Transient and Steady Spray Characteristics of Soybean Oil/2,5-Dimethylfuran Blended Fuel in an Underwater Stirling Engine

doi:10.1007/s12204-023-2630-y

Abstract

Abstract: The reduction of oxygen consumption is a key factor to improve the energy density of underwater Stirling engine. A series of fundamental experiments are carried out to elucidate the spray characteristics of soybean oil/2,5-dimethylfuran (DMF) blended fuel in an underwater Stirling engine. Spray characteristics such as spray penetration, spray angle, spray area, and light intensity level under low injection and ambient pressures are obtained using image post-processing method. The results show that the effects of injection pressure, ambient pressure, and nozzle diameter on the transient spray characteristics of underwater Stirling engine are similar to those of diesel engine. However, in the steady spray process, the injection pressure has little effect on spray near angle, and the spray far angle increases with the increase of the injection pressure. Compared with the spray far angle at injection pressure of 3 MPa, the spray far angle at 5 MPa and 7 MPa increased by 11.38% and 18.14% respectively. The addition of DMF can obviously improve the atomization of soybean oil/DMF blended fuel. The spray angle of blended fuel in transient process increases with the increase of the DMF concentration. The spray near angle has exceeded that of diesel (46.21◦) when the DMF volume fraction exceeds 25%. The spray far angle is equivalent to that of diesel when the DMF volume fraction reaches 75%. Moreover, the spray with gas ejection no longer keeps conical, the droplet diameter distribution is more dispersed, and the droplet diameter is smaller.

Key words: spray angle, steady spray, soybean oil, 2,5-dimethylfuran (DMF), Stirling engine

摘要： 降低耗氧量是提高水下斯特林发动机能量密度的关键因素。本文对大豆油/2,5-二甲基呋喃（DMF）混合燃料在水下斯特林发动机中的喷雾特性进行了一系列试验研究。利用图像处理方法获得了低喷射压力和背压下的喷雾贯穿距、喷雾锥角、喷雾面积、光强水平等喷雾特性。结果表明，喷射压力、背压和喷孔直径对斯特林发动机瞬态喷雾特性的影响与柴油机相似。但是，在稳态喷雾过程中，喷射压力对喷射近角的影响很小，喷雾远角随着喷射压力的增加而增加。与3 MPa时的喷射压力相比，5 MPa和7 MPa的喷雾远角分别增加了11.38%和18.14%。DMF的加入能明显改善大豆油/DMF混合燃料的雾化性能。瞬态喷雾过程中，混合燃料的喷雾锥角随着DMF浓度的增加而增大。当DMF体积分数超过25%时，喷雾近角已超过柴油的（46.21°）；当DMF体积分数达到75%时，喷雾远角与柴油的喷雾远角相当。此外，当有气流引射时，喷雾形貌不再保持圆锥形，液滴直径分布更加分散，并且液滴直径更小。

关键词: 喷雾锥角，稳态喷雾，大豆油，2, 5-二甲基呋喃（DMF），斯特林发动机

CLC Number:

U664.124

WANG Jigang(王继刚), QIAO Xinqi(乔信起), ZHOU Feng(周枫), WANG Lintao（王林涛）. Transient and Steady Spray Characteristics of Soybean Oil/2,5-Dimethylfuran Blended Fuel in an Underwater Stirling Engine[J]. J Shanghai Jiaotong Univ Sci, 2024, 29(2): 216-229.

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