| Atomizing nozzles are key equipment in aeroengine. Atomization performance directly affects the flight power output of aircraft engines. In this study, the working mechanism of the nozzle is atomized the ethanol fuel and make ethanol droplet fully contact with air. Getting suitable oil mist density to improve combustion efficiency. Using numerical simulation method to get the spray characteristics including the atomization cone angle, the size distribution of discrete droplet, the Sauter mean diameter, the pressure and velocity distribution, etc. These can provide an important basis for improving the design of the burner nozzle.Establishing the three-dimensional structure model for ethanol atomizing nozzle and determining the single-phase simulation model for ethanol and air flow. Outer atomizing field was simulated with the Wave breaking model and the Euler- Lagrange two-phase flow model. The establishment of these two models were based on the inter nozzle flow field simulation results.Comprehensively analyzing the spray index including the atomization cone angle, the size distribution of discrete droplet, the Sauter mean diameter and optimizing the nozzle structural parameters. Then got five optimal structure parameters of the two channel air-atomizing nozzle(L1=55mm,L=20mm,n=4,d1=10mm,θ=0) and seven optimal structure parameters of the three channel air-atomizing nozzle(L=20mm,L1=65mm,D=16mm,d1=8mm,n=5,θ=15,D1=30mm). Study shows that the mixing section length L, airflow incidence angle θ, air nozzle diameter d1 have great influence on the atomization effect for the two channel air-atomizing nozzle. The mixing section length L has little effect on the velocity near nozzle outlet, but has a great influence on the internal flow field. The effects of air nozzle diameter d1 and airflow incidence angle θ on the air velocity at the nozzle outlet is larger. The influence of air nozzle number n and gas flow duct length L1 on the atomization effect is relatively small. And for the three channel air-atomizing nozzle, the inside air flow duct diameter D and mixing section length L on the atomization effect is larger and other parameters’ influence on the atomization effect is small. The mixing section length has a great influence on the internal flow field, and the effect of inside air flow duct diameter D on the air velocity at the nozzle outlet is larger. Compare the atomization characteristics of both types of nozzles, I find that the mixing length has the greatest influence on atomization effect and airflow axial velocity effects slightly smaller. Three channel air-atomizing nozzle has better performance than the two channel air-atomizing nozzle. Because the three channel air-atomizing nozzle has an annular airflow entrance on the outer wall. And the annular airflow has secondary refinement on the primary particles stream. Then I studied the influence of injection parameters on jet crushing and mixing effect with the optimal nozzle.Study shows that when the gas-liquid mass ratio is increased or increase the air injection pressure, the impact of air flow on ethanol droplets will be greatly enhanced(particle SMD decreases significantly). If increasing the environment pressure alone or increasing the environmental pressure with the environmental pressure and injection pressure difference ?p unchanged, the atomization effect will be weakened(particle SMD increase rapidly). Once the nozzle geometry is fixed, the impact of changes of injection parameters on atomized spray cone angle will be small. The particle diameter distribution in spray field generally decreases along jet injection direction and fluctuations. The particle diameter is larger near the center of the jet, but particle diameter is small on the jet edge due to the strong impact. |
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