Articles with tag: "effects of ice"

1. Using Appendix C for Ice Shape Analysis

   
   Public domain image by Donald Cook.

   Summary

   Search within the Appendix C Continuous Maximum Icing definition for the thickest ice shape.

   Prerequisites

   You need to have completed Run a 2D simulation.

   Introduction

   "Aircraft Ice Protection" AC 20-73A faa.gov offers guidance on analysis for icing conditions. We will not cover the certification aspects in detail.

   Much of the detail is on ice protection systems.

   This advisory circular (AC) tells type certificate and supplemental type certificate applicants how to comply with the ice protection requirements of Title 14 of the Code of Federal Regulations (14 CFR) parts 23, 25, 27, 29, 33, and 35.

   However, it is also useful for analysing ice shapes on unprotected surfaces.

   It is noted that:

   Determination of critical ice shape configurations is not straightforward and may require engineering judgment.

   SAE AIR5903, "Droplet Impingement and Ice Accretion Computer Codes" sae.org notes:

   A balancing of accurate and …

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2. NASA-TM-D-2166

   "this correlation is a first-order approximation of the presently available aerodynamic and icing data for airfoils exposed to icing conditions"

   SAE Preprint No. 225, "Correlation of Airfoil Ice Formations and Their Aerodynamic Effects With Impingement and Flight Conditions"

   and

   NASA-TM-D-2166, "Prediction of Aerodynamic Penalties Caused by Ice Formations on Various Airfoils"

   The content of these two publications are almost identical. As NASA-TM-D-2166 is the one that was cited the most, and has a more legible copy available online, I will center the review around it.

   Summary

   A more general correlation of drag due to ice on an airfoil is developed.

   Key Points

   1. Several airfoils are studied in addition to the NACA 65A004 previously used.
   2. A more general correlation of drag due to ice on an airfoil is developed.
   3. For lift, "no systematic relation is readily apparent for a thin, sharp-nosed airfoil such as the 65A004 airfoil".

   Abstract

   An empirical equation …

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3. NACA-TN-4151

   "published aerodynamic data for performance penalties in icing conditions are not readily applicable to a very thin airfoil"

   NACA-TN-4151, "Correlations Among Ice Measurements, Impingement Rates, Icing Conditions and Drag Coefficients for an Unswept NACA 65A004 Airfoil"

   and

   NACA-TN-4155, "Aerodynamic Effects Caused by Icing of an Unswept NACA 65A004 Airfoil"

   These two publications reference each other, and so are reviewed together.

   Summary

   Correlations are develop between ice shapes, aerodynamic performance, and icing conditions.

   Key Points

   1. More than 60 ice shapes were measured in an icing wind tunnel for a thin airfoil section.
   2. Correlations were developed between ice shapes, aerodynamic performance, and icing conditions.

   Abstract

   NACA-TN-4155:

   The effects of ice formations on the section lift, drag, and pitching-moment coefficients of an unswept NACA 65A004 airfoil section of 6-foot chord were studied. The magnitude of the aerodynamic penalties was primarily a function of the shape and size of the ice formation near the …

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4. NACA-WR-L-292

   "The danger lies, not so much in the higher stalling speed, but more in the possibility that the stall may occur without advance warning to the pilot."

   NACA-WR-L-292, "Effects of a Simulated Ice Formation on the Aerodynamic Characteristics of an Airfoil" ¹

   Summary

   Airfoil characteristics with simulated residual ice are measured.

   Key Points

   1. An airline operator survey of ice shapes was conducted.
   2. A residual ice shape was tested at near full scale.
   3. A significant reduction in Cl_max values was found.
   4. Values are compared to NACA-TR-446.

   Abstract

   In connection with the general study of icing problems an item of major interest is the effect of ice on the aerodynamic characteristics of a wing. Of particular interest is the effect of the ice which remains on a wing, under some flight conditions in spite of the operation of rubber de-icers. At the request of the N.A.C.A. a questionnaire seeking …

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5. NACA-TR-446

   "As regards the lift at higher angles of attack ..., the [effect] becomes increasingly serious as the protuberance approaches a point near the leading edge."

   

   NACA-TR-446, "Airfoil Section Characteristics as Affected by Protuberances" ¹

   Summary

   "Protuberances" on an airfoil can have significant effects on section lift and drag.

   Key Points

   1. Position and height of the protuberance are important.
   2. While icing is not mentioned, later works will apply this data in an icing context.

   Abstract

   The drag and interference caused by protuberance from the surface of an airfoil have been determined in the N.A.C.A. Variable-Density Wind Tunnel at a Reynolds Number of approximately 3,100,000. The effects of variations of the fore-and-aft position, height, and shape of the protuberance were measured by determining how the airfoil section characteristics were affected by the addition of th various protuberances extending along the entire span of the airfoil. The results provide …

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