LUMEN Demonstrator - Project Overview

The DLR project LUMEN (liquid upper stage demonstrator engine) aims at developing and operating a modular LOX/LNG bread-board engine in the 25 kN thrust class for operation at the new P8.3 test facility in Lampoldshausen[1, 2]. The main focus of this project is to strengthen DLR's competence on rocket engine system level as well as to enable tests of new components in a representative system environment. This article gives an overview of the background of the LUMEN project. The planned bread-board engine is described and the reasoning behind propellant selection, choice of the expander-bleed scheme as the engine cycle layout and selection of technologies for key engine components is explained

Liquid Upper Stage Demonstrator Engine (LUMEN): Component Test Results and Project Progress

With the LUMEN (Liquid upper stage demonstrator engine) project, DLR is aiming to develop, build and operate a breadboard engine based on an expander bleed cycle scheme. The propellants for LUMEN will be liquid oxygen (LOX) and liquid natural gas (LNG). LUMEN will be a modular breadboard engine to be used on DLR test benches such as the P8.3 test facility. The modular approach will make it easy to take the engine of the test bench, exchange components and go testing again. This way the demonstrator will provide a test bed for future component development. The cycle will feature two turbopumps in order to simplify the turbopump design, while on the same time allowing more freedom for an exchange of components. By this approach the DLR will create a test bed for component research on engine level, open to any industrial or institutional partner. There have been several test campaigns before final assembly can take place. The combustor tests included a calorimetric combustor to obtain the heat load distribution by the combustion of LOX and LNG which determines the cooling channel design of the thrust chamber assembly (TCA). After this campaign the newly manufactured regeneratively cooled TCA tests will take place which will determine the turbines drive power. This is a crucial step, since LUMEN is an expander bleed cycle engine and hence it relies solely on the heat pickup in the TCA cooling channels. In parallel to the combustor tests a turbopump test campaign with the OTP was performed with water on the pump side and pressurized nitrogen on the turbine side. The campaign has been completed successfully and the operational envelope of the OTP has been confirmed. After that a cryogenic test campaign took place at the DLR test bench P8.3. The OTP was installed in the same configuration as in the engine tests of LUMEN and it was run for the first time in cryogenic fluids. The test campaign was successful proving the operation of the OTP in LOX. Especially the unconventional oil lubrication system of the LUMEN OTP worked without an issue and as expected. The thermal design of the turbopump was verified and the operation procedures in cryogenic environment were tested and refined. The next and final step in turbopump development will be cryogenic tests of the FTP. When the combustor and turbopump tests are completed, final assembly of LUMEN will start with first tests on engine level expected to take place in 202

Highly unsaturated fatty acid synthesis in marine fish: Cloning, functional characterization, and nutritional regulation of fatty acyl delta6 desaturase of Atlantic cod (Gadus morhua L.)

Fish contain high levels of the n-3 highly unsaturated fatty acids (HUFA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids that are crucial to the health of higher vertebrates. Biosynthesis of HUFA requires enzyme-mediated desaturation of fatty acids. Here we report cloning and functional characterisation of a ∆6 fatty acyl desaturase of Atlantic cod (Gadus morhua), and describe its tissue expression and nutritional regulation. PCR primers were designed based on the sequences of conserved motifs in available fish desaturases and used to isolate a cDNA fragment from liver of cod. The full-length cDNA was obtained by Rapid Amplification of cDNA Ends (RACE). The cDNA for the putative fatty acyl desaturase was shown to comprise 1980bp which included a 5’-UTR of 261bp and a 3’-UTR of 375bp. Sequencing revealed that the cDNA included an ORF of 1344 bp that specified a protein of 447 amino acids. The protein sequence included three histidine boxes, two transmembrane regions, and an N-terminal cytochrome b5 domain containing the haem-binding motif HPGG, all of which are characteristic of microsomal fatty acid desaturases. The cDNA displayed Δ6 desaturase activity in a heterologous yeast expression system. Quantitative real time PCR assay of gene expression in cod showed that the ∆6 desaturase gene, was highly expressed in brain, relatively highly expressed in liver, kidney, intestine, red muscle and gill, and expressed at much lower levels in white muscle, spleen and heart. In contrast, the abundance of a cod fatty acyl elongase transcript was high in brain and gill, with intermediate levels in kidney, spleen, intestine and heart, and relatively low expression in liver. The expression of the Δ6 desaturase gene and the PUFA elongase gene may be under a degree of nutritional regulation, with levels being marginally increased in livers and intestine of fish fed a vegetable oil blend by comparison with levels in fish fed fish oil. However, this was not reflected in increased Δ6 desaturase activity in hepatocytes or enterocytes, which showed very little highly unsaturated fatty acid biosynthesis activity irrespective of diet. The study described has demonstrated that Atlantic cod express a fatty acid desaturase gene with functional Δ6 activity in a yeast expression system. This is consistent with an established hypothesis that the poor ability of marine fish to synthesise HUFA is not due to lack of a Δ6 desaturase, but rather to deficiencies in other parts of the biosynthetic pathway. However, further studies are required to determine why the Δ6 desaturase appears to be barely functional in cod under the conditions tested

AUFBAU FÜR EXPERIMENTELLE UNTERSUCHUNGEN TRANSPIRATIV GEKÜHLTER STAUSTRAHLANTRIEBE

Weltweit wird zunehmend an alternativen, nachhaltigen und effizienten Antriebssystemen für Luft- und Raumfahrtanwendungen geforscht. Dabei wird ein Fokus auch auf die Staustrahltriebwerke mit Überschallverbrennung, sogenannte Supersonic Combustion Ramjets (SCRamjets), gelegt. Eine Herausforderung dieser Antriebssysteme liegt, neben der kurzen Aufenthaltsdauer des Brennstoffs in der Brennkammer, insbesondere bei deren effizienten und ausreichenden Kühlung. Ein vielversprechendes Kühlverfahren für solch thermisch hochbelastete Triebwerke stellt dabei die sogenannte Transpirationskühlung dar. Bei diesem Verfahren strömt Kühlfluid mit einem Phasenübergang zwischen flüssig und gasförmig aus einer porösen Wand in die Heißgasströmung des Triebwerks ein. Durch eine Anwendung der Transpirationskühlung wäre eine besonders gleichmäßige und flächige Verteilung des Kühlfluids in den Bereichen höchster thermischer Belastung bei gleichzeitig niedrigen Temperaturen in der Triebwerksstruktur erreichbar. Das Institut für Raumfahrtantriebe des DLR in Lampoldshausen baut zurzeit einen Prüfstand für Strömungsuntersuchungen an einem transpirativ gekühlten SCRamjet-Forschungskanal mit Grenzschichtverbrennung auf. Sowohl der Prüfstand, als auch der Forschungskanal werden im Detail vorgestellt und zukünftiger Forschungsbedarf wird konkretisiert

Predicting Flashing Phenomena: A Combined Approach of Numerical Simulation and Experiments

The German Aerospace Center (DLR) in Lampoldshausen is investigating new methods for injection and ignition of new green propellants at near vacuum conditions. In this case the focus is on energetic ionic liquids (EIL) based on ammonium dinitramide (ADN). These are thought to be promising substitutes for hydrazine. During the experimental campaign with di�erent transparent injectors (L/D, contraction ratio, nozzle length), nucleation en- hancing internal low regimes like cavitation and even hydraulic ip were detected. The latter two most likely lead to segregation of the propellants and crystallization of the solved ADN-salt. To predict and avoid these phenomena, test cases were repeated with ANSYS® CFX 15.0 and compared to the experimental data

Sorption of Highly Hydrophobic Organic Chemicals to Organic Matter Relevant for Fish Bioconcentration Studies

With regard to a potential underestimation of bioconcentration factors (BCF) in flow-through fish tests, sorption of 11 highly hydrophobic organic chemicals (HOCs) (log KOW 5.5-7.8) from different substance classes was systematically investigated for the first time in the presence of fish feed (FF) and filter residues (FR), the organic matter (OM) most relevant for fish bioconcentration studies. Sorption was investigated in batch-equilibrium experiments by solid-phase microextraction (SPME) resulting in partitioning coefficients of solid-water (Kd), total organic carbon-water (KTOC), and dissolved organic carbon-water (KDOC). Results prove a high affinity of HOCs for FF and FR supporting a significant impact on BCF studies and differing from sorption to Aldrich-humic acid (AHA) utilized as reference sorbent. Sorption is influenced by interactions between HOCs and OM characteristics