Energy Injection Research Articles

High-speed aerodynamics control using energy injection of pulsed discharges

We present a novel method of high-speed aerodynamic control that relies on active energy injection of pulsed discharges characterized by a high power density and long pulse width. The control principle, which is based on the manipulation of a shock wave by the energy injection, is investigated and verified via M5 wind tunnel experiments and a numerical simulation. The test model is a cone-shaped model with two compression ramps, and we organize four discharges which are connected in series and located on the surface of the model. We use high-resolution schlieren imaging and a fiber optic balance to analyze the control effects of these discharges on the flow topology and the aerodynamic force. Schlieren imaging reveals a notable change in the flow topology and a weakening of the attached shock wave due to the discharge plasma layer creating a virtual wedge that diverts the incoming flow and reducing the local Mach number. The quantitative balance data show a significant force reduction in the presence of the pulsed discharges, and reveals that the force reduction rate is associated with the energy ratio, which increases with an increase in the pulse energy and a decrease in the dynamic pressure. A larger energy ratio of discharge leads to a higher penetration depth of the plasma layer, which is more conducive to aerodynamic control. The simulation results show similar flow topologies and consistent variation tendency in the aerodynamic force to the experimental results.

Thermodynamic performance optimization and environmental analysis of a solid oxide fuel cell powered with biomass energy and excess hydrogen injection

Recently the energy systems' developers focused on the efficient exploitation of renewable resources and novel technologies to decrease fossil fuel consumption and environmental damage. The SOFC units are known in this regard as high-efficiency and versatile fuel-driven systems, for which the biofuel from biomass gasification is an abundant and clean fuel source. The current article investigates a biomass-driven SOFC that is hybridized with wind turbines in order to increase the hydrogen concentration of intake fuel. To do so, the generated electricity by wind turbines is given to a polymer electrolyte membrane electrolyzer for hydrogen generation and injection into the SOFC. Feasibility studies of the proposed framework are conducted based on thermodynamic laws, and its performance enhancement is appraised using three exergy-based environmental indices. A parametric study is carried out to indicate the influence of operating variables on system performance in terms of power output, exergy efficiency, and environmental indices, after which a multi-objective optimization is implemented. The results indicated significant efficiency enhancement of biomass-driven SOFC via integration with wind turbines for hydrogen injection. It is found that more power from wind turbines leads to more hydrogen input to the SOFC and increases net power as well as efficiency. Increasing the fuel utilization factor for the basic structure and the structure with HI, the exergetic efficiency decreases by 5% and 4%, respectively. Under optimal point, the overall system's environmental damage factor and net output power are found to be 0.0092 kW and 322 kW, respectively.

Statistical Characterization of the Dynamic Near‐Earth Plasma Sheet Relative to Ultra‐Low Frequency (ULF) Wave Growth at Substorm Onset

AbstractMagnetospheric substorms are a complex phenomenon. During the initial stages of a substorm a variety of important processes occur in near‐Earth space within a span of several minutes. The relative timing and links between these processes are critical to understanding how, where and when substorms may occur. One of the first observed signatures at substorm onset is the exponential increase in ULF (Ultra‐Low Frequency) wave power in the near‐Earth magnetotail (e.g., −7.5 ≤ XGSM ≤ −12.5 RE). We use the Time History of Events and Macroscale Interactions during Substorms spacecraft to examine the conditions in the magnetotail plasma sheet before, during and after local ULF wave growth. Prior to the ULF wave growth, the magnetotail stretches with convectional flows dominating. We then find strong earthward and azimuthal flows that peak at a similar time to the peak ULF wave power. These flows are found to be faster in the mid‐tail (−10 ≤ XGSM ≤ −12.5 RE) than the near‐tail (−7.5 ≤ XGSM ≤ −10 RE). Examining the local plasma energy density (magnetic, thermal and kinetic), we find no statistical decrease that could explain the exponentially growing ULF waves, in fact the local energy density is found to increase. This suggests that there may be an injection of energy from elsewhere in the magnetotail. Following the peak ULF wave power the tail is seen to dipolarize, and the local energy density is enhanced.

Branch module for an inductive voltage adder for driving kicker magnets with a short circuit termination

For driving kicker magnets terminated in a short circuit, a branch module for an inductive voltage adder has been designed and assembled. The module has been designed for a maximum charging voltage of 1.2 kV and an output current of 200 A considering the current doubling due to the short circuit termination. It features three consecutive modes of operation: energy injection, freewheeling, and energy extraction. Therefore, the topology of the branch module consists of two independently controlled SiC MOSFET switches and one diode switch. In order not to extend the field rise time of the kicker magnet significantly beyond the magnet fill time, the pulse must have a fast rise time. Hence, the switch for energy injection is driven by a gate boosting driver featuring a half bridge of GaN HEMTs and a driving voltage of 80 V. Measurements of the drain source voltage of this switch showed a fall time of 2.7 ns at a voltage of 600 V resulting in a voltage rise time of 5.4 ns at the output terminated with a resistive load. To meet both the rise time and current requirements, a parallel configuration of four SiC MOSFETs was implemented.

Statistical Properties of Plateau‐Like Turbulence Spectra in the Martian Magnetosheath: MAVEN Observations

AbstractThe Martian magnetosheath provides us with a natural laboratory to study plasma turbulence in the presence of pickup ions and locally generated instabilities. Unlike the typical magnetic‐field spectra with a single spectral scaling at magnetohydrodynamics (MHD) scales in Earth's magnetosheath, the magnetic‐field spectra in the Martian magnetosheath during 4 years of Mars Atmosphere and Volatile EvolutioN observations frequently present an additional spectral break‐point with a shallow slope at MHD scales which we define as a plateau‐like spectral feature. The average occurrence rate of plateau‐like magnetic‐field spectra is 56.6% of our measurement intervals. At moderate pick‐up angles, the occurrence rate increases to a maximum of ∼70.0%. Furthermore, we present a positive correlation with the local ion density and anti‐correlations with the local βi and the solar Extreme Ultra Violet irradiance. A similar occurrence rate in the quasi‐perpendicular and the quasi‐parallel magnetosheath (60.1% vs. 52.9%) indicates that the plateau‐like spectra are more likely formed locally than in the upstream solar wind. Our results suggest that energy injection from pickup ion driven micro‐instabilities, for example, in the form of proton cyclotron waves, has insufficient time to evolve into a fully developed cascade in such a confined space like the Martian magnetosheath.

MHD Simulation of a Solar Eruption from Active Region 11429 Driven by a Photospheric Velocity Field

Data-driven simulation is becoming an important approach for realistically characterizing the configuration and evolution of solar active regions, revealing the onset mechanism of solar eruption events, and hopefully achieving the goal of accurate space weather forecasting, which is beyond the scope of any existing theoretical modeling. Here we performed a full 3D MHD simulation using the data-driven approach and followed the whole evolution process from the quasi-static phase to eruption successfully for solar active region (AR) NOAA 11429. The MHD system was driven at the bottom boundary by a photospheric velocity field, which is derived by the DAVE4VM method from the observed vector magnetograms. The simulation shows that a magnetic flux rope was generated by a persistent photospheric flow before the flare onset and then triggered to erupt by torus instability. Our simulation demonstrates a high degree of consistency with observations in the preeruption magnetic structure, the timescale of the quasi-static stage, the pattern of flare ribbons, as well as the time evolution of the magnetic energy injection and total unsigned magnetic flux. We further found that an eruption can also be initiated in the simulation driven by only the horizontal components of the photospheric flow, but a comparison of the different simulations indicates that the vertical flow at the bottom boundary is necessary for reproducing more realistically these observed features, emphasizing the importance of flux emergence during the development of this AR.

Predicting the Efficiency of Solar Photovoltaic Energy Injection in a Localized Subtropical Grid by Modelling Actual Generation Trend Curves: Case Study of Douala

Predicting the Efficiency of Solar Photovoltaic Energy Injection in a Localized Subtropical Grid by Modelling Actual Generation Trend Curves: Case Study of Douala

Achievement of 200,000 hours of operation at KEK 7-GeV electron 4-GeV positron injector linac

KEK electron positron injector LINAC initiated the injection operation into Photon Factory (PF) light source in 1982. Since then for 39 years, it has served for multiple projects, namely, TRISTAN, PF-AR, KEKB, and SuperKEKB. Its total operation time has accumulated 200 thousand hours on May 7, 2020. We are extremely proud of the achievement following continuous efforts by our seniors. The construction of the injector LINAC started in 1978, and it was commissioned for PF with 2.5 GeV electron in 1982. In parallel, the positron generator linac was constructed for the TRISTAN collider project. The slow positron facility was also commissioned in 1992. After the KEKB asymmetric-energy collider project was commissioned in 1998 with direct energy injections, the techniques such as two-bunch acceleration and simultaneous injection were developed. As the soft structure design of the LINAC was too weak against the great east Japan earthquake, it took three years to recover. Then the construction and commissioning for the SuperKEKB project went on, and the simultaneous top-up injection into four storage rings contributes to the both elementary particle physics and photon science.

On the Stability of “Stable Systems” in the Presence of Dark Energy

The influence of dark energy on baryon objects and their system is considered. For such an analysis, the concept is adopted, according to which the entire baryonic Universe interacts with dark energy on all cosmic scales. It is shown that the interaction of baryonic objects with a carrier of dark energy inevitably leads to the injection of energy into the baryonic world with tangible physical consequences. The consequences seem quite dramatic, since the accumulation of energy in the baryonic world changes the virial theorem for all objects and systems, making them more and more unstable. This process of stability loss takes place at all spatial scales, including the micro world, where baryonic matter experiences the dark energy influence. It results decaying of all cosmic objects beginning with atomic nuclei and reaching the clusters of galaxies. Evolution under the influence of dark energy can take place in two different ways depending on the existence of the angular momentum of the body and its value. If the angular momentum is small, the object under the influence of dark energy obtains a more regular shape, otherwise at the equatorial plane would appear a structure consisting of less evolved matter.

Interpretation of radio afterglows in the framework of the standard fireball and energy injection models

ABSTRACT Gamma-Ray Bursts (GRBs) are panchromatic, highly energetic transients whose energy emission mechanism is still debated. One of the possible explanations is the standard fireball model, which can be tested with the closure relations (CRs), or relations between the temporal and spectral indices of a GRB. To test these, we compile an extensive sample of radio afterglow light curves (LCs) that span from 1997 to 2020, the most comprehensive analysis of GRBs with radio observations to date. We fit 202 LCs from 82 distinct GRBs with a broken power law, obtaining a sample of 26 that display a clear break and a sub-sample of 14 GRBs that present a radio plateau. We test these samples against CRs corresponding to a constant-density interstellar medium (ISM) or a stellar wind medium in both fast- and slow-cooling regimes, as well as three additional density profiles, k = 1, 1.5, 2.5, following n ∝r−k, and consider sets of CRs both with and without energy injection. We find that 12 of the 26 GRBs (46 per cent), of which 7/12 present a radio plateau, fulfill at least one CR in the sets tested, suggesting our data are largely incompatible with the standard fireball model. Of the fulfilled CRs, the most preferred environment is the ISM, SC, νm < ν < νc without energy injection. Our results are consistent with previous studies that test the standard fireball model via the CRs in radio.

(When) Can Wave Heating Balance Optically Thin Radiative Losses in the Corona?

Why the atmosphere of the Sun is orders of magnitudes hotter than its surface is a long standing question in solar physics. Over the years, many studies have looked at the potential role of magnetohydrodynamic (MHD) waves in sustaining these high temperatures. In this study, we use 3D MHD simulations to investigate (driven) transverse waves in a coronal loop. As the boundary-driven transverse waves propagate along the flux tube, the radial density profile leads to resonant absorption (or mode coupling) and phase mixing in the boundaries of the flux tube and the large velocity shears are subject to the Kelvin–Helmholtz instability (KHI). The combination of these effects leads to enhanced energy dissipation and wave heating. Considering both resonant and nonresonant boundary driving as well as different densities for the flux tube, we show that only wave heating associated with a resonant driver in a lower-density loop (with a loop core density ∼5 × 10−13 kg m−3) is able to balance radiative losses in the loop shell. Changing the model parameters to consider a denser loop or a driver with a nonresonant frequency, or both, leads to cooling of the coronal loop as the energy losses are greater than the energy injection and dissipation rates.

Molecular dynamics study of liquid–vapor transition in underwater electrical wire explosion

During underwater electrical wire explosion, liquid–vapor transitions are crucial to the energy deposition and the generation of shock waves. To explore the characteristics of liquid–vapor transition during electrical explosions in water, a large-scale molecular simulation method was designed. The modeling scales experimental exploding wires to nano-size and then tracks the motion of each atom. The surrounding water medium was simplified as an expanding wall, whose velocity was determined by experimental steak images. Using this model, the phase transition processes at different energy deposition rates were compared. The results show that high energy deposition rates can make the discontinuous liquid–vapor phase transition disappear, forming an axially uniform vapor column, while slow energy injection will change the exploding wire into a foamlike liquid–vapor mixture at a subcritical temperature. The different shapes of wire–water interfaces in the experimental shadowgraphs can be explained by these features of liquid–vapor transition.

Analysis of the Hybridization of PV Plants with a BESS for Annual Constant Power Operation

The electrical generation of photovoltaic systems is variable and non-dispatchable. Energy storage systems can provide the system with energy management capabilities. In particular, with a hybrid system that combines a photovoltaic system and an energy storage system, it is possible to deliver firm power to the grid, if it is correctly dimensioned and operated. The objective of this work is to study the most appropriate relationship between the capacity of the battery energy storage system (BESS) and the peak power of the photovoltaic generator that enables the delivery of constant power throughout the year. Analysis parameters are presented that help to decide the most convenient energy injection constant value (PV-CPG set point) and the size of the storage system. As a case study, the most suitable battery capacity for a 1 MWp photovoltaic system with a battery located in Zaragoza (Spain), and the most convenient annual setpoint values for its operation are analyzed.

Integration of EV in the Grid Management: The Grid Behavior in Case of Simultaneous EV Charging-Discharging with the PV Solar Energy Injection

The actual research in terms of energy focuses drastically on the use of green energy resources. Hydropower systems have been the most known green sources for years. However, the hydropower systems, which are seasonal and most exploited, do not cover the speed of increasing daily demand. The injection of solar power could be a supporting alternative, but it is only in daylight, weather dependent and intermittent. Therefore, a storage system is required. The batteries are the quick recourse. Not only the energy sector, but also the transport systems are not left behind; they are striving to turn green. Therefore, they are turning to electric vehicles (EVs) and electric moto-bicycles (EMBs). On the other hand, this option tends to be a sharply increasing demand that can be a burden to the grid, i.e., the increase in the EVs and EMBs implies increases in power demand, grid components and pressure on the grid. Fortunately, the EVs use batteries to store energy for their use. Therefore, the EVs are the power storage system, they become part of the power management system and they can save the power surplus. With the injection of PV solar power, there is no need for an extra storage system, as the EVs are charged from the grid and store the solar energy that can be used later after sunset. The bi-directional off-board charger is a solution as it allows the grid to charge the vehicle (G2V) and the vehicle to send power back to grid (V2G). The inclusion of EVs in power management introduces the concept of vehicle-to-vehicle (V2V) when one EV can charge another, and the vehicle-to-load (V2X) where the EV can supply power to EMBs or any load. The V2G, G2V, V2X, the inclusion on solar energy to the grid and the behavior of the grid in that scenario will be illustrated in this paper.

Dynamics of hot galactic winds launched from spherically-stratified starburst cores

ABSTRACT The analytic galactic wind model derived by Chevalier and Clegg in 1985 (CC85) assumes uniform energy and mass-injection within the starburst galaxy nucleus. However, the structure of nuclear star clusters, bulges, and star-forming knots are non-uniform. We generalize to cases with spherically-symmetric energy/mass injection that scale as r−Δ within the starburst volume R, providing solutions for Δ = 0, 1/2, 1, 3/2, and 2. In marked contrast with the CC85 model (Δ = 0), which predicts zero velocity at the centre, for a singular isothermal sphere profile (Δ = 2), we find that the flow maintains a constant Mach number of $\mathcal {M}=\sqrt{3/5} \simeq 0.77$ throughout the volume. The fast interior flow can be written as $v_{r \lt R} = (\dot{E}_T/3\dot{M}_T)^{1/2} \simeq 0.41 \, v_\infty$, where v∞ is the asymptotic velocity, and $\dot{E}_T$ and $\dot{M}_T$ are the total energy and mass injection rates. For $v_\infty \simeq 2000 \, \mathrm{km \, s^{-1}}$, $v_{r\lt R} \simeq 820 \, \mathrm{km\, s^{-1}}$ throughout the wind-driving region. The temperature and density profiles of the non-uniform models may be important for interpreting spatially-resolved maps of starburst nuclei. We compute velocity resolved spectra to contrast the Δ = 0 (CC85) and Δ = 2 models. Next generation X-ray space telescopes such as XRISM may assess these kinematic predictions.

Inverse cascades of kinetic energy and thermal variance in three-dimensional horizontally extended turbulent convection

Inverse cascades of kinetic energy and thermal variance in the subset of vertically homogeneous modes in spectral space are found to cause a slow aggregation to a pair of convective supergranules that eventually fill the whole horizontally extended, three-dimensional, turbulent Rayleigh-B\'{e}nard convection layer when a heat flux is prescribed at the top and bottom. An additional weak rotation of the layer around the vertical axis stops this aggregation at a scale that is smaller than the lateral domain extension and ceases the inverse cascade for the thermal variance. The inverse cascade for the kinetic energy remains intact, even for times at which the root mean square values of temperature and velocity have reached the statistically steady state. This kinetic energy inverse cascade sustains the horizontally extended convection patterns which are best visible in the temperature field. The resulting characteristic length of the aggregated convection patterns depends on the thermal driving and linearly on the strength of rotation. Our study demonstrates the importance of inverse energy cascades beyond the two-dimensional turbulence case in a three-dimensional convection flow that is subject to a multi-scale energy injection by thermal plumes and driven by boundary heat fluxes as typically present in natural geo- and astrophysical systems, such as solar convection.

Evidence for powerful winds and the associated reverse shock as the origin of the Fermi bubbles

ABSTRACT The Fermi bubbles are large gamma-ray-emitting structures. They are symmetric about the Galactic Centre (GC), and their creation is therefore attributed to intensive energy injection at the GC. In this study, we focus on the non-equilibrium X-ray gas structures associated with the bubbles. We show that a combination of the density, temperature, and shock age profiles of the X-ray gas can be used to distinguish the energy-injection mechanisms. By comparing the results of numerical simulations with observations, we indicate that the bubbles were created by a fast wind from the GC because it generates a strong reverse shock and reproduces the observed temperature peak there. On the other hand, instantaneous energy injection at the GC cannot reproduce the temperature profile. The wind had a speed of ${\sim} 1000\rm \: km\: s^{-1}$, and blew for ∼107 yr. Because the mass flux of the wind is large, the entrainment of interstellar gas by wide-angle outflows from the black hole is required. Thus, the wind may be the same as active galactic nuclei outflows often observed in other galaxies and thought to regulate the growth of galaxies and their central black holes.

Enhancing Power Quality Using Renewable Energy: A Review

In order to enhance the quality of the electricity in microgrids powered by renewable energy, this study introduces a three-phase Active Power Conditioner. The six IGBT bridge is managed by three hysteresis controllers. Disturbances in a microgrid, which is a fragile electrical grid, can be crucial. The Active Power Conditioner (APC), which is described in this paper, serves as a bridge between the microgrid's AC bus and renewable energy sources. The implementation of an upgraded control technique allows for the injection of electrical energy from renewable sources while also enhancing power quality inside the same microgrid. THDI (Total Harmonic Distortion), PF (Power Factor), and current can all be improved with the help of the control approach known as Extended Indirect Control Strategy.

Empirical constraints on the turbulence in QSO host nebulae from velocity structure function measurements

ABSTRACT We present the first empirical constraints on the turbulent velocity field of the diffuse circumgalactic medium around four luminous quasi-stellar objects (QSOs) at z ≈ 0.5–1.1. Spatially extended nebulae of ≈50–100 physical kpc in diameter centred on the QSOs are revealed in [O ii] $\lambda \lambda \, 3727,3729$ and/or [O iii] $\lambda \, 5008$ emission lines in integral field spectroscopic observations obtained using Multi-Unit Spectroscopic Explorer on the Very Large Telescope. We measure the second- and third-order velocity structure functions (VSFs) over a range of scales, from ≲5 kpc to ≈20–50 kpc, to quantify the turbulent energy transfer between different scales in these nebulae. While no constraints on the energy injection and dissipation scales can be obtained from the current data, we show that robust constraints on the power-law slope of the VSFs can be determined after accounting for the effects of atmospheric seeing, spatial smoothing, and large-scale bulk flows. Out of the four QSO nebulae studied, one exhibits VSFs in spectacular agreement with the Kolmogorov law, expected for isotropic, homogeneous, and incompressible turbulent flows. The other three fields exhibit a shallower decline in the VSFs from large to small scales. However, with a limited dynamic range in the spatial scales in seeing-limited data, no constraints can be obtained for the VSF slopes of these three nebulae. For the QSO nebula consistent with the Kolmogorov law, we determine a turbulence energy cascade rate of ≈0.2 cm2 s−3. We discuss the implication of the observed VSFs in the context of QSO feeding and feedback in the circumgalactic medium.

Full cycle modeling of inter-seasonal compressed air energy storage in aquifers

To study the operational characteristics of inter-seasonal compressed air storage in aquifers, a coupled wellbore-reservoir 3D model of the whole subsurface system is built. The hydrodynamic and thermodynamic properties of the wellbore-reservoir system during the initial fill, energy injection, shut-in, and energy production periods are analysed. The effects of well spacing and air injection temperature on the seasonal storage process are investigated. The results show that the ranges of variation in wellbore-aquifer pressure and temperature are within the acceptable level during the whole operational process. The maximum wellhead pressure, reaching 13.08 MPa, occurs during the first injection in the initial fill period. The temperature of the air released from the wellhead is 6 °C lower than the initial injection temperature due to heat loss. The horizontal transport distance of injected air in the aquifer is 2173.5 m away from the central well at the end. The overall energy storage efficiency is 94.3% and the energy lost by the wellbore during production is 0.09%. Parametric analysis shows that the system has an optimal performance at a well spacing of 150 m. The energy storage efficiency is 5% higher at an air injection temperature of 20 °C than 50 °C. The results strongly confirm the feasibility of IS-CAESA.