Date of Award
Master of Science in Engineering (MSE)
Mechanical and Aerospace Engineering
Robert A. Frederick Jr.
Liquid propellant rockets--Combustion, Spray combustion, Atomization, Injectors--Design and construction
Liquid rocket engines sometimes use jet impinging injection streams to atomize liquid fuels and oxidizers in the combustion chamber. The work examines the effect of injector steam velocity, injection angles, and injection stream misalignment on the resulting sheet angles and sheet breakup lengths for like-double injectors. A set of cold flow, water simulant experiments at atmospheric pressure were conducted at three different geometric conditions. Angularly skewed impingement conditions investigated nine impingement angles from 30° to 90° with each injector having identical or different impingement lengths. Linearly-skewed impingement conditions included a set of five offsets where the impingement length of the first injector was different from the second by 0 in, 0.5 in, 1 in, 1.5 in, and 2 in. Partial impingement conditions included alignment offsets in the injection plane of +0.0138 in, 0 in, and -0.0138 in. All these conditions were tested for two jet velocity conditions (49.21 ft/s and 82.02 ft/s) for the 0.04 in diameter jets. A Phantom V711 highspeed camera captured spray images at 10,000 frames per second. Phantom Cine Viewer software algorithms were tailored to estimate the spray sheet angles. MATLAB image processing tools were tailored to determine the sheet breakup lengths. Increased impingement angles resulted in increased spray sheet angles from 40° to 110° and decreased spray sheet breakup lengths from 2.16 in to 1.15 in. Sheet angles are relatively more sensitive and sheet breakup lengths are relatively less sensitive at angles of impingement between 55° to 65°. The jet velocities and y-offsets affect the visual sheet characteristics. Narrow sheets with diagonal ligaments are formed for the partial jet impingements and this results in the decreased sheet angles, and the increased sheet breakup lengths. The results of these experiments can be used as preliminary data for further hot firing tests, for comparison with numerical predictions, and the results show the possible effects of manufacturing inaccuracy on the spray patterns for the conditions investigated.
Kathalagiri Vasantha kumar, Swarnalatha, "Experimental investigation of spray characteristics for different geometrical misalignment cases of like doublet impinging injectors" (2020). Theses. 468.