Internal flow characteristics in scaled pressure-swirl atomizer

Ahmadi

2019

Teh. glas. (Online)

This paper focuses on the structure and performance of the pressure swirl nozzle and the study of liquid atomization. In this study, the atomizer has been designed and some experiments have been performed on it. Since image processing is an efficient method for measuring the size of the droplet and since it considerably reduces the total measuring time and eliminates the subjective observer’s error in sizing and counting spray drops, a digital camera has been used for capturing images and image processing has been done by the MATLAB software. The results show that by increasing the atomization air pressure, the spray angle increases and the droplet’s size decreases. It is concluded that the spray angle is a function of the atomization air pressure and orifice diameter. Moreover, when the distance from the spray centre line increases, the droplet’s average velocity decreases.

Section: Air Pressure Changes and Their Effect On The Pressurementioning

confidence: 81%

Section: Usage and Performance Of Pressure Swirl Nozzlementioning

confidence: 99%

Design and construction of the pressure swirl nozzle and experimental investigation of spray characteristics

Ahmadi

2019

Teh. glas. (Online)

Int. J. Eng. Tech. Mgmt. Res.

“…The hollow cone sheet disintegrates into ligaments and then forms droplets Lefebvre et al (2017), Rashad et al (2016), Cui et al (2017). Liu et al (2019) and Malý et al (2018) studied the motion of liquid in the pressure swirl atomizer and indicate that the flow mechanism inside and outside the atomizer is complex and not well understood. Amongst several causes, factors such as the operating condition, design, and size of the atomizer tested, complex atomization process, as well as limitations of drop measurement instrument and techniques are very key considerations.…”

Section: Introductionmentioning

confidence: 99%

Validation of Σ−yliq Atomization Model in Pressure Swirl Atomizer

Amedorme¹,

Roselina

2022

In many combustion and agricultural applications atomizers are used to increase the surface area of the liquid to ensure high rates of mixing and improve evaporation. The most common, simple, and reliable atomizer is the pressure swirl atomizer. This atomizer is said to have quality and effective atomization compared to others and induces swirling motion to the liquid and gives a hollow cone spray with air core as it emerges from the exit orifice. To enhance the understanding and prediction of the atomizing characteristics various atomization models are used and need to be investigated experimentally. This paper presents a validation of the Σ−Yliq atomization model of two-phase flow in a pressure swirl atomizer using commercial CFD star-cd code and laser-diffraction based drop measurements. To obtain the best results for the droplet mean diameter between the prediction and the experiment in terms of turbulence different k-e models were evaluated. The results show that the computational predictions of Sauter Mean Diameter (SMD) for the model have a good agreement with most of the experimental measurements in the radial positions when standard k-ɛ turbulence was used. However, more divergence was observed between the predictions and the experimental measurements when the RNG and Realizable k-ɛ turbulence models were used in the predictions. It was also observed that the model has good agreement with the mean droplet measurements on the spray centreline and radial axis with a percentage error of less than five percent.

“…Due to its importance in the industry, research studies on the atomization features of this kind of atomizer are varied. Experiments include high-speed imaging and the application of optical techniques such as Phase Doppler Anemometry (PDA) [6,7], Laser Doppler Anemometry (LDA) [8] or Mie-scattering [9]. These works reveal that the primary breakup takes place by the growth of disturbances on the liquid sheet that are generated by the external surrounding air as soon as the fuel leaves the atomizer.…”

Section: Introductionmentioning

confidence: 99%

Internal Numerical Simulation of a Swirl Simplex Atomizer to Predict Atomization Outputs

Ferrando

Belmar-Gil

Palanti

et al. 2021

ICLASS

Numerical simulation of injectors could help improving their designs. In particular, a two-phase flow simulation of a swirl simplex atomizer allows computing the main characteristic parameters such as the spray cone angle, the fuel sheet thickness and the air core diameter. This work describes an attempt to go a step further to characterize atomization and spray characteristics with the ultimate goal to predict the spray distribution in terms of size and velocity. A commercial injector has been used in the CORIA Rouen Spray Burner (CRSB) set up to study turbulent spray combustion. This experiment has produced a well-documented database for the last two TCS workshops (see TCS 6 and 7 at http://www.tcs-workshop.org/). Even though spray measurements are used to define the fuel injection in combustion numerical simulations, the spray injection characteristics remain the main cause of uncertainties. The present work aims at answering this question: Is it possible to complete our knowledge of spray injection by numerical simulation of the full atomization process? The first challenge is to measure the inner geometry. Standards techniques such as X-ray tomography and microscopy have been applied. In order to accurately reproduce the internal throat and swirl chamber, additional measurements have been performed by silicon molding, leading to the definition of a nominal geometry that can be used for further CFD simulation. The second challenge is to produce a mesh regular enough to be compatible with the interface capturing method. Several mesh strategies have been tested starting from the swirl chamber with very thin mesh layers to capture the liquid film at the injector wall and to describe the external liquid sheet. Then, a third challenge concerns the numerical simulation itself, since it must handle the multi-scale nature of such flows until the formation of the spray. A nonreactive condition has been tested with the interFoam solver (OpenFOAM library) in a Large Eddy Simulation (LES) framework. Eventually, the last challenge is to build an analysis to connect the numerical simulation that is limited to the close vicinity of the injector and the experimental measurements that are rejected farther downstream on the dispersed spray. This last step is based on the analysis of the surface curvature distribution that is described with more detail on another presentation at this ICLASS conference.