Design and Test of Sub Scaled Motor for Evaluation of Pressure Oscillations

Evaluation of pressure oscillation of solid rocket motors in actual conditions requires static tests. These test have a large application in evaluation of motor various parameters effect on its operation. Using of these tests are very limited due to their high costs and so, evaluation of various parameters is nearly impossible. To solve this problem, sub scaled solid rocket motor must be designed. In this paper, designing process of space shuttle sub scaled solid boosters, called 1881, with scale 1:31 has been proposed. Space shuttle and ariane 5 boosters have been argued to modeling and simulation. Sub scaled motor modeling and design parameters using Buckingham’s Pi theorem and then, operation and dimensional properties have been presented. Three tests for evaluation of designed motor were done successfully and pressure and thrust history and its oscillations have been evaluated. Results show that for facility of fitting and reduction of test cost in subscale motors, using of Tan-Cu in throat instead of graphite and flange design of joints are very useful. Despite of using Buckingham’s Pi theorem in solid motor scaling, propellant chemistry and its burning rate are affected of Crawford bomb and real flow of combustion products and in many case, error correction between Crawford and motor data is inevitable. On the other hand, existence of empty volume in forward segments and others, plays an important role in pressure oscillations and after end of burning or reducing, oscillations will be uniform.