In situ burning-rate determination using flash radiography
Abstract
A hybrid method for non-intrusive, in situ burning rate measurements in solid propellant rocket motors that combines the temporal continuity of the indirect method (employment of measured pressure and thrust data to predict detailed internal phenomena through a model of the internal processes) and the direct, time mean but spatially resolved measurements of the radiographic approach was developed and employed. Results indicate that the technique can determine propellant burning-rates within approximately 3.0%. Significant enhancements were made to the radiographic method by utilizing all of the radiograph's information (not just the edges). Detailed modeling of the flash x-ray process and digitized film-density data were employed to predict motor-port area versus length from each flash radiograph. Since port-area differences in sequential radiographs are directly proportional to the local time mean, circumferentially averaged mass burning-rate, these data are completely compatible with requirements of the indirect method's internal ballistics model. Details of the development and use of the cineradiography technique, Flash X-ray Process computer model, and unique internal ballistics program are presented. Also presented are data from the six small (2.2 $\times$ 6 in), graphite cased, internal burning rocket motors that were fired to collect performance and radiographic data for this research. These motors had two port sizes and four different throat diameters to vary the amount of erosive burning. Data from these motors are thoroughly reviewed for consistency. As a result, data from one motor were rejected because of an apparently malfunctioning microdensitometer. Results show computations of pre-fired port-areas are within 2.5% of measured values, computed base burning-rate expression parameters are within 1.2% of known values, and computer burning-rate values are within 3.2% of estimated values.
Degree
Ph.D.
Advisors
Osborn, Purdue University.
Subject Area
Aerospace materials
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