• 한국화재소방학회논문지
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• 제28권4호
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• pp.35-43
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• 2014

3개의 난류모델과 3개의 연소모델로 구성된 9개의 모델조합을 이용하여 난류 부분예혼합 제트화염 구조에 대한 수치적 예측성능을 검토하였다. 이용된 난류모델은 표준 ${\kappa}-{\varepsilon}$ 모델(SKE), Realizable ${\kappa}-{\varepsilon}$ 모델(RKE) 및 Reynolds 응력모델(RSM)이며 연소모델들은 Eddy Dissipation Concept 모델(EDC), Steady Laminar Flamelet 모델(SLF)와 Unsteady Laminar Flamelet 모델(ULF)이다. 9개 모델조합의 예측성능을 평가하기 위하여 실험결과가 알려진 Sandia D 화염인 난류 부분예혼합 제트화염을 대상으로 수치계산을 수행하였다. 얻어진 결과로서, 화염길이의 예측은 RSM > SKE > RKE순으로 길게 예측하였으며, RKE 난류모델은 화염길이를 너무 과소 예측하는 것을 확인하였다. RSM + SLF과 RSM + ULF의 조합은 화염길이는 비교적 잘 예측하였지만 하류에서의 화염온도를 과대 예측하였다. 반면에 SKE와 연소모델의 조합에서 SLF 또는 ULF 조합은 화염길이 뿐만 아니라 하류에서의 화염온도도 비교적 잘 예측하였는 것을 확인하였다. 반경방향 화염온도 및 화학종 농도분포를 비교해 본 결과 SKE와 연소모델의 조합이 가장 예측성능이 뛰어났으며 SKE + ULF의 조합이 가장 우수한 예측성능을 갖는 것을 확인하였다.

• 대한기계학회논문집B
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• 제28권5호
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• pp.569-579
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• 2004

The lift-off characteristics of lifted laminar propane jet flames highly diluted with nitrogen are investigated introducing acoustic forcing with a fuel tube resonance frequency. A flame stability curve is obtained according to forcing strength and the nozzle exit velocity for N2 diluted flames. Flame lift-off behavior is globally classified into three regimes; 1) a weakly varying partially premixed behavior caused by a collapsible mixing for large forcing strength, 2) a coexistent behavior of the edge flame and a weakly varying partially premixed behavior for moderate forcing strength, and 3) edge flame or triple flame behavior for small forcing. It is shown that the laminar lifted flame with forcing affects flame lift-off behavior considerably, and is also clarified that the flame characteristic of flame base is well described with the penetration depth of the degree of mixing, ${\gamma}$$\_$$\delta$/. It is also confirmed that the weakly varying partially premixed flame caused by a collapsible mixing fur large forcing strength behaves as that just near flame blow-out in turbulent lift-off flame.

• 설비공학논문집
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• 제7권3호
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• pp.353-358
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• 1995

The emission characteristics of a semi-Bunsen type burner for gas boilers were studied experimentally. The experimental results reveal that nitric oxide emission increases with fuel flow rate. It is linearly proportional to total fue flow rate at a small amount of fuel up to 0.4 liters per minute. It does not change significantly within the range of fuel flow rate from 0.4 to 1.2 liters per minute per nozzle and increases at large fuel flow rate. The carbon monoxide emission reveals to be dependent upon the fuel flow rate per each nozzle and the number of fuel injection nozzles. Diameter of an injection nozzle could have an effect on the emission characteristics of this type of burners. However, there is no marked change in the nitric oxide emission if the total fuel flow rate is same with different nozzle sizes.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.7-8
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• 2012

The effects of interaction between partially premixed and premixed swirl flames on CO and NOx emissions were experimentally investigated using a hybrid/dual swirl jet combustor for a micro-gas turbine. Under the condition of constant angle ($45^{\circ}$) for outer swirl vane, the angle and direction of inner swirl vane installed for a partially premixed flame were varied as main parameters with a constant fuel flow rate for each nozzle. It was found that for all conditions, CO and NOx emissions were measured below 4 ppm and 15 ppm at 15% $O_2$, respectively, in a wide range of equivalence ratio (0.6~0.9). For co-swirl flows, CO emission increased dramatically as the angle of inner swirl vane increased from $15^{\circ}$ to $45^{\circ}$ near lean-flammability limit (i.e. equivalence ratio of 0.5). On the other hand, the case of swirl $angle=45^{\circ}$ provided the lowest NOx emission at higher equivalence ratios than 0.6. For counter-swirl flows, the case of swirl $angle=45^{\circ}$ extended the lean-flammability limit but higher NOx emissions were found compared to those of co-swirl flows. These results could be inferred by interaction between (inner) partially premixed and (outer) premixed swirl flames. However, these estimations were not clear yet because there was insufficient data on turbulent flow structure and fuel-air mixing in the present experimental approach.