• 한국항공우주학회지
• /
• 제34권10호
• /
• pp.71-79
• /
• 2006

액체로켓엔진에서 고주파 연소불안정을 제어하기 위하여 다단 접선 유입구를 갖는 스월 인젝터를 분석하였다. 음향흡수자로서 인젝터의 효과를 분석하기위하여 인젝터는 1/4 파장 공명기로 해석하였고, 상온에서 감쇠 효과의 적합성을 검증하였다. 이러한 인젝터는 모델 챔버의 고유주파수에 동조시킬 수 있는 고유주파수를 갖게 된다. 다단의 접선 유입구를 갖는 인젝터가 단일 유입구를 갖는 인젝터 보다 인젝터 내부의 air core가 안정되었다. 또한, 다단 접선 유입구를 갖는 인젝터를 사용하였을 때 불안정 모드에 동조되는 인젝터 길이가 계산된 길이와 잘 일치하였다. 이러한 실험 결과로부터 인젝터 내부의 air core가 안정되게 유지된다면, 동조된 스월 인젝터는 모델 챔버의 불안정 모드를 효과적으로 감소시킬 수 있고, 감쇠율을 증가시킬 수 있음을 확인하였다.

• 한국추진공학회지
• /
• 제12권6호
• /
• pp.30-37
• /
• 2008

지금까지 액막두께나 air core 직경 변화 등과 같은 수력학적 과정에 대한 이론 실험 연구가 많이 이루어져왔다. 스월 노즐에서 수치적 해석 등을 통해 이에 대한 몇 가지 이론식들이 확립되었지만, 아직까지 내부유동에 대한 실험적 연구 결과 등은 명백히 정립되어 있지 않고 있다. 본 연구에서는 스월 챔버 내의 air core 구조를 가시화하고 오리피스에서의 액막두께를 측정함으로써 접선방향유입구 조건에 따른 내부유동의 안정성 여부를 판단해볼 수 있었다.

• 대한기계학회논문집B
• /
• 제33권9호
• /
• pp.666-673
• /
• 2009

The turbulent swirling flow field characteristics of a gun-type gas burner with a combustion chamber were investigated under the cold flow condition. The velocities and turbulent quantities were measured by hot-wire anemometer system with an X-type probe. The turbulent swirling flow field in the edge of a jet seems to cause a recirculation flow from downstream to upstream due to the unbalance of static pressure between a main jet flow and a chamber wall. Moreover, because the recirculation flow seems to expand the main jet flow to the radial and to shorten it to the axial, the turbulent swirling flow field with a chamber increases a radial momentum but decreases an axial as compared with the case without a chamber from the range of about X/R=1.5. As a result, these phenomena can be seen through all mean velocities, turbulent kinetic energy and turbulent shear stresses. All physical quantities obtained around the slits, however, show the similar magnitude and profiles as the case without a chamber within the range of about X/R=1.0.

• 설비공학논문집
• /
• 제1권4호
• /
• pp.265-275
• /
• 1989

An experimental study of decaying swirl air flow has been obtained by tangential inlet in a straight tube with Reynolds number range 20,000~40,000. The friction factor, swirl angle, velocity profiles and turbulent intensity are measured by using micro-manometer and hot-wire anemometer. It is found that the swirl flow behaviors depend on the swirl intensity along the test tube.

• 한국공작기계학회논문집
• /
• 제16권4호
• /
• pp.13-21
• /
• 2007

This paper presents characteristics of steady flow by variation of a combustion chamber and an intake port. Gas flow field inside a combustion chamber is the important factor in improving combustion stability and reduction of emission level. The flow characteristics such as flow coefficient, tumble ratio and swirl ratio are measured by the steady flow rig test with an impulse meter in this study. In the measuring, the valve lifts are varied between 1mm to 10mm. The three combustion chambers and two intake ports were applied to the steady flow apparatus in order to investigate the effect of swirl and tumble on the in-cylinder flow. As a result, tumble ratio were found to be different by variation of the combustion chambers and the intake ports. The data from the present study can be applied to design of a similar engine as basic data.

• 한국분무공학회지
• /
• 제11권3호
• /
• pp.147-154
• /
• 2006

A specially designed injector using electric conductivity was used to measure the liquid film thickness accurately. The measurement conducted through the precise calibration, accuracy is demonstrated in comparison with the previous theory and the results using other measurement method. The tendency of liquid film thickness for geometric parameters was examined by the precise measurement. The variation of air core and stability are examined through the visualization of the formation of air core in swirl chamber and the variation of liquid film thickness by the time.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2007년도 제29회 추계학술대회논문집
• /
• pp.198-203
• /
• 2007

본 연구의 목표는 air core의 길이 조절이 가능한 스월인젝터의 음향학적인 감쇠기능을 통해 고주파 연소불안정을 억제하는 것이다. air core(길이, 형상, 부피)와 인젝터의 위치에 대한 음향학적인 감쇠 효과는 선행 연구를 통해 실험되었다. 이러한 결과들을 바탕으로 다중 인젝터들의 효과에 대한 연구를 진행하였다. 실험 결과로부터 각 모드의 배(anti-node)에 장착된 인젝터들의 수의 증가로 감쇠효과가 증가하는 것을 확인하였다. 또한 각 모드들의 배(anti-node)에 장착되어 동조된 인젝터들이 동시에 개별적인 모드 감쇠 성능을 보일 수 있음을 확인했다.

• International Journal of Aeronautical and Space Sciences
• /
• 제14권4호
• /
• pp.398-407
• /
• 2013

Optical tomography was used to measure the pattern of spray cross-section. The maximum-likelihood estimation (MLE) algorithm was used to reconstruct the spray cross-section from the measured transmission rate of the spray. A swirl-type injector was used to form an optically dense spray, and the test was carried out in a high-pressure chamber, to control the pressure condition of the test site. Before the experiment, the reliability of the MLE-based reconstruction algorithm was verified, by comparing it with a conventional filtered back projection reconstruction (FBP) method. The MLE algorithm showed superior reconstruction of the image. In the spray patternation experiment, the results of the optical tomography and optical line patternator, which uses Mie scattering signal information, were compared. While measuring the cross-section of optically dense spray, the intensity of the scattering signal had attenuated to an uncorrectable level, which led to incorrect spray pattern measurement by the optical line patternator. However, reliable results were obtained by optical tomography, under the same condition. Finally, the pattern of the optically dense spray was measured at various chamber pressures, of up to 3 MPa. As the chamber pressure increased, the hollow cone-shaped swirl spray shrank, and the attenuation coefficient value of the inner region increased.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
• /
• pp.451-454
• /
• 2006

This paper describes the results of cold flow test and hot firing tests of an uni-element coaxial swirl injector and hot firing tests of a subscale combustor, as to the development effort of coaxial swirl injector for high performance liquid rocket engine combustor. A major design parameter for coaxial swirl injector is the recess number of a bi-swirl injector. The results of hot firing tests of the uni-element injector combustor and the sub-scale combustor are analyzed to investigate the effect of the recess number influencing on the combustion performance and pressure fluctuation. The test results of a cold flow test of the unielement combustor shows that it was shown that the change in recess number has significant effect on mixing characteristics and efficiency, while the effect of recess number on atomization characteristic is not The results of a series of firing tests using unielement and subscale combustor show that the recess length significantly affects the hydraulic characteristics, the combustion efficiency, and the dynamics of the liquid oxygen/kerosene bi-swirl injector. As a point of combustion performance, combustion efficiencies are 90% for unielement combustor and 95% for subscale combustor. The difference in the characteristic velocities between the unielement combustor and the subscale combustor may be caused by the difference in thermal loss to the combustor wall and the relative lengths of the combustion chamber. For a mixed type coaxial swirl combustor, the pressure drop across the injector increases as recess number becomes larger. The low frequency pressure fluctuation observed in unielement combustor can be related to the propellant mixing characteristics of the coaxial bi-swirl injector. The effect of the recess number on the pressure fluctuation inside the combustion chamber is more significant in un i-element combustor than the subscale combustor, of which the phenomena are also observed in time domain and frequency domain.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
• /
• pp.672-674
• /
• 2017

하이브리드 로켓의 연소 실험 과정에서 저 주파수 대역이 증폭하는 연소 불안정이 관찰되었다. 반면, 터빈 연소기에서는 혼합 특성 향상을 통하여 연소의 안정성을 얻기 위해 스월 유동을 사용한다. 본 연구에서는 하이브리드 로켓의 연소 불안정을 감소시키기 위하여 스월 인젝터를 사용하여 실험하였다. 그 결과, 하이브리드 로켓에서 스월 인젝터를 통하여 산화제를 주입한 경우 연소 불안정이 감소하였다. 산화제의 스월 유동의 변화는 연소실 내부의 난류유동 특성을 변화시키며 그 결과, 연소 불안정에 영향을 미친다. 따라서 스월 각도 변화를 통하여 스월 넘버 변화를 변화시킴으로써 유동 특성 변화에 대해 알아보았다. 유동 특성 변화가 주파수 특성에 미치는 영향, 압력진동과 연소진동의 상관관계에 대해 확인하였다.