Generation Of Pressure Pulses Research Articles

ALGORITHM FOR EXPERIMENTAL INVESTIGATION OF HYDROIMPULSE DEVICE FOR STRENGTHENING PARTS BY DEFORMATION

In the field of mechanical engineering, various methods and techniques are typically employed for the manufacturing of workpieces or machine components. In this context, it becomes necessary to determine the principles of selection and conduct a techno-economic assessment of various possible manufacturing approaches. Typically, the choice of the most optimal technological approach for producing a specific component involves comparing the technological cost of different manufacturing methods. Plastic deformation finds a wide range of applications beyond just restoring shapes and surfaces. It is also used to improve the physical and mechanical properties of the metal's surface, enhance roughness, and increase corrosion resistance. Plastic deformation is often combined with methods of metal buildup, such as welding, cladding, and others, to enhance the yield strength and, consequently, the service life of components. This process significantly enhances the reliability and durability of products and structures subjected to plastic deformation and metal buildup. This article presents a study aimed at identifying patterns that arise when changing the operating parameters of a high-speed hydroimpulse device designed for the deformation strengthening of parts. The influence of adjusting the parameters of the pressure pulse generator on the device's characteristics is investigated. The compliance of the vibration loading parameters of the striker, such as amplitudes and frequencies, with the specified values is verified. The change in the frequency of pressure pulse transmission in the pressure cavity of the drive due to changes in feed rate is analyzed. The capabilities of the technical equipment of the hydroimpulse device for the deformation strengthening of parts are assessed. The compatibility of the hydroimpulse device with the technology of deformation strengthening of parts is studied. Mechanical characteristics of objects before and after processing with the hydroimpulse device are compared. Conclusions are drawn based on the obtained results.

Influence of rheological parameters on cement slurry penetration characteristics of novel oscillating grouting technology

Traditional grouting techniques are primarily based on stable-pressure grouting, with slurry penetration performance limited. Research on the penetration behavior of pulsating slurry is relatively scarce, with even less research focused on the influence of slurry rheological parameters.This paper proposes an efficient oscillating grouting technology (OGT) that can generate pressure pulses and periodically change the direction of slurry motion. Through experiments and numerical simulations, its working mechanism is investigated, and the penetration distance of oscillating grouting and steady pressure grouting is compared under different soil parameters (porosity and particle size). The effect of cement slurry rheological parameters (viscosity of the Newtonian fluid and the K, τ0 and n, of the Herschel-Bulkley fluid) on penetration distance, grouting pressure, pressure pulse amplitude, and oscillating frequency are studied. Finally, the correlation analysis between penetration behavior, oscillating parameters, and rheological parameters is conducted. The results show that the oscillatory switching of the slurry is related to the interaction of vortexes within the tool, and the switching process leads to the generation of pressure pulsations. Under different soil parameters and rheological parameters, the penetration distance of oscillating grouting is larger than that of steady-pressure grouting. Furthermore, due to the pressure recovery process within the oscillatory grouting tool, the oscillating grouting exerts less pressure on the soil, which can prevent soil fracturing. The results also indicate that the oscillatory grouting requires a certain level of flow resistance to achieve optimal effect, but excessive resistance can impede the slurry switching process and reduce the penetration distance. And the optimal values for K, τ0 and n are around 0.015 Pa·sn, 1.5 Pa, and 0.5, respectively. According to the correlation analysis, oscillating frequency is positively correlated with penetration distance. Average pressure and rheological parameters are negatively correlated with penetration distance.

A plasma-based pressure pulse generator for simulating pellet-cladding mechanical interaction during reactivity-initiated accident.

This paper describes the characteristics of a plasma-based pressure pulse generator and its potential use as a simulator for studying pellet-cladding mechanical interaction (PCMI) during reactivity-initiated accidents (RIAs). In this device, a transient pressure pulse is generated by rapid heating and expansion of hot, dense plasma inside a nuclear fuel cladding. Thus, the parameters of a pressure pulse, such as peak pressure and pressure rise-rate, can be controlled by modifying the electrical parameters of a pulse discharge circuit. The pulse discharge circuit utilizes a capacitor bank comprising several energy storage capacitors connected in parallel and a high-power solid-state switch. A pressure loading system is attached as a load to the pulse discharge circuit. The power and energy delivered to the load are calculated by measuring the voltage and current waveforms at one end of the loading system. A piezoelectric sensor is connected at the other end of the loading system to simultaneously measure the pressure pulse inside the cladding tube. Preliminary experiments are carried out with a stainless-steel tube to characterize the performance of the device as well as with a pre-hydrided ZIRLO™ cladding tube to demonstrate the potential of the device as a simulator for studying the failure characteristics of the cladding as a result of an RIA. The high pressurization rate of the device is expected to offer unique advantages for studying the PCMI mechanism.

Characterization of a novel fluidic friction-reduction tool used in extended-reach well considering periodic particle-laden jet

Fluidic oscillators (FOs) can be used as an efficient fluidic vibration tool to solve high friction problems in extended-reach wells. However, the complex mechanism of FOs makes the design challenging, and the dynamic erosion behavior inside FOs is still unclear. In this paper, new FOs are proposed and the working characteristics under the influence of periodic particle-laden jets are investigated. Firstly, the results reveal the working mechanism of new FOs, showing that the generation of pressure pulses is closely connected with periodic jet switching and the development of vortices. Secondly, the important performance parameters, i.e., pressure pulse and oscillation frequency, are extensively studied through numerical simulation and experimental verification. It is found that the performance can be optimized by adjusting the tool structure according to different engineering requirements. Finally, the oscillating solid-liquid two-phase flow inside FO is studied. It is demonstrated that the accumulation of particles leads to a significant reduction in performance. The results also reveal five locations that are susceptible to erosion and the erosion behavior of these locations are studied. It has been shown that the periodic jet causes fluctuations in the amount of erosion at the outlet and splitter. This research can provide valuable references for the design and optimization of vibration friction-reduction tools.

A Proof-of-Concept Repetitive Pressure Source Based on Underwater Aluminum Exploding Wire

The work introduces a proof-of-concept source, repetitively generating strong pressure pulses using an underwater electrically exploded aluminum wire. When operated with a repetition rate of 0.1 Hz, the pressure source generates pressure pulses with a peak of about 0.6 MPa at a distance of 0.5 m.

DYNAMIC AND MATHEMATICAL MODELS OF THE HYDROIMPULSIVE VIBRO-CUTTING DEVICE WITH A PRESSURE PULSE GENERATOR BULT INTO THE RING SPRING

Structural calculation scheme of the hydropulse device for vibration cutting with built-in ring with pressure pulse generator (PPG) is considered. On the basis of the structural scheme and cyclogram of the working cycle of the device, its dynamic and mathematical models were developed, in which the hydraulic link is represented by a visco-elastic model of the working fluid (energy carrier) composed of the inertial elastic and dissipative elements (Kelvin-Foyga's body).

Hydropulse small-sized vibrators based on slotted springs

The article presents constructions and descriptions of the principles of operation of single-stage pressure pulse generators which are the main elements of the hydropulse drive used to generate vibrations of actuators in vibrating and vibratory shock machines for various purposes. Namely the pressure pulse generator with a solid body the pressure pulse generator with a floating seat and the pressure pulse generator with valve sealing degrees which were developed on the basis of Vinnytsia National Technical University. In the considered devices have the slotted spring as an elastic element which is executed as a separate detail or as a constructive element of other details which are a part of the device is used. The use of such elastic elements allows to ensure the speed of the devices and accordingly to increase the frequency characteristics of their operating modes. It is established that hydropulse vibrators - hydraulic cylinders based on cut or ring springs have the smallest dimensions with significant vibration force parameters.The text of the article highlights the main conditions for stable operation of these pressure pulse generators indicates and analyzes the mathematical dependences between the operating parameters of devices and the size of their structural elements offers the necessary correlation between structural dimensions of working surfaces of actuators and features of their positional parameters. The offered mathematical dependences can be used both for optimization of work of the designs of devices considered in article and at designing of new generators of pressure pulses with the hydropulse drive of various function. The shortcomings of individual designs of pressure pulse generators which may be related to the ways of sealing the working chambers of devices or options for interaction of structural elements of the device are identified and considered.

Experimental research on hydraulic fracture propagation in group of thin coal seams

The commingled production technology has been applied in group of thin coal seams exploitation. In order to explore the mechanism of fracture extension of multi-layer combined fracturing in thin coal seam groups with different perforating location, fracturing fluid displacement and fracturing fluid viscosity, this paper firstly adopted sand/coal (single and two-layer) indoor experiment to explore the basic law of fracture propagation and effective fracturing methods in cataclastic coal. After that, the multilayers experiment was carried out, and the fracture propagation law was studied by two types of (Model A: 3 layers sandstone and 2 layers coal) and (Model B: 3 layers coal and 2 layers sandstone). The experimental study of coal/sandstone (single and two-layer model) showed that the fracture morphology of primary structure coal was relatively simple. When the fracturing fluid was injected into the cataclastic coal, it was difficult to form effective fractures and the scale of the fracture was small. Therefore, the perforating location in the cataclastic coal should be avoided. In the secondary fracturing of the cataclastic coal seam, the fiber fracturing fluid could seal the fracture system of the primary fracturing of cataclastic coal, which provided technical reference for secondary temporary plugging fracturing. In addition, the law of fracture propagation in multi-layer coal measure strata was studied on the basis of the single and two-layer model, and the fracture propagation was evaluated from the aspects of fracture propagation morphology, fracture scale and fracture penetration. Multi-layers experiments showed that whether hydraulic fracture could achieve the penetration effect was mainly affected by the perforating location. If the perforating location was in the sandstone layer, the facture was easy to penetrate coal seam. When the fracture penetrated the interface between two layers, the generated pressure pulse activated the weak surface of developed fractures in coal seam, prompting the formation of complex fracture. In addition, the larger the fracturing fluid displacement and the lower fracturing fluid viscosity, the easier it was for hydraulic fractures to form branch fractures or activate natural fractures, increasing the fracture propagation volume to maximize hydraulic fracture complexity in the formation. In this experiment, the fracture propagation law of hydraulic fracturing in thin coal seam groups was studied under different engineering factors from multiple perspectives. The research results could provide reference for the fracturing construction design in thin coal seam groups.

DOWNHOLE PERIODIC ELECTROMAGNETIC SEISMIC SOURCE DESIGNS

Advancement of wave action stimulation and cross-well seismic imaging in mineral mining governs the need for downhole sources of elastic vibrations. The presented periodic electromagnetic seismic source is equipped with a mechanical–hydraulic drive for fixturing in a hole and for impulse transition to rock, and an electromagnetic impactor for pressure pulse generation. This article presents the experimental studies into the operation of the seismic source of three structural layouts. The features of the operation are discussed. The supply voltage dependences of the main parameters of the seismic source are obtained, and the practical application recommendations are formulated.

On using converging shock waves for pressure amplification in shock tubes

While conventional shock tubes have a distinct advantage in dynamic calibration methods due to their inherent capability to generate pressure pulses of desired amplitude and fast rise time, they are limited to the lower levels of the pressure amplitude realization range (≤7 MPa). With the increasing need for a traceable dynamic calibration standard across wider pressure ranges, a novel technique using converging shock waves is demonstrated in this work that pushes the upper limit of the standard shock tube into the medium-high pressure range. The experiments are conducted in the shock tube facility equipped with a test section that smoothly transforms the incident plane shock into a spherical shock wave that converges, accelerates and thereby amplifies its strength many folds. The experimentally recorded pressure traces are compared with numerical simulations performed by an in-house code. Using this technique, pressure pulses with peak amplitudes in the range of 30–40 MPa, with 3.4% uncertainty based on numerical reference profile, were realized in the test section with nominal usage of resources.

Stimulating illitic sandstone reservoirs using in-situ generated HF with the aid of thermochemicals

This work represents a method to stimulate illitic sandstone formations using in-situ generated hydrofluoric acid (HF) in the presence of thermochemicals. Using traditional mud acid for stimulating such reservoirs would cause a huge damage to the formation rather than enhancing its permeability. In this study, HF acid precursor reacts with an oxidizer in the presence of an exothermic reaction to generate HF acid downhole. Besides the high temperature generated inside the near-wellbore area, the pressure will build-up due to produced nitrogen gas from the thermochemicals reaction. The high pressure provides enough energy to flows back the well and removes any resulted precipitate.Firstly, the solubility of quartz and clay minerals in the new chemical mixture was tested. After that, core flooding tests were run for Scioto sandstone cores of 6-inch length and 1.5-inch diameter. Two different approaches were adopted for this treatment; (1) to remove the core damage and enhance its permeability using the acid generating fluids, (2) to stimulate the core using both the acid generating fluids and the thermochemicals. The core petrophysical and mechanical properties are evaluated before and after the acidizing process using core flooding tests, NMR scans and scratch tests.The core permeability got enhanced by about 37.5% after being treated with the acid generating fluids. The Inductively Coupled Plasma (ICP) analysis of the core flooding effluent showed that the total chelated amount of Si4+ ions from the core reached 49 mg. The scratch test showed a decrease in the Scioto core strength after the acid treatment by about 770 psi. Moreover, the core dynamic Young's modulus and Poisson's ratio were reduced by 550 ksi and 0.01 respectively. On the other hand, the NMR scanning for Scioto core showed an enhancement in the core total porosity after the acid treatment. The generated pressure pulse from the thermochemicals pushes the acid generated deeper into the formation and highly increased the stimulation process efficiency. Upon application of this new stimulation technology, the true production potential of sandstone reservoirs can be achieved, corrosivity will be minimized and handling hazardous chemicals (HF) will be avoided.

Acoustical monitoring of laser-matter interaction using nanosecond radiation pulses with periodically modulated intensity

Nanosecond laser ablation of metal target under the action of radiation pulses with periodically modulated intensity is investigated. Generated pressure pulses are detected by piezo-transducer (lithium niobate) on the back target side. Such approach permits to measure simultaneously recoil pressure behavior and calculate the irradiated surface displacement during laser action by comparison modulated parts of laser and acoustic signals. Nanosecond laser pulses contain 10–15 short peaks of 60 ps duration (1.08 μm wavelength) which provide fluence values up to 30 J cm−2 in the pulse. Plasma light emission is also registered with the help of photodiode. At the considered fluences surface displacement during the pulse turns out to be considerably smaller than theoretical estimation for free vacuum vaporization and measured experimental displacement which follows from the arrival time delay of another pressure signals generated with subsequent laser pulse directed to the same spot. Such behavior can be evidence that crater formation in the considered irradiation regime occurs after the pulse end.

ANALYTICAL STUDY OF THE IMPROVED MATHEMATICAL MODEL OF THE VIBRATION DRIVE FOR SOLID HOUSEHOLD WASTE ADDITIONAL COMPACTION IN THE DUST CART

On the base of the analysis, carried out, of the numerical studies of the complete. improved mathematical model of the vibrational compaction of the solid waste in the dust cart , using the  pressure pulse generator of the relay differential action and taking into account the density  and relative humidity of the dehydrated and pre- compacted solid waste the simplified improved mathematical model was suggested . In the process of comparison of the results, obtained using the  complete and simplified improved mathematical models of the vibrational additional compaction of the solid household waste in the dust cart , in particular, the degree of their compaction, the error was 4.35%, this value is acceptable for the realization of the previous design calculations of the basic parameters of the drive. For the analytical study of the simplified mathematical model the working cycle of the improved vibrational drive for the additional compaction of the solid household waste in the dust cart  is presented by six basic phases, each of them is described by the corresponding system of the differential equations with the initial and boundary conditions. For the analytical study of the simplified, improved mathematical model of the vibrational drive for the additional compaction of the solid household waste in the dust cart  such methods are used: solution of the system of ordinary linear differential equations, applying the Laplace  transformation, linearization of the  non-linearities, decomposition of the expression into the common fractions, solution of the incomplete cubic equation, applying Cardano formulas, computer simulation. Analytical study of the simplified mathematical model of the vibrational drive for the additional compaction of the solid household waste in the dust cart  enabled to obtain the analytical interdependences of its basic parameters and dependences of the frequency and amplitude on the basic parameters of the given drive with the error not exceeding  5.34%, they can be used for the realization of the preliminary design calculations of its parameters as one of the components for the solution of the problem, dealing with the development of the scientific-engineering fundamentals of the design of the efficient  tools of the  machines for the collection and   primary  processing of the solid household waste.

Characterization of a controlled shock wave delivered by a pneumatic table-top gas driven shock tube.

Blast simulators facilitate the creation of shock waves and measurement of pressure morphology in a controlled laboratory setting and are currently a vital model for replicating blast-induced neurotrauma. Due to the maintenance and operation cost of conventional blast simulators, we developed a pneumatic, table-top, gas-driven shock tube to test an alternative method of shock wave generation using a membrane-less driver section. Its unique operational mechanism based on air gun technology does not rely on a plastic membrane rupture for the generation of pressure pulses, allowing the simulator to be quickly reset and thus decreasing the experimental turnaround time. The focus of this study is to demonstrate that this proof-of-concept device can generate shock waves with diverse characteristics based on the selection of driver gas, driver pressurization, and driven section material. Pressure waves were generated using compressed nitrogen or helium at 15 psig and 80 psig and were analyzed based on their velocity and profile shape characteristics. At 15 psig, independent of the type of driver gas, driver pressurization, and driven section material, pressure pulses travelled at sonic velocities. At 80 psig, generation of shock waves was observed in all conditions. The choice of the driver gas affected the velocities of the resulting pressure waves and the shape of pressure waveforms, particularly the peak overpressure and rise time values. Our results demonstrate that depending on the selection of driver gas and magnitude of driver pressurization, the shock wave signatures can be controlled and altered using a piston-based driver section.

Generation of sub-microsecond quasi-unipolar pressure pulses

We present a method to generate sub-microsecond quasi-unipolar pressure pulses. Our approach is based on the laser irradiation of a thin copper wire submerged in water. The acoustic waveforms were recorded using two different, well characterized, wideband detection techniques: piezoelectric and optical interferometry. The results show that the irradiated target behaves as an omnidirectional source. Moreover, the peak pulse pressure linearly depends on the laser fluence and the source size. From the results, we propose an empirical equation for the spatial and temporal profile of the pressure pulse. The method has several advantages: ease of implementation, high repeatability, wide ultrasonic bandwidth and quasi-unipolar time profile. These features lead to potential applications of this acoustic source in ultrasonic characterization such as transducer systems, materials or passive devices.

Experimental and numerical investigation of flow field in flexible tube

The flexibility of walls influences the flow field in the cardiovascular system. The most of the existing experimental and numerical biomechanics work always tried to resolve this problem with rigid walls. In this work, an experimental simulation with the flexible wall will be carried out and the experimental data will be compared to the numerical solution. The aim of this work was to determine the influence of an elastic tube on final qualities of velocity profiles. Velocity profiles and deformations of the tube in the radial direction for any given time are the outcomes of this contribution. A high-speed camera was used in the experimental part of this work. The high-speed camera recordings enable to simultaneously detect the deformation of the flexible wall. The flexible tube was made of Tygon – a transparent material. Material parameters of Tygon were obtained from the uniaxial tensile test. The liquids used in the experimental measurement were air and water. The measurement was done for constant and pulsating volume flow. A pressure pulse generator was used to generate pulsatile flow. The computational simulation took advantage of the capability of commercial numerical solvers coupling between finite volume method CFD solution and finite element method mechanical solution. This approach is generally known as Fluid-structure interaction (FSI). Boundary conditions for numerical simulation were taken from measurement for reliable comparison of experimental and numerical results.

Scalable patterning using laser-induced shock waves

An advanced direct imprinting method with low cost, quick, and minimal environmental impact to create a thermally controllable surface pattern using the laser pulses is reported. Patterned microindents were generated on Ni50Ti50 shape memory alloys and aluminum using an Nd: YAG laser operating at 1064 nm combined with a suitable transparent overlay, a sacrificial layer of graphite, and copper grid. Laser pulses at different energy densities, which generate pressure pulses up to a few GPa on the surface, were focused through the confinement medium, ablating the copper grid to create plasma and transferring the grid pattern onto the surface. Scanning electron microscope and optical microscope images show that various patterns were obtained on the surface with high fidelity. One-dimensional profile analysis indicates that the depth of the patterned sample initially increases with the laser energy and later levels off. Our simulations of laser irradiation process also confirm that high temperature and high pressure could be generated when the laser energy density of 2 J/cm2 is used.

Laser Shock Wave-Assisted Patterning on NiTi Shape Memory Alloy Surfaces

Shape memory alloys (SMAs) are a unique class of smart materials and they were employed in various applications in engineering, biomedical, and aerospace technologies. Here, we report an advanced, efficient, and low-cost direct imprinting method with low environmental impact to create thermally controllable surface patterns. Patterned microindents were generated on Ni50Ti50 (at. %) SMAs using an Nd:YAG laser with 1064 nm wavelength at 10 Hz. Laser pulses at selected fluences were focused on the NiTi surface and generated pressure pulses of up to a few GPa. Optical microscope images showed that surface patterns with tailorable sizes can be obtained. The depth of the patterns increases with laser power and irradiation time. Upon heating, the depth profile of SMA surfaces changed where the maximum depth recovery ratio of 30% was observed. Recovery ratio decreased and stabilized when the number of pulses and thus the well depth were further increased. A numerical simulation of pressure evolution in shape memory alloys showed a good agreement with the experimental results. The stress wave closely followed the rise time of the laser pulse to its peak value and initial decay. Rapid attenuation and dispersion of the stress wave were found in our simulation.

On random pressure pulses in the turbine draft tube

The flow in the conical part of the hydroturbine draft tube undergoes various instabilities due to deceleration and flow swirling at off-design operation points. In particular, the precessing vortex rope develops at part-load regimes in the draft tube. This rope induces periodical low-frequency pressure oscillations in the draft tube. Interaction of rotational (asynchronous) mode of disturbances with the elbow can bring to strong oscillations in the whole hydrodynamical system. Recent researches on flow structure in the discharge cone in a regime of free runner had revealed that helical-like vortex rope can be unstable itself. Some coils of helix close to each other and reconnection appears with generation of a vortex ring. The vortex ring moves toward the draft tube wall and downstream. The present research is focused on interaction of vortex ring with wall and generation of pressure pulses.

Fracture Energy of Materials Exposed to Pulse Action

To study the process of brittle fracture, initiated by a microsecond range pulse action, we applied the magnetic pulse technique of controllable pressure pulse generation with pulse amplitude up to 2 GPa. The threshold energy level has been found, and related to a parameter specific of each material - energy accumulation time. With application of the thermodynamic approach, we develop and demonstrate the destruction criterion that allows us to define this material parameter. Following the results of experimental data and numerical simulation, we show how to describe the destruction process both for samples with crack-type macro defects, and defect-free samples. The study reveals the dependency of the surface energy from the load build-up and material properties when exposed to magnetic pulse action.