Gas Turbine Exhaust Temperature Measurement Approach Using Time-Frequency Controlled Sources

DeSilva, Upul; Bunce, Richard H.; Schmitt, Joshua; Claussen, Heiko

doi:10.1115/gt2015-42139

Cited by 6 publications

(6 citation statements)

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“…In this study, an acoustic pyrometer similar to the one proposed by DeSilva et al [7,8] was considered. Therefore, heavy-duty gas turbine exhaust was assumed to flow inside a stainless-steel pipe with a diameter of 1 m. The temperature and pressure of the turbine exhaust were supposed to be Texh = 813.15 K and pexh = 101325 Pa, respectively, whilst the gas relative humidity was considered RH = 70%.…”

Section: Case Studymentioning

confidence: 99%

“…They pointed out how, conversely to traditional methods, the technique is suitable for control as it does not suffer thermal lag. DeSilva et al [6,7] successfully used the method to measure a heavy-duty gas turbine's exhaust gas temperature distribution. In their investigation, they underlined how the turbomachinery's flow velocity, mass flow and turbulence levels require alternative sound signals conversely to highintensity pulses typically used in furnaces and boilers.…”

Section: Introductionmentioning

confidence: 99%

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Time-of-flight estimation in acoustic pyrometry: sensitivity to pulse characteristics

Pettinari

Ferrari

2023

J. Phys.: Conf. Ser.

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Acoustic pyrometry is a non-intrusive measurement technique that may have several applications in turbomachinery. This methodology estimates the gas temperature by measuring the time of flight of an acoustic wave moving through a medium. It can be accomplished by placing a sound source (emitter) and a set of microphones (receivers) on opposite sides of a section. The emitter generates a sound pulse, and the receivers detect it. Since the emitter-receiver distances are known and fixed, the average temperatures of the paths traversed by the acoustic pulse can be computed by estimating the time-of-flight through deconvolution techniques. However, despite the straightforward principle, an acoustic wave suffers a variation of amplitude when propagating within a medium because of energy losses and ambient noise. Hence, time-of-flight estimation becomes a critical task, especially when considering high-frequency waves or short distances between sensors. It is then fundamental to select proper acoustic waves to maximise the cross-correlation between the signals of the emitter-receiver couples, thus improving the accuracy of the time-of-flight measurements and, consequently, the estimation of the spatial temperature distribution within a specific area. This study is a preliminary investigation, based on a modelling approach, to estimate the impact of different acoustic waves on the accuracy of the time-of-flight measurement. The results of this analysis will be useful to design and setup an acoustic pyrometry application.

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Section: Case Studymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Time-of-flight estimation in acoustic pyrometry: sensitivity to pulse characteristics

Pettinari

Ferrari

2023

J. Phys.: Conf. Ser.

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“…In recent years, the use of acoustic measurements for nonintrusive gas turbine engine flow monitoring has been proposed and several studies have been conducted to assess its feasibility in practical applications [1][2][3][4][5]. An acoustic approach is of par ticular interest because it offers several unique advantages over optical methods (such as particle image velocimetry) in gas turbine engine environments.…”

Section: Introductionmentioning

confidence: 99%

“…Reported results showed that acoustically measured gas turbine exhaust temper atures were within 10 °C of thermocouple data. Siemens conducted a similar study in 2015, this time using improved sound source design for better time-of-flight estimation, and reported 0.36% bulk mean temperature error in temperatures up to 600 • C [3]. In both experiments, the impact of flow velocity on the measurements was not addressed in detail.…”

Section: Introductionmentioning

confidence: 99%

“…In both experiments, the impact of flow velocity on the measurements was not addressed in detail. The first article mentions that the assumption of sound traveling in a straight line is a 'good starting point for reconstruction of temperature maps' [2], while the second article specifies that velocity was measured 'by other means' and used to correct the temperature values [3]. While the negligible velocity effects may be justified at low Mach numbers, the inability to properly account for acoustic refraction, convection, and increased fluid compressibility at higher Mach numbers would result in significant errors if flow velocity is not considered.…”

Section: Introductionmentioning

confidence: 99%

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Non-intrusive acoustic measurement of flow velocity and temperature in a high subsonic Mach number jet

Otero

Lowe

2017

Meas. Sci. Technol.

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In previous studies, sonic anemometry and thermometry have generally been used to measure low subsonic Mach flow conditions. Recently, a novel configuration was proposed and used to measure unheated jet velocities up to Mach 0.83 non-intrusively. The objective of this investigation is to test the novel configuration in higher temperature conditions and explore the effects of fluid temperature on mean velocity and temperature measurement accuracy. The current work presents non-intrusive acoustic measurements of single-stream jet conditions up to Mach 0.7 and total temperatures from 299 K to 700 K. Comparison of acoustically measured velocity and static temperature with probe data indicate root mean square (RMS) velocity errors of 2.6 m s−1 (1.1% of the maximum jet centerline velocity), 4.0 m s−1 (1.2%), and 8.5 m s−1 (2.4%), respectively, for 299, 589, and 700 K total temperature flows up to Mach 0.7. RMS static temperature errors of 7.5 K (2.5% of total temperature), 8.1 K (1.3%), and 23.3 K (3.3%) were observed for the same respective total temperature conditions. To the authors’ knowledge, this is the first time a non-intrusive acoustic technique has been used to simultaneously measure mean fluid velocity and static temperatures in high subsonic Mach numbers up to 0.7. Overall, the findings of this work support the use of acoustics for non-intrusive flow monitoring. The ability to measure mean flow conditions at high subsonic Mach numbers and temperatures makes this technique a viable candidate for gas turbine applications, in particular.

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Influence of emitter-receiver number on measurement accuracy in acoustic pyrometry

et al. 2022

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Acoustic pyrometry is an interesting technique that may find several useful applications in turbomachinery. As the speed of sound is directly related a medium temperature, this measurement technique estimates the temperature of a gas by considering the time of flight of an acoustic wave moving through it. If only an acoustic emitter-receiver couple is used, only the average temperature along the acoustic path can be determined. If multiple emitter-receiver couples laying on the same plane are used, a reconstruction of the temperature map in the section is possible. This estimation is performed by considering that multiple acoustic paths travel across the same sub-portions of the section and, therefore, the temperature of each sub-portion affects the time of flight along several sound paths. Many parameters affect the accuracy of the measurement, and they are related to the physic of the phenomena involved in the measurement, the accuracy of the instrumentation used, the interaction between the acoustic wave and the flow velocity and the hardware set-up. In this study, the impact of some set-up parameters on the accuracy of the measurement was investigated and, in particular, the number of sound emitter-receiver couples and the number of investigation sub-portions in which the section is divided. A reference temperature map has been considered as a benchmark. This study, which is a preliminary investigation on this technique, was useful to assess the capability of this methodology to correctly describe a temperature distribution in an ideal condition. Therefore, it represents a first step in the set-up of an experimental investigation with an acoustic pyrometer..

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Gas Turbine Exhaust Temperature Measurement Approach Using Time-Frequency Controlled Sources

Cited by 6 publications

References 0 publications

Time-of-flight estimation in acoustic pyrometry: sensitivity to pulse characteristics

Time-of-flight estimation in acoustic pyrometry: sensitivity to pulse characteristics

Non-intrusive acoustic measurement of flow velocity and temperature in a high subsonic Mach number jet

Influence of emitter-receiver number on measurement accuracy in acoustic pyrometry

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