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An experimental setup for liquid jet applications was implemented at the Materials Imaging and Dynamics Instrument (MID) of the European XFEL. This setup is operated in the multi-purpose experimental chamber of MID at pressures down to 10 − 5 mbar. The motion of the nozzle was realized in three dimensions for alignment purposes and the investigation of liquids at different states of supercooling. For this purpose, an active nozzle temperature control is implemented and a catcher system has been installed to capture the liquid after passing the interaction region to maintain good vacuum conditions. The setup is compatible with different nozzle designs. For spill protection, additional housing with secondary pumping around the nozzle, liquid jet and catcher was implemented. A magnifying camera system for aligning the jet and shadow imaging is available. The setup has already been commissioned and operated with different jets and detector configurations.

Viscous effects on an ideal gas flow in a supersonic convergent–divergent nozzle are a well-studied subject in classical gas dynamics. However, the ideal assumption fails on fluids that exhibit complex behaviours such as near-critical-region and non-ideal dense vapours. Under those conditions, a realistic equation of state (EOS) plays a vital role for a precise and realistic computation. This work examines the problem for solving the quasi-one-dimensional viscous compressible flow using a realistic EOS. The governing equations are discretised and solved using the fourth-order Runge–Kutta method coupled with a state-of-the-art EOS to calculate the thermodynamic properties. The role of the Grüneisen parameter along with viscous and real gas effects and their influence on the sonic point formation are discussed. The study shows that the flow may not achieve the supersonic regime for any pressure ratio depending on the combination of that parameter and the normalised friction factor. In addition, the analysis yields the discharge coefficient and the isentropic nozzle efficiency, which may achieve maximum values as a function of the stagnation conditions. Finally, the study also evaluates the formation and intensity of normal shock waves by using the Rankine–Hugoniot relations, which now depend on the real gas and viscous effects in opposition to the inviscid solution. Moreover, the methodology used captures the sonic point and shock wave position by a space marching algorithm using the Brent method for scalar minimisation. Experimental data available in the open literature corroborate the approach.

Numerical analyses, validation and geometric optimization of a converging-diverging nozzle flows has been established in the present work. The optimal nozzle contour for a given nozzle pressure ratio and length yields the largest obtainable thrust for the conditions and thus minimises the losses. Application of such methods reduces the entry cost to the market, promote innovation and accelerate the development processes. A parametric geometry, numerical mesh and simulation model is constructed first to solve the problem. The simulation model is then validated by using experimental and computational data. The optimizations are completed for conical and bell shaped nozzles also to find the suitable nozzle geometries for the given conditions. Results are in good agreement with existing nozzle flow fields. The optimization loop described and implemented here can be used in the all similar situations and can be the basis of an improved nozzle geometry optimization procedure by means of using a multiphysics system to generate the final model with reduced number sampling phases.

In this study, a method for designing supersonic nozzles with axisymmetric plugs at high temperature has been proposed. The approach is based on the theory of Prandtl-Mayer expansion at high temperatures using the method of characteristics. For this purpose, a code in FORTRAN language was developed in order to obtain the nozzle design. Once the latter was obtained, we were interested in the evolution of the thermodynamic parameters of the flow such as pressure, temperature, and Mach number. The results achieved were confronted with those obtained for a perfect gas model. Regarding the design parameters (length, section ratio, thrust coefficient and mass coefficient), we found that the PG model gives very satisfactory results for values of and 0 below 2.00 and 1000 , respectively. As and 0 increase, this affects performance, requiring the use of our HT model to correct the calculations. In order to minimize the weight of this nozzle, this research is investigating the truncation of the Plug nozzle to increase its performances. All calculations were performed for air.

Informed by large-eddy simulation (LES) data and resolvent analysis of the mean flow, we examine the structure of turbulence in jets in the subsonic, transonic and supersonic regimes. Spectral (frequency-space) proper orthogonal decomposition is used to extract energy spectra and decompose the flow into energy-ranked coherent structures. The educed structures are generally well predicted by the resolvent analysis. Over a range of low frequencies and the first few azimuthal mode numbers, these jets exhibit a low-rank response characterized by Kelvin–Helmholtz (KH) type wavepackets associated with the annular shear layer up to the end of the potential core and that are excited by forcing in the very-near-nozzle shear layer. These modes too have been experimentally observed before and predicted by quasi-parallel stability theory and other approximations – they comprise a considerable portion of the total turbulent energy. At still lower frequencies, particularly for the axisymmetric mode, and again at high frequencies for all azimuthal wavenumbers, the response is not low-rank, but consists of a family of similarly amplified modes. These modes, which are primarily active downstream of the potential core, are associated with the Orr mechanism. They occur also as subdominant modes in the range of frequencies dominated by the KH response. Our global analysis helps tie together previous observations based on local spatial stability theory, and explains why quasi-parallel predictions were successful at some frequencies and azimuthal wavenumbers, but failed at others.

Critical flow Venturi nozzles (toroidal, cylindrical, convergent–divergent, or C–D) nozzles) have discharge coefficients predicted through numerical and experimental investigations. Unfortunately, the imprecision of the critical-flow Venturi nozzle design makes it impossible to study the influence of inlet curvature Rc on the discharge coefficient in the laminar boundary layer area. This study examines how the inlet curvature affects the discharge coefficient, or Cd, in the laminar boundary layer area of a critical-flow Venturi nozzle with a cylindrical throat and toroidal shape. The inlet curvature has a range from one throat diameter to three and a half throat diameters. This range of inlet curvatures was obtained by throat the inlet of a high-precision nozzle that was primarily compliant with ISO 9300. The C-D nozzle showed the impact of the convergence angle on the discharge coefficient. The results showed that the highest discharge coefficient occurs at Rc= 2dth for a throat diameter of 0.5588 mm, whereas for dth= 3.175 mm, it occurs at Rc= 2.5dth for toroidal nozzle. For this C-D nozzle, the highest discharge coefficient was observed to occur at a curvature of angle of 10°. Moreover, Cd increases significantly with increase of inlet stagnation pressure but with a small throat diameter.

Altitude-adapted nozzles are designed to facilitate flow adaptation during rocket ascent in the atmosphere, without requiring mechanical activation. As a consequence, the performance of the nozzle is significantly improved. The aim of this study is to develop a new profile of axisymmetric supersonic nozzles adapted at altitude (Dual Bell Nozzle with Central Body), which is characterized by an E-D nozzle as a basic profile. The performances obtained for this nozzle (E-D Nozzle) are then compared to those of a Plug nozzle. The E-D nozzle shows significant performance advantages over the Plug nozzle, including a 13.02% increase in thrust, knowing that the length of the E-D nozzle is half that of the Plug nozzle under the same design conditions. Finally, viscous calculations using the k-ω SST turbulence model were conducted to compare the performance of the dual bell nozzle with central body (DBNCB) and the E-D nozzle with the same cross-sectional ratio, and to assess the impact of nozzle pressure ratio (NPR) variations on the operation mode of the DBNCB. The results obtained show that the DBNCB offers the best performance in most phases of flight.

Melt electrowriting is an additive manufacturing technique utilizing electrohydrodynamic forces to create nano‐ to micro‐scale fibrous polymer objects. It is a useful research tool but has yet to reach commercial scale‐up mainly due to the intrinsically slow nature of extruding a single polymer jet. Here the concept of dual nozzle melts electrowriting requiring no new hardware other than the nozzle is introduced. Experimental data using a dual nozzle shows the possibility of doubling throughput including the phenomenon of semi‐woven structures with fibers from one nozzle either on top or under the fiber from the other nozzle depending on programmed collector movement. The study highlights the complexity of melt electrowriting when using more than one nozzle, and provides a framework for multi‐nozzle, high‐throughput melt electrowriting. Melt electrowriting is an emerging additive manufacturing method for making fibrous polymer scaffolds with extremely large porosity. A limitation, however, is the low throughput thereby hindering upscaling. Here a dual nozzle concept to double throughput and create semi‐woven scaffolds is introduced. Looking to the future, guidance on how to extend the approach to multi‐nozzles is produced.

Fungicide application technology to control soybean rust (SBR) is lacking and requires optimization to improve spray coverage in the lower part of the crop canopy as well as the spray distribution uniformity. The goal of this study was to evaluate the effects of flat fan nozzles with different angles and spray volumes on the optimization of fungicide application in soybean, as well as on SBR and its effect on crop yield. For this purpose, a 2-year (2016–2018) field experiment was conducted in Botucatu, SP, Brazil. Three spray nozzles were evaluated: flat fan, double flat fan and angled flat fan, with two spray volumes. A quantitative analysis of the spray deposition was conducted, assessing the spray deposits on the lower and upper part of the plants with Brilliant Blue tracer. Furthermore, SBR severity was evaluated based on the number of pustules cm−2 and on the AUDPC, as well as the establishment of treatment control efficacy and its effect on soybean yield. Irrespective of the spray nozzles and volumes, the penetration of the droplets into the crop canopy was impaired at the reproductive stage, with less deposition in the lower part of the plant, although the larger spray volume provided greater spray deposition. All the treatments promoted effective control of the disease, with no changes in efficacy due to a larger spray volume or angled nozzles. The correct spray volume, especially with respect to the different growth stages, greatly influences spray deposition and penetration.

There is growing interest in voxelated matter that is designed and fabricated voxel by voxel 1 – 4 . Currently, inkjet-based three-dimensional (3D) printing is the only widely adopted method that is capable of creating 3D voxelated materials with high precision 1 – 4 , but the physics of droplet formation requires the use of low-viscosity inks to ensure successful printing 5 . By contrast, direct ink writing, an extrusion-based 3D printing method, is capable of patterning a much broader range of materials 6 – 13 . However, it is difficult to generate multimaterial voxelated matter by extruding monolithic cylindrical filaments in a layer-by-layer manner. Here we report the design and fabrication of voxelated soft matter using multimaterial multinozzle 3D (MM3D) printing, in which the composition, function and structure of the materials are programmed at the voxel scale. Our MM3D printheads exploit the diode-like behaviour that arises when multiple viscoelastic materials converge at a junction to enable seamless, high-frequency switching between up to eight different materials to create voxels with a volume approaching that of the nozzle diameter cubed. As exemplars, we fabricate a Miura origami pattern 14 and a millipede-like soft robot that locomotes by co-printing multiple epoxy and silicone elastomer inks of stiffness varying by several orders of magnitude. Our method substantially broadens the palette of voxelated materials that can be designed and manufactured in complex motifs. Voxelated soft matter is designed and fabricated using multimaterial multinozzle three-dimensional printing, which switches between different viscoelastic inks along the same print filament to print multiple materials simultaneously.