Acoustic pyrometer

Claim 1

An apparatus for measuring high temperatures of a medium in a space containing acoustic noise and bounded by side walls at a known distance from each other, comprising: an acoustic transmitter having a wave guide connected to a horn in one side wall for transmitting frequency modulated non-periodic pulses of acoustic waves toward the other side wall, the pulses of acoustic waves having a selected waveform defined by a start frequency, a stop frequency, and a duration controlled by the number of cycles required to linearly sweep between the start and stop frequencies, and being transmitted at selected transmission times; an acoustic receiver having a wave guide connected to a horn in the other side wall for receiving the pulses, plus the acoustic noise in the space, to form a received signal; means for storing a sample of the waveform; means for comparing the sample to the received signal in a cross-correlation operation during a time period which is greater than a maximum transit time of the pulses between the side walls, for determining a point of maximum correlation between the sample and the signal which is taken as the arrival time for the pulses, the amount of time between the transmission time and the arrival time being the actual transit time of pulses between the transmitter and the receiver; means for calculating an offset time, based on the surface temperature of said wave guides, to correct said actual transit time for the temperature of the medium within the wave guides and horns; and means for calculating the temperature of the medium as a function of the actual transit time, said offset time, and the known distance between the side walls which yields a velocity of the pulses through the medium, as well as a function of the molecular weight and the specific heat ratio of the medium.

Claim 2

An apparatus for measuring high temperatures of a medium in a space containing acoustic noise and bounded by side walls at a known distance from each other, comprising: an acoustic transmitter having a wave guide connected to a horn in one side wall for transmitting frequency modulated non-periodic pulses of acoustic waves toward the other side wall, the pulses of acoustic waves having a selected waveform defined by a start frequency, a stop frequency, and a duration controlled by the number of cycles required to linearly sweep between the start and stop frequencies, and being transmitted at selected transmission times; an acoustic receiver having a wave guide connected to a horn in the other side wall for receiving the pulses, plus the acoustic noise in the space, to form a received signal; means for storing a sample of the waveform; means for comparing the sample to the received signal in a cross-correlation operation during a time period which is greater than a maximum transit time of the pulses between the side walls, for determining a point of maximum correlation between the sample and the signal which is taken as the arrival time for the pulses, the amount of time between the transmission time and the arrival time being the actual transit time of pulses between the transmitter and the receiver; means for calculating an offset time, based on the surface temperature of said wave guides, to correct said actual transit time for the temperature of the medium within the wave guides and horns; and means for calculating the temperature of the medium as a function of the actual transit time, said offset time, and the known distance between the side walls which yields a velocity of the pulses through the medium, as well as a function of the molecular weight and the specific heat ratio of the medium.

Claim 8

A method for measuring high temperatures of a medium in a space containing acoustic noise and bounded by side walls at a known distance from each other, comprising: transmitting pulses of acoustic waves from one side wall toward the other at a transmission time, each pulse having a selected waveform; storing a sample of the waveform; receiving the pulses, plus the acoustic noise, at the other side wall to form a received signal; comparing the received signal to the sample during a time period which is greater than a maximum transit time of the pulses between the side walls, for determining a point of maximum correlation between the sample and the signal which is taken as the arrival time for the pulses, the amount of time between the transmission time and the arrival time being the actual transit time of each pulse; and determining the amount of correlation between the sample and the signal at the point of maximum correlation as a qualifier for quantifying the quality of the comparison, the qualifier being from 0 to 1, and using only maximum correlations having a qualifier of more than 0.45 for calculating the temperature of the medium as a function of the actual transmit time and the known distance which yields a velocity for the pulses through the medium, as well as a function of the molecular weight and specific heat ratio of the medium.

Claim 9

A method for measuring high temperatures of a medium in a space containing acoustic noise and bounded by side walls at a known distance from each other, comprising: transmitting pulses of acoustic waves from one side wall toward the other at a transmission time, each pulse having a selected waveform; storing a sample of the waveform; receiving the pulses, plus the acoustic noise, at the other side wall to form a received signal; comparing the received signal to the sample during a time period which is greater than a maximum transit time of the pulses between the side walls, for determining a point of maximum correlation between the sample and the signal which is taken as the arrival time for the pulses, the amount of time between the transmission time and the arrival time being the actual transit time of each pulse; and determining the amount of correlation between the sample and the signal at the point of maximum correlation as a qualifier for quantifying the quality of the comparison, the qualifier being from 0 to 1, and using only maximum correlations having a qualifier of more than 0.45 for calculating the temperature of the medium as a function of the actual transmit time and the known distance which yields a velocity for the pulses through the medium, as well as a function of the molecular weight and specific heat ratio of the medium.

Claim 16

An apparatus for measuring high temperatures of a medium along various acoustic paths in a plane in a space containing acoustic noise and bounded by side walls at a known distance from each other, to give a temperature profile within the plane, comprising: multiple sets of acoustic transmitters and acoustic receivers located in said walls, each of said transmitters and said receivers in said sets located opposite each other and having a wave guide connected to a horn, said transmitters for transmitting, at selected transmission times, frequency modulated non-periodic pulses of acoustic waves having a selected waveform, defined by a start frequency, a stop frequency, and a duration controlled by the number of cycles required to linearly sweep between the start and stop frequencies, along said paths to said receivers, said receivers for receiving said pulses, plus the acoustic noise in the space, to form received signals; means for storing a sample of the waveform; means for comparing the sample to the received signals in a cross-correlation operation during a time period which is greater than a maximum transmit time of the pulses along said paths, for determining points of maximum correlation between the sample and the signals which are taken as the arrival time for the pulses, the amount of time between the transmission time and the arrival time being the actual transit time of pulses between the transmitters and the receivers along said paths; means for calculating an offset time, based on the surface temperature of said wave guide, to correct said actual transit time for the temperature of the medium within the wave guides and horns; means for calculating the temperature of the medium along each of said paths as a function of the actual transit time along each of said paths, said offset time, and the known distance between the side walls which yields a velocity of the pulses along each of said paths through the medium, as well as a function of the molecular weight and the specific heat ratio of the medium; and means for processing said temperature of the medium along each path by a deconvolution technique to give the temperature profile of the medium within said plane.

Claim 17

An apparatus for measuring high temperatures of a medium along various acoustic paths in a plane in a space containing acoustic noise and bounded by side walls at a known distance from each other, to give a temperature profile within the plane, comprising: multiple sets of acoustic transmitters and acoustic receivers located in said walls, each of said transmitters and said receivers in said sets located opposite each other and having a wave guide connected to a horn, said transmitters for transmitting, at selected transmission times, frequency modulated non-periodic pulses of acoustic waves having a selected waveform, defined by a start frequency, a stop frequency, and a duration controlled by the number of cycles required to linearly sweep between the start and stop frequencies, along said paths to said receivers, said receivers for receiving said pulses, plus the acoustic noise in the space, to form received signals; means for storing a sample of the waveform; means for comparing the sample to the received signals in a cross-correlation operation during a time period which is greater than a maximum transmit time of the pulses along said paths, for determining points of maximum correlation between the sample and the signals which are taken as the arrival time for the pulses, the amount of time between the transmission time and the arrival time being the actual transit time of pulses between the transmitters and the receivers along said paths; means for calculating an offset time, based on the surface temperature of said wave guide, to correct said actual transit time for the temperature of the medium within the wave guides and horns; means for calculating the temperature of the medium along each of said paths as a function of the actual transit time along each of said paths, said offset time, and the known distance between the side walls which yields a velocity of the pulses along each of said paths through the medium, as well as a function of the molecular weight and the specific heat ratio of the medium; and means for processing said temperature of the medium along each path by a deconvolution technique to give the temperature profile of the medium within said plane.