High-pressure Gas Research Articles

A Recent Review on Nanocrystal Manufacturing Techniques with Pharmaceutical Application

Abstract: This review article constitutes an introductory report on nanotechnology focusing on the various manufacturing approaches of nanocrystals. Nanocrystals are a solid form to tackle the issue identified with poor fluid solvency. Hence, it is a useful technique in improving the bioa-vailability of various poorly soluble drugs. On a broader way, nanocrystal technology is mainly classified as top-down technology, bottom-up technology and a combination of top-down and bottom-up technology. Top-down technology is based on the principle of breaking down a com-plex into small crystals. This process is executed by using high-pressure homogenization, laser ablation, media mills, ultrasound technology, vacuum dissolution, gas condensation and mechani-cal attrition. Bottom-up technology is based on the principle of preparation by gathering at-oms/molecules together. It is achieved by using precipitation, supercritical fluid, gel-gel technol-ogy, spray drying, hydrolysis, and condensation. Due to the diverse characteristics and properties of drugs, a combination of top-down and bottom-up techniques is best for manufacturing nano-crystals. Some of the promising technique includes nano-edge technology and smart-crystal tech-nology. These techniques are discussed in this review.

Structural safety of compressed air energy storage sealing materials

The structural safety of sealing materials is one of the important technical problems of compressed air energy storage. FLAC3D is used to analyze and compare various combination schemes using steel lining and flexible material as sealing materials and evaluate the safety of each scheme, which provides a reference for the design of high-pressure gas storage. The contact surface between the concrete and the steel lining is set up to enhance the relative sliding between them, which is conducive to the coordination of steel plate deformation and the reduction of steel plate stress. The stress of steel plate can be significantly reduced by placing some flexible materials in steel plate and lining concrete, and the lower the modulus of flexible materials is, the better the stress of steel plate structure is.

Insight into the evolution of membrane chemical degradation in proton exchange membrane fuel cells:From theoretical analysis to model developing

The chemical degradation of the proton exchange membrane (PEM) causes the changes in membrane properties and morphology, which directly affects the cell performance and membrane degradation. In this work, the changes of PEM during the chemical degradation are theoretically analyzed at both microscopic and mesoscopic levels. Based on the theoretical study, a bidirectionally coupled physical model of PEM fuel cell (PEMFC) performance and PEM chemical degradation is developed, which is used to investigate the evolutions of cell performance and chemical degradation. It can be found that the open circuit voltage first increases slightly and then decreases with time, and the ohmic loss increases rapidly under accelerated degradation conditions. The membrane chemical degradation is analyzed in terms of four aspects: the mass loss rate of the membrane, the region of pronounced degradation, the contribution of different degradation mechanisms and the proportion of ionomer species remaining. Furthermore, the effect of operating conditions on the degradation is examined. The degradation is most sensitive to voltage and has the fastest rate at high voltage, high temperature, high gas pressure and relative humidity of 60%. This work provides a deep insight into the PEM chemical degradation, which is instructive for the long-term prediction of PEMFC lifetime.

Proactive Emergency Response Strategies for First Responders to Hydrogen Gas Leakages in Vehicles

The widespread use of fossil fuels in automobiles has become a concern, particularly in light of recent frequent natural disasters, prompting a shift towards eco-friendly vehicles to mitigate greenhouse gas emissions. This shift is evident in the rapidly increasing registration rates of hydrogen vehicles. However, with the growing presence of hydrogen vehicles on roads, a corresponding rise in related accidents is anticipated, posing new challenges for first responders. In this study, computational fluid dynamics analysis was performed to develop effective response strategies for first responders dealing with high-pressure hydrogen gas leaks in vehicle accidents. The analysis revealed that in the absence of blower intervention, a vapor cloud explosion from leaked hydrogen gas could generate overpressure exceeding 13.8 kPa, potentially causing direct harm to first responders. In the event of a hydrogen vehicle accident requiring urgent rescue activities, the appropriate response strategy must be selected. The use of blowers can aid in developing a variety of strategies by reducing the risk of a vapor cloud explosion. Consequently, this study offers a tailored response strategy for first responders in hydrogen vehicle leak scenarios, emphasizing the importance of situational assessment at the incident site.

Design, development and characterization of Blumlein Pulse Forming Line based pulsed power system for High Power Microwave source research

This paper describes a complete cycle of designing, developing, and characterising a Pulsed Power System (PPS) and generating microwaves using the relativistic source. For low impedance relativistic High Power Microwave (HPM) sources, Blumlein Pulse Forming Line (BPFL) based high voltage pulsed power systems are the most suited. An HPM source such as a virtual cathode oscillator (VIRCATOR) operating in nanosecond durations consists of a primary voltage source that charges a Marx pulse generator’s capacitor bank over a long time. The requirements of a diode load are met by compressing the output pulse width of a Marx generator by a BPFL. This article describes the novel design, construction and characterization of a circulating De-Ionized (DI) water insulated BPFL pulsed power system. A novel approach of insulating gas filled Marx generator of this class/rating is attempted. A pulse power system consisting of high pressure gas insulated Marx generator and circulating DI water-based BPFL was developed and experimented with the resistive load as well as HPM source. The PSPICE simulation of the Blumlein circuit for various load conditions is described. Criticalities in the design of end bushings are elaborated along with the development and testing of a compact BPFL-based pulsed power system.

Establishment and application of temperature–pressure coupling model for opening and closing wells in HTHP gas wells

Switching wells in high-temperature and high-pressure gas wells will affect parameters such as the temperature and pressure of the fluid in the wellbore. Dynamic monitoring of temperature and pressure is difficult, and wellbore temperature, pressure, and fluid physical parameters are coupled to each other. Obtaining them separately will lead to large calculation errors. In order to improve the prediction accuracy of temperature and pressure in high-temperature and high-pressure gas wells, Based on the temperature–pressure coupling algorithm, this study compares the advantages and disadvantages of nine classic algorithms based on the temperature–pressure coupling algorithm, considers the impact of high temperature and high pressure on the temperature and pressure of the gas wellbore fluid, and establishes an unsteady temperature–pressure coupling model for high-temperature and high-pressure gas wells under on–off well conditions. Comparing with the measured data, it is proved that the prediction accuracy of the unsteady temperature–pressure coupling model of high-temperature and high-pressure gas wells meets the construction requirements of switch wells. The established model is used to simulate the temperature and pressure distribution of two high-temperature and high-pressure gas wells under switching conditions. The analysis shows that the distribution of wellbore temperature and pressure under the switch on and off conditions is affected by the gas–water ratio, heat transfer coefficient, tube size, and gas well production. Among them, the gas–water ratio increased by 1.5 times, the wellhead temperature increased by 25%, and the wellhead pressure decreased is 7.68%; When the heat transfer coefficient is increased by 1.5 times, the wellhead temperature drops to 34.38% and the wellhead pressure drops to 2.29%. When the tube size is increased by 1.125 times, the wellhead temperature is reduced by 44.20% and the pressure is increased by 6.09%. When the production of gas well is doubled, the wellhead temperature increases by 40.79% and the wellhead pressure decreases by 2.29%. The results can be used as a basis for the construction of high-temperature and high-pressure gas wells.

A Study on the Transient Response of Compressed Air Energy Storage in the Interaction between Gas Storage Chambers and Horseshoe-Shaped Tunnels in an Abandoned Coal Mine

This study focuses on the renovation and construction of compressed air energy storage chambers within abandoned coal mine roadways. The transient mechanical responses of underground gas storage chambers under a cycle are analyzed through thermal-solid coupling simulations. These simulations highlight changes in key parameters such as displacement, stress, and temperature within the chamber group during the loading and unloading processes of compressed air energy storage. It is found that within a cycle, the small circular chamber experiences the most significant deformation, with an average peak displacement of 0.24 mm, followed by the large circular chamber and horseshoe-shaped tunnels. The small circular chamber exhibits maximum tensile and compressive stresses. Therefore, special attention in engineering practice should be paid to the long-term safety and stability of small circular tunnels, and the stability of horseshoe-shaped tunnels should be also carefully considered. The findings from this study offer some insights for theoretical support and practical implementation in the planning, design, construction, and operation of high-pressure underground gas storage chambers for compressed air energy storage.

Vortex of a Symmetric Jet Structure in a Natural Gas Pipeline via Proper Orthogonal Decomposition

The impact of particle addition jets on the flow field in natural gas pipelines was investigated, and the structural information of the flow field at different flow velocities in a symmetric jet flow was analyzed via numerical simulation. The results of coherent structures in the high-pressure natural gas pipeline reveal vortex structures of varying sizes both upstream and downstream of the jet flow. To determine the spatial distribution of the main vortex structures in the flow field, proper orthogonal decomposition (POD) mode analysis was performed on the unsteady numerical results. Moreover, the detailed spatial characteristics of the coherent vortex structures represented by each mode were obtained. The results indicate that the large-scale vortex structures within the pipeline are balanced and stable, with their energy increasing as the jet flow velocity increases. Additionally, higher-order modes exhibit significant shedding of small-scale vortex structures downstream of the jet flow. In this research, coherent structures present in symmetric particle addition jets are provided, offering theoretical support for future investigations on the distribution of particle image velocimetry (PIV) flowmeters.

Determination of the Reserved Gap Between the Obturator Ring and the Breechblock in the Metallic Obturation Mechanism of a Large Caliber Gun Howitzer

A reserved gap between the obturator ring and the breechblock in the obturation mechanism of a large-caliber gun is required in the locked state of the gun, which is the main cause of gas leakage. In this study, the finite element analysis of the dynamic contact between the obturator ring and the breechblock and the computational fluid dynamics (CFD) analysis of the high-pressure gas flow through the gap between the obturator ring and the breechblock are conducted. The results show that the smaller the reserved gap is, the shorter the time period during which the contact pressure is zero after the obturator ring contacts with the breechblock will be under a low-bore pressure condition. The results also demonstrate that the leakage flow at the outlet of the gap and the gas flow in the external domain increase with the reserved gap size, and the gas flow in the external domain decays rapidly if the reserved gap is less than or equal to 0.02 mm under a high bore pressure condition. Based on the simulation results, the appropriate reserved gap value is determined and adopted in the studied gun, and good results are achieved in the firing tests.

Investigation on the pressure drop characteristics of ITER thermal shield cooling pipes

This paper presents the experimental results of the pressure drop through the cooling pipes of the ITER Thermal Shield (TS) panels. High pressure and room temperature nitrogen gas is selected for the experiment, which is equivalent operating condition with the 80 K helium gas from fluid mechanics point of view. Flow rate is set by a mass flow controller and pressure difference between the inlet and the outlet of the cooling pipe is measured by a differential pressure gauge. The experimental set-up is open loop type, which is connected to high pressure gas bottle. Flexible corrugated pipes are used to connect the TS cooling pipes with the measurement system line. The effect of the corrugated pipe is evaluated separately and excluded from the measurement results of the TS pipes. Test results of several TS panels are shown in this paper and are compared with the calculation using existing friction factor correlation and local loss coefficient of the pipe bends. The limitation of the calculation is discussed considering the hydrodynamic developing flow in the pipe routing.

MATRESHCA: Microtesla Apparatus for Transfer of Resonance Enhancement of Spin Hyperpolarization via Chemical Exchange and Addition.

We present an integrated, open-source device for parahydrogen-based hyperpolarization processes in the microtesla field regime with a cost of components of less than $7000. The device is designed to produce a batch of 13C and 15N hyperpolarized (HP) compounds via hydrogenative or non-hydrogenative parahydrogen-induced polarization methods that employ microtesla magnetic fields for efficient polarization transfer of parahydrogen-derived spin order to X-nuclei (e.g., 13C and 15N). The apparatus employs a layered structure (reminiscent of a Russian doll "Matryoshka") that includes a nonmagnetic variable-temperature sample chamber, a microtesla magnetic field coil (operating in the range of 0.02-75 microtesla), a three-layered mu-metal shield (to attenuate the ambient magnetic field), and a magnetic shield degaussing coil placed in the overall device enclosure. The gas-handling manifold allows for parahydrogen-gas flow and pressure control (up to 9.2 bar of total parahydrogen pressure). The sample temperature can be varied either using a water bath or a PID-controlled heat exchanger in the range from -12 to 80 °C. This benchtop device measures 62 cm (length) × 47 cm (width) × 47 cm (height), weighs 30 kg, and requires only connections to a high-pressure parahydrogen gas supply and a single 110/220 VAC power source. The utility of the device has been demonstrated using an example of parahydrogen pairwise addition to form HP ethyl [1-13C]acetate (P13C = 7%, [c] = 1 M). Moreover, the Signal Amplification By Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei (SABRE-SHEATH) technique was employed to demonstrate efficient hyperpolarization of 13C and 15N spins in a wide range of biologically relevant molecules, including [1-13C]pyruvate (P13C = 14%, [c] = 27 mM), [1-13C]-α-ketoglutarate (P13C = 17%), [1-13C]ketoisocaproate (P13C = 18%), [15N3]metronidazole (P15N = 13%, [c] = 20 mM), and others. While the vast majority of the utility studies have been performed in standard 5 mm NMR tubes, the sample chamber of the device can accommodate a wide range of sample container sizes and geometries of up to 1 L sample volume. The device establishes an integrated, simple, inexpensive, and versatile equipment gateway needed to facilitate parahydrogen-based hyperpolarization experiments ranging from basic science to preclinical applications; indeed, detailed technical drawings and a bill of materials are provided to support the ready translation of this design to other laboratories.

Assessment of the industrial emissions impact on the quality of atmospheric air in the Burlin district of West Kazakhstan region DEVELOPMENT

The article is devoted to the study of air pollution in the Burlin district of the West Kazakhstan region, where one of the main sources of air pollution is the Karachagan oil and gas condensate field, the main feature of which is the high content of hydrogen sulfide in natural gas from 4 to 4.3%. The analysis showed that the atmospheric air state in the specified area is determined by the characteristics of harmful emissions sources, composition, volumes of pollutant emissions and climatic characteristics of the territory, which determine the conditions for the polluting components dispersion. The qualitative and quantitative characteristics of the chemical composition of the atmospheric air in the study area, as well as the features of their changes over the years end climatic seasons, are largely determined by emissions of nitrogen oxides, carbon, sulfur dioxide, hydrogen sulfide, volatile organic compounds and inorganic dust into the atmosphere by oil and gas facilities. The anthropogenic influence of industry in this area is also evidenced by the calculated value of the integral coefficient of air pollution. At the same time, industrial enterprises, having increased the anthropogenic impact on the environment, have the ability to prevent negative environmental consequences. The system of industrial environmental control of the chemical composition of industrial emissions at the Karachagnak field facilities is carried out on an ongoing basis. The analysis showed that a reduction in emissions and, accordingly, a reduction in ground-level concentrations of air pollutants at the Karachagnak field facilities is ensured by a whole range of technological and organizational measures, among which the technology of high-pressure gas reinjection deserves special attention. It necessitates the need to carry out systematic work to study the ecological state of the territory of the Karachagnak field, using not only ground-based research methods, but also modern geoinformation and aerospace technologies that make it possible to dynamically assess the changes taking place, conduct a geo-ecological assessment and make a forecast for the development of the environmental situation in this area. territories. The work carried out contributes to further analysis of the regional assessment of the environmental state of the atmosphere of large industrial centers.

Impact of breech geometry and propellant flow on the release of large pellets for the ITER disruption mitigation system

Studies have been performed on the release mechanism for large pellets using high pressure gas in a shattered pellet injector. Typically, pellets are dislodged from the cryogenic surface and accelerated down a barrel using high pressure gas delivered by a fast-acting propellant valve. The pellets impact an angled surface which shatters the pellet into many small fragments before entering the plasma. This technique was initially demonstrated on DIII-D (Commaux et al 2016 Nucl. Fusion 56 046007) and is now deployed on JET, KSTAR, ASDEX-Upgrade, and other tokamaks around the world in support of ITER’s disruption mitigation system design and physics basis. The large hydrogen, 28.5 mm diameter, 2 length-to-diameter ratio, pellets foreseen for ITER SPI operation have low material strength and low heat of sublimation, which cause the pellets to be fragile and highly reactive to the impact of warm propellant gas. Due to the size of the pellets, significantly more propellant gas is required to dislodge and accelerate them. This creates a potentially significant propellant gas removal issue as 2–6 bar-L of gas is expected to be required for release and speed control. The research presented in this paper is an in-depth exploration of the parameters that are keys to reliable pellet release and speed control. Computational fluid dynamics (CFD) modeling of propellant flows through various breech designs was conducted to determine the force generated on the back surface of a pellet. These simulations assumed the use of the ORNL designed flyer plate valve. CFD modeling combined with experimental measurements provide adequate insight to determine a path to an optimal valve and breech design for ITER SPI pellet release and speed control while minimizing propellant gas usage.

Stability analysis of braking and control system of pipeline intelligent plugging robot

In the maintenance and emergency repair of oil and gas long-distance pipelines, the pipeline intelligent plugging robot is a new type of intelligent and efficient plugging device inside the pipeline. The stability of its braking and control system determines whether it can successfully seal high-pressure oil and gas inside the pipeline. This research is about intelligent plugging robots for pipelines that use the friction between the rubber hose and the pipe wall for braking. A hydraulic control system is designed, and a braking model for the robot is established. The hydraulic control system is simulated using a numerical simulation method, and the influence of different braking distances on system stability is investigated for various initial velocities of the robot. The results indicate that the fuzzy PID control hydraulic system exhibits a faster response with a maximum overshoot acceleration of −12.8 m/s2. The system achieves the desired acceleration of −0.14 m/s2 within 7 seconds and successfully completes the braking process. The fuzzy PID control approach effectively reduces parameter fluctuations, improves system stability, and decreases acceleration variations when faced with different initial speeds and braking distance signals. Consequently, the positioning accuracy of the robot is enhanced, and power consumption is reduced. This research provides important guidance for the development of new technologies in pipeline maintenance and emergency repair, particularly in the area of plugging operations under pressure.

Radical generation and bactericidal activity of nanobubbles produced by ultrasonic irradiation of carbonated water

Our previous study showed that nanobubbles (NBs) encapsulating CO2 gas have bactericidal activity due to reactive oxygen species (ROS) (Yamaguchi et al., 2020). Here, we report that bulk NBs encapsulating CO2 can be efficiently generated by ultrasonically irradiating carbonated water using a piezoelectric transducer with a frequency of 1.7 MHz. The generated NBs were less than 100 nm in size and had a lifetime of 500 h. Furthermore, generation of ROS in the NB suspension was investigated using electron spin resonance spectroscopy and fluorescence spectrometry. The main ROS was found to be the hydroxyl radical, which is consistent with our previous observations. The bactericidal activity lasted for at least one week. Furthermore, a mist generated by atomizing the NB suspension with ultrasonic waves was confirmed to have the same bactericidal activity as the suspension itself. We believe that the strong, persistent bactericidal activity and radical generation phenomenon are unique to NBs produced by ultrasonic irradiation of carbonated water. We propose that entrapped CO2 molecules strongly interact with water at the NB interface to weaken the interface, and high-pressure CO2 gas erupts from this weakened interface to generate ROS with bactericidal activity.

Flyrock in surface mining Part II - Causes, sources, and mechanisms of rock projection

The fracturing and movement of rock that occurs in the vicinity of a stemmed borehole charge in open pit mining operations are described by examining the effects of the emitted stress waves - shock and elastic - and the expansion of high-pressure detonation product gases. Three principal modes of momentum transfer to fractured rock are identified, all linked to gas expansion work. This work can be delivered radially (burden), axially (stemming), and in the collar zone (cratering). Flyrock is generated under unusual combinations of blast parameters and rock properties. Although infrequent and seldom predictable, the generation of flyrock can nonetheless be interpreted and modelled in terms of the principal mechanisms of rock projection described in this study. The physical processes underlying these principal mechanisms are identified and will permit the development of predictive models for flyrock velocities.

Characterization of fracture behavior under impact-like loading conditions of elastomeric grades for high-pressure gas applications

Rapid gas decompression (RGD) is a major concern for elastomeric sealing components in cyclic gas exposure conditions as it generates cracks and can even cause total mechanical damage threatening the sealing integrity. Therefore, to analyze the fracture behavior of elastomeric grades under impact-like loading conditions, a test methodology was developed using a single edge notch in tension (SENT) specimen. To gain more insights into the behavior of differently formulated four nitrile butadiene rubber (NBR) grades (carbon black (CB) or Silica-filled, with different curing characteristics), tests were conducted at a wide range of temperatures, −20, 23, and 80 °C and under a wide range of loading rates (0.2–5 m/s). The single fracture parameters, strain energy release rate (G) at stable crack initiation and G at maximum load, as well as multiple fracture parameters from crack resistance curves (R-curves), G–Δa and crack growth rate vs crack extension curves, da/dt–Δa, were derived. All the grades showed distinct temperature and loading rate sensitivity on fracture behavior, however, the effect was more pronounced in sulfur-cured grades. Higher cross-link density, delivered a lower resistance to fracture and a uniform higher crack growth rate, conversely higher filler loading improved the fracture resistance. Within the tested conditions, the component-level instrumented tests on RGD failure revealed a similar ranking to the tested grades and it emphasizes the importance and relevance of intrinsic fracture properties. The generated information on single fracture parameters and crack growth kinetics is vital in phenomenological modeling attempts of the actual failure of components as well.

Effect of disturbed coal pore structure on gas adsorption characteristics: mercury intrusion porosimetry

Studying pore structures of disturbed coal and their influences on adsorption characteristics is conducive to in-depth understanding of occurrence and migration of gas in reservoirs in areas prone to coal and gas outbursts. A mercury porosimeter and a high-pressure gas adsorption instrument were separately used to investigate pore structures and measure adsorption characteristics of disturbed coal and undisturbed coal in Ningtiaota Coal Mine and Xigu Coal Mine (Shaanxi Province, China). In addition, pore structures and gas adsorption characteristics of coal samples were studied. The Menger’s sponge model was adopted to calculate fractal dimensions of coal samples, to estimate influences of pore structures and fractal features on the gas adsorption characteristics of disturbed and undisturbed coal. Results show that the pore volume of undisturbed coal is mainly contributed by micropores and transitional pores, while that of disturbed coal arises mainly from macropores and mesopores. Micropores and transitional pores account for large proportions of the specific surface area of pores in both disturbed and undisturbed coal. The adsorption isotherms of disturbed and undisturbed coal conform to the Langmuir equation and tectonism increases the limiting adsorption quantity of coal. The fractal dimensions D1 of the four types of coal samples in the experiments are in the range of 2.7617–2.9961, while the fractal dimensions D1 and D2 of disturbed coal are both larger than those of undisturbed coal, indicating that disturbed coal is more likely to collapse under high pressure. The total pore volume, total specific surface area of pores, and fractal dimensions are positively correlated with the adsorption constant a, while they have U-shaped correlations with the adsorption constant b of coal samples. The adsorption constant a of disturbed coal is always greater than that of undisturbed coal, while no obvious trend is observed between the adsorption constant b and tectonism. The research results can provide theoretical basis for further study of gas occurrence in disturbed coal seams.

Aspects of Gas Storage: Confined Geometry Effects on the High-Pressure Adsorption Behavior of Supercritical Fluids.

During the last decades, major progress was made concerning the understanding of subcritical low-pressure adsorption of fluids like nitrogen and argon at their boiling temperatures in nanoporous materials. It was possible to understand how structural properties affect the shape of the adsorption isotherms. However, within the context of gas storage applications, supercritical high-pressure gas adsorption is important. A key feature here is that the experimentally determined surface excess adsorption isotherm may exhibit a characteristic maximum at a certain pressure. For a given temperature and adsorptive/adsorbent system, the surface excess maximum (and the corresponding adsorbed amount) is related to the storage capacity of the adsorbent. However, there is still a lack of understanding of how key textural properties such as surface area and pore size affect details of the shape of supercritical high-pressure adsorption isotherms. To address these open questions, we have performed a systematic experimental study assessing the effect of pore size/structure on the supercritical adsorption isotherms of pure fluids such as C2H4, CO2, and SF6 over a wider range of temperatures and pressures on a series of model materials exhibiting well-defined pore sizes, i.e., ordered micro- and mesoporous materials (e.g., NaY zeolite, KIT-6 silica, and MCM-48 silica). A fundamental result of our experiments is a unique fluid-independent correlation between the pressure of the surface excess maximum pmax (at a given temperature) and the pore size (by taking into account the kinetic diameter of the fluid and the underlying effective attractive fluid-wall interaction). Summarizing, our results suggest important structure-property relationships, allowing one to determine, for given thermodynamic conditions, important information related to the optimal operating conditions for supercritical adsorption applications. The insights may also serve as a basis for optimizing and tailoring the properties of nanoporous adsorbent materials for gas storage applications.

Analysis of stall characteristics of the cuspidal waverider at subsonic conditions

The stall characteristics of the cuspidal waverider under subsonic conditions were studied at M = 0.4 and H = 0 km incoming flow. The stall characteristics were compared with those of delta wing models with the same leading-edge swept angle and the same aspect ratio. It can be found that the flow field changes of the cuspidal waverider are similar to those of Model 1 and Model 2. The critical angle of attack of the cuspidal waverider is more influenced by the aspect ratio, but less related to the leading-edge swept angle. The lift change of the cuspidal waverider is closely related to the vortex structure on the leeward side. As the angle of attack increases, the vortex structure becomes thicker and stronger, and moves toward the middle of the model under the action of the overflowing high pressure gas on the lower surface. Under the same angle of attack, the vortex structure under the effect of the adverse pressure gradient, the intensity along the flow direction decreases while the vortex continues to move away from the wall. Besides, the possible splitting of large vortex into smaller ones will be another result of the effect of the inverse pressure gradient. The smaller the overall aspect ratio of the model, the greater actual swept angle and the greater effective swept angel of the vortex structure, which allows the vortex to exist at higher angles of attack. When the vortex structure is broken to form a larger recirculation area in the leeward area, the negative pressure at the leeward surface decreases, the lift coefficient decreases, and a stall occurs.