scholarly journals Effects of Upstream Component and Air Injection on Water Droplet Impingement Characteristics for Downstream Surfaces

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xiaobin Shen ◽  
Yundan Tan ◽  
Rendong Yu ◽  
Xiaochuan Liu ◽  
Guiping Lin ◽  
...  
Keyword(s):  
Water Droplet ◽  
Collection Efficiency ◽  
Droplet Diameter ◽  
Air Injection ◽  
Movement Direction ◽  
Aircraft Icing ◽  
Droplet Impingement ◽  
Hot Air ◽  
Present Collection ◽  
Aircraft Component

Water droplet changes its movement direction and velocity when it bypasses an aircraft component with the surrounding airflow or gets blown by air injection from the inner part. When the deflected droplet impacts on the downstream surface, its impingement characteristics would be different from those without the frontal effects. In this article, a Lagrangian method was developed to include those upstream effects on the droplet collection efficiency. Validation cases were carried out for a cylinder and an MS (1)-0317 airfoil, whereas a multielement airfoil and an engine cone with a hot air film-heating anti-icing system were computed to investigate the effects of the upstream component and air injection on the impingement characteristics of downstream surfaces. It is found that the present collection efficiencies are in good agreement with the experimental data and the simulation results obtained by the Eulerian and traditional Lagrangian methods when not affected by those upstream factors. The droplet deflections and trajectory crossings are observed clearly under the influence of the upstream component, and the Lagrangian results of downstream surfaces differ from those of the Eulerian method. In addition, due to the air injection from the inner engine cone, the peak collection efficiency on the cone surface increases with the decrease of the droplet diameter and the value even exceeds one when the droplet is small. This work is helpful for the understanding of the droplet motion and the accuracy of aircraft icing simulation.

Analysis of Droplet Impingement Characteristics of Aero-Engine Nose Cone With Hot Air Film

2016 ◽  
Author(s):  
Huiyun Yang ◽  
Peng Ke ◽  
Chunxin Yang
Keyword(s):  
Droplet Diameter ◽  
Simulation Methods ◽  
Droplet Impingement ◽  
Blowing Ratio ◽  
Hot Air ◽  
Impingement Heat Transfer ◽  
Aero Engine ◽  
Nose Cone ◽  
Numerical Simulation Methods ◽  
Air Film

A new nose cone ice protection configuration with hot air film slot was investigated, where the surface need to be protected could be heated with interior impingement heat transfer and exterior hot air film. Numerical simulation methods using computational fluid dynamics code were developed and validated to find the effects of the jetted air film on the droplet impingement characteristics. Combination of two-dimensional axisymmetric algorithm and Lagrangian method were adopted to solve the air flow field and the droplet trajectories. The simulation methods were validated with the results from the experimental data. The droplet impingement characteristics on two structures were investigated respectively, the intact cone without film slot and the slotted cone. Results show that the surface local collection coefficient changes significantly behind the film slot because of the blowing effect of the air film on the incoming droplets, and the variation of the local collection coefficient is very dependent on the droplet diameter for a given blowing ratio, or the blowing ratio for a given droplet size. Some different effects, such as “fully blowing-off”, “blowing behind” and “limited blowing-off”, may happen for different combination of droplets size and blowing ratio. Compared with the cone without film slot, the blowing effect is more significant for smaller droplets or higher blowing ratio. Besides that, the total collection coefficient maybe only half of those without film for some conditions.

The Effect of Using Ramps with Trench Cylindrical Holes on Film Cooling Effectiveness

2015 ◽  
Vol 3 (2) ◽  
pp. 15-27
Author(s):  
Ahmed A. Imram ◽  
Humam K. Jalghef ◽  
Falah F. Hatem
Keyword(s):  
Numerical Simulation ◽  
Film Cooling ◽  
Air Injection ◽  
Baseline Model ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Hot Air ◽  
Test Study ◽  
Cylindrical Holes

     The effect of introducing ramp with a cylindrical slot hole on the film cooling effectiveness has been investigated experimentally and numerically. The film cooling effectiveness measurements are obtained experimentally. A test study was performed at a single mainstream with Reynolds number 76600 at three different coolant to mainstream blowing ratios 1.5, 2, and 3. Numerical simulation is introduced to primarily estimate the best ramp configurations and to predict the behavior of the transport phenomena in the region linked closely to the interaction between the coolant air injection and the hot air mainstram flow. The results showed that using ramps with trench cylindrical holes would enhanced the overall film cooling effectiveness by 83.33% compared with baseline model at blowing ratio of 1.5, also  the best overall flim cooling effectevness was obtained at blowing ratio of 2 while it is reduced at blowing ratio of 3.

Influence of Water Droplet Size and Temperature on Wet Compression

2007 ◽  
Author(s):  
M. Bianchi ◽  
F. Melino ◽  
A. Peretto ◽  
P. R. Spina ◽  
S. Ingistov
Keyword(s):  
Gas Turbine ◽  
Water Droplet ◽  
Droplet Diameter ◽  
Axial Compressor ◽  
Combined Cycle ◽  
Water Evaporation ◽  
Air Cooling ◽  
Compression Process ◽  
Two Phase ◽  
Wet Compression

In the last years, among all different gas turbine inlet air cooling techniques, an increasing attention to fogging approach is dedicated. The various fogging strategies seem to be a good solution to improve gas turbine or combined cycle produced power with low initial investment cost and less installation downtime. In particular, overspray fogging and interstage injection involve two-phase flow consideration and water evaporation during compression process (also known as wet compression). According to the Author’s knowledge, the field of wet compression is not completely studied and understood. In the present paper, all the principal aspects of wet compression and in particular the influence of injected water droplet diameter and surface temperature, and their effect on gas turbine performance and on the behavior of the axial compressor (change in axial compressor performance map due to the water injection, redistribution of stage load, etc.) are analyzed by using a calculation code, named IN.FO.G.T.E. (INterstage FOgging Gas Turbine Evaluation), developed and validated by the Authors.

Water droplet impingement on airfoils and aircraft engine inlets foricing analysis

1991 ◽  
Vol 28 (3) ◽  
pp. 165-174 ◽  
Author(s):  
Michael Papadakis ◽  
R. Elangovan ◽  
George A. Freund ◽  
Marlin D. Breer
Keyword(s):  
Water Droplet ◽  
Aircraft Engine ◽  
Droplet Impingement

scholarly journals Icing Measurements on Fixed and Rotating Cylinders

1983 ◽  
Vol 4 ◽  
pp. 174-179
Author(s):  
P. McComber ◽  
J.-L. Laforte ◽  
D. Bouchard ◽  
D. D. Nguyen
Keyword(s):  
Transmission Lines ◽  
Liquid Water ◽  
Collection Efficiency ◽  
Droplet Diameter ◽  
Ice Accretion ◽  
Rotating Cylinders ◽  
Wind Velocities ◽  
Method Of Measurement ◽  
Temperature Constant ◽  
Water Contents

There is at present a need to develop a better technique for measuring the rate of icing on structures such as, for example, overhead transmission lines. For aircraft and helicopter icing, the most widely used method of measurement is the rotating cylinder. However, for measuring the icing of structures, this method is difficult to apply and also less accurate due to lower wind velocities. Different approaches are now being developed using fixed cylinders.Icing tests were conducted with fixed and rotating cylinders in a wind tunnel. The rate of icing was obtained through measurements of volume, accretion cross-section and time of deposition. Tests were made using five different liquid water contents and droplet diameter spectra, and four cylinder diameters, keeping the wind velocity and temperature constant. The rate of icing is presented as a function of the diameters of the fixed and rotating cylinders for each of the liquid water contents tested. Results indicate that at lower wind velocities the accretion rate is overestimated for the smaller rotating cylinders. This difference is probably due to the variation of the collection efficiency with diameter. From these results it is suggested that the rate of ice accretion on structures should be based on at least two fixed cylinders of different small sizes in order to take into account the effect of the collection efficiency.

The Evaporation of Water Droplets in Superheated Steam

1968 ◽  
Vol 90 (4) ◽  
pp. 445-451 ◽  
Author(s):  
Kwan Lee ◽  
D. J. Ryley
Keyword(s):  
Reynolds Number ◽  
Glass Fiber ◽  
Water Droplet ◽  
Superheated Steam ◽  
Droplet Diameter ◽  
Steam Pressure ◽  
Water Droplets ◽  
Heating Up ◽  
Correlating Equation

The evaporation of a water droplet, diameter 230-1130μ, suspended on a 50μ diameter glass fiber was measured optically for the following range of variables: droplet Reynolds number 64-250, superheated steam pressure 14.7–29 psia, degrees of superheat 5–61 deg F; velocity 9–39 fps. The correlating equation was found to be Nu¯=2+0.74Re0.5Pr0.33 The apparatus and technique were proven using air as the evaporating medium. Calculations were made of the heating-up period at the beginning, and the drop asphericity at the end of a given test.

A Eulerian Method for Water Droplet Impingement by Means of an Immersed Boundary Technique

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Francesco Capizzano ◽  
Emiliano Iuliano
Keyword(s):  
Water Droplet ◽  
Numerical Solutions ◽  
Experimental Testing ◽  
Three Dimensional ◽  
Immersed Boundary ◽  
Test Cases ◽  
Ice Accretion ◽  
Droplet Impingement ◽  
Protection Systems ◽  
Numerical Approaches

The estimation of water droplet impingement is the first step toward a complete ice accretion assessment. Numerical approaches are usually implied to support the experimental testing and to provide fast responses when designing ice protection systems. Basically, two different numerical methodologies can be found in literature: Lagrangian and Eulerian. The present paper describes the design and development of a tool based on a Eulerian equation set solved on Cartesian meshes by using an immersed boundary (IB) technique. The tool aims at computing the evolution of a droplet cloud and the impingement characteristics onto the exposed surfaces of an aircraft. The robustness of the methodology and the accuracy of the approach are discussed. The method is applying to classical two- and three-dimensional test cases for which experimental data are available in literature. The results are compared with both experiments and body-fitted numerical solutions.

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