Total Temperature Measurements Using a Rearward Facing Probe in Supercool Liquid Droplet and Ice Crystal Clouds

2018 ◽  
Author(s):  
Juan H. Agui ◽  
Peter M. Struk ◽  
Tadas P. Bartkus
Keyword(s):  
Liquid Droplet ◽  
Temperature Measurements ◽  
Ice Crystal ◽  
Total Temperature

scholarly journals Development of two-moment cloud microphysics for liquid and ice within the NASA Goddard Earth Observing System Model (GEOS-5)

2014 ◽  
Vol 7 (4) ◽  
pp. 1733-1766 ◽  
Author(s):  
D. Barahona ◽  
A. Molod ◽  
J. Bacmeister ◽  
A. Nenes ◽  
A. Gettelman ◽  
...  
Keyword(s):  
Liquid Droplet ◽  
Cloud Microphysics ◽  
Linear Increase ◽  
Moist Convection ◽  
Ice Crystal ◽  
Microphysics Scheme ◽  
Earth Observing System ◽  
Cloud Properties ◽  
Satellite Retrievals ◽  
Ice Crystal Size

Abstract. This work presents the development of a two-moment cloud microphysics scheme within version 5 of the NASA Goddard Earth Observing System (GEOS-5). The scheme includes the implementation of a comprehensive stratiform microphysics module, a new cloud coverage scheme that allows ice supersaturation, and a new microphysics module embedded within the moist convection parameterization of GEOS-5. Comprehensive physically based descriptions of ice nucleation, including homogeneous and heterogeneous freezing, and liquid droplet activation are implemented to describe the formation of cloud particles in stratiform clouds and convective cumulus. The effect of preexisting ice crystals on the formation of cirrus clouds is also accounted for. A new parameterization of the subgrid-scale vertical velocity distribution accounting for turbulence and gravity wave motion is also implemented. The new microphysics significantly improves the representation of liquid water and ice in GEOS-5. Evaluation of the model against satellite retrievals and in situ observations shows agreement of the simulated droplet and ice crystal effective radius, the ice mass mixing ratio and number concentration, and the relative humidity with respect to ice. When using the new microphysics, the fraction of condensate that remains as liquid follows a sigmoidal dependency with temperature, which is in agreement with observations and which fundamentally differs from the linear increase assumed in most models. The performance of the new microphysics in reproducing the observed total cloud fraction, longwave and shortwave cloud forcing, and total precipitation is similar to the operational version of GEOS-5 and in agreement with satellite retrievals. The new microphysics tends to underestimate the coverage of persistent low-level stratocumulus. Sensitivity studies showed that the simulated cloud properties are robust to moderate variation in cloud microphysical parameters. Significant sensitivity remains to variation in the dispersion of the ice crystal size distribution and the critical size for ice autoconversion. Despite these issues, the implementation of the new microphysics leads to a considerably improved and more realistic representation of cloud processes in GEOS-5, and allows the linkage of cloud properties to aerosol emissions.

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 https://www.scipedia.com/public/Pan_et_al_2021a

2021 ◽  
Vol 37 (4) ◽  
Author(s):  
J. Pan ◽  
Z. Zhang ◽  
Y. Ouyang ◽  
H. Cheng
Keyword(s):  
Flow Field ◽  
Particle Diameter ◽  
Internal Flow ◽  
Mass Transfer Process ◽  
Ice Crystals ◽  
Aviation Industry ◽  
Ice Crystal ◽  
Total Temperature ◽  
Isentropic Efficiency ◽  
Water Contents

The aviation industry found that a number of engine power-loss events were related to the ice crystal icing, and the research on ice crystal icing had gradually attracted the attention of scholars. In this work, the compressor and ice crystals ingested are regarded as study objects, and the trajectories of particles are calculated based on the Lagrangian approach. Moreover, the two-way coupling method is applied to solve the heat and mass transfer process between ice crystals and the flow field. The variation of particle diameter and temperature under different MVD (Medium Volume Diameter), RH (Relative Humidity) and TWC (Total Water Contents), and the variation of temperature, velocity and pressure of internal flow field are also studied. The result indicates that the MVD, RH and TWC play an important role in the ice crystals motion. Moreover, the temperature and velocity of internal flow field are also greatly affected by the three parameters while the pressure is little affected. In addition, without considering the ice crystal icing, the ice crystals ingested by the compressor would reduce the total temperature at the outlet of compressor, and improve the isentropic efficiency and mass flow rate.

scholarly journals Development of two-moment cloud microphysics for liquid and ice within the NASA Goddard earth observing system model (GEOS-5)

2013 ◽  
Vol 6 (4) ◽  
pp. 5289-5373 ◽  
Author(s):  
D. Barahona ◽  
A. Molod ◽  
J. Bacmeister ◽  
A. Nenes ◽  
A. Gettelman ◽  
...  
Keyword(s):  
Liquid Droplet ◽  
Cloud Microphysics ◽  
Linear Increase ◽  
Moist Convection ◽  
Ice Crystal ◽  
Microphysics Scheme ◽  
Earth Observing System ◽  
Cloud Properties ◽  
Satellite Retrievals ◽  
Ice Crystal Size

Abstract. This work presents the development of a two-moment cloud microphysics scheme within the version 5 of the NASA Goddard Earth Observing System (GEOS-5). The scheme includes the implementation of a comprehensive stratiform microphysics module, a new cloud coverage scheme that allows ice supersaturation and a new microphysics module embedded within the moist convection parameterization of GEOS-5. Comprehensive physically-based descriptions of ice nucleation, including homogeneous and heterogeneous freezing, and liquid droplet activation are implemented to describe the formation of cloud particles in stratiform clouds and convective cumulus. The effect of preexisting ice crystals on the formation of cirrus clouds is also accounted for. A new parameterization of the subgrid scale vertical velocity distribution accounting for turbulence and gravity wave motion is developed. The implementation of the new microphysics significantly improves the representation of liquid water and ice in GEOS-5. Evaluation of the model shows agreement of the simulated droplet and ice crystal effective and volumetric radius with satellite retrievals and in situ observations. The simulated global distribution of supersaturation is also in agreement with observations. It was found that when using the new microphysics the fraction of condensate that remains as liquid follows a sigmoidal increase with temperature which differs from the linear increase assumed in most models and is in better agreement with available observations. The performance of the new microphysics in reproducing the observed total cloud fraction, longwave and shortwave cloud forcing, and total precipitation is similar to the operational version of GEOS-5 and in agreement with satellite retrievals. However the new microphysics tends to underestimate the coverage of persistent low level stratocumulus. Sensitivity studies showed that the simulated cloud properties are robust to moderate variation in cloud microphysical parameters. However significant sensitivity in ice cloud properties was found to variation in the dispersion of the ice crystal size distribution and the critical size for ice autoconversion. The implementation of the new microphysics leads to a more realistic representation of cloud processes in GEOS-5 and allows the linkage of cloud properties to aerosol emissions.

Coherent Anti-Stokes Raman Scattering (CARS) Thermometry in a Model Gas Turbine Can Combustor

1992 ◽  
Author(s):  
J. Y. Zhu ◽  
T. Tsuruda ◽  
W. A. Sowa ◽  
G. S. Samuelsen
Keyword(s):  
Raman Scattering ◽  
Gas Turbine ◽  
Dielectric Breakdown ◽  
Liquid Droplet ◽  
Temperature Measurements ◽  
Measured Temperature ◽  
Spatially Resolved ◽  
Spray Flames ◽  
Instantaneous Temperature ◽  
Anti Stokes

Non-intrusive, spatially resolved instantaneous temperature measurements are presented that were obtained from a reacting spray flame in a model gas turbine can combustor using coherent anti-Stokes Raman scattering (CARS) thermometry. The results show that CARS measurements agree with thermocouple measurements at the exit of the combustor. The liquid droplet induced dielectric breakdown is not an obstacle in applying CARS to reacting sprays. The CARS measured temperature field also indicates that there is a relatively cool region (T < 1000 K) near the nozzle tip. Reaction occurs in the region where large numbers of droplets are present and in the interface of the swirl-induced recirculation zone. This study demonstrates that CARS is a viable diagnostic tool for non-intrusive, instantaneous temperature measurements in practical spray flames.

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.

High speed rotor wake total temperature measurements using a hot-film anemometer

1997 ◽  
Author(s):  
Robert Johnston ◽  
Sanford Fleeter ◽  
Robert Johnston ◽  
Sanford Fleeter
Keyword(s):  
High Speed ◽  
Temperature Measurements ◽  
Rotor Wake ◽  
Total Temperature ◽  
Hot Film
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