A Numerical Study of the Internal Flow in a Pressure Swirl Atomizer

Journal of Propulsion and Power

Jícha

et al. 2021

An experimental investigation into small pressure-swirl spill-return atomizers was made to determine the effect of the entry port number, swirl-chamber shape, spill-line design, and the manufacturing precision on the spray quality and stability. The atomizers were studied using phase-Doppler anemometry, high-speed visualization, and mechanical patternation. Jet A-1 fuel was sprayed at inlet pressures of 0.5, 1.0, and 1.5 MPa and for spill-to-feed ratios of 0, 0.4, and 0.8. The chamber shape influenced the spray characteristics of the simplex atomizers only moderately with no systematic effect of conical chambers to the others. The spray was found to be circumferentially heterogeneous; its uniformity improved with increase in the pressure, while the effect of swirling port number was negligible. Atomizers with axial spill orifice demonstrated strong spray pulsations at a spill-to-feed ratio of zero. A periodic decay of the air core was identified as a possible reason for the pulsations. Atomizers with off-axis spill orifices always produced a stable spray. Atomizers with tangential inlet ports provided a finer spray than those with helical ports. Manufacturing precision, axial symmetry, and matching of the surfaces of connected parts were found important for the spray symmetry and homogeneity.

Section: B Test Benchmentioning

confidence: 99%

“…Cooper et al [10] have shown that differently shaped swirl-chamber geometries lead to different internal flow patterns. Xue et al [11] and Qian et al [12] numerically studied the effect of the convergence angle of the conical swirl chamber on both the discharge coefficient and SCA. However, they did not study the effect on the spray.…”

mentioning

confidence: 99%

Importance of Geometrical Factors on Spray Characteristics of Spill-Return Atomizers

Jedelský

Journal of Propulsion and Power

Jícha

et al. 2021

“…They also noted that the flow field was consistent for LES and k-ε model, while, surprisingly, the RSM had some discrepancies. Qian [9] found RSM to be superior over the laminar model at Re = 16,000, while Nouri-Borujerdi [10] found opposite conclusions for even larger Re in range of 18,000-40,000. Baharanchi et al [11] examined several schemes to capture the liquid-air interface using a 2D simulation with RNG k-ε turbulence model.…”

Section: Introductionmentioning

confidence: 97%

Comparison of numerical models for prediction of pressure-swirl atomizer internal flow

Slama²,

Cejpek

et al. 2021

ICLASS

Numerical prediction of discharge parameters allows to design a pressure-swirl atomizer in fast and cheap manner, yet it must provide reliable results for a wide range of geometries and operating regimes. Many authors used different numerical setups for similar cases and often concluded opposite suggestions on numerical setup. This paper compares 3D (threedimensional) periodic numerical models used for estimation of the internal flow characteristics of a pressure-swirl atomizer. The computed results are compared with experimental data in terms of spray cone angle, discharge coefficient (C D ), internal air-core dimensions, and velocity profiles. The internal air-core was visualized by high-speed camera with backlit illumination. Tested conditions covered wide range of the Reynolds numbers within the inlet ports, Re = 1000, 2000, 4000. The flow was treated as both steady and transient flow. The numerical solver used laminar and several turbulence models, represented by k-ε and k-ω models, Reynolds Stress model (RSM) and Large Eddy Simulation (LES). The laminar solver was capable to closely predict the C D , air-core dimensions and velocity profiles compared with the experimental results. The LES performed similarly to the laminar solver for low Re and was slightly superior for Re = 4000. The two-equation models were sensitive to proper solving of the near wall flow and were not accurate for low Re. Surprisingly, the RSM produced worst results.

“…The internal vortex behaves as a Rankine vortex since the swirl velocity has its maximum located at the air-core surface which behaves like a virtual solid cylinder [1]. Secondary flow effects, as Görtler vortices, could be also presented in a boundary layer inside the swirl chamber [2,3].…”

Section: Introductionmentioning

confidence: 99%

Searching for a Numerical Model for Prediction of Pressure-Swirl Atomizer Internal Flow

Slama²,

Cejpek

et al. 2022

Applied Sciences

Numerical prediction of discharge parameters allows design of a pressure-swirl atomizer in a fast and cheap manner, yet it must provide reliable results for a wide range of geometries and operating regimes. Many authors have used different numerical setups for similar cases and often concluded opposite suggestions on numerical setup. This paper compares 2D (two-dimensional) axisymmetric, 3D (three-dimensional) periodic and full 3D numerical models used for estimation of the internal flow characteristics of a pressure-swirl atomizer. The computed results are compared with experimental data in terms of spray cone angle, discharge coefficient (CD), internal air-core dimensions, and velocity profiles. The three-component velocity was experimentally measured using a Laser Doppler Anemometry in a scaled transparent model of the atomizer. The internal air-core was visualized by a high-speed camera with backlit illumination. Tested conditions covered a wide range of the Reynolds numbers within the inlet ports, Re = 1000, 2000, 4000. The flow was treated as both steady and transient flow. The numerical solver used laminar and several turbulence models, represented by k-ε and k-ω models, Reynolds Stress model (RSM) and Large Eddy Simulation (LES). The laminar solver was capable of closely predicting the CD, air-core dimensions and velocity profiles compared with the experimental results in both 2D and 3D simulations. The LES performed similarly to the laminar solver for low Re and was slightly superior for Re = 4000. The two-equation models were sensitive to proper solving of the near wall flow and were not accurate for low Re. Surprisingly, the RSM produced the worst results.