An experimental study of the spray structure from air-shrouded dual-stream injectors with different air mixing mechanisms was carried out extensively to understand the spray characteristics of dual-stream port injectors for applications to four-valve gasoline engines. The injectors were tested under both steady and transient conditions at different injection pressures and air shrouding pressure differentials. The global spray structure was visualized using the planar laser Mie scattering technique and spray atomization processes were characterized by the phase-Doppler anemometry method. The experimental results showed that spray atomization characteristics are improved markedly by the air-shrouding technique and also strongly dominated by the air-mixing mechanisms. When the air flows into the injector tip mainly from the radial direction, two streams of the spray are forced to merge together and as a result a single-stream spray is formed. When the radial velocity component of the air is reduced and the air is made to mix well with the fuel inside the injector tip, however, the two streams of the spray are well separated over different injection conditions. Moreover, other spray parameters are also modified by the air shrouded into the injector, which must be optimized in order to achieve the best performance of the air-shrouded injector.

Issue Section:
Internal Combustion Engines
Topics:
Fuel injectors, Sprays, Ejectors, Air flow, Electromagnetic scattering, Fuels, Lasers, Pressure, Radiation scattering, Scattering (Physics), Transients (Dynamics), Gasoline engines, Valves
1.
Amer, A. A., and Lai, M.-C., 1995, “Time-Resolved Measurements of a Transient Gasoline Spray,” SAE Technical Paper No. 950509.
2.
Amer, A. A., Chue, T.-H., Zhao, F.-Q., and Lai, M.-C., 1995, “Modeling Turbulence Primary Breakup and Its Application in Director-Plate-Compounded Port Injectors,” Proc. 8th Annual Conference on Liquid Atomization and Spray Systems, ILASS-America, Troy, MI, May 21–24, 1995, pp. 129–133.
3.
Chen, J. L. and Chen, G., 1995, “Slow Heating Process of a Heated Pintle-Type Gasoline Fuel Injector,” SAE Technical Paper No. 950068.
4.
Harada, K., Shimizu, R., Kurita, K., Muramatsu, M., Makimura, T., and Ohashi, M., 1992, “Development of Air-Assisted Injector System,” SAE Technical Paper, No. 920294.
5.
Inamura
T.
,
Nagai
N.
, and
Sunanaga
H.
,
1992
, “
Improvement for Spray Performance of a Low-Pressure Atomizer by Conical Sheet Formation
,”
JSME Trans.
, Vol.
58
, No.
551
, pp.
2296
–
2301
. [in Japanese].
6.
Kashiwaya, M., Kosuge, T., Nakagawa, K., and Okamoto, Y., 1990, “The Effect of Atomization of Fuel Injectors on Engine Performance,” SAE Technical Paper, No. 900261.
7.
Lai, M.-C., Zhao, F.-Q., Amer, A. A., and Chue, C.-H., 1994a, “The Structure of Port Injector Sprays in Gasoline Engines,” Proc. of International Symposium on Advanced Spray Combustion (ISASC), Hiroshima, Japan, July 6–8, pp. 79–89.
8.
Lai, M.-C., Zhao, F.-Q., Amer, A. A., and Chue, C.-H., 1994b, “An Experimental and Analytical Investigation of the Spray Structure From Automotive Port Injectors,” SAE Technical Paper, No. 941873.
9.
Lai, M.-C., and Zhao, F.-Q., 1995, “The Spray Characteristics of Automotive Port Fuel Injectors—Implications to the Mixture Formation Process and Engine Performance,” Proc. 1995 KSEA International Technical Conference, Aug. 31-Sept. 2, San Francisco, CA, pp. 112–131.
10.
Nagaoka, M., Kawazoe, H., and Nomura, N., 1994, “Modeling Fuel Spray Impingement on a Hot Wall for Gasoline Engines,” SAE Technical Paper, No. 940525.
11.
Namiyama, K., Nakamura, H., Kokubo, K., and Hosogai, D., 1989, “Development of Ultrasonic Atomizer and Its Applications to S.I. Engines,” SAE Technical Paper, No. 890430.
12.
Nogi
T.
,
Ohyama
Y.
, and
Fujieda
M.
,
1992
, “
Study on the Intermittent Impinging Atomization of Fuel Injector for Gasoline Engine
,”
JSME Trans.
, Vol.
58
, No.
552
, pp.
2607
–
2611
. [in Japanese].
13.
Okamoto, Y., Arai, N., Nakagawa, K., Kosuge, T., and Atago, T., 1992, “Atomization Characteristics of Two-Stream Injector for 4-Valve Engines,” SAE Technical Paper, No. 920705.
14.
Parish, S. E., and Evers, L. W., 1995, “Spray Characteristics of Compound Silicon Micro Machined Port Fuel Injector Orifices,” SAE Technical Paper, No. 950510.
15.
Saikalis, G., Byers, R., and Nogi, T., 1993, “Study on Air Assist Fuel Injector Atomization and Effects on Exhaust Emission Reduction,” SAE Technical Paper, No. 930323.
16.
Saito, A., Kawamura, K., Tani, Y., and Ogiwara, Y., 1993, “Analysis of Spray Characteristics of Heated Nozzle for Gasoline Injection (1st Report, Observation of Nozzle Inside and Spray Shape),” Proc. 2nd ILASS-Japan Symposium, pp. 157–162 [in Japanese].
17.
Takeda, K., and Sugimoto, T., 1992, “Development of 2-Hole Air-Assist Injector for 4-Valve Engines,” Proc. 1st ILASS-Japan Symposium, pp. 107–112 [in Japanese].
18.
Zhao, F.-Q., Lai, M.-C., and Harrington, D. L., 1995a, “The Spray Characteristics of Automotive Port Fuel Injection—A Critical Review,” SAE Technical Paper, No. 950506.
19.
Zhao, F.-Q., Amer, A. A., Lai, M.-C., and Dressier, J. L., 1995b, “Atomization Characteristics of Velocity-Modulated Port Injector Sprays in Gasoline Engines,” Proc. 8th Annual Conference on Liquid Atomization and Spray Systems, ILASS-America, May 21–24, Troy, MI.
20.
Zhao, F.-Q., Amer, A. A., Lai, M.-C., and Dressier, J. L., 1995c, “The Effect of Fuel-Line Pressure Perturbation on the Spray Atomization Characteristics of Automotive Port Fuel Injectors,” SAE Technical Paper, No. 952486.
21.
Zhao, F.-Q., Lai, M.-C., Amer, A. A., and Dressier, J. L., 1995d, “Atomization Characteristics of Pressure-Modulated Automotive Port Injector Sprays,” Atomization and Sprays, accepted for publication.
22.
Zhao, F.-Q., Yoo, J.-H., and Lai, M.-C., 1995e, “The Spray Characteristics of Dual-Stream Port Fuel Injectors for Applications to 4-Value Gasoline Engines,” SAE Technical Paper, No. 952487.
23.
Zhao, F.-Q., Yoo, J.-H., and Lai, M.-C., 1996, “Spray Targeting Inside a Production-Type Intake Port of a 4-Value Gasoline Engine,” SAE Technical Paper No. 960115.
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