Erosion of tungsten marker layers in W7-X

In order to get first insight into net tungsten erosion in W7-X, tungsten (W) marker layers were exposed during the operational phase OP 1.2b at one position of the Test Divertor Unit (TDU), at 21 different positions of the inner heat shield, and at two scraper elements. The maximum tungsten erosion rate at the TDU strike line was 0.13 nm/s averaged over the whole campaign. The erosion was inhomogeneous on a microscopic scale, with higher erosion on ridges of the rough surface inclined towards the plasma and deposition of hydrocarbon layers in the recessed areas of the rough surface. The W erosion at the inner heat shield was below the detection limit of 3 – 6x1012 W-atoms/cm2s, and all inner heat shield tiles were covered with a thin B/C/O layer with thickness in the range 2x1017 – 1018 B + C atoms/cm2 (about 20 – 100 nm B + C). W-erosion of the marker layers on the scraper elements was also below the detection limit.

Characterization of Spatter and Sublimation in Alloy 718 during Electron Beam Melting

Due to elevated temperatures and high vacuum levels in electron beam melting (EBM), spatter formation and accumulation in the feedstock powder, and sublimation of alloying elements from the base feedstock powder can affect the feedstock powder’s reusability and change the alloy composition of fabricated parts. This study focused on the experimental and thermodynamic analysis of spatter particles generated in EBM, and analyzed sublimating alloying elements from Alloy 718 during EBM. Heat shields obtained after processing Alloy 718 in an Arcam A2X plus machine were analyzed to evaluate the spatters and metal condensate. Comprehensive morphological, microstructural, and chemical analyses were performed using scanning electron microscopy (SEM), focused ion beam (FIB), and energy dispersive spectroscopy (EDS). The morphological analysis showed that the area coverage of heat shields by spatter increased from top (<1%) to bottom (>25%), indicating that the spatter particles had projectile trajectories. Similarly, the metal condensate had a higher thickness of ~50 μm toward the bottom of the heat shield, indicating more significant condensation of metal vapors at the bottom. Microstructural analysis of spatters highlighted that the surfaces of spatter particles sampled from the heat shields were also covered with condensate, and the thickness of the deposited condensate depended on the time of landing of spatter particles on the heat shield during the build. The chemical analysis showed that the spatter particles had 17-fold higher oxygen content than virgin powder used in the build. Analysis of the metalized layer indicated that it was formed by oxidized metal condensate and was significantly enriched with Cr due to its higher vapor pressure under EBM conditions.

LOW THERMAL CONDUCTIVITY COMPOSITE SKIN MATERIALS

Triton Systems, Inc. and our academic partner University of Dayton Research Institute (UDRI) developed and demonstrated a lightweight, affordable composite heat shield sandwich panel for aerospace applications capable of protecting an underlying Polymer Matrix Composite (PMC) sandwich panel from 500℉ external impingement. Our design outperforms the incumbent heat shield, a bolt-on metallic sheet with an air gap, in both thermal protection (15% lower skin surface temperature) and weight (40% lighter) at an equivalent thickness (about 0.3”). Our panel has very low thermal conductivity (0.08 W/mK) but is also impact resistant, strong (~300 psi flatwise tensile strength), and tolerant to typical aerospace environmental conditions. Additionally, we demonstrated that our design could be produced as a curved panel configuration to match vehicle outer mold lines (OML’s). Now at Technology Readiness Level (TRL) 4, Triton’s panel design is ready to move to the next stage of development which we envision to be additional proof-of-concept testing including chemical and additional environmental exposure, cold exposure, thermal shock, and vibration as we scale up to a larger 4’x8’ panel. STEVE SCHOENHOLTZ

Effects of Bypass Flow Distribution on Cold Flow Characteristics of Integrated Afterburner

Integrated design is a trend in the development of afterburners, and the distribution of cold flow is directly related to their flow field characteristics, combustion organization, and the cooling effect of components. Numerical simulations were performed to illustrate the effects of bypass flow distribution on the flow distribution, mixing characteristics, and cooling efficiency of the components by varying the cooling flow path structure parameters. Within the range of parameters in this study, it can be indicated that with the increase of heat shield inlet height and afterburner annulus height, the total pressure recovery coefficient along the path increased accordingly, and the increasing rate at the afterburner outlet is 1.12% and 1.19%, respectively. The average cooling efficiency of radial flameholder, circumferential flameholder, and fuel injector all decrease, but the rate of decrease varies slightly depending on the location of the components. The increase of heat shield inlet height would reduce thermal mixing efficiency by approximately 5.4% at the afterburner outlet, and the increase of afterburner annular height would increase about 2.9%.

CREATION OF MATHEMATICAL MODELS FOR PARAMETRIC IDENTIFICATION DURING TESTS TO DETERMINE THE FUEL CONSUMPTION OF THE HELICOPTER WITH EXHAUST- HEAT SHIELDS

With the increasing effectiveness of guided missile weapons, the problem of protecting helicopters from these means of destruction is becoming increasingly important. To date, the issue of assessing the protection of helicopters in tests of helicopter equipment are insufficiently developed and require more careful consideration. Therefore, the research of the protection of helicopters equipped with an integrated protection system against guided missiles with infra-red target seeker devices and the impact of exhaust-heat shields on the values of flight characteristics of the helicopter is quite relevant. The article researches the influence of exhaust-heat shields on the flight technical characteristics of helicopters, their change during the installation of exhaust-heat shields. The estimation of the change in geometric, mass and center characteristics of helicopters by the calculation method is given and the method determining the characteristics of fuel consumption by the calculation and experimental method is given. The methodology and results of experimental researches of flight technical characteristics of the helicopter with the established exhaust-heat shield are described. The basic result of the research is the study of existing methods for determining the impact of exhaust-heat shields on the flight characteristics of helicopters. Methods of parametric identification for determination of fuel consumption are worked out and the analysis of flight technical characteristics of the helicopter is developed. The fuel consumption of the helicopter with exhaust-heat shield is defined. Integrated assessment of the effectiveness of protection of helicopters from guided missiles with infra-red targeting device can be directly used in practice in test systems for the protection of upgraded and the latest models of helicopters. According to the results of research, mathematical models for determining the fuel consumption of a helicopter with exhaust-heat shields have been developed.