Simple Nozzle Research Articles

The Effect of Hyperconjugation and Hydrogen Bonding on the Conformers of Methylated Monosaccharides.

The conformational landscapes of four 1-O-methylated monosaccharides-methyl a-glucose, methyl b-glucose, methyl a-galactose, and methyl b-galactose-were characterized using jet-cooled broadband rotational spectroscopy, supported by density functional theory calculations. A newly designed, simple pulsed nozzle assembly was used to introduced the sugar samples into a jet expansion without thermal degradation, eliminating the need for a complex and expensive laser ablation system. Ten conformers were experimentally identified by assigning their rotational spectra, and the intricate methyl internal rotation splittings were analysed. Notably, methylation alters the directionality of intramolecular hydrogen bonding of a-galactose highlighting its impact on structural preference. Natural bond orbital, intrinsic bond strength, and non-covalent interaction analyses were conducted to explore the interplay between hydrogen bonding and hyperconjugation. A set of σ to σ* neutral hyperconjugative interactions were found to override a strong hydrogen bond, driving a preference for the gauche conformers.

Experimental Study on Submerged Nozzle Damping Characteristics of Solid Rocket Motor

Acoustic instabilities in solid rocket motors (SRMs) can lead to severe performance deterioration and structural damage. Nozzle damping accounts for the main acoustic dissipation source, and it is highly dependent on geometric parameters and operating conditions. This study experimentally investigated the acoustic damping characteristics of submerged nozzles in SRMs, focusing on the effects of submerged cavity dimensions, nozzle convergent angle, throat-to-port area ratio, and mean pressure variations on the longitudinal instability. The steady-state wave decay method was used to quantify the acoustic damping, and a designed rotary valve system was employed to introduce periodic pressure oscillations in the high-pressure combustion chamber. The results revealed that a larger submerged cavity would reduce the nozzle damping efficiency, with the elimination of the submerged cavity enhancing the nozzle decay coefficient magnitude by 41.9%. Furthermore, increasing the nozzle convergent angle was found to amplify acoustic wave reflection, thereby diminishing damping performance. A linear inverse relationship was observed between the throat-to-port area ratio and the decay coefficient, with a 125% increase in the ratio resulting in a 24.3% reduction in the decay coefficient. Interestingly, despite the formation of complex vortices in the submerged cavity, the mean pressure variation presented negligible effects on acoustic damping characteristics, and its damping performance is similar to a simple nozzle without a cavity. These findings provide valuable experimental data for predicting the stability of a solid rocket motor with a submerged nozzle and offer insights into the optimization of submerged nozzle designs for higher acoustic damping in SRMs.

Co-axial hydrogel spinning for facile biofabrication of prostate cancer-like 3D models

Glandular cancers are amongst the most prevalent types of cancer, which can develop in many different organs, presenting challenges in their detection as well as high treatment variability and failure rates. For that purpose, anticancer drugs are commonly tested in cancer cell lines grown in 2D tissue culture on plastic dishes in vitro, or in animal models in vivo. However, 2D culture models diverge significantly from the 3D characteristics of living tissues and animal models require extensive animal use and time. Glandular cancers, such as prostate cancer—the second leading cause of male cancer death—typically exist in co-centrical architectures where a cell layer surrounds an acellular lumen. Herein, this spatial cellular position and 3D architecture, containing dual compartments with different hydrogel materials, is engineered using a simple co-axial nozzle setup, in a single step utilizing prostate as a model of glandular cancer. The resulting hydrogel soft structures support viable prostate cancer cells of different cell lines and enable over-time maturation into cancer-mimicking aggregates surrounding the acellular core. The biofabricated cancer mimicking structures are then used as a model to predict the inhibitory efficacy of the poly ADP ribose polymerase inhibitor, Talazoparib, and the antiandrogen drug, Enzalutamide, in the growth of the cancer cell layer. Our results show that the obtained hydrogel constructs can be adapted to quickly obtain 3D cancer models which combine 3D physiological architectures with high-throughput screening to detect and optimize anti-cancer drugs in prostate and potentially other glandular cancer types.

Active Fluidic Control of a Nozzle Guide Vane Throat

Abstract Experiments were conducted to validate the building blocks of a fluidically controlled variable area turbine concept that uses injected high-pressure air to effectively reduce the choke area of the turbine inlet. Preliminary results from a simple quasi-1D converging-diverging nozzle, with an injection flow slot upstream of the throat, showed a 2.2:1 ratio between throttled mass flowrate and injected mass flowrate at a constant nozzle pressure ratio. The penetration of the injection flow and corresponding reduction in the primary flow streamtube were successfully visualized using a shadowgraph technique. Building on this success, a representative single passage nozzle guide vane transonic flowpath was constructed to demonstrate feasibility beyond the quasi-1D converging-diverging nozzle. Both secondary slot blowing from the vane pressure surface and vane suction surface just upstream of the passage throat again successfully reduced primary flow. In addition, fluidic vortex generators were used on the adjacent suction surface to reduce total pressure loss and further throttle the primary flow. Implications for the application of this active flow control technology to a variable area turbine are considered.

On the possibility of flight of a single-stage rocket to the planets of the Solar system

A new concept for building a small-sized rocket engine containing a special gas ionizer in the combustion chamber to increase its conductivity to an optimal value with a corresponding improvement in the fuel combustion process is proposed. A simplified calculation for the relative velocity of gases in a conical nozzle is given when heating the supersonic flow of gases by plasma in a conical nozzle by means of a powerful, electromagnetic, high-frequency field, and the influence of some technical parameters on the efficiency of the rocket's flight is also considered. A comparison of the flight altitude of a rocket with plasma heating of the gas flow in a conical nozzle with a scale model corresponding to the well-known single-stage Zenit rocket with the same weight and geometry, taking into account air resistance for the cargo version of the rocket with one small-sized engine, is made. The result is a significant reduction in fuel consumption and an increase in the maximum flight altitude by 2 times with an increase in specific impulse by 2.7 times, other things being equal. It is established that under certain conceptual parameters, it is possible to rapidly accelerate and fly a single-stage cargo rocket with a launch weight of 17.25-20.00 tons to the planets of the solar system directly from the Earth's surface using a bunch of engines of the same type. The use of many of the same type of small-sized engines allows you to abandon the Laval nozzle in favor of a simple conical nozzle, which reduces the size of the rocket as a whole. This is determined by the need to reduce the diameter of the conical nozzle in order to achieve a greater specific heating power of the plasma compared to the specific power of the fuel burned in the combustion chamber. It is also proposed a complete rejection of the steering engines, the function of which will be performed by part of the engines located closer to the diameter of the rocket. As electric generators, it is proposed to use promising prototypes of electric generators MEG-6NS, MEG-15NS and others, the company "NaukaSoft", with good weight indicators that allow in the future to produce such a liquid rocket engine of small dimensions. The redistribution of part of the fuel used to produce electricity is compensated by a significant increase in the specific impulse of the liquid rocket engine to increase the speed and overall efficiency of the flight with an optimal ratio of the amount of fuel to the weight of the rocket before refueling.

Numerical and experimental analyses of a novel natural gas cooking burner with the aim of improving energy efficiency and reducing environmental pollution

Any optimization performed on home stoves can substantially reduce natural gas consumption due to their widespread utilization. The advantages of these optimizations include reduced energy consumption, economic benefits, and reduced emissions. Hence, the present study aims to perform experimental and numerical analyses on the effect of parameters such as outlet port swirling, port number, conical inlet nozzle, and the vessel height (burner-to-vessel distance) on the performance of home stoves. The numerical modeling was initially performed to observe the impact of the mentioned parameters on the stove performance. Subsequently, the combustion performance of the burner was investigated in an experimental study for different gas stoves to evaluate the results. Eventually, the validity of the numerical study was confirmed by the experimental data. The simple inlet nozzle demonstrated a uniform temperature distribution that reached the bottom of the vessel with a higher temperature. The maximum flame temperature was approximately 1300 K, which exhibited a wider range for a simple nozzle. Based on the conditions of this study, the amount of heat flux at the bottom of the vessel was 5 kW/m2. Increasing the number of ports did not lead to a complete flame distribution around the burner, and the flame was observed only in four areas adjacent to the burner. The experimental study showed that the highest efficiency belonged to the vessel height of 32.2 mm. Finally, the analysis revealed that the swirl burner with a 1.5 mm port and at a vessel height of 32.2 mm caused two types of ovens with efficiencies of 59.6% and 64.5% to increase the efficiency by 2.46% and 1.6%, respectively. This increase in efficiency led to the conversion of the studied stove to a higher-grade gas stove.

Investigation of novel passive methods of generation of swirl flow in supersonic separators by the computational fluid dynamics modeling

In this paper, three passive methods for the generation of swirl flow in the supersonic separator (3S) were investigated, and their structures were optimized by computational fluid dynamics (CFD) modeling. The influence of the structural and operational parameters on the dew point depression, phase envelope diagram, rate of natural gas liquid (NGL) recovery, and separation efficiency have also been evaluated. The collection efficiency was significantly improved for the nozzle equipped with the passive swirler compared with the simple nozzle. The selection of passive swirler type played a crucial role in the natural gas liquefaction and separation. The side injected swirler, and serpentine swirler showed the most significant improvement in separation efficiency than the U-turn swirler. For the side injected swirler at the optimum injection angle, the maximum collection efficiency was about 89% at the pressure loss ratio (PLR) of 0.2. Besides, the simulation results demonstrated that for the serpentine 3S, with the increase in serpentine twist number, the highest improvement on the collection efficiency of the investigated nozzle was obtained. In addition, it was observed that, when the convergent section profile was designed according to the Witoszynski line-type, a larger refrigeration zone was obtained than other considered profiles.

On Predicting the Frequency of a Flip-Flop Jet Nozzle

This research deals with the oscillation frequency of a classical and simple flip-flop jet nozzle with one feed-back loop based on the measurements of pressure and velocity. From these measurements, the traces of pressure difference between both ends of a connecting tube are modeled by a triangular wave, and the flow velocities in the connecting tube are calculated numerically. The resulting accumulated flow work, which consists of the time integral of mass flux into the re-circulation region on the low pressure side wall from the re-circulation region on the opposite high-pressure side wall through the connecting tube, is more adequate to determine jet-oscillation frequency than any other time integrals. This includes those of momentum flux and kinetic-energy flux. It is confirmed that jet-oscillation frequency predicted on the basis of this accumulated flow work agrees well with experiment.

High-coherence jets for focused fluid delivery in grinding

Jet coherence is of critical importance in grinding fluid application. Prior works to this end have largely delved into engineering contoured nozzles to promote coherence, with modest results. Inspired by decorative laminar fountains that display coherent jets, the present research focused instead on laminarizing the flow through a simple cylindrical nozzle. Augmented by the intriguing phenomenon of hydraulic flip, such jets possess extreme coherence and resemble smooth, transparent glass rods. Investigations indicate them to be valuable in applications like flute/groove grinding that necessitate precision fluid delivery and in instances that constrain the proximity of the nozzle to the grinding zone.

Low Cost and Simple PMMA Nozzle Fabrication by Laser Cutting and PDMS Curing Bonding

Electrohydrodynamic (EHD) printing can rapidly fabricate micro- or nano-scale lines without employment of any mask, which is suitable for small volume production in industrial applications. However, it is required that the nozzles should be disposable since they can easily be blocked by the un-cleaned ink. CO2 laser is an excellent tool for fabrication of micro-trenches in most of polymers with low-cost and high-speed. This paper presented a low-cost PMMA (Polymethyl methacrylate) nozzle fabrication method based on laser cutting and PDMS (Polydimethylsiloxane) curing bonding. The influence of thickness on the maximum stress and deformation rate of PMMA substrate was investigated to decrease the deformation of PMMA nozzle after laser cutting. To avoid stress concentration in PMMA nozzle after thermal bonding, PDMS curing bonding method was proposed. The effect of spin-coating speed on PDMS thickness was studied. The O2 plasma conditions were optimized based on contact angle to improve the bonding strength of PMMA nozzle. The EHD printing experiments demonstrated the practicability of proposed nozzle fabrication method.

Experimental observations of the transition between heterogeneous to homogeneous nucleation regimes in flash-boiling atomization

Here we present an experimental study of the transition from heterogeneous to homogeneous-nucleation in flash-boiling atomization. The study is based on a wide set of experimental results obtained with a high-pressure fluid flowing through a simple nozzle. We used the TSI's Phase Doppler Particle Analyzer to measure the spray characteristics; droplets velocity profile, mean velocity, droplets size and droplets size distribution. We conclude that in the heterogeneous-nucleation regime, a higher temperature results in droplets with a lower mean velocity. Upon transition to the homogeneous-nucleation regime at constant pressure, the mean velocity and the size of droplets noticeably increases. Likewise, while in the heterogeneous-nucleation regime, a higher temperature or a higher-pressure results in a lower droplets size (lower SMD), in the homogeneous nucleation regime this trend reverses for both, i.e., a higher temperature or a higher pressure results in a higher droplets size (higher SMD).

CO2 IR radiation modelling with a multi-temperature approach in flows under vibrational nonequilibrium

The aim of this paper is to develop a line by line model for CO2 vibrational nonequilibrium radiation and to investigate nonequilibrium effects in the case of some applications involving high temperature expanding flows. A vibrational specific collisional relaxation model is developed and is incorporated in a multi-temperature thermodynamic description of the gas mixture, in order to compute vibrational level populations along the flow. The HITEMP-2010 spectroscopic database is employed with a model for level energy splitting to provide line by line absorption and emission total and per-vibrational mode specific spectra. The specific spectra allow us to derive the radiative source terms to be used in the multi-temperature model if a coupled approach is required. The model is applied first to a simple conical nozzle flow and then to the plume of a high altitude solid propellant rocket engine. It is shown that, for the considered applications, the partial freeze of vibrational excitation in the expanding flow increases significantly the radiative intensity escaping from the mixture.

Heat transfer characteristics of high flow rate electrospray and droplet cooling

Electrospray cooling is experimentally examined for high volumetric flow rates (80 mL/h) stabilized by a novel hemispherical nozzle. Stability of the Taylor cone-jet mode of this nozzle is increased by interaction of the discharging liquid with the outer wall of a hemispherical cap, installed at the tip of a simple nozzle. The liquid can then be discharged at high flow rates at the same mode. The liquid is ethanol and the test surface temperature as well as the cooling heat flux are measured. The results of the surface temperature, the heat flux and the heat transfer coefficient are compared between the three cases. The first and main case is the electrospray using the novel hemispherical nozzle. The second case is the electrospray using a corresponding simple conventional nozzle. The third case is again the simple nozzle but without any applied voltage which results in a train of droplet impact cooling. All cases are studied and compared at the same flow rates, and the distance from the nozzle to the surface. Depending on the flow rate and the applied voltage, the critical heat flux for the case of electrospray cooling with hemispherical nozzle varies between 5.66 and 15.13 W/cm2. At the same flow rate and distance to the test surface, the cooling is improved compared to the electrospray cooling with a simple nozzle (maximum heat flux between 1.75 and 7.84 W/cm2) and drop impact cooling (maximum heat flux between 3.80 and 11.54 W/cm2). Finally, a parametric study indicates an improvement in maximum heat flux (and maximum heat transfer coefficient) by increasing the liquid flow rate and applied voltage, and by reducing the distance from the nozzle to the test surface.

Numerical investigation of performance refinement of a drag wind rotor using flow augmentation and momentum exchange optimization

Numerical ascertainment of improving performance of modified Savonius rotor as decreasing the minimum wind speed required for initiating the rotation is investigated using 3D flow predictions executed in ANSYS-FLUENT. For making the comparison feasible, the design represented in a similar paper is simulated and performance is compared with empirical data. Different types of nozzles are added after observing acceptable agreement between empirical and simulation results. Nozzle acts like an air intake on the advancing blade and fortifies the acting flow; it also eliminates the reverse moment caused by contacting the flow with returning blade. Therefore, increasing in power coefficient is anticipated. Systematic analysis of obtained torque and power coefficients with and without nozzle are presented. In the next step, this work is dedicated to bucket shape optimization. Buckets with multi-curvature are introduced and have been investigated in three stages. By installing a simple nozzle with tail in front of a Savonius wind turbine with double-curved two stage buckets, the Savonius turbine maximum power coefficient is improved from 0.13 to 0.39.

Thrust Augmentation by Airframe-Integrated Linear-Spike Nozzle Concept for High-Speed Aircraft

The airframe-integrated linear-spike nozzle concept applied to an external nozzle for high-speed aircraft was evaluated with regard to the thrust augmentation capability and the trim balance. The main focus was on the vehicle aftbody. The baseline airframe geometry was first premised to be a hypersonic waverider design. The baseline aftbody case had an external nozzle comprised of a simple divergent nozzle and was hypothetically replaced with linear-spike external nozzle configurations. Performance evaluation was mainly conducted by considering the nozzle thrust generated by the pressure distribution on the external nozzle surface at the aftbody portion calculated by computer simulation at a given cruise condition with zero angle of attack. The thrust performance showed that the proposed linear-spike external nozzle concept was beneficial in thrust enhancement compared to the baseline geometry because the design of the proposed concept had a compression wall for the exhaust flow, which resulted in increasing the wall pressure. The configuration with the boattail and the angled inner nozzle exhibited further improvement in thrust performance. The trim balance evaluation showed that the aerodynamic center location appeared as acceptable. Thus, benefits were obtained by employing the airframe-integrated linear-spike external nozzle concept.

The influence of cavitation on the flow characteristics of liquid nitrogen through spray nozzles: A CFD study

Spray cooling with cryogen could achieve lower temperature level than refrigerant spray. The internal flow conditions within spray nozzles have crucial impacts on the mass flow rate, particle size, spray angle and spray penetration, thereby influencing the cooling performance. In this paper, CFD simulations based on mixture model are performed to study the cavitating flow of liquid nitrogen in spray nozzles. The cavitation model is verified using the experimental results of liquid nitrogen flow over hydrofoil. The numerical models of spray nozzle are validated against the experimental data of the mass flow rate of liquid nitrogen flow through different types of nozzles including the pressure swirl nozzle and the simple convergent nozzle. The numerical studies are performed under a wide range of pressure difference and inflow temperature, and the vapor volume fraction distribution, outlet vapor quality, mass flow rate and discharge coefficient are obtained. The results show that the outlet diameter, the pressure difference, and the inflow temperature significantly influence the mass flow rate of spray nozzles. The increase of the inflow temperature leads to higher saturation pressure, higher cavitation intensity, and more vapor at nozzle outlet, which can significantly reduce mass flow rate. While the discharge coefficient is mainly determined by the inflow temperature and has little dependence on the pressure difference and outlet diameter. Based on the numerical results, correlations of discharge coefficient are proposed for pressure swirl nozzle and simple convergent nozzles, respectively, and the deviation is less than 20% for 93% of data.

Coupled Analysis of Thermo-Fluid-Flexible Multi-body Dynamics of a Two-Dimensional Engine Nozzle

Various components of an engine nozzle are modeled as flexible multi-body components that are operated under high temperature and pressure. In this paper, in order to predict complex behavior of an engine nozzle, thermo-fluid-flexible multibody dynamics coupled analysis framework was developed. Temperature and pressure on the nozzle wall were obtained by the steady-state flow analysis for a two-dimensional nozzle. The pressure and temperature-dependent material properties were delivered to the flexible multi-body dynamics analysis. Then the deflection and strain distribution for a nozzle configuration was obtained. Heat conduction and thermal analyses were done using MSC.NASTRAN. The present framework was validated for a simple nozzle configuration by using a one-way coupled analysis. A two-way coupled analysis was also performed for the simple nozzle with an arbitrary joint clearance, and an asymmetric flow was observed. Finally, the total strain result for a realistic nozzle configuration was obtained using the one-way and two-way coupled analyses.

A Very Stable High Throughput Taylor Cone-jet in Electrohydrodynamics.

A stable capillary liquid jet formed by an electric field is an important physical phenomenon for formation of controllable small droplets, power generation and chemical reactions, printing and patterning, and chemical-biological investigations. In electrohydrodynamics, the well-known Taylor cone-jet has a stability margin within a certain range of the liquid flow rate (Q) and the applied voltage (V). Here, we introduce a simple mechanism to greatly extend the Taylor cone-jet stability margin and produce a very high throughput. For an ethanol cone-jet emitting from a simple nozzle, the stability margin is obtained within 1 kV for low flow rates, decaying with flow rate up to 2 ml/h. By installing a hemispherical cap above the nozzle, we demonstrate that the stability margin could increase to 5 kV for low flow rates, decaying to zero for a maximum flow rate of 65 ml/h. The governing borders of stability margins are discussed and obtained for three other liquids: methanol, 1-propanol and 1-butanol. For a gravity-directed nozzle, the produced cone-jet is more stable against perturbations and the axis of the spray remains in the same direction through the whole stability margin, unlike the cone-jet of conventional simple nozzles.

A new design of vane-shaped hole pre-swirl nozzle

Theoretical analysis shows that the temperature drop of a pre-swirl system directly relates to the pre-swirl effectiveness of the pre-swirl nozzle. Besides, increasing the discharge coefficient and reducing the actual flow angle are the main ways to increase the pre-swirl effectiveness. A new design of pre-swirl nozzle called vane-shaped hole nozzle was introduced and analyzed in this paper. By keeping the throat area, the radial location and the pre-swirl angle (15°), numerical comparisons were carried out between the vane-shaped hole nozzle and other three typical nozzles, widely used in industry: simple drilled nozzle, aerodynamic nozzle and cascade vane nozzle. In order to involve the mixing and rotating effects in the pre-swirl cavity downstream of the nozzles, the rotating pre-swirl cavity and receiver hole were included in the computational models. Numerical results show that aerodynamic nozzle could alleviate the rapid acceleration and deflection at nozzle inlet, which results in 13.7% higher discharge coefficient than the simple drilled nozzle. The discharge coefficient of the cascade vane nozzle can be as high as 0.97 due to the aerodynamical design; however, the pre-swirl effectiveness is only 0.86 because of a large deviation angle (2.4°). For the vane-shaped hole nozzle, the vane height/pitch ratio could be flexibly adjusted to an appropriate value, which makes its performance better than that of the traditional ones. Higher vane height/pitch ratio and close to zero trailing edge radius lead to a small deviation angle (0.56°). Consequently, the pre-swirl effectiveness of the vane-shaped hole nozzle is about 8% higher than that of the cascade vane nozzle, though the discharge coefficient is about 5% lower. Additionally, the volume of the solid block in the vane-shaped hole nozzle is larger than that in the cascade vane nozzle, which could reduce the difficulty in manufacturing but increase the total weight.

Simple and compact nozzle design for laser vaporization sources

We have developed and implemented a compact transparent nozzle for use in laser vaporization sources. This nozzle eliminates the need for an ablation aperture, allowing for a more intense molecular beam. We use this nozzle to prepare a molecular beam of aluminum monohydride (AlH) suitable for ion trap loading of AlH+ via photoionization in ultra-high vacuum. We demonstrate stable AlH production over hour time scales using a liquid ablation target. The long-term stability, low heat load and fast ion production rate of this source are well-suited to molecular ion experiments employing destructive state readout schemes requiring frequent trap reloading.