• 한국가시화정보학회지
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• 제16권2호
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• pp.45-52
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• 2018

The tangential and axial cyclones were fabricated using a 3D printer and the total collecting efficiency, cut-diameter, and pressure drop characteristics of the two types of cyclones with the same inlet area were investigated experimentally. The results show that the total collecting efficiency tends to increase as the inlet velocity increases. However, at a 20m/s condition of the tangential cyclone, the collected particles were re-entrained to the ascending vortex flow, resulting in a decrease of the total collecting efficiency. In the axial cyclone, the cross-sectional area is designed to increase at the inlet and the velocity is reduced, so that the re-entrainment effect does not appear in this study. The pressure loss of the tangential cyclone was larger than that of the axial cyclone. The cut-diameter tends to decrease with increasing the inlet velocity in two types of cyclones, except for the 20m/s condition of the tangential cyclone.

• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1892-1899
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• 2001

An experimental study was performed for measuring velocity and turbulence intensity in a circular tube for Re= 10,000, 15,000 and 20,000, with swirl and without swirling flow. The velocity fields were measured using PIV techniques and swirl motion was produced by a tangential inlet condition. Some preliminary measurements indicated that over the first 4 diameter, two regions of flow reversal were set up (the so called 2-cell structure). At the highest Reynolds numbers, the maximum values of the measured axial velocity components had moved toward the test tube wall and produce more flow reversal at the conter of the tube. As the Reynolds number increased, the turbulence intensity of swilling flow at the tube inlet also increased.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.2042-2052
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• 2003

An experimental study was performed to investigate heat transfer characteristics of turbulent swirling flow in an axisymmetric annuli. The static pressure, the local flow temperature, and the wall temperature with decaying swirl were measured by using tangential inlet conditions and the friction factor and the local Nusselt number were calculated for Re=30000∼70000. The local Nusselt number was compared with that obtained from the Dittus-Boelter equation with swirl and without swirl. The results showed that the swirl enhances the heat transfer at the inlet and the outlet of the test tube.

• Journal of Advanced Marine Engineering and Technology
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• 제35권7호
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• pp.907-913
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• 2011

Swirling flows are related to the spiral motion in the tangential direction in addition to the axial and radial direction using several swirl generators. These type of flows are used in combustion chambers to improve flame stability, heat exchanger to enhance heat transfer coefficients, agricultural spraying machines and some vertical pipes to move slurries or transport of materials. However, only a few studies three dimensional velocity profiles in a vertical pipe have been reported. In this present paper, 3 dimension particle image velocimetry(PIV) technique was employed to measure the velocity profiles in water along a vertical circular pipe with Reynolds number from 6000 to 13,000. A tangential inlet condition was used as the swirl generator to produce the required flow. The velocities were measured with swirling flow in the water along the test section using the PIV technique.

• 한국가시화정보학회지
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• 제1권1호
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• pp.82-91
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• 2003

The study of swirl flow has been of technical and scientific interest because it has an internal recirculation field and its tangential velocity is related to the curvature of the streamline. The fluid flow for ducts or elbows of an internal engine has been much studied through numerical methods and experiments, but studies about swirl flow has been insufficient. Using the PIV (Particle Image Velocimetry) method, this study found the time-mean velocity distribution, time-mean turbulent intensity, with swirl and without swirl flow for Re=10,000, 15,000, 20,000, and 25,000 along longitudinal sections and the results appear to be physically reasonable. In addition, axial velocity distribution is compared with that of Jeong's, Kodadadi's and Murakami's. It was found that the highest velocity of swirl and non-swirl flow occurs in the opposite position at the center of a round tube, $\phi$=45$^{\circ}$

• 한국가시화정보학회지
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• 제1권2호
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• pp.38-46
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• 2003

An experimental investigation was performed to study the turbulent characteristics of swirling flow a 90$^{\circ}C$ circular tube for Re = 10,000, 15,000 and 20,000. 2D-PIV(Particle Image Velocimetry)technique was employed to measure the fluctuation velocity field. The results include spatial distributions of mean velocity vectors, turbulence intensity and turbulence kinetic energy. The axial and radial turbulence intensities, and kinetic energy profiles show double-peak structures in the inlet region of the 90 degree bend and the profiles are disappeared along the test tube with decaying the swirl intensity.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.840-845
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• 2001

Development of a small gas-turbine combustor for 100kW class APU(Auxiliary Power Unit) has been performed. This combustor is a reverse-annular type and has a tangential swirler in the liner head to improve the fuel/air mixing and flame stability. Three main and three pilot fuel injectors of the simplex pressure-swirl type are used. The performance target at the design condition includes a turbine inlet temperature of 1170K, a combustion efficiency of 99%, a pattern factor of 30%, and an engine durability of 3000 hours. Under developing the combustor, we conducted performance test of our first prototype(TS1) with some variants. As a result of the test, the performance targets of the combustor are satisfied except that the pattern factor is about 4% higher than target value. So, we redesigned the second prototype(TS2) and conduct performance test with the critical focus on pattern factor and exit mean temperature. We adopted TS2 four variant to check the improvement of pattern factor. As the result, the pattern factors of several variants were satisfied with the performance target. Finally, We chose the TS2A variant as a final combustor for our APU model.

• 한국가시화정보학회지
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• 제8권1호
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• pp.53-60
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• 2010

Experimental investigations were conducted to study the characteristics of turbulent swirling flow in an axisymmetric annuli. Swirl angle measurements were performed using a flow visualization technique using smoke and dye liquid for Re=60,00080,000. Using the two-dimensional particle image velocimetry method, we found the time-mean velocity distribution and turbulent intensities in water with swirl for Re=20,000, 30,000, and 40,000 along longitudinal sections. Neutral points occurred for equal axial velocity at y/(R-r)=0.70.75, and the highest axial velocity was recorded near y/(R-r)=0.9. Negative axial velocity was observed near the convex tube along X/(D-d)=3~23. Another experimental study was performed to investigate heat transfer characteristics of turbulent swirling flow in an axisymmetric annuli. Static pressure, and local flow temperature were measured using tangential inlet condition and the friction factors and Nusselt number were calculated for several Reynolds numbers.

• 한국수자원학회논문집
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• 제50권2호
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• pp.129-138
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• 2017

대심도 저류 및 배수터널은 기 개발된 도시의 부족한 배수관망 능력을 보강하기 위하여 지하에 설치하는 대규모 도시홍수 배제 시설물로 원활한 홍수 유입을 위해 적정한 규모의 수직유입구가 요구되어진다. 접선형 수직유입구 설계 시 유입구의 능력을 평가하는 중요인자로 Yu and Lee(2009)가 지배유량개념을 소개하였는데, 본 연구에서는 서울시에 설치하고자 하는 신월빗물저류배수시설의 수직유입구 3개소를 대상으로 수리모형실험을 실시하고 제안된 지배유량 개념의 적정성을 평가하였다. 지배유량 이론식($Q_{cp}$)을 이용하여 실제 측정된 지배유량($Q_{cm}$)과 비교 분석하였는데, 그 결과 이론식 대비 66~69%로 이론식이 지배유량을 과대 산정하는 것으로 평가되었다. 지배유량 이론식의 과대산정 원인을 분석하기 위하여 Yu and Lee (2009)가 사용한 자료들과 본 연구에서 측정된 자료들을 활용하여 지배유량비($Q_{cm}/Q_{cp}$)를 3가지 영역으로 분류하고 각 인자에 대한 민감도 분석을 실시하였다. Yu and Lee (2009)가 제안한 지배유량식은 접선형 수직유입구 설계인자인 B, z, ${\beta}$, e/B에 대한 영향만 고려하였으나 ${\theta}$, L과 연계된 변수들로 복합적으로 고려하는 식의 개선이 필요한 것으로 판단된다.

• 대한기계학회논문집B
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• 제26권6호
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• pp.805-810
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• 2002

Development of a small gas-turbine combustor for 100㎾ class APU(Auxiliary Power Unit) has been performed. This combustor is a reverse-annular type and has a tangential swiller in the liner head to improve the fuel/air mixing and flame stability. Three main and three pilot fuel injectors of the simplex pressure-swirl type are used. The performance target at the design condition includes a turbine inlet temperature of l170k, a combustion efficiency of 99%, a pattern factor of 30%, and an engine durability of 3000 hours. Under developing the combustor, we conducted the performance test of our first prototype(TS1) with some variants. As a result of the test, the performance targets of the combustor are satisfied except that the pattern factor is about 4% higher than the target value. Therefore, the second prototype(TS2) was redesigned and the performance test was conducted with the critical focus on the pattern factor and the exit mean temperature. We adopted TS2 four variants to check the improvement of the pattern factor. As a result, the pattern factors of several variants were satisfied with the performance target. Finally, the TS2A variant was chosen as a final combustor fur our APU model.