Status of the Vinci Combustion Chamber Vacuum Ignition Tests

Abstract

In the frame of the Vinci Thrust Chamber development program, a significant milestone has been achieved with the ignition tests. More than 50 tests were performed which could be evaluated, under all possible boundary conditions for the injector (i.e. H2-and LOX-inlet pressures and temperatures, various GHe-purge flowrates, LOX-valve opening strokes, vacuum conditions, etc.), and the igniter torch. The results are highly valuable, and the ignition quality in the combustion chamber was always very smooth. One of the prime goals of these tests was also to search for perhaps a lower ignition limit, below which no ignition occurs anymore. However, this limit was not found! HE Vinci Combustion Chamber (CC) and engine are designed to ignite and start with a H2-lead sequence; i.e. the H2 fuel flows through the injector and the chamber before the oxidizer valve is opened. The injected O2 leads immediately to a combustible O2/H2 mixture in the combustion chamber which is then ignited by the hot gases supplied by a torch igniter. The igniter itself is an electric torch which is fed by gaseous O2 and H2, which are stored under a pressure of about 200 bar (~ 2900 psia), and which operates in a blow-down mode. The system is designed to allow five ignitions, and under orbital conditions. Some previous papers have already gone into the design details of the igniter blow-down system, and will not be repeated here. 1, 2, 3 Two CC ignition campaigns were performed. The first campaign with nine tests, was basically used for screening purposes. These tests were performed with a Battleship Igniter (BSI) whose function and performance is identical with the current Engineering Model Igniter (EMI). The EMI is an improved design, and has completed its development tests at SPE Stork Product Engineering B.V. in the Netherlands with no problems. The EMI was used in the last part of the second test campaign. The second campaign was used basically to investigate the extreme margins and limits of ignition for the CC, and the igniter torch. The CC was capacitively cooled, which was adequate for the relatively short combustion time of not more than about 1 s, and with the low expected chamber pressures of 1.5 bars; the main objective was only to detect if CC ignition had taken place, and to verify that combustion was taking place and the chamber was truly running.