Shock Wave Intensity Research Articles

Research on the Mechanism and Propagation Characteristics of Combustion and Explosion of Natural Gas/Ammonia/Hydrogen Mixed Gas Fuel.

The addition of ammonia and hydrogen into natural gas fuel is an effective method to reduce carbon emissions. This study aims to investigate the effect of adding ammonia and hydrogen on the mechanism of natural gas combustion and emission characteristics. Based on a self-developed mixed gas deflagrate experimental platform, the deflagrate characteristics, emission characteristics, and chemical reaction kinetics mechanism of mixed gas fuels under different composition ratios (natural gas 0-100%, hydrogen 10-85%, and ammonia 0-100%) were studied. The results indicate that the propagation of the deflagration shock wave can be categorized into an initial stage (L < 3 m) and a development stage (L > 3 m) based on the observed trend of shock wave intensity variation with distance. The intensity of the deflagration shock wave for the mixed gases increases monotonically as the hydrogen content ratio rises. In contrast, the impact of the ammonia content ratio on the shock wave intensity exhibits a distinct pattern that varies with changes in the equivalence ratio and hydrogen content ratio. In terms of carbon emissions per unit of heat value produced by the fuel, adding hydrogen to natural gas proves to be more effective at reducing carbon emissions than adding ammonia. When the ammonia content ratio is 50% and the hydrogen content ratio is 40%, the combustion performance of the mixed gas fuel is similar to that of natural gas, but its carbon emissions are lower than 30% of natural gas, making it a new type of mixed fuel with potential application value; the interaction between reflected pressure waves and flames is the main reason for the fluctuation of deflagrate shock wave pressure; ammonia lowers the temperature of the reaction system by reducing the concentration of OH radicals.

(098) LOW INTENSITY SHOCKWAVE THERAPY FOR WOMEN WITH SEXUAL DYSFUNCTION

Abstract Introduction Low intensity shockwave therapy (LiSWT) has been used to treat sexual dysfunction by inducing genital tissue mechanotransduction. Mechanotransduction is the ability of a cell to actively convert contraction/expansion mechanical stimuli induced by exposure to the shockwave energy into biochemical signals with physiological effects including synthesis of nitic oxide, upregulation of vascular endothelial growth factors, recruitment of endothelial progenitor cells, vasodilation, and expression of tumor necrosis factor alpha mRNA with anti-inflammatory activity. The greater the shockwave energy absorbed in genital tissues, the greater the opportunity for mechanotransduction physiologic effects to occur and improve sexual function. Therefore, effectiveness of LiSWT depends, in part, on applied energy (mJ/mm2) and number of applications (total shocks). In 2019, our sexual medicine clinic began utilizing the SoftWave (Urogold 100™) LiSWT device, FDA cleared for pain amelioration, connective tissue activation, wound healing, and improved blood flow, to treat individuals with vulvas with sexual dysfunction. Objective To review the various sexual health concerns in individuals with vulvas effectively treated by LiSWT. Methods A chart review was performed of individuals with vulvas with various sexual dysfunctions, including genital pain and genito-pelvic dysesthesia (GPD), who received LiSWT between April 2019 and June 2023. In general, 2400 shocks were applied at energy flux density 0.05-0.08 mJ/mm2, Hz = 3, membrane pressure = 1. The Patient Global Impression of Improvement (PGI-I) was used to assess post-LiSWT outcome; improvement was positive if the post-LiSWT PGI-I ranged from 1-3. Results 189 women, mean age 32 (range 18–67) years, with sexual dysfunction underwent LiSWT treatments in the 38 months. 18 women with neuroproliferative vestibulodynia (NPV) who underwent vestibulectomy received 3-6 post-operative vestibular LiSWT to reduce post-operative pain and improve wound healing; 83% reported improved PGI-I. 24 patients with hormone-mediated vestibulodynia who elected not to use hormone treatment, underwent vestibular LiSWT; 54% reported improved PGI-I. 25 menopausal patients with persistent symptoms of Genito-Urinary Syndrome of Menopause (GSM) received multiple vestibular LiSWT treatments; 64% improved PGI-I, including reduction of urinary incontinence. 36 women with PGAD/GPD from lumbosacral annular tear-and/or Tarlov cyst-induced sacral radiculopathy who were not candidates for minimally invasive spine surgery or continued to have symptoms after recovering from spine surgery, underwent multiple treatments of lumbosacral spine LiSWT; 58% reported improved PGI-I. 86 patients with neuroproliferative vestibulodynia (NPV) underwent 2-3 pre-operative sessions of vestibular LiSWT immediately prior to complete subepithelial vestibulectomy surgery; they used significantly fewer opioids post-op than those without pre-operative LiSWT based on historical data prior to 2019. All patients received multiple LiSWT sessions to maximize mechanotransduction effects on genital tissues. There were no significant adverse events noted with LiSWT use. Conclusions Multiple LiSWT sessions are utilized in individuals with vulvas with sexual dysfunction to maximize mechanotransduction. LiSWT is associated with improved sexual health symptoms ranging from 54% - 75%, not associated with any side effects. More research is needed regarding the role of LiSWT for management of various sexual dysfunctions. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: Softwave TRT.

Research on the Combustion Mode and Thrust Performance of Rotating Detonation Scrarmjet Engines

Decades of research in hypersonic science and engineering have shown that scramjet engines are the preferred choice for powering hypersonic vehicles. In these engines, oblique shock combustion and rotating detonation combustion are two common combustion modes. This article primarily focuses on the numerical simulation and theoretical analysis of these two combustion modes. The research indicates that as the combustible mixture injected into the combustion chamber increases, the combustion mode transitions from deflagration combustion to self-sustaining detonation combustion and then to forced detonation combustion to maintain stable combustion in the chamber. Under self-sustaining detonation combustion mode, as the amount of combustible mixture injected into the chamber increases, the number of detonation waves gradually increases from one to multiple and the angle between the detonation waves and the inflow changes from acute to right angles. In the forced detonation combustion mode, the minimum shock wave intensity required to initiate detonation combustion can be obtained by drawing a tangent from the Rayleigh line. The structure generating oblique shock waves in the combustion chamber needs to match the shock wave intensity. In the detonation combustion mode, both the exit total temperature and specific impulse of the combustion chamber increase with the increase in Mach number at the inlet, while the pressure ratio decreases. This article provides a reference for the design of the combustion chamber in supersonic combustion ramjet engines.

Ion kinetic effects on the formation of intense laser-driven shock waves

The ion kinetic effect on the formation of intense laser-driven collisional shock waves is investigated via hybrid fluid-particle-in-cell simulations. It is found that the ion heat flux dominates the shock formation, which is considerably larger than the electron heat flux in the shock region. The rise of the temperature due to the laser energy deposition drives a heatwave into the overdense plasma, creating an electron–ion energy exchange zone between the critical surface and heat wave front. The heated ions, which are generated at the electron–ion energy exchange zone via the friction force, are found to travel to the high-density region and cause a tail distribution gain. Despite the small quantity, the heated tail ions contribute most of the ion heat flux during the shock formation. Additionally, as the electron heat flux decreases, the population of the heated tail ions is reduced, leading to a fall in the ion heat flux. This results in the delay or even suppression of the shock formation, because the ions are in a non-equilibrium state in the vicinity of the shock region, the ratio of the downstream ion temperature to the upstream ion temperature tends to a modestly decrease in comparison to the theory. The study provides a clear picture of the formation process of laser-driven shock waves.

ЧИСЕЛЬНЕ МОДЕЛЮВАННЯ ПРОЦЕСУ ВПЛИВУ ПРОДУКТІВ ДЕТОНАЦІЇ НА НАДЗВУКОВИЙ ПОТІК ПОВІТРЯ

Currently, there is a large number of control bodies used in modern rocket technol-ogy. Gasdynamic systems are usually used in rocket engines to change the thrust vector, less often - to create asymmetric air flow around the case. But the application of the det-onation process for such scheme can have better energy and dynamic characteristics compared to existing systems. The driving force in such scheme is created not only by the reactive mass force of detonation products ejected from the gas generator, but also by the effect of an intense shock wave on the pattern of supersonic flow around the rocket. Therefore, it is necessary to evaluate the performance and efficiency of the experiment. The purpose of the study is a priori numerical study of the detonation wave effect on the supersonic flow in the nozzle. Modeling was carried out in the Solid Works application software package. The geometric parameters of the model coincide with the experimental model. It is a flat nozzle, one of the walls is longer than the other and imitates the surface of the rocket. Air, accelerating in the nozzle to supersonic speeds with Mach number M=1.3...2, flows around this wall. Setting devices affecting the flow in it, it is possible to investigate their influence and the possibility of creating a lateral (controlling) force. When detonation is used to disturb the flow, an intense shock wave is generated in it, which changes the pres-sure distribution on the wall surface. Some holes for pressure sensors are made in the wall to fix this disturbance over time. A priori numerical modeling was carried out in order to estimate the parameters of the interaction of detonation products with the supersonic air flow. The pressure range and duration of the process have been determined, which allows selection of equipment and planning of the experiment. Patterns of velocity and pressure distribution in the model over time were obtained.

Three-dimensional characteristics of aerodynamic shockwave and condensation shockwave in steam ejectors

Characteristics of aerodynamic and condensation shockwaves are not clear in steam ejectors as the three-dimensional and non-equilibrium condensation effects in many simulation research are ignored. In the article, a non-equilibrium condensation model was developed to study the three-dimensional shockwave characteristics of steam ejectors. The formation, physical form, occurrence condition, location, quantity, intensity, and asymmetry of aerodynamic and condensation shockwave in different regions of three-dimensional steam ejectors were illustrated from mechanism. The coupling effect and interaction mechanism of aerodynamic and condensation shockwave were investigated. The influences of aerodynamic and condensation shockwaves on the flow field were analyzed. The similarities and differences between aerodynamic and condensation shockwaves were clarified. Results show that non-equilibrium condensation induces the condensation shockwave, but the condensation shockwave inhibits the non-equilibrium condensation. There is mutual inhibition between condensation shock and aerodynamic shock. A condensation shockwave appears downstream of the steam ejector's nozzle throat and another condensation shockwave may appear in the mixing chamber. The condition of the condensation shockwave in the mixing chamber is that the supercooling degree and the supersaturation ratio after the expansion wave exceed their critical values. In the critical condition, the supercooling degree is 19.6 K when the condensation shockwave appears in the mixing chamber.

The effect of the inlet steam superheat degree on the non-equilibrium condensation in steam turbine cascade

Due to the high steam velocity and low thermal parameters at the turbine's final stage, steam generates non-equilibrium condensation and forms a large number of small droplets during the process of pressure expansion. The wet steam mixed with droplets impinges on the turbine blades, endangering turbine operation safety and reducing turbine work efficiency. This article modifies the non-equilibrium condensation control equation and embeds it into the numerical simulation software to make the numerical calculation results more accurate. By modifying the inlet steam superheat in the classical experiments, the condensation characteristics of wet steam in Moses–Stein nozzles and Dykas cascades are studied. The results show that increasing inlet superheat can effectively suppress the generation of non-equilibrium condensation and reduce outlet liquid mass fraction. The minimum supercooling temperature of non-equilibrium condensation is only related to the working fluid characteristics (the steam model used in this article is around 20 K). When the inlet superheat of the cascade is large, the rapid condensation region is mainly near the suction surface. In contrast, when the superheat is low, the rapid condensation zone is mainly near the pressure surface. The condensation location is mainly affected by the intensity of internal condensation shock waves in the cascade. Increasing inlet superheat not only increases the shock wave intensity but also decreases the shock wave angle in the passage. When the inlet temperature increases by 20 K, the heat efficiency of the cascade increases by about 1%.

Bio-inspired pulsed power switch under shock wave

The spark gap switch is a crucial component in the primary energy drive system for large pulse power devices. The switch electrodes are composed of high-density artificial graphite, possessing excellent erosion resistance. However, insufficient mechanical strength in the graphite electrodes makes them especially susceptible to mechanical damage under the enormous impact force caused by the increasing arc current, which seriously affects the reliability and service life of the switch. The distribution of the shock wave overpressure on the graphite electrode surface is deduced and calculated, and the refraction and reflection process of the shock wave from the air to the graphite interface is analyzed based on the Huygens–Fresnel principle. Furthermore, the doubling of refracted shock wave intensity into the graphite electrode is a preliminary characterization. The propagation process of stress wave after the shock wave enters the electrode is investigated by establishing two conventional graphite electrode structure models, namely T-shape and reverse T-shape, which reveal that severe stress concentration occurs in both structures. Drawing inspiration from the physiological structure of the woodpecker’s head, renowned for its exceptional impact resistance, the macroscopic geometry of the graphite electrode and the assembly structure of the switch have been bionically designed. The simulation results demonstrate that, in comparison to the conventional electrode structure, the bionic electrode structure eliminates stress concentration at the bolt end and electrode corner, while significantly reducing maximum equivalent stress and the degree of the stress concentration on the bottom surface of the electrode. These features contribute to the enhancement of the current capacity and reliability of the spark gap switch.

(268) Intracavernous Prostaglandin Injection as a Predictor and Effectiveness Measure for LISWT Sessions in ED Patients: A Single Urologist's Experience

Abstract Introduction In recent years, therapeutic approaches for treating vasculogenic Erectile Dysfunction (ED) have evolved, with Low Intensity Shock Wave Therapy (LISWT) emerging as a promising modality. Objective To objectively evaluate the efficacy of LISWT for ED patients and to predict the required number of sessions, we examined the effects of administering up to 10 mcg of intracavernous alprostadil injections both before and after treatment Methods 85 vasculogenic ED patients (Average age: 57); 33 with mild to moderate ED and 52 with moderate or severe ED. Intracavernous injection (ICI) of ≤10 mcg of alprostadil was given before LISWT and one month post-treatment. Depending on ICI response, patients underwent either six (Erection Hardness Score (EHS) ≤3) or four (EHS=4) weekly LISWT sessions using PiezoWave2 from Richard WOLF. LISWT Parameters: 0.16mj/mm2 energy flux density, 8 Hz frequency, 10mm wave focus penetration depth, and 6000 shocks per session distributed among the two crura of the penis (2000 shocks), dorsum penis (2000 shocks), and lateral penis (2000 shocks). Results 33 patients showed a robust response to the 10mcg ICI and were treated with four LISWT sessions. 52 patients exhibited a partial response to the 10mcg ICI, necessitating six LISWT sessions. 78.6% (26 out of 33) of the patients who initially responded well to 10 mcg ICI had a consistent response to 8 mcg ICI; 63.6% (33 out of 52) of those with a partial initial response to 10 mcg ICI demonstrated an improved reaction to the same dosage post-treatment (table 1) (fig. 1). No complications were reported from the ICI. Conclusions Intracavernous prostaglandin injection can serve as a predictor for the required number of LISWT sessions and can objectively gauge the treatment's effectiveness in ED patients. Further randomized studies, incorporating parameters such as EHS, IIEF, and the ICI dosage, are recommended to validate this method's feasibility Disclosure No.

(193) Low Intensity Shockwave Therapy in Combination with Phosphodiesterase-5 Inhibitors is an Effective and Safe Treatment Option in Patients with Vasculogenic ED who are PDE5i Nonresponders: A Multicenter Single-Arm Clinical Trial

Abstract Introduction Low-intensity shockwave therapy (Li-ESWT) has been shown to be an effective and safe treatment for vasculogenic erectiledysfunction (ED) Objective We aim to evaluate the effectiveness and safety of LiESWT in treating patients affected from vasculogenic ED who did not respond to oral treatment with Phosphodiesterase 5 inhibitors (PDE5-i) Methods It is a multicentric open-label prospective study, in a cohort of patients non-responders to PDE-5i. Li-ESWT was performed in an outpatient setting by using the following schedule: 3000 shockwaves with an energy of 0.25 mJ/mm2 and a frequency of 4–6 Hz, twice a week for 3 weeks. International Index of Erectile Function, Erection Hardness Score and Sexual Quality of Life-Male questionnaires, and penile doppler ultrasound (PDU) are the outcome measurements. Results The Student t-test or Wilcoxon signed-rank test were applied to compare variables, with results considered statistically significant at p &amp;lt; 0.05. 106 (97.2%) completed treatment and performed follow-up visit after 4 weeks. At follow up visit, the mean IIEF-EF increased by 8.6 points (13.47 ± 4.61 vs 22.07 ± 5.27; p &amp;lt; 0.0001). A clinically significant improvement of IIEF-EF was achieved in 75 patients (70.7%). An EHS score ≥ 3, sufficient for a full intercourse, was reported by 72 patients (67.9%) at follow-up visit. 37 (34.9%) patients reported a full rigid penis (EHS = 4) after treatment. Li-ESWT treatment was also able to improve quality of life (SQOL-M: 45.56 ± 8.00 vs 55.31 ± 9.56; p &amp;lt; 0.0001). Li-ESWT significantly increased mean PSV (27.79 ± 5.50 vs 41.66 ± 8.59; p &amp;lt; 0.0001) and decreased mean EDV (5.66 ± 2.03 vs 1.93 ± 2.11; p &amp;lt; 0.0001) in PDU. Conclusions Combination of Li-ESWT and PDE5-i represents an effective and safe treatment for patients affected from ED who do not respond to first line oral therapy Disclosure No.

Energy density source levels of underwater explosive charges

This paper presents experimental measurements of energy density source levels of small explosive charges for high frequencies to 18 kHz. The experiments were carried out using Signals Underwater Sound (SUS) charges deployed at a deep water site in a coastal fiord north of Vancouver BC. The waveform of an underwater explosion is characterized by a high intensity shock wave signal followed by a series of bubble pulses of decreasing intensity. The bubble pulses dominate the SUS energy density spectrum at frequencies below 1 kHz, but at higher frequencies the spectrum is dominated by the characteristics of the decay envelope of the shock wave signal. The explosive material in SUS charges is packed in a thin cylindrical cavity, resulting in a non-uniform decay envelope with secondary pulses when detonated, and a non-spherical distribution of the radiated sound. The impact of the cylindrical charge shape on energy density source level was investigated experimentally. Data were recorded for SUS deployments that generated in-line and broadside sound propagation to the receiver with respect to the axis of the cylindrical charge. Experimental measurements indicate significant differences in the high frequency SUS energy density spectrum depending upon the SUS and receiver geometry.

Experimental investigation on the characteristics of the shock wave emitted by the cavitation bubble near the air bubble

This study explores the mitigation of cavitation damage in hydraulic engineering through air entrainment. The primary aim is to experimentally analyze the shock wave characteristics emitted by cavitation bubbles adjacent to air bubbles affixed to a tube nozzle. The schlieren optical system is utilized to visualize the shock wave, while a hydrophone measures its pressure. Experiments are conducted on cavitation bubbles induced by the spark-generated method in the vicinity of air bubbles, varying the dimensionless distances and sizes of the air bubbles. The results indicate that (1) The introduction of an air bubble noticeably changes the morphology, kinematic behavior, and shock wave features of the cavitation bubble. (2) Four distinct shock wave patterns are identified based on the quantity and shape of the shock wave, with variations in the cavitation bubble's collapsing behavior and shock wave characteristics across different patterns. (3) The dimensionless distance γ and size δ exert significant influence on the shock wave's quantity, pressure peak, shape, and energy. With γ decreases or δ increases, the shock wave quantity increases while the shock wave intensity decreases. This investigation of the interaction between cavitation bubbles and air bubbles is essential for elucidating the mechanism through which air entrainment mitigates cavitation damage.

Comparative analysis of blast load transfer and structural damage in multi-cabin structures during air and underwater explosions

This study presents comprehensive experimental and numerical findings regarding the impact of the fluid medium on blast load transfer and structural damage mechanisms in multi-cabin structures subjected to air and underwater explosions. The experiments demonstrated that the structure primarily underwent a comprehensive dynamic response during an air explosion. In contrast, underwater explosions induced severe localized damage, with fluid properties significantly influencing the shockwave intensity. The observed plastic deformation, shear tearing of the structure, and shock wave characteristics in the experiment were successfully predicted through numerical simulations. Additionally, the numerical simulation unveiled distinct mechanisms of pressure changes in the cabin, attributing air and underwater explosions to transmitted pressure waves and compression shocks of the outer plate, respectively. The high-intensity shock waves generated by underwater explosions and bubble loads sequentially impacted the structure, resulting in more pronounced structural damage compared to the weaker shock wave effect of an air explosion. This study provides valuable insights for comprehending and predicting the response of multi-cabin structures in diverse explosion scenarios.

(152) Energy Absorption Simulation During Low Intensity Shockwave Therapy

Abstract Introduction Low intensity shockwave therapy (LiSWT) has been used to treat erectile dysfunction since 2010 by inducing mechanotransduction. The greater the shockwave energy absorbed in cavernosal erectile tissue, the greater the opportunity for mechanotransduction regenerative mechanisms to occur and improve erectile function. Effectiveness of LiSWT depends, in part, on applied energy (mJ/mm2) and number of applications (total shocks). Although intensity of LiSWT energy cannot be arbitrarily increased due to side effects, energy absorption may be improved by performing treatment to an erect vs flaccid penis. Intracavernosal pressure and penile volume are both determinants of velocity of the energy wave in tissue and therefore absorption of shockwave energy in tissue. Intracavernosal penile pressure when erect (100 mmHg) is 16-fold higher than flaccid (6 mmHg), and blood volume when erect (142.6 cm3) is &amp;gt;2 times more than flaccid (62.18 cm3), therefore LiSWT in the erect state with larger blood-filled lacunar spaces should be associated with greater shockwave energy absorption. Use of a symmetry-matched secondary reflector can further increase the energy absorption of each applied shockwave by reflecting the wave back. Objective The aim of this study was to perform a simulation of energy absorption during LiSWT with a reflector in both the flaccid and erect penis. Methods This energy model used the MTS UroGold electrohydraulic shockwave device [Softwave TRT]. When sound waves pass through an interface between 2 media with different impedances, sound propagation can be significantly altered. If impedances of the media are different, part of the sound energy is reflected into the incident medium; the rest of the sound energy is transferred to the second medium. Sound propagation in tissue can be illustrated via computer simulation by mathematically calculating the damping and deflection of the sound wave by different tissue structures. Finite Element Method (FEM) simulation models are particularly suitable for the mathematical description of complex processes of shockwave propagation, such as in the flaccid and erect penis. Based on results, a “prediction” of propagation of LiSWT in tissue is possible. This patient-specific procedure is based on consideration of individual anatomical structures: corporal lacunar spaces and physical-acoustic laws. For FEM modeling of LiSWT propagation, program systems ANSYS, MATLAB and PZFLEX/ONSCALE were used. Results Using the FEM calculation model of the simulation analyses, the shockwave pulse is applied at the bottom edge of the model (Fig 1). It propagates through the erect (Fig 2a) and flaccid (Fig 2b) states, with the most energy absorption in the erect penis, shown in red. The effect of increased penile pressure on energy absorption with a constant volume is shown in Fig 3. Conclusions More energy is absorbed in cavernosal tissue during erection than in the flaccid state, with a further increase in absorption with use of a symmetric reflector. This provides greater opportunity for beneficial mechanotransduction regenerative mechanism due, in part, to increased intracavernosal pressure and tissue volume with larger blood-filled lacunar spaces during erection. LiSWT to treat erectile dysfunction should be more effective when performed in the erect state utilizing a reflector. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: MTS Medical, Softwave TRT.

SPH simulation of shock-induced chemical reactions in reactive powder mixtures

Reactive materials (RMs) are a mixture of two or more nonexplosive solid components in which, under extreme conditions, self-sustaining chemical reactions occur with the release of a high amount of energy. Knowing the kinetics of chemical reactions in RMs plays the key role in their efficient applications. In this work, we propose a macroscopic mathematical model of shock-induced chemical reactions based on smoothed particle hydrodynamics (SPH) for particle-scale simulation. The model includes the elastic-plastic deformation of materials, heating due to deformation and chemical reactions, diffusion of components, and heat transfer. The test calculations performed for the zero- and first-order reactions in the Al/S mixture showed a need for a more reliable determination of criteria and constants of chemical reactions. For this purpose, we propose a schematic experimental arrangement for the experimental and theoretical determination of the critical reaction pressure and the rate constant of the reaction. The type and corresponding constants of chemical reactions can be determined, for example, by the maximum likelihood method. We theoretically determined the zones of chemical reaction with different modes and found the influence of the projectile velocity and the intensity of shock waves on the development and completion of chemical reactions.

Research on diffusion characteristics of liquid jet effected by shock wave in supersonic high-enthalpy crossflow

The diffusion characteristics of liquid jets with phase transition under the action of shock waves in supersonic high-enthalpy crossflow were discussed in this paper. Numerous numerical simulations were carried out in high enthalpy inflow (Tt = 1680 K) under different shock wave intensity and injection parameter conditions. The Euler-Lagrangian method was employed to solve the gas-liquid two-phase flow coupling, and the evaporation, diffusion and mixing processes of kerosene were obtained. By analyzing simulation results, the influence and the mechanism of shock waves on enhanced kerosene mixing were revealed. The results show that increasing the shock wave intensity effectively improves the penetration and mixing of kerosene in general by changing the flow state and evaporation process. The penetration depth can be increased by up to 63.54 % in this paper. To balance the contradiction between total pressure loss and mixing efficiency, it is necessary to select an appropriate shock wave intensity. The enhanced diffusion and mixing process of kerosene by shock waves are related to the injection momentum ratio, evaporation momentum ratio and streamwise vortex intensity. Weakening mainstream momentum while boosting evaporation and vortex intensity effectively strengthens kerosene diffusion and mixing. This research significantly contributes to enhancing the diffusion and mixing of liquid kerosene and improving combustor performance.

Variations in Low Intensity Shockwave Treatment Protocols for Erectile Dysfunction: A Review of the Literature and Guide to Offering Treatment.

Low-intensity shockwave therapy (LiSWT) for erectile dysfunction (ED) continues to gain popularity in both clinical practice and the academic literature. The majority of trials and meta-analysis studies have shown LiSWT to be low risk with a trend toward positive improvements in International Index of Erectile Function (IIEF) scores. However, there is still debate over the clinical utility of LiSWT and there is no agreed upon optimal treatment protocol. In this review article we summarize published meta-analysis studies of LiSWT for ED, and review the treatment protocols from randomized sham-control trials published in the last 10 years. We found the most common device settings were an energy of 0.09 mJ/mm² and a frequency of 5 Hz. Shock number and location varied, but the most common protocol was 1,500 shocks per session, with 900 shocks to the penis (shaft, base, or hilum) and 600 shocks to the proximal corpora/crura. Protocols ranged from 4 to 12 treatment sessions. We also describe our institutional experience with LiSWT, including patient counseling and treatment protocol.

The effect of an explosive shock wave on the plate of a protective structure of a critical infrastructure

The article presents the outcomes of an analysis on the stress-strain conditions of reinforced concrete structures subjected to an explosive shock wave resulting from the detonation of a combat unit from a kamikaze drone against a protective screen. When designing protective structures for critical infrastructure, employing computer simulation enables an assessment of the genuine impact of explosive loading on the structural elements' strength. The active phase of explosive loading is exceptionally brief, lasting only a fraction of a second. Under such circumstances, modeling is best performed using explicit methods of direct integration in time.&#x0D; The structure considered in this work is a reinforced concrete slab supported by a metal beam cage with I-beam cross-sections, topped with a sand backfill. The study was executed within the SIMULIA Abaqus software suite, incorporating models depicting nonlinear material behavior in a three-dimensional context. Discretely positioned reinforcement was considered for reinforced concrete structures, and the "Concrete Damage Plasticity" model was applied for concrete, accounting for damage accumulation. The devised computational scheme for the shelter represents a section of the protective structure's roof under conditions of cyclic symmetry.&#x0D; The article elucidates the core principles of incorporating explosive loading according to algorithm CONWEP.The results demonstrate that during the detonation of a kamikaze drone, an explosive wave created a crater in the sand backfill, exposing the slab. The study illustrates the development of damage in the reinforced concrete slab at various time intervals. Despite the identified damage to the slab, the protective structure overall withstood the explosive load. The intensity of the explosive shock wave diminishes significantly as it propagates away from the explosion site.

Experimental Investigation on the Control of Hypersonic Shock Wave/Boundary Layer Interaction Using Surface Arc Plasma Actuators at Double Compression Corner

Compression corner shock wave/boundary layer interaction (SWBLI) is a typical shock wave/boundary layer interaction (SWBLI) problem in supersonic/hypersonic flows. In previous studies, the separation flow is usually caused by a single shock wave. However, in the actual aircraft surface configuration, two-stage compression or even multistage compression will produce more complex SWBLI problems. The multi-channel shock structure makes the flow field structure more complicated and also puts forward higher requirements for the flow control scheme. In order to explore a flow control method for the double compression corner shock wave/boundary layer interaction problem, an experimental study is carried out to control the double compression corner shock wave/boundary layer interaction with a high-energy flow pulsed arc discharge array under the condition that the incoming flow velocity Ma 6.0 has both noise flow fields and quiet flow fields. The results show that when UDC = 0.5 kV actuation is applied, the influence range of the hot gas mass flow direction is about 65 mm, which can weaken the shock wave intensity to a certain extent. When UDC = 1 kV actuation is applied, the influence range of the hot gas mass flow direction extends to 85 mm, and the actuation has a significant control effect on the flow field. Through spatio-temporal evolution analysis and spatial gradient threshold processing of high-speed schlieren images of actuated flow fields, the feasibility of controlling the hypersonic double compression corner shock wave/boundary layer interaction by using a high-energy flow pulsed arc discharge array is verified. The control law of a high-energy flow pulsed arc discharge array acting on the double compression corner shock wave/boundary layer interaction is revealed.

Effects of activation energy on irregular detonation structures in supersonic flow

In this work, high-precision numerical simulations of detonations in supersonic hydrogen–oxygen premixed gases with different activation energies are carried out. The open-source program Adaptive Mesh Refinement in Object-Oriented C++ is adopted, and the monotone upstream–centered scheme for conservation laws total variation diminishing numerical scheme is utilized to solve the Euler equations coupled with a one-step, two-component reaction model. The wave structure characteristics of the irregular cellular detonation process are obtained, and its initiation and propagation characteristics under different activation energies are analyzed in depth. The results show that, unlike a regular detonation wave structure, the Mach stem of an irregular detonation wave is prone to bifurcation in a supersonic mixture with high activation energy. In addition to the incident shock wave and the Mach stem structure, a hybrid shock wave structure also appears between the two due to the random generation of weak triple points. Moreover, the leading shock wave intensity of the irregular detonation weakens, resulting in the generation of many unburned jets whose sizes and shapes depend on the triple point type. Although the oscillation amplitude of the irregular detonation is large and its regularity is weak, the detonation wave can achieve approximate dynamic stability in the channel.