The measurement of temperature in hot gases plays an important role in many engineering applications, such as the efficiency and performance of an engine. As such, understanding the accuracy of these temperature measurements is also important. One of the common ways in which temperature is measured is through the use of total temperature probes. Previous research both at Virginia Tech and in outside studies has been performed to quantify the errors associated with total temperature probe measurements. This work has led to the development of low-order models which can be used to calculate the performance of a total temperature probe as a first-order estimate. These low-order models require knowledge of the heat transfer to the total temperature sensor in order to calculate the probe performance. However, the heat transfer to the sensor is a difficult quantity to calculate and has only been quantified over a set range of operating conditions for a single probe design. This research seeks to expand the range of applicability of the Virginia Tech low-order model by quantifying the heat transfer to the sensor of a total temperature probe over a range of probe geometries through the use of computational models. Key geometry parameters were altered to understand how altering these geometry features would impact the heat transfer to the sensor. In order to quantify the heat transfer to the sensor for varied probe geometries, a new method of characterizing the flow conditions about the sensor was also developed. By characterizing the flow conditions about the sensor, a better quantification of the heat transfer can be obtained. This thesis presents the correlation that was developed to quantify the changes in the flow about the sensor caused by varying the key geometry parameters. The flow conditions encompassed total temperatures from 294 K to 727 K at a Mach number of 0.4. The changes in the flow conditions about the sensor are then used to develop a heat transfer correlation to allow the heat transfer to the sensor to be calculated based off the changes in the flow conditions. The heat transfer to the sensor can then be substituted into the low-order model and used to calculate the performance of a total temperature probe. / Master of Science / The measurement of temperature in hot gases plays an important role in many engineering applications, such as the efficiency and performance of an engine. As such, understanding the accuracy of these temperature measurements is also important. One of the common ways in which temperature is measured is through the use of total temperature probes. Previous research has been performed to quantify the errors associated with total temperature probe measurements. This work has led to the development of low-order models which can be used to calculate probe errors. These low-order models require knowledge of the heat transfer to the total temperature sensor in order to calculate the probe errors. However, the heat transfer to the sensor is a difficult quantity to calculate and has only been quantified over a set range of flow conditions for a single probe design. This research seeks to quantify how the heat transfer to the sensor of a total temperature probe changes for different probe designs. Key geometry parameters were altered to understand how changing these geometry features would impact the heat transfer to the sensor. This thesis presents how the heat transfer to the total temperature sensor can be calculated over a range of different probe designs. The heat transfer to the sensor can then be substituted into the low-order model and used to calculate the performance of a total temperature probe.

<div>The quiet-flow capabilities of the Boeing/AFOSR Mach-6 Quiet Tunnel have been well established in the last decade, but a full characterization of the nozzle flow is an ongoing project. Pitot probes outtted with Kulite pressure transducers were used to further the investigation of the tunnel's flowfield. Noise levels were calculated by integrating the power spectral densities of the measured pitot pressure fluctuations, and experiments were performed to investigate several aspects of the flow.</div><div><br></div><div><div>First, the temperature distribution along the nozzle was varied to determine if heating had an effect on the stability of the laminar nozzle-wall boundary layer. Runs made with initial stagnation pressures slightly above the maximum quiet pressure determined that additional nozzle-wall heating did not have an effect on the amount of runtime which experienced quiet flow. In addition, pitot-probe measurements were taken at various locations to better determine the axial dependence of the noise levels. Experiments were also performed using pitot probes of varying forward-facing diameters to determine the effects of probe geometry on the measured fluctuations. The results were found to differ signicantly from simulations and from a previous set of experimental data, but a likely cause of the discrepancies was not found. A pitot probe mounted on the base of a cone confirmed that the aft end of a model does experience quiet flow. Finally, characterization of the flowfield was attempted when the tunnel is run using helium. The measured pressures for these experiments have a signicant level of uncertainty because the sensor calibration changes as helium diffuses across the diaphragm. Nevertheless, the measurements suggest that there may be periods of uniform flow, although these periods remain unstable and unsteady.</div></div><div><br></div><div><br></div>