# Research on Performance Prediction Model of Impeller-Type Breather
## 1 Introduction
The radial turbulent intensity distribution in the ventilation duct can avoid splashes of oil droplets and greatly improve the separation efficiency. In 2012, [PERSON] et al. [9] used the Euler-Lagrange equation to conduct numerical simulation of the flow field in the cavity of a certain type of aeroengine impeller breather, and obtained the influence of oil-gas ratio, rotational speed, and air flow on the minimum separation diameter, separation efficiency, and pressure drop. In 2013, [PERSON] et al. [10] used the RSM model and the DPM model to simulate the two-phase flow field in a centrifugal breather. The effects of different rotational speeds and ventilation rates on oil droplet distribution and breather separation characteristics were analyzed. In 2014, [PERSON] et al. [11] took the centrifugal breather as the research object and used numerical simulation to study the influence of the eccentric distance of the vent hole and the addendum circle radius on separation efficiency. It was concluded that the separation efficiency could be improved by increasing the addendum circle radius and the eccentric distance of the vent hole. In 2014, [PERSON] et al. [12] used the DPM model and the EWF (Eulerian Wall Film Model) model to predict the interaction between droplets and the wall and the atomization of liquid film. Molecular models including splash, peeling, and separation made the simulation of liquid film more accurate. The accuracy of the coupling method was verified by experiments. In 2015, [PERSON] et al. [13] studied the influence of inlet velocity on the axial velocity, tangential velocity, pressure of the breather, and the size distribution of oil droplets at the outlet, through numerical simulation. In 2015, [PERSON] [14] and others used experimental methods to study the impact of low viscosity fluid on an aluminum surface. This low viscosity fluid is suitable for the automobile, aerospace, and other fields. An empirical model of the maximum spreading diameter of droplets was obtained. The accuracy of this model was 5%. In 2016, [PERSON] et al. [15] used the Euler-Lagrange equation to simulate the two-phase flow field of an ultra-high speed centrifugal breather. The results showed that the separation efficiency can be improved by optimizing the structure of the rotating hallow shaft at ultra-high speed. In 2016, [PERSON] et al. [16] used VOF (Volume of Fluid) and a liquid-solid wetting model to study the impact of droplets with different sizes on the dry wall. It was found that the properties of droplets at the micron level would have a stronger impact on the diffusion process of droplets after impact than droplets at the millimeter level, and the critical parameter of droplet splash at the micron level was K = 122. In 2017, [PERSON] et al. [17] proposed a new model based on the experiment of droplet impact on the dry wall and droplet morphology dynamics. The model considered the wall conditions, summarized and analyzed various splash modes, and was verified under different conditions. At present, the research methods of breather performance are mostly experiments and numerical simulation. Experiments are often limited by the amount of specimen processing, flow field control, and measurements. Numerical simulation is mainly to explore the influence of the working condition and main structural parameters on the performance of the breather. Many factors can affect the performance of the breather. When evaluating the significance of factors and the optimal level, a performance prediction model for a breather is established in consideration of multiple factors, which has practical significance for the engineering design and optimization of the breather. This paper verifies the accuracy of the numerical simulation method by comparison with the experimental data. The impeller breather is numerically studied by means of orthogonal experimental design. The significance and optimal level of different influencing factors are determined by range analysis.