Morphogenetic modelling of in-flight icing

• US 6,868,721 B2
• Filed: 06/05/2003
• Issued: 03/22/2005
• Est. Priority Date: 06/05/2002
• Status: Active Grant

• Current Assignee: National Research Council Canada
• Original Assignee: National Research Council Canada
• Inventors: Szilder, Krzysztof
• Primary Examiner(s): Swiatek, Robert P.
• Application Number:
  US10/454,514
• Publication Number:
  US 20040155151A1
• Time in Patent Office: 656 Days
• Field of Search: 731/702.6, 244/134.R, 244/134.F
• US Class Current: 73/170.26
• CPC Class Codes: B64D 15/20 Means for detecting icing or initiating de-icing

Abstract

The accretion of ice on an aerodynamic surface is predicted by identifying predetermined atmospheric parameters relevant to ice formation in a particular fluid environment. Then the behaviour of individual fluid elements is simulated based on the identified parameters to create a model of the ice accretion.

Claims

1. A method of predicting icing on a surface in a fluid stream, comprising the step of:

identifying predetermined macroscopic physical variables relevant to ice formation in a particular fluid environment;

calculating the behaviour of individual fluid elements based on said identified macroscopic physical variables taking into account the effect on collision efficiency of non-linear droplet trajectories and the distribution of heat transfer over the surface; and

predicting ice accretion based on the calculated behaviour of said individual fluid elements.

2. A method as claimed in claim 1, wherein said behaviour includes the freezing and shedding of said individual fluid elements.

3. A method as claimed in claim 2, wherein the behaviour of said individual fluid elements is assumed to be stochastic.

4. A method as claimed in claim 2, wherein said variables are selected from the group consisting of fluid stream velocity, fluid stream liquid water content, droplet volume median diameter, altitude and fluid temperature.

5. A method as claimed in claim 2, wherein step of calculating the behaviour of said individual fluid elements involves calculating the freezing probability thereof in said particular fluid environment.

6. A method as claimed in claim 5, wherein the accretion domain for said ice is defined by a lattice and the freezing probability at a location π

is calculated by determining the difference between a total upstream impinging mass of water $\underset{i=1}{\overset{m}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>M_{\mathrm{WVi}}$

and a total upstream mass of frozen water $\underset{j=1}{\overset{n-1}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>M_{\mathrm{Fj}}.$

7. A method as claimed in claim 6, wherein said lattice is a two-dimensional lattice.

8. A method as claimed in claim 6, wherein said lattice is a three-dimensional lattice.

9. A method as claimed in claim 5, wherrein said freezing probability is given by the expression $\begin{array}{c}{P}_n=\frac{1}{\frac{4}{\pi }}\end{array}$

⁢

∑

i=1m⁢

 

⁢

Si,n-S1,n⁢

∑

j=1n-1⁢

 

⁢

1S1,j⁢

 

⁢

whereSi,j=mWVimFj;

n=1,2,…

,n,;

m≤

n

10. A method as claimed in claim 5, wherein said freezing probability varies in a time-dependent manner.

11. A method as claimed in claim 2, wherein the behaviour of said individual fluid element is calculated successively for the total number of fluid elements in an intercepted mass flux.

12. A method as claimed in claim 11, wherein the distribution of freezing probability is recalculated after calculating the behaviour of each said fluid element.

13. A method as claimed in claim 1, wherein an azimuthal distribution of the heat transfer to the fluid stream is taken into account in the calculation of the behaviour of said individual fluid elements.

14. A method as claimed in claim 1, wherein said surface is an airfoil.