Combustion Stability Characteristics of the Model Chamber with Various Configurations of Triplet Impinging-Jet Injectors

Sohn Chae-Hoon,Seol Woo-Seok,Shibanov Alexander A. The Korean Society of Mechanical Engineers 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.6

Combustion stability characteristics in actual full-scale combustion chamber of a rocket engine are investigated by experimental tests with the model (sub-scale) chamber. The present hot-fire tests adopt the combustion chamber with three configurations of triplet impinging-jet injectors such as F-O-O-F, F-O-F, and O-F-O configurations. Combustion stability bound-aries are obtained and presented by the parameters of combustion-chamber pressure and mixture (oxidizer/fuel) ratio. From the experimental tests, two instability regions are observed and the pressure oscillations have the similar patterns irrespective of injector configuration. But, the O-F-O injector configuration shows broader upper-instability region than the other configurations. To verify the instability mechanism for the lower and upper instability regions, air-purge acoustic test is conducted and the photograph or the flames is taken. As a result, it is found that the pressure oscillations in the two regions can be characterized by the first impinging point of hydraulic jets and pre-blowout combustion, respectively.

A scaling method for combustion stability rating of coaxial gas-liquid injectors in a subscale chamber

손채훈,Young Jun Kim,Young-Mog Kim,Valery P. Pikalov 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.11

A scaling method to examine combustion-stability characteristics of a coaxial injector is devised based on the acoustics and combustion dynamics in a chamber. The method is required for a subscale test of stability rating with a model chamber, which is cost-effective compared with an actual full-scale test. First, scaling and similarity rules are considered for stability rating and thereby, three conditions of acoustic, hydrodynamic, and flame-condition similarities are proposed. That is, for acoustic similarity, the natural or resonant frequencies in the actual chamber should be maintained in the model chamber. And, two parameters of density ratio and velocity ratio are derived for the requirement of hydrodynamic and flame-condition similarities between the actual and the model conditions. Next, one example of an actual combustion chamber with high performance is selected and the proposed scaling method is applied to the chamber for understanding of the method. The design operating condition for a model test is presented by mass flow rates of propellants. Stability boundaries can be identified on the coordinate plane of chamber pressure and mixture ratio of fuel and oxidizer by applying the scaling method.

KSR-Ⅲ 로켓엔진의 연소 안정성 평가

손채훈(Chae-Hoon Sohn),김영목(Young-Mog Kim) 한국항공우주학회 2004 韓國航空宇宙學會誌 Vol.32 No.3

액체 로켓엔진 개발과정에서 수행되는 여러 가지 시험 중 연소 안정성 평가 시험을 통해, KSR-Ⅲ 로켓엔진의 연소 안정성을 평가하였다. 안정성 평가시험에서, 엔진이 외부 교란에 의한 압력 진동을 감쇠시켜 본래의 안정한 연소를 회복하는 경우, 그 엔진은 연소 안정화 능력을 가지고 있다고 판정할 수 있다. 로켓엔진은, 교란의 크기를 예측하기 어려운 외부 섭동에 노출될 수 있으므로, 연소 안정화 가능 여부를 확인하는 것과 더불어 엔진이 갖고 있는 연소 안정화 성능을 정량화하여 파악하는 작업이 필요하다. 이를 위해 몇 가지 주요 인자를 도입하였고, 이를 평가하는 방법을 검토하였다. 성공적으로 완료된 KSR-Ⅲ, 로켓 개발과정에서 로켓엔진의 안정성 확보를 위해 6회의 안정성 평가 시험이 수행되었다. 이를 토대로, 연소 안정화 성능의 정량화 방법을 KSR-Ⅲ 엔진에 적용하여 엔진의 안정화 성능을 분석하였다. Stability rating of KSR-Ⅲ rocket engine is conducted based on stability rating tests in the course of development of KSR-Ⅲ rocket engine. Rocket engine is approved to have combustion stabilization ability when it can suppress the external perturbation or pressure oscillation with finite amplitude and recover the original stable combustion. Rocket engine in flight may be perturbed by unexpectedly large-amplitude pressure oscillation and thus a designer should not only assure combustion stabilization ability of the engine but also quantify the stabilization capacity. For this, principal quantitative parameters and their evaluation are introduced. To verify dynamic stability of KSR-Ⅲ rocket engine, six stability rating tests have been conducted. Based on these test results, such parameters are quantified and thereby, the stabilization capacity of KSR-Ⅲ rocket engine is evaluated.

Investigations of multiple injection strategies for the improvement of combustion and exhaust emissions characteristics in a low compression ratio (CR) engine

Applied Science Publishers 2011 APPLIED ENERGY Vol.88 No.12

The experimental analysis was conducted for a better understanding of the combustion stability and reduction of exhaust emission in low compression ratio (CR) engine. The combustion stability was analyzed in terms of combustion pressure, the rate of heat release (ROHR), the indicated mean effective pressure (IMEP), and coefficient of variation of indicated mean effective pressure (COV<SUB>IMEP</SUB>), and formation of exhaust emissions such as CO, HC, NO<SUB>X</SUB>, and soot was measured and compared in the low compression ratio single cylinder CI engine. It was revealed that maximum value of combustion pressure (P<SUB>max</SUB>) in two pilot injections was increased to almost the same level of single injection combustion although its maximum rate of heat release (ROHR) was decreased to 47.2% compared to single injection combustion. It was also observed that two pilot injections improves combustion efficiency, and these injection strategies operate engine more stably in low compression ratio engine, based on the results of increased IMEP (2.1%) and decreased COV<SUB>IMEP</SUB> (5.7%). Moreover, in multiple injection combustion, more CO formation and less HC emission were observed during combustion process, and remarkable simultaneous reduction of NO<SUB>X</SUB> up to 58.7% and soot up to 25% can be achieved in low compression ratio engine.

재생냉각 연소기 연소시험의 연소안정성 분석

안규복(Kyubok Ahn),임병직(Byoungjik Lim),이광진(Kwang-Jin Lee),한영민(Yeoung-Min Han),최환석(Hwan-Seok Choi) 한국추진공학회 2009 한국추진공학회지 Vol.13 No.5

Hot-firing tests were performed on two 30 tonf-class regenerative cooling combustion chambers, with different injector distribution and wall cooling method. In the paper, the combustion stability test results were analyzed and presented. The pressure fluctuation and stability rating test(SRT) results of the combustion chambers were examined to evaluate combustion stability. The combustion chambers exhibited satisfactory results on combustion stability. The RMS values of the chamber pressure fluctuation were less than 3% of the chamber pressure and the decay time of artificial pressure peaks was measured to be around 10% of the reference decay time. It is interesting that the RMS values of pressure fluctuation in the combustion chamber with film cooling are smaller than those in the chamber with cooling injectors at the periphery row.

Combustion Stability Characteristics of the Model Chamber with Various Configurations of Triplet Impinging-Jet Injectors

Chae Hoon Sohn,Woo-Seok Seol,Alexander A. Shibanov 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.6

Combustion stability characteristics in actual full-scale combustion chamber of a rocket engine are investigated by experimental tests with the model (sub-scale) chamber. The present hot-fire tests adopt the combustion chamber with three configurations of triplet impinging-jet injectors such as F-O-O-F, F-O-F, and O-P-O configurations. Combustion stability boundaries are obtained and presented by the parameters of combustion-chamber pressure and mixture (oxidizer/fuel) ratio. From the experimental tests, two instability regions are observed and the pressure oscillations have the similar patterns irrespective of injector configuration. But, the O-F-O injector configuration shows broader upper-instability region than the other configurations. To verify the instability mechanism for the lower and upper instability regions, air-purge acoustic test is conducted and the photograph of the flames is taken. As a result, it is found that the pressure oscillations in the two regions can be characterized by the first impinging point of hydraulic jets and pre-blowout combustion, respectively.

Gas turbine combustion characteristics of H₂/CO synthetic gas for coal integrated gasification combined cycle applications

Lee, Min Chul,Yoon, Jisu,Joo, Seongpil,Yoon, Youngbin Elsevier 2015 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.40 No.34

<P><B>Abstract</B></P> <P>This paper describes the gas turbine combustion characteristics of coal-derived synthetic gas (syngas), particularly for the syngases at the Taean IGCC plant in Korea and the Buggenum IGCC plant in the Netherlands. To evaluate the combustion performance of these syngases, we conducted combustion tests with elevated temperature and ambient pressure in a GE7EA model combustor. We observed flame stability, dynamic pressure characteristics, NO<SUB>x</SUB> and CO emissions, temperature in the combustion chamber, and flame structures while varying the heat input and diluent integration ratio. Without dilution, Buggenum's stable regime is larger than that of Taean, since a higher hydrogen content causes sustained flames, even at a very high flame stretch rate. However, when considering nitrogen dilution, Taean's syngas has a more stable burn than that of Buggenum, since an increase in nitrogen at Buggenum has negatively affected flame stability. From the results of NO<SUB>x</SUB>/CO emissions and combustion efficiency, we report that both syngases are sufficient to control NO<SUB>x</SUB> emissions at under 5 ppm with almost complete and stable combustion; however, quantitatively, the effect of nitrogen dilution is slightly different at Taean and Buggenum due to slight differences in the H<SUB>2</SUB>/CO ratio and diluent heat capacity. All the tested results and conclusions drawn are considered for optimal operation and trouble shooting at the Taean IGCC plant, which is scheduled to be complete toward the end of 2016.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Taean syngas burns more stably than Buggenum syngas due to lower N<SUB>2</SUB> composition. </LI> <LI> Syngas flame exists under 82 mol% N<SUB>2</SUB>, the lower flammable limit by Chatelier rule. </LI> <LI> Optimal operating condition for low NO<SUB>x</SUB>/CO emission is 1230 °C < <I>T</I> <SUB> <I>ad</I> </SUB> < 1500 °C. </LI> <LI> NO<SUB>x</SUB> is reduced to <3 ppm when IR<SUB>N2</SUB> >50%, but excessive IR<SUB>N2</SUB> causes flame unstable. </LI> <LI> Syngas flame attachment/detachment is the key mechanism of combustion instability. </LI> </UL> </P>

EFFECTS OF INTAKE VALVE ANGLE ON COMBUSTION CHARACTERISTIC IN AN SI ENGINE

엄인용 한국자동차공학회 2013 International journal of automotive technology Vol.14 No.4

In this study, 2 different valve-angle engines, one is wide and the other is narrow, were prepared for investigating the effects of the angle on the combustion. For this purpose, the part load performances were evaluated and the pressures were measured for combustion analysis at an engine bench under 5 different operating conditions, varying the compression ratio. The results show that the combustion proceeds so faster in the small IVA engine that its MBT timings are retarded considerably compared with that of large one and result in lower NOx emission level; however, unburned HC is higher because of its geometrical feature. In addition, there is no substantial difference between 2 IVA engines in the timings of combustion initiation and completion as a crank-angle-position-base in spite of the considerable difference of spark timing,on the other hands, the ignition delay of the small IVA is shorter than that of large one. Also the phenomena that the flame propagation is faster and the instant heat release rate is more concentrated and higher in the small were observed. Also, the burn duration of small one is shorter and the combustion process is more accelerated up to the mid-combustion stage; however,the process of large one is faster as the combustion approaches the last stage and the differences of combustion duration reduce as the compression ratio increases. Finally, the engine runs more stable when the IVA is small without any exception because of its rapid burn at the initial combustion stage.

발전용 가스터빈의 실시간 연소안정성 평가 소프트웨어 개발

인병구(Byeung Goo In),송원준(Won Joon Song),차동진(Dong Jin Cha) 대한설비공학회 2017 설비공학 논문집 Vol.29 No.6

This study introduces a software for real-time assessment of combustion stability for utility gas turbines. The software was written with LabView, and implemented the time-domain kurtosis as a parameter to proactively access the instantaneous combustion stability during operation of the industrial gas turbine. The simple time-domain assessment algorithm incorporated in the software is advantageous over conventional frequency-domain signal processing of dynamic pressure signal since it reduces the computational cost, thereby making the algorithm more appropriate for real-time monitoring of combustion stability. Benchmark data obtained from a model gas turbine combustor were used for the reproducibility test of the software. The assessment obtained from the software agreed well with previously published results, indicating that incorporation of the software could enhance the performance of systems monitoring the combustion stability for gas turbines during power generation.

Hot- Fire Injector Test for Determination of Combustion Stability Boundaries Using Model Chamber

Sohn Chae Hoon,Seol Woo-Seok,Shibanov Alexander A.,Pikalov Valery P. The Korean Society of Mechanical Engineers 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.9

This study realizes the conceptual method to predict combustion instability in actual full-scale combustion chamber of rocket engines by experimental tests with model (sub-scale) chamber. The model chamber was designed based on the methodologies proposed in the previous work regarding geometrical dimensions and operating conditions, and hot-fire test procedures were followed to obtain stability boundaries. From the experimental tests, two instability regions are presented by the parameters of combustion-chamber pressure and mixture (oxidizer/fuel) ratio, which are customary for combustor designers. It is found that instability characteristics in the chamber with the adopted jet injectors can be explained by the correlation between the characteristic burning or mixing time and the characteristic acoustic time: In each instability region, dynamic behaviors of flames are investigated to verify the hydrodynamically-derived characteristic lengths of the jet injectors. Large-amplitude pressure oscillation observed in upper instability region is found to be generated by lifted-off flames.