The Droplet Deformation and Breakup Model was used to predict deformation of droplets approaching the leading edge stagnation line of an airfoil. The quasi-steady model was solved for each position along the droplet path. A program was developed to solve the non-linear, second order, ordinary differential equation that governs the model. A fourth order Runge-Kutta method was used to solve the equation. Experimental slip velocities from droplet breakup studies were used as input to the model which required slip velocity along the particle path. The center of mass displacement predictions were compared to the experimental measurements from the droplet breakup studies for droplets with radii in the range of 200 to 700 mm approaching the airfoil at 50 and 90 m/sec. The model predictions were good for the displacement of the center of mass for small and medium sized droplets. For larger droplets the model predictions did not agree with the experimental results. Vargas, Mario Glenn Research Center WBS 648987.02.02.03.10

The Droplet Deformation and Breakup Model was used to predict deformation of droplets approaching the leading edge stagnation line of an airfoil. The quasi-steady model was solved for each position along the droplet path. A program was developed to solve the non-linear, second order, ordinary differential equation that governs the model. A fourth order Runge-Kutta method was used to solve the equation. Experimental slip velocities from droplet breakup studies were used as input to the model which required slip velocity along the particle path. The center of mass displacement predictions were compared to the experimental measurements from the droplet breakup studies for droplets with radii in the range of 200 to 700 mm approaching the airfoil at 50 and 90 m/sec. The model predictions were good for the displacement of the center of mass for small and medium sized droplets. For larger droplets the model predictions did not agree with the experimental results.

The Droplet Deformation and Breakup Model was used to predict deformation of droplets approaching the leading edge stagnation line of an airfoil. The quasi-steady model was solved for each position along the droplet path. A program was developed to solve the non-linear, second order, ordinary differential equation that governs the model. A fourth order Runge-Kutta method was used to solve the equation. Experimental slip velocities from droplet breakup studies were used as input to the model which required slip velocity along the particle path. The center of mass displacement predictions were compared to the experimental measurements from the droplet breakup studies for droplets with radii in the range of 200 to 700 mm approaching the airfoil at 50 and 90 m/sec. The model predictions were good for the displacement of the center of mass for small and medium sized droplets. For larger droplets the model predictions did not agree with the experimental results.

The field of multiphase flows has grown by leaps and bounds in the last thirty years and is now regarded as a major discipline. Engineering applications, products and processes with particles, bubbles and drops have consistently grown in number and importance. An increasing number of conferences, scientific fora and archived journals are dedicated to the dissemination of information on flow, heat and mass transfer of fluids with particles, bubbles and drops. Numerical computations and "thought experiments" have supplemented most physical experiments and a great deal of the product design and testing processes. The literature on computational fluid dynamics with particles, bubbles and drops has grown at an exponential rate, giving rise to new results, theories and better understanding of the transport processes with particles, bubbles and drops. This book captures and summarizes all these advances in a unified, succinct and pedagogical way. Contents: Fundamental Equations and Characteristics of Particles, Bubbles and Drops; Low Reynolds Number Flows; High Reynolds Number Flows; Non-Spherical Particles, Bubbles and Drops; Effects of Rotation, Shear and Boundaries; Effects of Turbulence; Electro-Kinetic, Thermo-Kinetic and Porosity Effects; Effects of Higher Concentration and Collisions; Molecular and Statistical Modeling; Numerical Methods-CFD. Key Features Summarizes the recent important results in the theory of transport processes of fluids with particles, bubbles and drops Presents the results in a unified and succinct way Contains more than 600 references where an interested reader may find details of the results Makes connections from all theories and results to physical and engineering applications Readership: Researchers, practicing engineers and physicists that deal with any aspects of Multiphase Flows. It will also be of interest to academics and researchers in the general fields of mechanical and chemical engineering.

Ice accretion is an issue that has affected aircraft since the early years of powered ight. Although it was a known problem, the full extent was not known. Both small and large droplets were of concern. The effects of both were countered with ice protection systems based initially on computer codes that predict the size, shape, and location of ice on aerodynamic surfaces for small droplets. The codes have been tested and validated for the conditions described in Federal Aviation Regulation Part 25 Appendix C (small droplets, up to 50 m) and aircraft only had to be certied for those conditions. Supercooled large droplets (SLD) reach locations further aft on the surfaces than small droplets making the ice protection systems insufficient in SLD icing conditions. The protection systems remove ice but do not reach the limits of the SLD ice and ridges remain on the wing surfaces which continue to negatively impact the performance of the aircraft. Certication regulations regarding SLD have been implemented but the codes do not yet accurately predict ice accretion due to SLD. To validate the codes, experimental data on the behavior of larger droplets when impacting a lifting surface are necessary. The results of an experimental study on the deformation and breakup of supercooled droplets near the leading edge of an airfoil are presented. The experiment was conducted in the Adverse Environment Rotor Test Stand (AERTS) facility at The Pennsylvania State University with the intention of comparing the results to prior room temperature droplet deformation results. To collect the data, an airfoil model was placed on the tip of a rotor blade mounted onto the hub in the AERTS chamber. The model was moved at speeds between 50 and 80 m/s while a monosize droplet generator produced droplets of various sizes which fell from above, perpendicular to the path of the model. The temperature in the chamber was set to -20C. The supercooled droplets were produced by maintaining the temperature of the water at the droplet generator under 5C.The supercooled state of the droplets was determined by measurement of the temperature of the droplets at various distances below the tip of the droplet generator. A prediction code was also used to estimate the temperature of the droplets based on the size, vertical velocity, initial temperature, and distance traveled by the droplets. The droplets reached temperatures between -5 and 0C. The deformation and breakup events were observed using a high-speed imaging system. A tracking software program processed the images captured and provided droplet deformation information along the path of the droplet as it approached the airfoil stagnation line. It was demonstrated that to compare the effects of water supercooling on droplet deformation, the slip velocity and the initial droplet velocity must be the same in the cases being compared. A case with a slip velocity of 40 m/s and an initial droplet velocity of 60 m/s was selected from both room temperature and supercooled droplet tests. In these cases, the deformation of the weakly supercooled and warm droplets did not present different trends when tested in room temperature and mild supercooling environments. The similar behavior for both environmental conditions indicates that water supercooling has no effect on particle deformation for the limited range of the weak supercooling of the droplets tested and the selected impact velocity.