Rocket Wake Flow Interaction Testing in the Hot Plume Testing Facility (HPTF) Cologne

Abstract

Rocket wake flows were under investigation within the Collaborative Research Centre SFB/TRR40 since the year 2009. The current paper summarizes the work conducted during its third and final funding period from 2017 to 2020. During that phase, focus was laid on establishing a new test environment at the German Aerospace Center (DLR) Cologne in order to improve the similarity of experimental rocket wake flow–jet interaction testing by utilizing hydrogen–oxygen combustion implemented into the wind tunnel model. The new facility was characterized during tests with the rocket combustor model HOC1 in static environment. The tests were conducted under relevant operating conditions to demonstrate the design’s suitability. During the first wind tunnel tests, interaction of subsonic ambient flow at Mach 0.8 with a hot exhaust jet of approx. 920 K was compared to previously investigated cold plume interaction tests using pressurized air at ambient temperature. The comparison revealed significant differences in the dynamic response of the wake flow field on the different types of exhaust plume simulation.

Plume and wall temperature impact on the subsonic aft-body flow of a generic space launcher geometry

“…For the cold gas interaction tests, the enclosed high-pressure air supply operates up to a maximum pressure of 150 bar. The GH2/GO2 supply facility (Kirchheck and Gülhan 2016) was built primarily to feed wind tunnel models including integrated combustion chambers in order to provide more realistic jet composition and jet stagnation conditions during wind tunnel testing. It consists of a 300 bar gas storage and a control station employing a closed loop mass flow controller.…”

“…The thrust nozzle is a 5°half-angle conical nozzle with expansion ratio ε = 5.6298. The outer model dimensions are similar to previous investigations by Saile et al (2019b, details on the design are provided in Kirchheck et al (2019).…”

“…Unsteady pressure sensors from Kulite ® Semiconductors Inc. were placed on the base plane of the backward-facing step with a recess of 0.5 mm (XCQ-080) and in the combustion chamber with a transmission length of 52.77 mm (XCE-062). They were sampled at 100 kHz and 10 kHz respectively in order to capture the relevant wake flow and chamber modes (see Kirchheck et al 2019, for an assessment of the prevailing frequencies). Particle Image Velocimetry (PIV) was applied in the near-wake using a 532 nm laser with an image acquisition rate of 16 Hz.…”

“…Since 2008, aft-body flows of space launch vehicles in various flow regimes have been investigated on generic launcher configurations within the frame of the Collaborative Research Centre (SFB) Transregio 40 (TRR40) (Haidn et al 2018;Adams et al 2021). Since 2016, one of the key interests has been laid in the interaction of the high subsonic ambient freestream with the supersonic overexpanded propulsive jet during the ascent phase of a launcher.…”

“…In order to improve the knowledge on their driving mechanisms and consequently enhance predictability of qualitative and quantitative loads for future launcher design, these effects have been studied at the German Aerospace Center (DLR). It was achieved through a complementary experimental and numerical approach on a generic Ariane 5 geometry, using ambient temperature air (denoted 'cold') and hot gas generated from the combustion of gaseous hydrogen (GH2) and gaseous oxygen (GO2) for the exhaust jet (Kirchheck et al 2021;Schumann et al 2021a).…”