"For a complete appraisal of the problem of ice prevention on aircraft, further water-droplet impingement data are needed" 1
Figure 5 of NACA-TN-1397
Water Drop Impingement on Surfaces Thread
Summary
Water-drop impingement quantification is key to aircraft ice protection design.
Introduction
Part of designing for aircraft icing is determining how much ice the airplane can accumulate. For ice protection systems, determining how much water that might freeze hits a surface is a key detail.
An important effect is that the airflow around a surface such as a wing airfoil deflects water-drops, so that all of the water-drops in the frontal area view will not hit the surface.
Water-drop impingement quantification methods were developed to assess how many drops can hit where on a surface. Direct test methods involved the use of blotter paper to absorb water drops on a surface. Mathematical analysis of the paths individual water drops were developed. However, any method was involved and resource intensive. So, extensive libraries of water-drop impingement data for several airfoils and conditions were collected into design manuals.
Other surfaces (non-airfoils) were also included (more than half of the publications in this category), as noted in the rest of the quote from above:
"As part of a comprehensive research program concerning the problem
of ice prevention on aircraft, an investigation of the impingement of
cloud droplets on airfoils, aerodynamic bodies, and other aircraft
components has been undertaken by the NACA Lewis laboratory. The
investigation includes a study of cloud-droplet impingement on low-drag airfoils
(refs. 1 to 3) and on cylinders (refs. 4 and 5). Previous investigators
have calculated the water-droplet trajectories for cylinders (refs. 6 to 9)
and for Joukowski airfoils (refs. 10 and 11).
For a complete appraisal of the problem of ice prevention on aircraft,
further water-droplet impingement data are needed for aircraft components,
including the curved sections or elbows in air-intake ducts."
1
The importance of this "investigation of the impingement" is shown by noting that of the 17 categories identified in The Historical Selected Bibliography of NACA-NASA Icing Publications.md, the largest category is "Impingement of Cloud Droplets" with 25 publications (out of 132 total publications).
There were also important additional publications included below.
Discussion
We have extensively reviewed the impingement of water drops in the Icing on Cylinders thread, so that will not be repeated here. However, we are never far from cylinders in the NACA-era, so they will come up in some publications here.
Reviews
Methods of Water Drop Impingement Quantification
"One of the first essentials ... is a method for estimating or calculating the area over which water will strike the wing, and the distribution of water impingement over that area."
Bodies of revolution
"The presence of radomes and instruments that are sensitive to water films or ice formations in the nose section of all-weather aircraft and missiles necessitates a knowledge of the droplet impingement characteristics of bodies of revolution."
- Dorsch, Robert G., Brun, Rinaldo J., and Gregg, John L.: Impingement of Water Droplets on an Ellipsoid with Fineness Ratio 5 in Axisymmetric Flow. NACA-TN-3099, 1954.
- Brun, Rinaldo J., and Dorsch, Robert G.: Impingement of Water Droplets on an Ellipsoid with Fineness Ratio 10 in Axisymmetric Flow. NACA-TN-3147, 1954.
- Dorsch, Robert G., Saper, Paul G., and Kadow, Charles F.: Impingement of Water Droplets on a Sphere. NACA-TN-3587, 1955.
- Lewis, James P., and Ruggeri, Robert S.: Experimental Droplet Impingement on Four Bodies of Revolution. NACA-TN-4092, 1957.
Shadow zones and concentration zones
"... local concentration factors should be considered when choosing the location of devices that protrude into the stream from aircraft fuselages or missiles, or when determining anti-icing heat requirements for the protection of these devices."
- Lewis, William, Kline, Dwight B., and Steinmetz, Charles P.: A Further Investigation of the Meteorological Conditions Conducive to Aircraft Icing. NACA-TN-1424, 1947.
> previous review: NACA-TN-1424 - Dorsch, Robert G., and Brun, Rinaldo J.: Variation of Local Liquid-Water Concentration about an Ellipsoid of Fineness Ratio 5 Moving in a Droplet Field. NACA-TN-3153, 1954.
- Brun, Rinaldo J., and Dorsch, Robert G.: Variation of Local Liquid-Water Concentration about an Ellipsoid of Fineness Ratio 10 Moving in a Droplet Field. NACA-TN-3410, 1955.
Impingement in Engine Inlets
"In spite of the simplicity, the configurations are reasonable approximation of those found on aircraft"
- Brun, Rinaldo J.: Cloud-Droplet Ingestion in Engine Inlets with Inlet Velocity Ratios of 1_0 and 0_7. NACA-TR-1317 (supersedes NACA-TN-3593), 1956.
- Gelder, Thomas F.: Droplet Impingement and Ingestion by Supersonic Nose Inlet in Subsonic Tunnel Conditions. NACA-TN-4268, 1958.
Impingement in Elbows and Ducts.md
"Icing of air-intake ducts and scoops with subsequent reduction in pressure recovery and in air flow may adversely affect the operation of the aircraft."
- Hacker, Paul T., Brun, Rinaldo J., and Boyd, Bemrose: Impingement of Droplets in 90° Elbows with Potential Flow. NACA-TN-2999, 1953.
- Hacker, Paul T., Saper, Paul G., and Kadow, Charles F.: Impingement of Droplets in 60° Elbows with Potential Flow. NACA-TN-3770, 1956.
Airfoils
- Bergrun, Norman R.: A Method for Numerically Calculating the Area and Distribution of Water Impingement on the Leading Edge of an Airfoil in a Cloud. NACA-TN-1397, 1947.
- Guibert, A. G., Janssen, E., and Robbins, W. M.: Determination of Rate, Area, and Distribution of Impingement of Waterdrops on Various Airfoils from Trajectories Obtained on the Differential Analyzer. NACA-RM-A905, 1949.
- Dorsch, Robert G., and Brun, Rinaldo J.: A Method for Determining Cloud-Droplet Impingement on Swept Wings. NACA-TN-2931, 1953.
- Brun, Rinaldo J., Gallagher, Helen M., and Vogt, Dorothea E.: Impingement of Water Droplets on NACA 65A004 Airfoil and Effect of Change in Airfoil Thickness from 12 to 4 Percent at 4° Angle of Attack. NACA-TN-3047, 1953.
- Brun, Rinaldo J., Gallagher, Helen M., and Vogt, Dorothea E.: Impingement of Water Droplets on NACA 651-208 and 651-212 Airfoils at 4° Angle of Attack. NACA-TN-2952, 1953.
- Serafini, John S.: Impingement of Water Droplets on Wedges and Double-Wedge Airfoils at Supersonic Speeds. NACA-TR-1159, 1954. (Supersedes NACA-TN-2971.)
- Brun, Rinaldo J., Gallagher, Helen M., and Vogt, Dorothea E.: Impingement of Water Droplets on NACA 65A004 Airfoil at 8° Angle of Attack. NACA-TN-3155, 1954.
- Brun, Rinaldo J., and Vogt, Dorothea E.: Impingement of Water Droplets on NACA 65A004 Airfoil at 0° Angle of Attack. NACA-TN-3586, 1955.
- Gelder, Thomas F., Smyers, William H., Jr., and von Glahn, Uwe H.: Experimental Droplet Impingement on Several Two-Dimensional Airfoils with Thickness Ratios of 6 to 16 Percent. NACA-TN-3839, 1956.
- Brun, Rinaldo J., and Vogt, Dorothea E.: Impingement of Cloud Droplets on 36_5-Percent-Thick Joukowski Airfoil at Zero Angle of Attack and Discussion of Use as Cloud Measuring Instrument in Dye-Tracer Technique. NACA-TN-4035, 1957.
Dye Tracer test technique
These have been reviewed elsewhere, as indicated below.
- von Glahn, Uwe H.: Use of Truncated Flapped Airfoils for Impingement and Icing Tests of Full-Scale Leading-Edge Sections. NACA-RM-E56E11, 1956.
> previous review: Scaling in NACA Icing Wind Tunnel Tests - von Glahn, Uwe H., Gelder, Thomas F., and Smyers, William H., Jr.: A Dye-Tracer Technique for Experimentally Obtaining Impingement Characteristics of Arbitrary Bodies and a Method for Determining Droplet Size Distribution. NACA-TN-3338, 1955.
> previous review: NACA-TN-3338 - Brun, Rinaldo J., and Vogt, Dorothea E.: Impingement of Cloud Droplets on 36_5-Percent-Thick Joukowski Airfoil at Zero Angle of Attack and Discussion of Use as Cloud Measuring Instrument in Dye-Tracer Technique. NACA-TN-4035, 1957.
> previous review: Airfoils - Lewis, James P., and Ruggeri, Robert S.: Experimental Droplet Impingement on Four Bodies of Revolution. NACA-TN-4092, 1957.
> previous review: Bodies of Revolution - Gelder, Thomas F.: Droplet Impingement and Ingestion by Supersonic Nose Inlet in Subsonic Tunnel Conditions. NACA-TN-4268, 1958.
> previous review: Impingement in Engine Inlets
Impingement on Other Surfaces
- Brun, Rinaldo J., and Mergler, Harry W.: Impingement of Water Droplets on a Cylinder in an Incompressible Flow Field and Evaluation of Rotating Multicylinder Method for Measurement of Droplet-Size Distribution, Volume-Median Droplet Size, and Liquid-Water Content in Clouds. NACA-TN-2904, 1953.
> previous review: NACA-TN-2904 - Brun, Rinaldo J., Serafini, John S., and Gallagher, Helen M.: Impingement of Cloud Droplets on Aerodynamic Bodies as Affected by Compressibility of Air Flow Around the Body. NACA-TN-2903, 1953.
> previous review: NACA-TN-2903 - von Glahn, Uwe H., Gelder, Thomas F., and Smyers, William H., Jr.: A Dye-Tracer Technique for Experimentally Obtaining Impingement Characteristics of Arbitrary Bodies and a Method for Determining Droplet Size Distribution. NACA-TN-3338, 1955.
> previous review: NACA-TN-3338 - Brun, Rinaldo J., Lewis, William, Perkins, Porter J., and Serafini, John S.: Impingement of Cloud Droplets and Procedure for Measuring Liquid-Water Content and Droplet Sizes in Supercooled Clouds by Rotating Multicylinder Method. NACA-TR-1215, 1955. (Supersedes NACA TN’s 2903, 2904, and NACA-RM-E53D23)
> previous review: NACA-TR-1215, NACA-TR-1215 Thermodynamics - Lewis, William, and Brun, Rinaldo J.: Impingement of Water Droplets on a Rectangular Half Body in a Two-Dimensional Incompressible Flow Field. NACA-TN-3658, 1956.
- von Glahn, Uwe H.: Use of Truncated Flapped Airfoils for Impingement and Icing Tests of Full-Scale Leading-Edge Sections. NACA-RM-E56E11, 1956.
> previous review: Scaling in NACA tests