Use of X-Ray Radiography for Measuring Mass Distributions of Rocket Injectors.

摘要

Current limitations in available data and computational tools have led to an on-going reliance on experimental measurements for injector design. Unfortunately, the mass flow rates typically encountered in rocket engines create sprays with high optical densities and render the vast majority of optical and laser techniques ineffective. Data has been obtainable through mechanical patternation, but the technique has limitations especially near the injector. Time-gated ballistic imaging has also shown promise in rocket injectors but produces only qualitative information about the mass flux. An x- ray radiographic technique with a high-power x-ray source (the Advanced Photon Source at Argonne National Laboratory) has been applied to these high-optical- density sprays. To achieve this testing a mobile flow facility was constructed; this facility simulates the rocket flows using water and nitrogen instead of fuel and oxidizer. The x-ray radiography technique can be applied in two ways. Time-averaged measurements provide information related to the mass flux and droplet velocity while time-resolved measurements have the ability to provide droplet size and velocity distributions. Both techniques have been applied to a specific injector type of interest in rocket propulsion, a gas-centered swirl-coaxial injector, and the results are used to show the complexities and strengths of x-ray radiography and illustrate the types of useful information that can be extracted, information that will aid in the development and improvement of rocket injectors.