Atomization performance of a mouthpiece nozzle on the pressure atomizers

• Main Authors: Yuh-Long Liu, 劉玉龍
• Other Authors: Muh-Rong Wang
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/45530603146744345957

碩士 === 國立成功大學 === 航空太空工程學系 === 88 === Abstract The idea proposed in this study is to attach an external atomization mask to the original fuel nozzle to provide a secondary atomization process at the outlet of the existing fuel nozzle. Two types of the external atomization masks are designed: the radial air impinging type and the tangential air impinging type. It is found that only few injection ports is needed to achieve good performance. SMD can be reduced to 100μm when the air/fuel ratio is only 0.15 with 6 injection ports. This amount only occupies 1% of the total combustion air requirement. Hence the influence of the extra air flow on the combustion flow can be neglected. It is concluded that the size of the combustor can be further reduced using this technique. Results also show that the performance of the atomizer is essentially dependent on the fuel/air ratio and is approaching a limit when the fuel/air ratio is over 0.3. However, the spray cone angles are relatively constant when the atomizer is operated at higher pressure. For example, when the atomizer is operated at Pw= 5kg/cm2, the spray cone angle remains at 60o as the atomizing air increases from Pair= 2kg/cm2 to 5kg/cm2. The fuel mass flow rate is slightly reduced as the air flow rate increases in the 6-port case. It is suggested that the fuel injection pressure might have to increase to maintain the required fuel flow rate. Comparison on the injection of the tangential and axial air shows that the tangential design can achieve the better performance with less injection ports. Both them they have the same atomizing efficiency, but the injection of tangential air has more wide spray con angle. However, the injection of axial air has better performance when the injection ports increase. In a summary, it is demonstrated that the technique has been successful in reducing the spray size by providing the external atomization mechanism. This technique can be extended to other atomizers to improve the combustion performance. Furthermore, it can be used in the low pressure and high pressure operation and achieve a higher turn down ratio than the conventional atomizer. Keywords : Fuel nozzle , Atomization Mask , Secondary Atomization , Reduced SMD