet diffuser for factory ventilation. Swirl number ranges from 0(nonswirl jet) to 0.6 when the angle of swirl vane is 60 degree. As swirl becomes strong, the maximum velocity in the plane perpendicular to jet axis decreases fast and the uniformity of velocity becomes good, particularly in the ventilated area. The similarity in velocity profiles has been found for axial velocity from even when swirl number equals 0.6. The flow characteristics of the swirl-jet which has the swirl number of 0.6 is thought to be the best among these three swirl numbers for factory ventilation. However, the pressure drop in the diffuser increases as the swirl becomes strong. This should be considered in the design of the total ventilation system including a duct system.

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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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    • v.4 no.1
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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.

An Experimental Study on Thermal Stratification of Pressurized Plenum Underfloor Air Distribution System during Cooling (가압식 바닥급기 시스템의 여름철 성층화 경향에 관한 실험적 연구)

  • Kim, Dong-Hee;Yu, Ki-Hyung;Cho, Dong-Woo;Seo, Jung-Seok;Han, Sung-Phil
    • Proceedings of the SAREK Conference
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    • 2007.11a
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    • pp.340-345
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    • 2007
  • The underfloor air distribution system has been attracting to architects and building owners as one of valuable system for the renovated and newly office building. In this paper, we discussed the thermal stratification profile of pressurized plenum underfloor air distribution(UFAD) according to indoor setting temperature, diffuser number, diffuser type. For this, the space of office building(H corp.) is selected for measuring the air volume of underfloor diffuser and vertical temperature profile. As a result, the thermal stratification profile is influenced by the number and type of the underfloor diffuser and thermal storage character of the underfloor. Whereas indoor setting temperature have a lower significant impact on thermal stratification.

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Unstable Flow in a Vaneless Diffuser of 2-Dimensional Centrifugal Compressor (2차원 원심 압축기의 깃 없는 디퓨저에서의 불안정 유동)

  • Kang, Kyung-Jun;Shin, You-Hwan;Kim, Kwang-Ho;Lee, Yoon-Pyo
    • The KSFM Journal of Fluid Machinery
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    • v.14 no.4
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    • pp.5-11
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    • 2011
  • This study investigated on details of flow characteristics in a vaneless diffuser of a compressor with 2-dimensional impeller at various flow rates. Experiment for a low speed compressor model in a water reservoir was performed to analyze the flow field in the vaneless diffuser and volute casing, which was done by PIV measurement. It was also focused on the periodic flow patterns occurring at low flow rate near unstable operating region of the compressor. At low flow rate condition, the flow visualization clearly shows that the flow energy from impeller is highly accumulated at the compressor exit by the blockage effect of a flow damper and consequently the reverse flow occurs in the diffuser.

Application of Shock Generator to Supersonic Ejector Diffuser System (초음속 이젝터 디퓨져 시스템에서의 충격파 발생기 응용)

  • Lijo, Vincent;Kim, Heuy-Dong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.04a
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    • pp.200-203
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    • 2011
  • Supersonic ejectors are simple mechanical components, which generally perform mixing and recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for high altitude testing (HAT) 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 (SED). This paper aims at the improvement in HAT facility by focusing attention on the vertical firing rocket test stand with shock generators. Shock generators are mounted inside the SED for improving the pressure recovery. The results clearly showed that the performance of the ejector-diffuser system was improved with the addition of shock generators. The improvement comes in the form of reduction of the starting pressure ratio and the vertical height of test stand. It is also shown that shock generators are useful in reducing the total pressure loss in the SED.

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Three-One Check Valve 및 Suction Diffuser로 원가절감 효과를

  • 대한설비건설협회
    • 월간 기계설비
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    • s.22
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    • pp.124-125
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    • 1992
  • 토출배관에 Three-One Check Valve로 흡입배관에 Suction Diffuser로 시공하면 유체 차단기능, 역류방지 및 유량조절 기능 등을 겸하게 되므로 설치공간의 축소, 자재비$\cdot$인건비 절감효과를 얻을 수 있다.

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