• 제목/요약/키워드: 천이액정법

검색결과 11건 처리시간 0.02초

블레이드 팁의 Groove 형상이 터빈 캐스케이드 팁 열전달 계수분포에 미치는 영향에 대한 실험적 연구 (Effect of Groove Shape of Blade Tip on Tip Surface Heat Transfer Coefficient Distributions of a Turbine Cascade)

  • 노영철;조용화;이용진;김학봉;곽재수
    • 한국추진공학회지
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    • 제14권6호
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    • pp.60-68
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    • 2010
  • 본 연구에서는 팁 형상이 가스터빈 블레이드의 팁 열전달에 미치는 영향을 알아보기 위하여 선형 캐스케이드의 블레이드에 설치된 평면 팁, 스퀼러 팁, Groove 팁들에 대하여 열전달 계수가 측정되었다. 블레이드 팁에서의 열전달 계수는 색상검출방식에 기반을 둔 천이액정법을 이용하여 측정되었으며 각각의 팁 형상에 대하여 팁 간극은 블레이드 스팬의 1.5%와 2.3% 두 조건에서 실험을 수행하였다. 캐스케이드 출구 속도와 블레이드 코드길이에 기초를 둔 Reynolds 수는 $2.48{\times}10^5$ 이다. Groove 팁 표면에서의 열전달 계수는 평면 팁보다 낮게 측정되었으며, 특히 흡입면을 따라 경사진 홈이 파인 팁에서는 스퀼러 팁보다 낮은 열전달 계수가 측정되었다.

블레이드 팁의 Groove 형상이 터빈 캐스케이드 팁 열전달 계수분포에 미치는 영향에 대한 실험적 연구 (Effect of Groove Shape of Blade Tip on Tip Surface Heat Transfer Coefficient Distributions of a Turbine Cascade)

  • 노영철;조용화;이용진;김학봉;곽재수
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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    • pp.311-318
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    • 2010
  • 본 연구에서는 팁 형상이 가스터빈 블레이드의 팁 열전달에 미치는 영향을 알아보기 위하여 선형 캐스케이드의 블레이드에 설치된 평면 팁, 스퀼러 팁, Groove 팁들에 대하여 열전달 계수가 측정되었다. 블레이드 팁에서의 열전달 계수는 색상검출방식에 기반을 둔 천이액정법을 이용하여 측정되었으며 각각의 팁 형상에 대하여 팁 간극은 블레이드 스팬의 1.5%와 2.3%로 변경 하에 실험을 수행하였다. 캐스케이드 출구 속도와 블레이드 코드길이에 기초를 둔 Reynolds 수는 $2.48{\times}10^5$ 이다. Groove 팁 표면에서의 열전달 계수는 평면 팁보다 낮게 측정되었으며, 특히 흡입면을 따라 경사진 홈이 파인 팁에서는 스퀼러 팁보다 낮은 열전달 계수가 측정되었다.

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색상 검출방식의 천이 액정법에서 색상 변화 시간 산정의 정확도 향상 (Improvement of Accuracy in Evaluating Hue Change Time in the Hue Detection Based Transient Liquid Crystals Technique)

  • 신소민;전창수;정용운;곽재수
    • 대한기계학회논문집B
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    • 제31권11호
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    • pp.918-925
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    • 2007
  • In this paper, different criteria fur determining hue change time in the hue detection based transient liquid crystals technique were compared. Results showed that methods utilizing threshold of intensity or saturation gave many missing points and quality of the calculated results were strongly depends on the value of threshold. Wider bandwidth in the hue bandwidth method showed better distribution of calculated hue change time, but induced ambiguity in the hue change time. In the time-hue curve fitting method, the distribution of evaluated hue change time was smooth and reasonable, and, by the nature of curve fitting, the noise effect on the hue was successfully considered in calculating of the hue change time. Compared to other methods, it is expected that the time-hue curve fitting method would provide better and accurate hue change time in the hue detection based transient liquid crystals technique.

딤플이 설치된 회전 유로에서의 열전달 계수 분포 측정 연구 (Measurement of the Detailed Heat Transfer Coefficient in the Rotating Dimpled Rectangular Channel)

  • 박승덕;이기선;전창수;곽재수;전용민
    • 한국유체기계학회 논문집
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    • 제12권1호
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    • pp.51-56
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    • 2009
  • The detailed heat transfer coefficient on a rotating dimpled channel were measured using the transient liquid crystal technique. The channel height to dimple diameter was 2, dimple center distance to dimple diameter was 1.5 and channel aspect ratio was 4. Tested Reynolds number based on the channel hydraulic diameter was varied from 15000 to 35000 and corresponding rotation number was ranged from 0.026 to 0.057. Results showed that the Coriolis force by rotation enhanced the heat transfer coefficient on the trailing surface. As the Reynolds number increased, i.e. rotation number decreased, the heat transfer coefficient increased and the thermal performance factor decreased.

이중 충돌 제트를 갖는 내부 유로의 열전달 계수 측정 (Measurement of Heat Transfer Coefficient in a Duct with Double Imingement Jets)

  • 곽재수
    • 한국항공운항학회지
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    • 제14권1호
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    • pp.9-14
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    • 2006
  • Averaged heat transfer coefficients in the trailing edge model of a turbine blade with double impingements were measured using transient liquid crystals technique and conventional copper plate-thermocouple technique. The detailed distributions of heat transfer coefficients by transient liquid crystals technique were also presented. Results showed that increased heat transfer coefficient due to the inpingements and the averaged heat transfer coefficients increased as Reynolds number increased. Results by transient liquid crystals technique showed that the heat transfer coefficient strongly depended on the main stream temperature used in heat transfer coefficient calculation. The averaged heat transfer coefficients measured by different methods showed similar trend as Reynolds number changed, but the value varied up to 40% depending on the measurement technique.

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딤플이 설치된 회전 유로의 높이가 열전달 계수에 미치는 영향에 대한 실험적 연구 (Effect of channel height on the heat transfer coefficient of a rotation dimpled channel)

  • 김석범;이용진;최은영;전창수;곽재수
    • 한국유체기계학회 논문집
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    • 제13권3호
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    • pp.30-36
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    • 2010
  • The detailed heat transfer coefficients on a rotating dimpled channel were measured by the hue detection based the transient liquid crystal technique. The dimples were fabricated on the one side of the channel and the tested channel aspect ratio was 4, 6, and 12 with fixed channel width. Tested Reynolds number based on the channel hydraulic diameter was varied from 21,000 to 47,000. A stationary case and two different rotating conditions were tested so that the dimple fabricated surface became leading or trailing surface. For all rotating conditions, the minimum averaged heat transfer coefficient was measured for the channel aspect ratio of 6. Generally, the highest averaged heat transfer coefficient was observed for the highest aspect ratio cases due to increased dimple induced vortex strength.

가스터빈 블레이드 끝단 형상에 따른 블레이드 끝단 및 그 주변에서의 열전달 계수 변화 (Effect of Blade Tip Geometry on Heat Transfer Coefficients on Gas Turbine Blade Tips and Near Tip Regions)

  • 곽재수
    • 대한기계학회논문집B
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    • 제30권4호
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    • pp.328-336
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    • 2006
  • Detailed heat transfer coefficient distributions an two. types of gas turbine blade tip, plane tip and squealer tip, were measured using a hue-detection base transient liquid crystals technique.. The heat transfer coefficients an the shroud and near tip regions of the pressure and suction sides af the blade were also. measured. The heat transfer measurements were taken at the three different tip gap clearances af 1.0%, 1.5%, and 2.5% of blade span. Results shaw the overall heat transfer coefficients on the tip and shroud with squealer tip blade were lower than those with plane tip blade. By using squealer tip, however, the reductions af heat transfer coefficients near the tip regions of the pressure and suction sides were nat remarkable.

입구 속도 분포가 매끈한 회전유로 내 열전달계수에 미치는 영향 (Effect of Inlet Velocity Distribution on the Heat Transfer Coefficient in a Rotating Smooth Channel)

  • 최은영;이용진;전창수;곽재수
    • 한국유체기계학회 논문집
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    • 제14권6호
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    • pp.76-84
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    • 2011
  • The effect of inlet velocity profile on the heat transfer coefficient in a rotating smooth channel was investigated experimentally. Three simulated inlet flow conditions of fully developed, uniform, and distorted inlet conditions were tested. The Reynolds number based on the channel hydraulic diameter was ranged from 10,000 to 30,000 and the transient liquid crystal technique was used to measure the distribution of the heat transfer coefficient in the rotating channel. Results showed that the overall heat transfer coefficient increased as the Reynolds number increased. Also, the distribution of the heat transfer coefficient was strongly affected by the inlet flow condition. Generally, the fully developed flow simulated condition showed the highest heat transfer coefficient.

가스터빈 베인 끝벽의 열전달 특성 및 정압분포 측정 (Measurement of Heat Transfer and Pressure Distributions on a Gas Turbine Vane Endwall)

  • 이용진;신소민;곽재수
    • 한국항공운항학회지
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    • 제14권2호
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    • pp.33-38
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    • 2006
  • Heat transfer coefficients and static pressure distributions on a gas turbine vane endwall were experimentally investigated in a 5 bladed linear cascade. The Reynolds number based on an axial chord length and the cascade exit velocity was 500,000. Both heat transfer and pressure measurements on the vane endwall were made at the two different turbulence intensity levels of 6.8% and 10.8%. Detailed heat transfer coefficient distributions on the vane endwall region were measured using a hue detection based transient liquid crystals technique. Results show various regions of high and low heat transfer coefficients on the vane endwall surface due to several types of secondary flows and vortices. Heat transfer coefficient and endwall static pressure distributions showed similar trends for both turbulence intensity, however, the averaged heat transfer coefficients for higher turbulence intensity case was higher than the lower turbulence intensity case by 15%.

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4:1 종횡비를 갖는 가스터빈 블레이드 냉각 유로에서의 립-딤플 복합 냉각 특성 연구 (Rib-Dimple Compound Cooling Techniques in a Gas Turbine Blade Cooling Channels with an Aspect ratio (4:1))

  • 최용덕;김석범;이용진;김진곤;곽재수
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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    • pp.304-310
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    • 2010
  • 본 연구에서는 딤플이 설치된 유로, 립이 설치된 유로, 립과 딤플이 함께 설치된 유로에서의 열전달 성능을 천이액정법을 이용하여 측정하였다. 실험에 사용된 유로의 종횡비(W/H)는 4이고, 립의 높이는 6 mm, 립 간 거리(P/e)는 10, 립이 설치된 각도는 $60^{\circ}$이며, 딤플의 직경은 6 mm, 딤플 중심간 거리(s/D)는 1.2로 하였다. 레이놀즈 수는 30000-50000에 대해 실험을 수행하였다. 립이 설치된 유로에서는 경사 립에 의해 발생된 이차유동이 열전달 계수를 증가시켰고, 립과 딤플이 함께 설치된 유로에서는 립 사이에 설치된 딤플이 열전달 계수를 더욱 증가시켰다. 열전달계수는 립과 딤플이 복합 적용된 유로, 립이 적용된 유로, 딤플이 적용된 순으로 나타났고, 열성능계수도 립과 딤플이 복합 적용된 유로에서 크게 나타났다.

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