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Schematic drawing of nozzles design concept. The previously sharpened glass capillary is fitted in the ceramic body (which comprises here the blue body as well as the alignment bearings) made by CIM. As the axial view (right) shows there is still enough space for a proper gas flow
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Serial crystallography experiments at X-ray free-electron lasers can utilize specially designed ceramic nozzles to generate a strongly focused liquid jet of sample. Several nozzle design options have been evaluated and a concept using a sharpened glass capillary mounted in a self-centering ceramic nozzles is detailed. Filling simulations and tool c...
Citations
... Concerning the features of the design of modern ejection systems that are operated under aggressive conditions, some authors suggest the use metallic ceramics or ceramic coatings to provide the required operational life of the nozzle [60][61][62]. Recommendations have been made on the technology of forming, optimal design and calculation of the operational properties of single layer [63,64], flexible [65,66] or multilayer ceramic coatings [67][68][69]. Thermoplastic composite materials are also widely used [70][71][72][73]. ...
During oil fields operation, gas is extracted along with oil. In this article it is suggested to use jet pumps for utilization of the associated oil gas, burning of which causes environmental degradation and poses a potential threat to the human body. In order to determine the possibility of simultaneous application of a sucker-rod pump, which is driven by a rocking machine, and a jet pump (ejector) in the oil well, it is necessary to estimate the distribution of pressure along the borehole from the bottomhole to the mouth for two cases: when the well is operated only be the sucker-rod pump and while additional installation of the oil-gas jet pump above its dynamic level. For this purpose, commonly known methods of Poettman-Carpenter and Baksendel were used. In addition, the equations of high-pressure and low-pressure oil-gas jet pumps were obtained for the case, when the working stream of the jet pump is a gas-oil production mixture and the injected stream is a gas from the annulus of the well. The values which are included in the resulting equations are interrelated and can only be found in a certain sequence. Therefore, a special methodology has been developed for the practical usage of these equations in order to calculate the working parameters of a jet pump based on the given independent working parameters of the oil well. Using this methodology, which was implemented in computer programs, many operating parameters were calculated both for the well and for the jet pump itself (pressures, densities of working, injected and mixed flows, flow velocities and other parameters in control sections). According to the results of calculations, graphs were built that indicate a number of regularities during the oil well operation with such a jet pump. The main result of the performed research is a recommendation list on the choice of the oil-gas jet pump location inside the selected oil well and generalization of the principles for choosing the perfect location of such ejectors for other wells. The novelty of the proposed study lays in a systematic approach to rod pump and our patented ejector pump operation in the oil and chrome plating of pump parts. The result of scientific research is a sound method of determining the rational location of the ejector in the oil well and the calculation of its geometry, which will provide a complete selection of petroleum gas released into the annulus of the oil well. To ensure reliable operation of jet and plunger pumps in oil wells, it is proposed to use reinforcement of parts (bushings, plungers, rods, etc.) by electrochemical chromium plating in a flowing electrolyte. This has significantly increased the wear resistance and corrosion resistance of the operational surfaces of these parts and, accordingly, the service life of the pumps. Such measures will contribute to oil production intensification from wells and improve the environmental condition of oil fields.
... Compared with diaphragm pumps, this pump type is usually large. Nevertheless, based on improved manufacturing methods, such as micro injection moulding [93][94][95], miniaturization is pushed. ...
There is an increasing amount of research on microfluidic actuators with the aim to improve drug dosing applications. Micropumps are promising as they reduce the size and energy consumption of dosing concepts and enable new therapies. Even though there are evident advantages, there are only few examples of industrial microdosing units and micropump technology has not yet found widespread application. To answer the evoked question of what limits the application of microdosing technology for drug delivery, this work provides a comprehensive insight into the subject of drug delivery. We highlight and analyse specific microfluidic challenges and requirements in medical dosing: safety relevant aspects, such as prevention of free flow and backflow; dosing-specific requirements, such as dosing precision and stability; and system-specific aspects, such as size, weight, and power restrictions or economic aspects. Based on these requirements, we evaluate the suitability of different mechanical micropumps and actuation mechanisms for drug administration. In addition to research work, we present industrial microdosing systems that are commercially available or close to market release. We then summarize outstanding technical solutions that ensure sufficient fluidic performance, guarantee a safe use, and fulfil the specific requirements of medical microdosing.
... In SFX, the jet is usually generated by aerodynamically focusing (Gañán-Calvo, 1998;DePonte et al., 2008;Zahoor et al., 2018) a liquid stream with a GDVN-like ejector. The production of long and thin jets imposes severe constraints on the geometrical design of issuing nozzles (DePonte et al., 2008;Beyerlein et al., 2015;Piotter et al., 2018;Wiedorn et al., 2018). ...
We study both theoretically and experimentally the whipping instability in axisymmetric gaseous flow focusing realized in a converging-diverging nozzle. The lateral oscillation of both the tapering meniscus and emitted jet is explained in terms of the global linear instability of the lateral mode with the azimuthal number m=1. A comparison with previous experiments shows good agreement. The distance between the feeding capillary and the nozzle neck hardly affects the m=1 stability limit for the conditions considered in those experiments. We analyze the influence of the nozzle shape on the parameter conditions leading to whipping. As the nozzle convergence rate (the inverse of the length over which the diameter reduction takes place) increases, the flow becomes more stable under m=1 perturbations. The above results are in marked contrast with those of the axisymmetric mode m=0. For the axisymmetric mode, the minimum flow rate increases with the nozzle convergence rate, while the capillary-to-neck distance has considerable influence on the jetting-to-dripping transition. We also conduct experiments with different nozzles and capillary-to-neck distances to examine the effect of those factors on the stability of the jetting regime. The experiments allow us to distinguish between absolute whipping, in which both the tapering meniscus and the emitted jet oscillate, and convective whipping, in which the jet oscillates while the meniscus remains practically steady. Absolute whipping is observed for water and 1-cSt silicone oil focused with the nozzle with the smallest convergence rate and capillary-to-neck distance. The increase of the liquid viscosity stabilizes the liquid meniscus, producing the transition from absolute to convective whipping. In the high-viscosity case, the oscillation of the emitted jet far away from the discharge orifice is considerably affected by the shape of the nozzle in front of its neck. In fact, the increase of the convergence rate and capillary-to-neck distance eliminates the convective whipping as well. The reduction of surface tension enhances absolute whipping. We explain the appearance of the two types of whipping in terms of the flow pattern induced by the nozzle shape in front of the neck.
... These so called gas dynamic virtual nozzles (GDVNs), prepared initially from glass, were later replaced by ceramic injection moulded GDVNs (Beyerlein et al., 2015). To overcome the axial alignment issues, (Piotter et al., 2017) introduced self-centring injection moulded nozzles and Nelson et al. (2016) introduced 3D printed nozzles. The new additive manufacturing approach enables extreme flexibility in the design, high manufacturing precision, reproducibility and minimal manual effort for nozzle assembly. ...
In this paper we present a numerical study on the influence of liquid properties on gas-focused micro-jets, such as used for sample delivery in serial femtosecond crystallography. The study is based on solving mixture formulation of Newtonian, compressible two-phase model with the finite volume method and algebraic volume of fluid for treatment of the phase-interface. The density, viscosity and surface tension of the focused fluid span around the material properties of pure water in the range of ±30%, thus representing a large range of possible sample delivery fluids. Fixed liquid and helium gas flow rates are used for jet focusing and the length, diameter, velocity and temperature of the jet are assessed as a function of material properties of the liquid. A thicker and slower jet is observed in case of increased density and surface tension of the focused fluid, while change in liquid viscosity has no effect on flow characteristics. This study expands previous work on experimental validation of the model: influence of operating parameters (Zahoor et al., 2018a), nozzle geometry (Zahoor et al. 2018b) and types of focusing gas (Zahoor et al. 2018c) on the liquid jet behaviour and thus provides a complete computational fluid dynamics insight into jet production.
... These so called gas dynamic virtual nozzles (GDVNs), prepared initially from glass, were later replaced by ceramic injection moulded GDVNs (Beyerlein et al., 2015). To overcome the axial alignment issues, (Piotter et al., 2017) introduced self-centring injection moulded nozzles and Nelson et al. (2016) introduced 3D printed nozzles. The new additive manufacturing approach enables extreme flexibility in the design, high manufacturing precision, reproducibility and minimal manual effort for nozzle assembly. ...
... However, such nozzles are still prone to misalignment of the inner capillary that is centered using small photo-etched spacers. Further improvements include self-centered micro-injectionmolded ceramic nozzles (Piotter et al. 2017) and 3D-printed nozzles (Nelson et al. 2016). ...
We present the development of an experimentally validated computational fluid dynamics model for liquid micro jets. Such jets are produced by focusing hydrodynamic momentum from a co-flowing sheath of gas on a liquid stream in a nozzle. The numerical model based on laminar two-phase, Newtonian, compressible Navier–Stokes equations is solved with finite volume method, where the phase interface is treated by the volume of fluid approach. A mixture model of the two-phase system is solved in axisymmetry using ~ 300,000 finite volumes, while ensuring mesh independence with the finite volumes of the size 0.25 µm in the vicinity of the jet and drops. The numerical model is evaluated by comparing jet diameters and jet lengths obtained experimentally and from scaling analysis. They are not affected by the strong temperature and viscosity changes in the focusing gas while expanding at nozzle outlet. A range of gas and liquid-operating parameters is investigated numerically to understand their influence on the jet performance. The study is performed for gas and liquid Reynolds numbers in the range 17–1222 and 110–215, and Weber numbers in the range 3–320, respectively. A reasonably good agreement between experimental and scaling results is found for the range of operating parameters never tackled before. This study provides a basis for further computational designs as well as adjustments of the operating conditions for specific liquids and gases.
... Such a nozzle is also knows as gas dynamic virtual nozzle (GDVN). Due to the limited strength of the glass polished capillaries for high-pressure gas flows and due to difficulties in aligning the liquid feeding capillary, (Beyerlein et al., 2015;Piotter et al., 2017) introduced injection moulded GDVNs. They consist of an injection moulded ceramic nozzle where the axial alignment of the inner and the outer capillaries is obtained by photo-etched spacers. ...
Liquid micro-jets, produced from gas dynamic virtual nozzles
(GDVNs), are used as sample carriers for interaction with X-ray beam in serial
femtosecond crystallography (SFX). A numerical investigation of the effect of
the focusing gas type on the liquid micro-jet properties (its length and
thickness) is presented. The study complements our previous research on the
influence of operating conditions and the nozzle geometry on GDVN
performance. The influence of helium, argon, carbon dioxide and nitrogen
gases (at a fixed mass flow rate of 1.6 × 10^4 mg/min) on focusing pure water jet
(flow rate of 33 μl/min) is analysed. An experimentally validated numerical
model, based on laminar two-phase Newtonian compressible flow with ideal
gas assumption, finite volume method and volume of fluid interface tracking, is
used. Helium is found to be the most suitable gas among the tested ones for
producing thin, long and fast jets. The study provides a basis for the focusing
gas selection in SFX experiments.
... Piotter et al. [Piotter et al., 2017] further improved injection molded GDVN by developing them as self-centered. High-speed gases for focusing jets can apply stresses up to 10 MPa to nozzles, which require a material with high compression strengths and elastic modulus. ...
... Micro-injection molded ceramic nozzles are used to produce micro-jets due to their benefits discussed in Piotter et al., 2017]. ...
The main aim of dissertation is to develop an experimentally verified computational fluid dynamic (CFD) model of micron-sized liquid jet, produced by an injection molded Gas Dynamic Virtual Nozzle (GDVN). In these nozzles, liquid jets are efficiently orientedly transporting mass and momentum. They are produced by intelligently projecting hydrodynamic focusing effect from a high-speed stream of a co-flowing lower density and lower viscosity gas on a stream of liquid from a feeding capillary. Liquid micro-jets are used for delivery of protein crystal samples in a hard X-ray beam in serial femtosecond crystallography experiments. The diffraction patterns of crystals are collected just before their destruction. The samples are hard to crystallize and very precious, so a thorough knowledge of the jet used in delivering them is required. The jet characteristics are analyzed as a function of operating parameters, geometry and material properties.
The physical model is described by mixture formulation and Navier-Stokes equations for transient, Newtonian, two-phase, compressible flow. Multiphase flow problem is solved with finite volume method (FVM), where fluid-fluid interface tracking is obtained with volume of fluid (VOF). The implementation of FVM-VOF CFD model is available in open source codes OpenFOAM and Gerris. They are validated by performing a series of standard interface advection and multiphase flow test cases. Both open source codes are compared for their abilities in solving GDVN flow problem. Due to the compressible nature of the focusing gas flow, OpenFOAM was chosen for GDVN simulations, since Gerris has no compressible flow option.
Constant effective material properties are used in the phases together with ideal gas density constitutive relation. A mixture model of the two-phase system is solved in axisymmetry. The discretization of the nozzle and chamber system uses approximately 300 000 finite volumes. Mesh independent results are obtained with the finite volumes of the size 0.25 µm in the vicinity of the jet and drops. The simulations are compared with experimental results according to the jet thickness and length for distilled water jet and helium focusing gas, discharging into low-pressure environment of 150 Pa. Reynolds numbers of the liquid and gas are in the range 413-3828 and 17-1222, respectively and Weber number in the range 3-353. A reasonably good agreement with experimental and scaling results is found for the range of nozzle operating parameters never tackled before.
Subsequently, a numerical study of effects of nozzle geometry on stability, shape and flow characteristics of micron-sized liquid jets is performed. The jet characteristics are described as a function of (i) capillary-to-orifice distance, (ii) nozzle outlet orifice diameter and (iii) liquid feeding capillary angle. The study is performed for two sets of liquid flow rates while keeping the gas flow rate unchanged. It is observed that for each value of capillary-to-orifice distance and nozzle outlet diameter, there exists a minimum liquid flow rate below which the jet stability cannot be achieved. It is found that the changes in the nozzle outlet diameter have the biggest influence on the jet diameter, length and velocity, while the liquid capillary angle has no observable effect on the jet characteristic. Change in capillary-to-orifice distance does not affect the flow field around micro jet, so the jet stability and shape is found to be affected by the way liquid-gas interacts near meniscus.
The same numerical model is used to additionally analyze the jet performance under the influence of Argon, Carbon dioxide and Nitrogen focusing gases. The study shows that the helium gas at the same mass flow rate provides twice the length of the jet compared to other gases. The jet focused with helium is also much thinner, faster and interestingly shows no considerable temperature drop at the nozzle outlet.
This work for the first time discuss the computational model of an injection molded micron-sized nozzle and produces valuable information for their design.
... However, the geometry of conventional GDVNs is prone to variability, fragility of flame polished tips and non-perfect axial alignment. Micro-injection molded nozzles can overcome many of these manufacturing difficulties and are also highly reproducible ( Beyerlein et al., 2015;Piotter et al., 2017 ). The outer flame polished glass part was replaced with a molded ceramic converging nozzle capillary. ...
In this paper we present a numerical study investigating the effects of nozzle geometry on stability, shape and flow characteristics of micron-sized liquid jets, produced by injection molded gas dynamic virtual nozzles (GDVNs) operating in vacuum. The jet characteristics are described as a function of (i) capillary-to-orifice distance, (ii) nozzle outlet orifice diameter, and (iii) liquid feeding capillary angle. An experimentally verified numerical model of GDVN with laminar two-phase Newtonian compressible flow, based on finite volume method and volume of fluid interface tracking, is used to assess the changes. The study is performed for two sets of liquid flow rates while keeping the gas flow rate constant. It is observed that for each value of capillary-to-orifice distance and nozzle outlet diameter there is a minimum liquid flow rate below which the jet is unstable. We find that the nozzle outlet diameter has the biggest influence on the jet diameter, length and velocity, while liquid capillary angle has no observable effect on jet characteristic. Varying capillary-to-orifice distance does not affect the flow field around micro-jet. It is found that the liquid and the gas interaction near the meniscus primarily affect the jet stability and shape.
Serial femtosecond crystallography (SFX) is the most remarkable application of gaseous flow focusing. In this application, the gaseous stream driving the jet is normally discharged into a vacuum chamber, which makes the gas current reach the sound velocity in the nozzle orifice. We devote the first part of this chapter to analyzing this transonic version of flow focusing.
Gaseous flow focusing can be employed to produce fibers and films when the liquid phase is a viscoelastic fluid. The second part of this chapter describes these interesting applications of flow focusing.
The large strain rates produced in the tip of the tapering meniscus of flow focusing can trigger the coil-stretch transition of the polymers dissolved in the liquid, which leads to the building of large axial viscoelastic stresses. This can fundamentally change the behavior of weakly viscoelastic flow focusing, increasing the stability of both the tapering meniscus and the emitted jet. This chapter closes by analyzing this novel and interesting phenomenon. Attention is paid to this viscoelastic transition and the superstability of the jets emitted when that transition occurs.
