Sonic anemometer
Techniques are described herein for displacing liquid away from a signal path of sonic signals in a signal anemometer. A sonic anemometer may include a membrane positioned between a sonic transducer and the open environment. The membrane may be formed of a hydrophobic material that repels the liquid. The membrane may also include a plurality of pores that impede the flow of liquid through the membrane but enables sonic signals to pass through the membrane. The sonic anemometer may also include a reflector that displaces liquid away from the signal path of the sonic anemometer. The reflector may include one or more pores that wick liquid away from the signal path.
1. A sonic anemometer, comprising:
a first sonic transducer configured to emit a sonic signal along a signal path;
a second sonic transducer positioned in the signal path spaced away from the first sonic transducer; and
a hydrophobic structure positioned in the signal path and configured to repel liquid away from the signal path.
2. The sonic anemometer of claim 1 , wherein the sonic signal is configured to be reflected between the first and second sonic transducers.
3. The sonic anemometer of claim 1 , wherein multiple hydrophobic structures are positioned in the signal path.
4. The sonic anemometer of claim 1 , wherein the hydrophobic structure comprises a circular perimeter.
5. The sonic anemometer of claim 1 , wherein the hydrophobic structure is configured to displace liquid from the signal path.
6. The sonic anemometer of claim 1 , wherein the hydrophobic structure comprises a surface facing the first sonic transducer or the second sonic transducer.
7. The sonic anemometer of claim 6 , wherein the surface is substantially flat.
8. The sonic anemometer of claim 1 , wherein the first and second sonic transducers are oriented at non-orthogonal angles relative to an airflow direction across the signal path.
9. The sonic anemometer of claim 1 , further comprising a housing supporting the first and second sonic transducers and including an aperture in which the hydrophobic structure is positioned.
10. The sonic anemometer of claim 1 , further comprising a housing supporting the first and second sonic transducers and defining an air gap, wherein the signal path passes through the air gap, and wherein the hydrophobic structure comprises a surface facing the air gap.
11. A sonic anemometer, comprising:
a sonic transducer configured to emit a sonic signal along a signal path;
a reflector having a top surface positioned in the signal path, the top surface being configured to reflect the sonic signal;
wherein the reflector is configured to remove liquid from the sonic signal path.
12. The sonic anemometer of claim 11 , wherein the reflector is configured to displace liquid away from the top surface.
13. The sonic anemometer of claim 11 , wherein the reflector is configured to displace liquid in a lateral direction relative to the top surface.
14. The sonic anemometer of claim 11 , further comprising a base supporting the reflector, wherein the reflector is configured to displace liquid toward the base from the top surface.
15. The sonic anemometer of claim 11 , further comprising a second sonic transducer configured to receive the sonic signal after reflection of the sonic signal by the reflector.
16. The sonic anemometer of claim 11 , wherein the reflector is disk-shaped.
17. A method of using a sonic anemometer, the method comprising:
transmitting a sonic signal from a first sonic transducer at a first end of a signal path, the signal path crossing an air gap;
removing liquid from the signal path in the air gap by permitting the liquid to contact a hydrophobic material exposed to the air gap in the signal path;
measuring the sonic signal at a second sonic transducer at a second end of the signal path; and
determining a characteristic of air movement through the air gap based on the sonic signal.
18. The method of claim 17 , further comprising reflecting the sonic signal between the first and second ends of the signal path.
19. The method of claim 17 , wherein removing liquid from the signal path comprises repelling liquid in a direction away from the signal path.
20. The method of claim 17 , wherein the liquid is removed from a circular area on the hydrophobic material.