Noise robust time of flight estimation for acoustic pyrometry

Patent metadata

Field	Value
Publication number	US-9702768-B2
Application number	US-201313961292-A
Country	US
Kind code	B2
Filing date	Aug 7, 2013
Priority date	Sep 5, 2012
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

An acoustic signal traversing a hot gas is sampled at a source and a receiver and is represented in overlapping windows that maximize useable signal content. Samples in each window are processed to represented in different sparsified bins in the frequency domain. Determining a signal delay between the source and the receiver from a summation of maximum smoothed coherence transform cross-correlation values of different data windows wherein a sparseness of a mean smoothed coherence transform cross-correlation of windows is maximized. Determining a set of delay times wherein outliers are deleted to estimate a time of flight from which a temperature of the hot gas is calculated.

First claim

The invention claimed is:

1. A method for acoustic pyrometry comprising:
recording, by a receiver of an acoustic pyrometer system, an acoustic signal generated by a source included in the acoustic pyrometer system and propagating through a gas medium traveling through a pipe or other channel;
arranging a plurality of samples representing the acoustic signal at the source and the receiver into a plurality of windows based on a physically minimum possible propagation delay from the source to the receiver given a temperature range of interest;
processing, by a processor within the acoustic pyrometer system, the plurality of samples representing the acoustic signal at the source and the receiver to generate data that represent the plurality of samples in a frequency domain;
arranging, by the processor within the acoustic pyrometer system, the data that represent the samples in the frequency domain in a plurality of frequency ranges and selecting one or more frequency ranges with a minimal influence of noise;
correlating, by the processor within the acoustic pyrometer system, the data in each selected frequency range of the source with corresponding data of the receiver to determine a weighted cross-spectral power estimate value for each selected frequency range related to the source corresponding to a delay time;
determining, by the processor within the acoustic pyrometer system, a summation of the maximum weighted cross-spectral power estimate value of each of the selected frequency ranges by using a range of delays wherein the summation has a maximum, such that a sparseness of a mean weighted cross-spectral power estimate of the selected frequency ranges is maximized; and
applying, by the processor within the acoustic pyrometer system, the determined signal delay between the source and the receiver to calculate a temperature of the gas medium.

2. The method of claim 1 , further comprising, the processor arranging the data that represent the plurality of samples in the frequency domain in a plurality of bins and selecting one or more bins with a minimal influence of noise.

3. The method of claim 1 , wherein the plurality of weighted cross-spectral power estimates apply a smoothed coherence transform (SCOT) cross-correlation.

4. The method of claim 1 , wherein a function that maximizes the sparseness is expressed as:

arg
⁢

⁢
max

t

⁢



1
N

⁢

∑

n
=
1

N

⁢

⁢

R

n
,
k
,
m

⁡

(

τ
+

t
n

)



1

⁢

⁢
with

⁢

-
d

≤

t
n

≤
d

,

wherein t n is a time variation within a range [−d, d];
N is a number of windows;
τ is a delay time of a signal;
n is an index indicating a window;
k is an index indicating a source;
m is an index indicating a receiver; and
R n,k,m (τ+t n ) represents a smoothed coherence transform cross-correlation for a signal represented in window n, from source k and received at receiver m at a time difference (τ+t n ).

5. The method of claim 1 , wherein a window is based on a physically minimum possible propagation delay from the source to the receiver given a temperature range of interest.

6. The method of claim 1 , further comprising:
determining a plurality of signal delays for a plurality of signals generated by a plurality of sources and received by a plurality of receivers.

7. The method of claim 6 , wherein a preferred signal delay is determined from the plurality of signal delays by applying a physical model based on a distance traversed by the acoustical signal.

8. The method of claim 1 , wherein the method is applied to determine a temperature in a gas turbine.

9. The method of claim 1 , wherein the method is applied to determine a temperature in a nuclear power plant.

10. An acoustic pyrometry system comprising:
an acoustic signal source enabled to generate an acoustic signal in a gas medium with a temperature;
a receiver enabled to record the acoustic signal traveling through the gas medium;
a memory enabled to store data and instructions;
a processor enabled to execute instructions retrieved from the memory to perform the steps:
arranging a plurality of samples representing the acoustic signal at the source and the receivers into a plurality of windows based on a physically minimum possible propagation delay from the source to the receiver given a temperature range of interest;
processing the plurality of samples representing the acoustic signal at the source and the receiver to generate data that represent the plurality of samples in a frequency domain;
arranging the data that represent the samples in the frequency domain in a plurality of frequency ranges and selecting one or more frequency ranges with a minimal influence of noise;
correlating the data in each selected frequency range of the source with corresponding data of the receiver to determine a weighted cross-spectral power estimate value for each selected frequency range related to the source corresponding to a delay time;
determining a summation of the maximum weighted cross-spectral power estimate value of each of the selected frequency ranges by using a range of delays wherein the sum

Assignees

• Claussen Heiko
• Rosca Justinian
• Yan Michelle Xiaohong
• Desilva Upul P
• Ulerich Nancy H
• Siemens Corp

Inventors

• Claussen Heiko
• Rosca Justinian
• Yan Michelle Xiaohong
• Desilva Upul P
• Ulerich Nancy H

Classifications

• G01K13/02

  for measuring temperature of moving fluids or granular materials capable of flow · CPC title

• G01K2013/024

  Physics · mapped topic

• G01K11/24 Primary

  of the velocity of propagation of sound · CPC title

• G01K13/024

  of moving gases · CPC title