This work reports the convection calibration of Schmidt-Boelter heat flux gages in shear and stagnation air flow. The gages were provided by Sandia National Laboratories and included two one-inch diameter and two one-and-one-half-inch diameter Schmidt-Boelter heat flux gages. In order to calibrate the sensors a convection calibration facility has been designed, including a shear test stand, a stagnation test stand, an air heater and a data acquisition system. The current physical model for a combined radiation and convection heat transfer environment uses an additional thermal resistance around the heat flux gage. This model clearly predicts a non-linear dependency of the gage sensitivity over a range of heat transfer coefficients. A major scope of this work was to experimentally verify the relation found by the model assumptions. Since the actual heat sink temperature is not known and cannot be measured, three different cases have been examined resulting in three different sensitivities for one pressure value, which is the gage sensitivity for the not cooled case and the gage sensitivity for the cooled case, based on the plate temperature or on the cooling water temperature. All of the measured sensitivities for shear as well as for stagnation flow fit well in the theory and show the non-linear decay for increasing heat transfer coefficient values. However, the obtained data shows an offset in the intersection with the sensitivity at zero heat transfer coefficient. This offset might arise from different radiation calibration techniques and different surface coatings of test gage and reference standard. / Master of Science

The purpose of this study is to quantify the effects of heat flux sensor design and interaction with both test article material choice and geometry on heat flux measurements. It is the public domain component of a larger study documenting issues inherent in heat flux measurement. Direct and indirect heat flux measurement techniques were tested in three thermally diverse model materials at the same Mach 6 test condition, with a total pressure of 1200 psi and total temperature of 1188° R, and compared to the steady analytic Fay-Riddell solution for the stagnation heat flux on a hemisphere. A 1/8 in. fast response Schmidt-Boelter gage and a 1/16 in. Coaxial thermocouple mounted in ¾ in. diameter stainless steel, MACOR, and Graphite hemispheres were chosen as the test articles for this study. An inverse heat flux calculation was performed using the coaxial thermocouple temperature data for comparison with the Schmidt-Boelter gage. Before wind tunnel testing, the model/sensor combinations were tested in a radiative heat flux calibration rig at known static and dynamic heat fluxes from 1 to 20 BTU/ft2/s. During wind tunnel testing, the chosen conditions yielded stagnation point convective heat flux of 15-60 BTU/ft2/s, depending on the stagnation point wall temperature of the model. A computational fluid dynamic study with conjugate heat transfer was also undertaken to further study the complex mechanisms at work. The overall study yielded complex results that prove classic methodology for inverse heat flux calculation and direct heat flux measurement require more knowledge of the thermal environment than a simple match of material properties. Internal and external model geometry, spatial and temporal variations of the heat flux, and the level of thermal contact between the sensor and the test article can all result in a calculated or measured heat flux that is not correct even with a thermally matched sensor. The results of this study supported the conclusions of many previous studies but also examined the complex physics involved across heat flux measurement techniques using new tools, and some general guidance for heat flux sensor design and use, and suggestions for further research are provided. / Ph. D.

This thesis is centered around the computional program PASGO. PASGO is used for calculations for making performance monitoring of the steam generators in Ringhals reactor 3 and 4, especially concerning fouling of the steam generator tubes. The main goal of this thesis project was to convert the program code from the programming language Turbo Pascal 6.0 into a more modern language that works with the current Windows operative systems. Apart from a straight conversion of the code, a function to make automatic input from an Excel-file to the program was also requested. The thesis also includes analyzing the correlations used for heat transfer in PASGO, to determine if these can be replaced with more exact correlations. The Dittus-Boelter correlation was used in the original program, and while it was not a bad correlation, studies show that the more modern Gnielinski correlation has a smaller margin of error. The program code was converted successfully into C++ in Visual Studio, which was the programming language of choice. A function to enable automatic input of data from Excel-files was successfully implemented as well. This function allows the user to run performance calculations regarding tube fouling and pressure correction values for hundreds of performance tests at the same time. Versions of PASGO using the Gnielinski correlation were also created. These versions are recommended for future tests, while the version using the Dittus Boelter correlation is recommended for tests which will be compared to studies made white the previous version of PASGO.