Total pressure and total temperature measurement in wet gas condition
A probe for the measurement of the total pressure or temperature of a two phase wet gas flow is also disclosed. Embodiments provide a stem, a tip on the top of the stem, a cup serving as a shield is formed in the tip, a at least one tube or thermal element positioned within the cup serving as a measuring device for the incoming wet gas flow; at least one hole which passes through at least one wall of the cup; and a pressure changing device configured to accelerate the wet gas flowing around the cup. A method and system for the measurement of the total pressure or temperature of a two phase wet gas flow is also disclosed.
1. A probe for the measurement of the total pressure or temperature of a two phase wet gas flow, the probe comprising:
a stem;
a tip on the top of the stem;
a cup serving as a shield is formed in the tip, the cup having a longitudinal axis perpendicular to the longitudinal axis of the stem and comprising an open front end perpendicular to its longitudinal axis by the side of the incoming wet gas flow and a closed back end on the opposite side;
at least one tube or thermal element positioned within the cup serving as a measuring device for the incoming wet gas flow;
at least one hole which passes through at least one wall of the cup; and
a pressure changing device configured to accelerate the wet gas flowing around the cup whereby a pressure depression is created near said at least one hole to suck the liquid, that forms a phase of the wet gas flow, from inside the cup.
2. The probe of claim 1 , wherein the pressure changing device comprises at least one nozzle having a longitudinal axis parallel to the longitudinal axis of the cup.
3. The probe of claim 2 , wherein the tip is cylindrical and the cup coincide with the tip and the at least one nozzle is positioned adjacent the external surface of the cup, the external surface of the cup forming a wall of the nozzle.
4. The probe of claim 2 , wherein the tip is elliptical and the at least one nozzle is formed in the tip, adjacent to the cup, on the side of the major axis of the ellipse.
5. The probe of claim 2 , wherein the cup coincides with the tip and the nozzle is formed, adjacent to the cup, in the stem.
6. The probe of claim 2 , wherein the at least one nozzle is approximately semi-conical and tapered along its longitudinal axis with the greater aperture on the side of the incoming wet gas flow.
7. The probe of claim 1 , wherein for the measurement of total temperature a miniaturized shield is used to protect the measuring device from the direct droplet impact.
8. The probe of claim 1 , wherein the at least one tube or thermal element inside the cup is positioned in such a way that its open end is tangential to the gas flow and not adjacent to the at least one wall of the cup and comprises a part running into the stem parallel to the longitudinal axis of the stem.
9. The probe of claim 1 , wherein the at least one tube or thermal element connects its open end with transducers and a data collection system at the end of the stem.
10. A method to measure total pressure and temperature of a two phase wet gas flow, the method comprising:
using a probe provided with a cup wherein the two phase wet gas flow can be slowed down until the two phase wet gas flow is at rest;
creating a pressure drop around the cup through a pressure changing device; and
sucking the liquid forming one of the two phases from inside the cup through one or more holes formed in at least one wall of the cup.
11. A system for measuring the performances of a centrifugal wet gas compressor, the system comprising:
miniaturized probes placed inside the compressor for measuring the total pressure and total temperature of the gas stream laden with liquid droplets, the probes comprising:
a cup wherein the gas stream can be slowed down until the gas stream is at rest; and
a pressure changing device configured to create a pressure drop around the cup in order to suck the liquid droplets from inside the cup through one or more holes formed in at least one wall of the cup.
12. The system of claim 11 , further comprising a tip, wherein the tip is cylindrical and the cup coincides with the tip and at least one nozzle is positioned adjacent the external surface of the cup, the external surface of the cup forming a wall of the nozzle.
13. The system of claim 12 , wherein the at least one nozzle is approximately semi-conical and tapered along its longitudinal axis with the greater aperture on the side of the incoming wet gas flow.
14. The system of claim 11 , further comprising a tip, wherein the tip is elliptical and the at least one nozzle is formed in the tip, adjacent to the cup, on the side of the major axis of the ellipse.
15. The system of claim 11 , further comprising a tip, wherein the cup coincides with the tip and the at least one nozzle is formed, adjacent to the cup, in a stem.
16. The system of claim 11 , wherein for the measurement of total temperature a miniaturized shield is used to protect the measuring device from the direct droplet impact.
17. The system of claim 11 , wherein the at least one tube or thermal element inside the cup is positioned in such a way that its open end is tangential to the gas flow and not adjacent to the at least one wall of the cup and comprises a part running into a stem parallel to the longitudinal axis of the stem.
18. The system of claim 11 , wherein the at least one tube or thermal element connects its open end with transducers and a data collection system at the end of a stem.
19. The system of claim 11 , wherein the pressure changing device comprises at least one nozzle having a longitudinal axis parallel to the longitudinal axis of the cup.