• 한국기계기술학회지
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• 제13권4호
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• pp.57-62
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• 2011

In this study, a experimental work to investigate the influence of a turbulent wake flow on the velocity distribution of a diffuser with PIV method. The turbulent wake is generated by a rectangular prism, which is installed at the inlet of a diffuser. The results show that the velocity recovery of the subsonic diffuser is dependent on the height and location of rectangular prism. It is found that a certain height of the rectangular prism to generate the turbulent wake give a better velocity recovery, compared with no rectangular prism.

• 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.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.120-125
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• 2001

The effects of various vaned diffuser configurations, such as throat area ratios and rectangular and conical cross-section shapes. to the performance of a small-size turbo-compressor are studied. Numerical analyses were carried out for the region of diffuser and casing only. The pressure recovery coefficient was calculated to estimate the performance of the diffuser, and then compared with the measured data. Results show that the shapes and the throat area ratios of the diffuser strongly influence on the performance of a turbo-compressor.

• 한국유체기계학회 논문집
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• 제4권3호
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• pp.21-28
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• 2001

The effects of diffuser shapes on the flowfields of a small-size turbo-compressor have been investigated numerically and experimentally. The optimal design of elements shapes is important to develop the high efficiency turbo-compressor. Typical range of rotating speed for a small-size turbo-compressor is 40,000-70,000rpm. Numerical analyses were conducted to the rectangular and conical shapes of diffuser Three-dimensional, steady and viscous governing equations were solved by SIMPLE algorithm. To confirm the numerical results, the experimental measurements for the static pressure and temperature at the inlet and outlet boundaries were performed. Comparisons of these results were done, and the reasonable agreements were acquired.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.187-192
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• 2000

The effects of diffuser shapes on the flowfields of a small-size turbo-compressor have been investigated by numerically and experimentally. It is important to optimal design of each elements for developing the small-size turbo-compressor Typical range of rotating speed of a small-size turbo-compressor is 40,000-70,000rpm. Numerical analyses are conducted to the rectangular and conical shapes of diffusers. Three-dimensional, steady, viscous governing equations are solved by SIMPLE algorithm. To prove the numerical results, experimental studies for the measurements of static pressure and temperature at the inlet and outlet boundaries are performed. Comparisons of these results are executed, and reasonable agreements are acquired.

• 한국전자파학회논문지
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• 제12권5호
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• pp.837-843
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• 2001

전자파 잔향실은 일반적으로 직사작형 구조의 차폐실에 전자기장 균일도를 향상시키기 위한 모드 스터러 또는 모드-튜너로 구성된다. 본 논문은 기존에 많이 사용되는 직사각형의 잔향실 구조 대신 두 종류의 비대칭 구조를 사용하였을 경우의 전자기장 균일도 개선효과에 관하여 검토한 것이다. 하나는 Quadratic Residue Diffuser (QRD)를 사용한 비대칭 구조, 그리고 다른 하나는 Randomly Made Diffuser(RMD)를 사용한 비대칭 구조의 전자파 잔향실이다. Finite-Difference Time-domain(FDTD) 수치해석 방법을 사용하여 두 종류의 전자파 잔향실에 관한 전자기장 균일도 특성을 조사하였다.

• 한국전자파학회논문지
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• 제11권5호
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• pp.839-848
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• 2000

본 논문은 전자파 장해 및 복사내성 측정에 사용되는 전자파 무반사실의 대용 방법으로 활용될 수 있는 전자파 잔향실의 전자기장 특성에 관하여 연구하였다. 체적이 동일한 직사각형 및 삼각형 구조의 잔향실 내부 필드균일성을 확보하기 위하여 Shroeder diffuser 방식을 적용하였으며, FDTD(Finite-Difference Time-Domain) 방법을 사용하여 잔향실 내부의 필드 특성을 조사하였다. 앞에서 언급한 두 가지 형태의 잔향실 내부에서 필드 특성을 조사하기 위해 시험공간 내의 75% 샘플을 가지고 분석하였다. 직사각형 잔향실의 경우 최대 $\pm$3dB, 삼각형 잔향실의 경우 최대 $\pm$4.4dB 내의 tolerance를 나타내었으며, 또한 직사각형 잔향실의 경우 편파에 대해서도 독립적이라는 결과를 얻을 수 있었다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.219-225
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• 2000

Primary function of a centrifugal compressor volute is to serve the flow from the impeller and diffuser to pipe system. But losses in volutes at off-design lead to poor stage efficiency and reduction of operating range. This is largely caused by the interaction between the impeller and volute flow fields. The magnitude of distortion is increased as the operating point is away from the design point and, as a result, the interaction between the impeller and volute is stronger. The objective of present study is to find the characteristics of tile flow in the diffuser and volute of the centrifugal compressor with rectangular cross-sectional volute. The measurements are carried out in two cases with the existence and nonexistence of the volute casing. The detailed pressure is presented by comparing the experimental results obtained at two cases with each others.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2003년도 하계학술대회 논문집
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• pp.6-6
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• 2003

• 한국공작기계학회논문집
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• 제16권4호
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• pp.93-100
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• 2007

The flow velocity distribution at inlet and exit of Diesel Particulate Filter(DPF) by fabricating L-shape connector with the DPF was measured using a Pitot-tube and 2-D transverse machine. An adaptor designed for making the Pitot tube probe access to the inlet and exit of the DPF was connected with the inlet and exit flange of the DPF, respectively. The Pitot tube which was mounted in the 2-D positioning machine could access to the inlet and exit of the DPF through the rectangular window of the adaptor. The L-shape connector in the DPF inlet has a flow guide which is a perforated steel pipe. The flow velocity distribution at the inlet of the DPF showed a chaotic velocity distribution which is different from that with a diffuser type connector. The velocity distribution at the exit of the DPF showed a crown shape which is similar to that of the diffuser type connector. The velocity distribution at the exit of DPF showed different patterns according to the air flow rate.