In this study we examined numerically the electrostatic spray transfer processes in the rotary bell spray applicator, which is this case implemented in a full 3D representation. The algorithm implemented and developed for this simulation includes airflow, spray dynamics, tracking of paint droplets and an electrostatic modularized solver to present atomization and in-flight spray phenomena for the spray forming procedure. The algorithm is implemented using the OpenFOAM package. The shaping airflow is simulated via an unsteady 3D compressible Navier-Stokes method. Solver for particle trajectory was developed to illustrate the process of spray transport and also the interaction of airflow and particle that is solved by momentum coupling. As the numerical results in this paper indicates dominant operating parameter voltage setting, further the charge to mass ratio and air-paint flow rate deeply effect the spray shape and the transfer efficiency (TE). The spin of the bell forced the paint to fall off from the bell edge into the high-velocity airflow. By increasing the shaping airflow more uniform distribution of mass of paint is produced but the…

This SAE Aerospace Recommended Practice (ARP) describes the etching of fluoropolymer electrical wire insulations to ensure that all facets of the process from the chemistry to the processing, to the storage and handling are well defined.

Ice accretion can cause numerous inefficiencies, structural stresses, and failures in applications ranging from building design to power generation and aerospace applications. Currently, some of the leading de-icing technologies, such as the ICE-WIPS system, utilize a heating element coupled with a superhydrophobic surface. The high power consumption inherent in these systems can make them expensive and impractical, especially when coupled with power generating systems. Reduced power consumption in these de-icing technologies can be achieved through increased absorption of solar radiation in the visible range while maintaining hydrophobic performance of a coating. In this work, a Polytetrafluorethylene (PTFE) and graphite-based superhydrophobic surface is proposed, which maintains similar hydrophobic performance to standard superhydrophobic surfaces. The novel coating demonstrates contact angles of upwards of 130o and sliding angles of less than 4o, while increasing solar radiation absorption in the visible range by approximately 139% over PTFE-based hydrophobic coatings. Icing wind tunnel tests where the coatings were exposed to visible light in order to simulate solar radiation were performed in a variety of different conditions in order to verify…

Structures in cold weather environments are susceptible to atmospheric ice formation. A fracture mechanics based approach is proposed for in situ characterization of the interfacial fracture energy of ice on different substrates. This paper summarizes the development of the experimental and analytical framework to measure the ice adhesion energy, calibrated on static ice. The testing configuration utilizes a shaft-loaded blister test to produce stable crack propagation, from a well-defined pre-crack at the interface of the ice layer and the substrate. Measurements of the fracture energy are taken over a range of ice thicknesses and surface roughnesses. The developed analytical framework to estimate adhesion energy are verified and calibrated via finite element numerical simulation of the proposed geometric configuration and employing cohesive surfaces along the interface to simulate the crack nucleation and propagation process. Several different phenomena were observed include the transition from adhesive to cohesive fracture. The measured interfacial adhesion energy was almost independent of the surface roughness in the range of examined roughness. The measured interfacial R-curve showed a steady state plateau for range…

Icing is a major safety issue for flight operations in the civil, defense and space sectors. Ice can form on critical components during takeoff/landing, or while in service, depending on prevailing weather conditions. Aircraft manufacturers relies on two different approaches to prevent ice buildup using an active anti-icing system to melt ice buildup or deicing chemicals/ice repellent surface to minimize the buildup ice. The use of active anti-icing systems offers good protection, however can add significant penalty to overall weight, energy consumption and cost. Aerospace industry is in need for an advanced ice repellent surface to effectively minimize ice buildup on critical components with no modification to existing design can provide significant relief to ice prone systems. In this paper, Oceanit will present its most advanced nanocomposite low ice adhesion icephobic coating technology that was developed and demonstrated for application on metallic surfaces to provide the lowest ice adhesion to significantly reduce ice buildup. Oceanit’s advanced icephobic coating was tested to be one of the lowest ice adhering coating (ice adhesion strength = 5.1kPa) ever…

An explorative study was performed to demonstrate the feasibility of using a novel hybrid anti-/de-icing strategy for aircraft icing mitigation. The hybrid method was developed by combining the electro-thermal heating mechanism and specialized surfaces/coatings with different wettabilities. While an electrical film heater was utilized to provide thermal energy around the leading edge of a NACA0012 airfoil model, two different coating strategies, (i.e., (a). Superhydrophobic coating covering the entire airfoil surface to increase droplets bounce-off and accelerate surface water runback vs. (b). super-hydrophilic coating at the leading edge to increase evaporation area + superhydrophobic coating in downstream to prevent runback refreezing) were proposed and evaluated aiming at maximizing the anti-/de-icing efficiency of the hybrid method. While a series of experiments were conducted to examine the dynamics of droplet impinging onto the different surfaces (i.e., superhydrophobic vs. super-hydrophilic), a comprehensive experimental study was carried out in the Icing Research Tunnel at Iowa State University (i.e., ISU-IRT) to evaluate the anti-/de-icing performance of the hybrid method with the different coating strategies. It was found that, while both of…

Elastic soft material/surface, such as Polydimethylsiloxane (PDMS), is a perspective, useful and low-cost hydrophobic and icephobic coating. While it has been reported to have good mechanical durability, its erosion durability under the high impacting of water droplets pertinent to aircraft inflight icing phenomena has not been explored. In this study, the droplet imping erosion characteristics of an icephobic PDMS surface/material is evaluated systematically upon the dynamic impinging of water droplets at different impact velocities (~ up to 75m/s), in comparison with other state-of-the-art icephobic materials/surfaces, such as superhydrophobic surface (SHS) and slippery liquid-infused porous surface (SLIPS). Surprisingly, the contact angle (CA) of the elastic PDMS is shown to have an over 20° increase (from 105° to 128°), which represents better hydrophobicity, after the erosion test which is mainly contributed to the higher roughness of the eroded PDMS surface. As for the icephobicity evaluation, intact PDMS was found to has ultra-low ice adhesion (~8 kPa), in comparison with SHS (i.e., ~100kPa) and SLIPS (i.e., ~35kPa). PDMS also shows outstandingly stable ice adhesion during the erosion test…