A Fast-Response High Spatial Resolution Total Temperature Probe Using a Pulsed Heating Technique

1998 ◽  
Vol 120 (3) ◽  
pp. 601-607 ◽  
Author(s):  
D. R. Buttsworth ◽  
T. V. Jones
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Convective Heat Transfer Coefficient ◽  
Fast Response ◽  
Temperature Probe ◽  
Total Temperature

This paper discusses the operation of a fast-response total temperature probe based on transient thin film heat flux gage technology. The probe utilizes two thin film gages located close to the stagnation point of a hemispherically blunted fused quartz cylinder. Development of the present total temperature probe was motivated by the need for a fast-response device with a high spatial resolution. The diameter of the probe was 2.8 mm and the two films were separated by a distance of less than 1 mm. Measurement of the flow total temperature requires the films to operate at different temperatures. In the present work, the temperature difference was generated using a current pulse (approximately 70 mA with a duration of around 1 s) to heat one of the thin film resistance gages. With this technique, temperature differences between the hot and cold films of around 120 K were achieved. The interpretation of the transient surface temperature measurements is discussed, and the validity and utility of the technique are demonstrated with reference to total temperature and convective heat transfer coefficient measurements in a compressible free jet. The results demonstrate that accurate total temperature and convective heat transfer coefficient measurements with high spatial and temporal resolution can be obtained with the present device.

A Fast-Response High Spatial Resolution Total Temperature Probe Using a Pulsed Heating Technique

1997 ◽  
Author(s):  
D. R. Buttsworth ◽  
T. V. Jones
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Convective Heat Transfer Coefficient ◽  
Fast Response ◽  
Temperature Probe ◽  
Total Temperature

This paper discusses the operation of a fast-response total temperature probe based on transient thin film heat flux gauge technology. The probe utilizes two thin film gauges located close to the stagnation point of a hemispherically-blunted fused quartz cylinder. Development of the present total temperature probe was motivated by the need for a fast-response device with a high spatial resolution. The diameter of the probe was 2.8 mm and the two films were separated by a distance of less than 1 mm. Measurement of the flow total temperature requires the films to operate at different temperatures. In the present work, the temperature difference was generated using a current pulse (approximately 70 mA with a duration of around 1 s) to heat one of the thin film resistance gauges. With this technique, temperature differences between the hot and cold films of around 120 K were achieved. The interpretation of the transient surface temperature measurements is discussed, and the validity and utility of the technique are demonstrated with reference to total temperature and convective heat transfer coefficient measurements in a compressible free jet. The results demonstrate that accurate total temperature and convective heat transfer coefficient measurements with high spatial and temporal resolution can be obtained with the present device.

Unsteady Total Temperature Measurements Downstream of a High-Pressure Turbine

1998 ◽  
Vol 120 (4) ◽  
pp. 760-767 ◽  
Author(s):  
D. R. Buttsworth ◽  
T. V. Jones ◽  
K. S. Chana
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Wind Tunnel ◽  
Convective Heat Transfer Coefficient ◽  
Fast Response ◽  
Temperature Measurements ◽  
High Pressure Turbine ◽  
Response Device ◽  
Temperature Probe ◽  
Total Temperature

An experimental technique for the measurement of flow total temperature in a turbine facility is demonstrated. Two thin film heat transfer gases located at the stagnation point of fused quartz substrates are operated at different temperatures in order to determine the flow total temperature. With this technique, no assumptions regarding the magnitude of the convective heat transfer coefficient are made. Thus, the probe can operate successfully in unsteady compressible flows of arbitrary composition and high free-stream turbulence levels without a heat transfer law calibration. The operation of the total temperature probe is first demonstrated using a small wind tunnel facility. Based on results from the small wind tunnel tests, it appears that the probe total temperature measurements are accurate to within ±1 K. Experiments using the probe downstream of a high-pressure turbine stage are than described. Both high and low-frequency components of the flow total temperature can be accurately resolved with the present technique. The probe measures a time-averaged flow total temperature that is in good agreement with thermocouple measurements made downstream of the rotor. Frequencies as high as 182 kHz have been detected in the spectral analysis of the heat flux signals from the total probe. Through comparison with fast-response aerodynamic probe measurements, it is demonstrated that the current measurement location, the total temperature fluctuations arise mainly due to the isentropic extraction of work by the turbine. The present total temperature probe is demonstrated to be an accurate, robust, fast-response device that is suitable for operation in a turbomachinery environment.

scholarly journals Unsteady Total Temperature Measurements Downstream of a High Pressure Turbine

1997 ◽  
Author(s):  
D. R. Buttsworth ◽  
T. V. Jones ◽  
K. S. Chana
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Wind Tunnel ◽  
Convective Heat Transfer Coefficient ◽  
Fast Response ◽  
Temperature Measurements ◽  
High Pressure Turbine ◽  
Response Device ◽  
Temperature Probe ◽  
Total Temperature

An experimental technique for the measurement of flow total temperature in a turbine facility is demonstrated. Two thin film heat transfer gauges located at the stagnation point of fused quartz substrates are operated at different temperatures in order to determine the flow total temperature. With this technique, no assumptions regarding the magnitude of the convective heat transfer coefficient are made. Thus, the probe can operate successfully in unsteady compressible flows of arbitrary composition and high free-stream turbulence levels without a heat transfer law calibration. The operation of the total temperature probe is first demonstrated using a small wind tunnel facility. Based on results from the small wind tunnel tests, it appears that the probe total temperature measurements are accurate to within ± 1K. Experiments using the probe downstream of a high pressure turbine stage are then described. Both high and low frequency components of the flow total temperature can be accurately resolved with the present technique. The probe measures a time-averaged flow total temperature that is in good agreement with thermocouple measurements made downstream of the rotor. Frequencies as high as 182 kHz have been detected in the spectral analysis of the heat flux signals from the total temperature probe. Through comparison with fast-response aerodynamic probe measurements, it is demonstrated that at the current measurement location, the total temperature fluctuations arise mainly due to the isentropic extraction of work by the turbine. The present total temperature probe is demonstrated to be an accurate, robust, fast-response device that is suitable for operation in a turbomachinery environment.

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