Cavity Pressure Research Articles

Development of a methodical approach to set-up the injection velocity profile dependent on the part geometry

Abstract The injection volume rate is an important setting parameter of the injection moulding process as it determines local process parameters as melt front velocity, respectively, shear rate, pressure and temperature in the mould cavity. In order to avoid too low or too high melt front velocities, profiling of the injection volume rate during the injection is necessary dependent on the part geometry. However, the set-up of a volume rate profile at the machine is an iterative and subjective process so far. Therefore, a method is developed that determines a suitable volume rate profile based on the process simulation gaining a constant melt front velocity or melt front shear rate. A developed process model enables the transmission from simulation to the machine based on a volume rate balance in the screw antechamber. The simulative and experimental results show a good agreement of the cavity filling.

Radiation damping effect on the sound pressure response in a structural-acoustic cavity

A structural-acoustic system consisting of an enclosed cavity with flexible wall panels is considered to evaluate the effect of sound radiation-damping resulting from the panel vibration on the sound pressure level in the cavity. The interior cavity pressure can excite the flexible wall panels that will radiate noise to the exterior that in turn can reduce the interior noise due to the energy loss to the exterior surroundings. This energy loss is described as radiation damping of the interior cavity system. An enclosed rectangular cavity-plate system subjected to external random pressure excitation is used to evaluate the effect. The radiation damping is evaluated using a modal approach (FEM, BEM) to determine the radiation efficiency of the vibrating panels. The effect of the radiation damping for the example of a box-plate structure is evaluated using the CMA (classical modal analysis) method for the low-frequency range and the AMA (asymptotic modal analysis) method for the mid- and high-frequency ranges. The inclusion of radiation damping due to rigid body cavity mode excitation is shown to provide an improved prediction of the sound transmission loss especially in the low-frequency range.

Mechanical Performance Analysis of Hydrostatic Thrust Bearing under Microbevel Parameters

Background: Heavy-duty hydrostatic bearings of the original parallel friction pair are prone to hydrostatic loss problems during operation. Aims: To solve the failure problem, the original hydrostatic oil pad was designed as a micro-inclined plane, and the dynamic pressure caused by the micro-wedge of the oil pad at a higher speed was used to compensate for the static pressure loss of the bearing. objective: For a new type q1-205 microbevel double rectangular cavity hydrostatic bearing. Objective: This study aims to design a new type of q1-205 micro bevel double rectangular cavity hydrostatic bearing. Method: The mathematical model of oil film theoretical analysis of hydrostatic bearing with the micro-inclined surface was established, including the flow equation of a double rectangular cavity with a micro-inclined surface and static and dynamic bearing capacity equation. result: The oil film lubrication performance of the bearing with the wedge parameters of 0mm, 0.02mm, 0.04mm, 0.06mm, 0.08mm and 0.10mm was simulated by the finite volume method, the comprehensive influence law of the wedge-shaped parameters on the vorticity and flow rate of the oil cavity pressure fluid was revealed. Finally, the oil cavity pressure changes of oil films with different wedge parameters under certain load and speed were tested by design experiments, and the theoretical analysis and simulation were verified. Result: In this paper, the mechanical properties of oil film with tilt height between 0 and 0.1mm were simulated with variable viscosity, and the distribution law of pressure field under different working conditions was obtained. Through the experimental study, the pressure data of parallel flat pads and tilting pads under different working conditions are measured and compared with the simulation data. Conclusion: The pressure loss value of the oil pad designed in this paper is relatively small under extreme working conditions. The overall loss rate is about 10% ~ 20%, and the dynamic pressure compensation rate is about 16%. The dynamic pressure generated by the slight inclination Angle can well compensate for the static pressure loss.

In-cavity pressure measurements for failure diagnosis in the injection moulding process and correlation with numerical simulation

The pressure profile analysis for monitoring and diagnosis processing failures during an injection moulding process, such as burn marks and short shots, is a useful instrument for process and part quality control and production with zero defects and greater efficiency. Therefore, this work aims to demonstrate the in-cavity pressure monitoring feasibility for failure diagnosis and injection moulding process optimization. The methodology used to analyse the obtained pressure variation is presented. The results were correlated to the typical cavity pressure profile, which enables the acquisition of information about the process and the moulding tool. This way, it was possible to determine the origin of the defects present in the injected parts, focusing not only on the velocity to pressure switchover but also on the initial part of the curve, related to the filling phase. Moreover, the obtained results and the studied processing conditions were correlated with the injection moulding process simulation.

Feasibility assessment of injection molding online monitoring based on oil pressure/nozzle pressure/cavity pressure

Abstract This study produced a box-like product through injection molding, and pressure sensors were installed at the nozzle in the injection molding machine and mold cavity. Injection molding experiments were conducted with various process parameters to understand the correlations between the pressure of the cavity, nozzle, and oil pump. A high correlation (R > 0.95) between oil pressure and nozzle pressure could be found in the study. The oil pressure in the injection molding machine could fully describe the pressure variation of the molten plastic at the nozzle. However, the correlation between nozzle pressure and cavity pressure was slightly reduced due to changes in injection speed, melting temperature, and packing time. Thus, a suitable molding window can improve the correlation between oil pressure, nozzle pressure, and cavity pressure. This study provides a correlation between the three pressures and a reference for the future selection of process variables, an essential pretreatment for online monitoring.

A Review of the Thermochemical Behaviour of Fluxes in Submerged Arc Welding: Modelling of Gas Phase Reactions

This review is focused on the thermochemical behaviour of fluxes in submerged arc welding (SAW). The English-language literature from the 1970s onwards is reviewed. It was recognised early on that the thermochemical behaviour of fluxes sets the weld metal total ppm O and the element transfer extent from the molten flux (slag) to the weld pool. Despite the establishment of this link between the flux-induced oxygen potential and element transfer, it is also well accepted that the slag–metal equilibrium does not control SAW process metallurgy. Instead, the gas phase must be taken into account to better describe SAW process metallurgy equilibrium calculations. This is illustrated in the gas–slag–metal equilibrium simulation model developed by Coetsee. This model provides improved accuracy in predicting the weld metal total ppm O values as compared to the empirical trend of Tuliani et al. Recent works on the application of Al metal powder with alloying metal powders provide new insights into the likely gas phase reactions in the SAW process and the modification of the flux oxygen behaviour via Al additions. Aluminium may lower the partial oxygen pressure in the arc cavity, and aluminium also lowers the partial oxygen pressure at the weld pool–slag interface. The weld metal total ppm O is lowered with the addition of aluminium in SAW, but not to the same extent as would be expected from steelmaking ladle metallurgy de-oxidation practice when using Al as de-oxidiser. This difference indicates that slag–metal equilibrium is not maintained in the SAW process.

The effect of OSA on the negative pressure and acoustic compliance of middle ear cavity in children.

To explore the effect of obstructive sleep apnea (OSA) on the negative pressure and acoustic compliance of middle ear cavity in children. The clinical data of 258 children with suspected OSA, who complained of mouth breathing or snoring at night in the Department of Otolaryngology Head and neck surgery of the Second Affiliated Hospital of Xi'an Jiao Tong University from August 2020 to March 2022, were enrolled and analyzed retrospectively. The OSA and otitis media with effusion (OME) were determined by polysomnography (PSG) and acoustic immittance examination, respectively. Then, the parameters of tympanometry were compared between OSA and non-OSA children or among the children with various severity of OSA. There was no significant difference in the incidence of OME between children with OSA and those with non-OSA (15.80% vs 11.80%, P=0.422). Compared with non-OSA children, OSA children had lower negative pressure (-56.42 vs -12.38, P<0.001) and higher acoustic compliance (0.45 vs 0.38, P=0.030) in middle ear cavity. There were also significant differences in negative pressure and acoustic compliance among children with mild, moderate and severe OSA (P<0.001; P=0.001). However, only the absolute value of negative pressure was markedly decreased after surgical therapy accompanied with transformation from OSA to non-OSA (-156.67 vs -45.67, P<0.05), while this was not observed for acoustic compliance (0.48 vs 0.40, P>0.05). OSA may have an adverse influence on the negative pressure and acoustic compliance of middle ear cavity in children.

Measurement of pressure–volume–temperature diagrams based on simulated melt temperature and actual cavity pressure

Pressure–volume–temperature (pvT) diagrams illustrate the behavior of a polymer melt during injection molding and can be used to determine the optimal process parameter settings for producing quality parts. However, the measurements of pvT diagrams are costly and time-consuming and have limitations for process control. This study generated an economic pvT diagram based on sensor data and simulation analysis. To avoid the use of expensive infrared sensors and inaccurate pressure simulations, a pvT curve was constructed by combining the melting temperature, which was simulated using computer-aided engineering, and the actual cavity pressure. The specific volume of the polymer melt was then calculated using a modified Tait model. The pvT diagram could be used to investigate the changes in specific volume at various injection stages, which could be applied to quality prediction. In this study, a flat plate with uneven thickness was used as the research vehicle. The specific volume of each sensor position of the plastic component cooled to room temperature was calculated. Thereafter, a correlation analysis between the changes in specific volume and the shrinkage ratio of the plastic part was conducted. The experiment indicated that both variables were highly correlated. Therefore, monitoring changes in specific volume could predict part size. Additionally, the proposed measurements of the pvT diagram could be used to compute the cooling time, which greatly affects the quality and production efficiency of injection-molded parts. A 25-s cooling time setting demonstrated a stable molding quality compared with the traditional heat transfer formula (16 s) and the commercial simulation (17 s).

Modeling Exhaust-Generated Aerodynamic Pressure Loads on Airfield Matting Repair Systems

Airfield matting systems are commonly used for rapid repair of damaged runways to facilitate continuity of critical operations. Under normal service conditions, matting repair systems are subject not only to wheel loads exerted by airfield traffic but also to aerodynamic pressure loads resulting from high-speed, turbulent exhaust plumes produced by jets during taxi and take-off. Matting systems employed by the U.S. Air Force have been tested with respect to wheel loads, but probabilities of failure because of pressure loads produced by jet exhaust have not yet been established. This study presents a numerical approach for preliminary estimation of worst-case matting anchor forces resulting from exhaust-generated pressure loads. Using a two-dimensional computational fluid dynamics model, system behavior is evaluated by means of a parametric study of six system variables, of which the most significant are: (1) distance between engine and matting, (2) depth of cavity openings at matting edges, and (3) engine exhaust velocity. The results demonstrate that matting systems are likely to experience net uplift in typical service scenarios, driven by the combined effects of flow separation and cavity pressurization. Worst-case anchor pull-out forces, computed according to a tributary-area approach, are estimated to fall in the range of 130 lb (581 N) to 979 lb (4,350 N), depending on assumed load-sharing behavior among anchors and the size of the repair site. Field testing of instrumented matting systems during jet taxi and take-off sequences is recommended as the best next step toward understanding system behavior.

Clinical effect of standardized nursing for lymphoma patients and the influencing factors of nosocomial infection.

To analyze the clinical effect of standardized nursing for lymphoma patients and the influencing factors of nosocomial infection, a total of 360 diffuse large B-cell lymphoma patients with disease recurrence or progression after first-line treatment were retrospectively selected from our hospital from January 2021 to July 2022. After standardized nursing, the overall infection rate of lymphoma patients was 2.50% (9/360), which was significantly lower than the overall infection rate of our hospital in 2021 (7.44%, 844/11342) (P < .05). The proportion of 3 kinds of pathogenic bacteria detected were G+ bacteria (33.5%), G- bacteria (53.3%), and fungi (13.2%). The pathogenic bacteria genus with the most G+ bacteria is Enterococcus, the pathogenic bacteria genus with the most G+ bacteria is Enterobacteriaceae, and the pathogenic bacteria with the most fungi is Candida albicans. Female infection rate was significantly higher than male (P < .05). There was no significant difference in nosocomial infection among different marital status/fertility status (P > .05). The nosocomial infection of patients with different hospitalization times was statistically significant (P < .05). The duration of hospitalization in the infected group was significantly higher than that in the non-infected group (P < .05). The clinical effect of standardized nursing for lymphoma patients is significant, and the influencing factors of nosocomial infection include patient gender, hospitalization frequency, and hospitalization duration.

Cavity pressure profile study during foam injection molding and its effect on cell formation of polypropylene/chemical blowing agent foam

AbstractIn the current scenario, many automotive and aerospace industries have exaggerated replacement of most of the metal parts with polymers to achieve the pursuit of lightweight thereby to reduce fuel consumption and carbon emission. Foam injection molding (FIM) is among one of the cost‐effective approaches to produce lightweight polymer products. During FIM, stringent control over various processing parameters is crucial to ensure the precision and reliability of molded parts. This work aims toward the investigation of cavity pressure and its effect on microstructure or cell morphology in chemical blowing agent mixed polypropylene (PP) foams produced by FIM. In particular, effect of varying injection temperature, injection speed and plasticization parameters (screw rotation speed and back pressure) have been examined on the cavity pressure profiles and its conforming influence on cell nucleation and growth have been discussed acutely. The results of this study indicate that various process parameters significantly influence the trajectory of cavity pressure profile during FIM which in turn critically decides structural uniformity of foamed product.

Theoretical research and maintenance of electro hydraulically controlled injectors

Introduction. Nowadays the part of the diesel engines for KamAZ-740 cars are operated with fuel equipment, in which the injectors have hydro mechanical control. Their main disadvantage is the low fuel pressure in front of the injector openings (less than 60 MPa) and the lack of fuel supply control.The use of injectors with electro hydraulic control (EHC) increases the pressure in the injector cavity up to 250 MPa and control the fuel injection process. The disadvantage of the injectors with EHC is a structural complexity of a control valve, the difficulty of its regulation and coding. The object of the study is the injectors of KamAZ-740 diesel engine with electro hydraulic control of the atomizer needle stroke.The purpose of this work is to carry out theoretical research and improve the methods of maintenance of injectors with electro hydraulic control (control valve regulation and coding), which will increase their reliability, durability and ensure a reduction in diesel fuel consumption.Research methods. The study of the nozzle control valve is theoretical and calculated. The paper proposes a calculation method and performs theoretical studies for the influence of pressure (50 – 250 MPa) on the value of the effective flow section and the diameter of the nozzle holes of the sprayer.For the injectors with EHC, the control valve regulation procedure has been clarified, which consists in the fact that at the beginning of regulation, the main force acting on the ball from the side of the maximum pressure in the control chamber (for example, 200 MPa) equal to 76 N is calculated (see Figure 4). Then the required spring force of 100 N is determined (20-40% more, see Figure 5). Next, the strength of the electromagnet is estimated at 140 N (20 – 40% more of the spring force, see Figure 6).The results of theoretical research. The results of computational (theoretical) studies for the effective flow section of the sprayer and the diameter of the nozzle holes, depending on the pressure P in front of the nozzle holes, are presented.The paper defines. 1. The forces acting on the ball (57 – 105 N) depending on the pressure in the control chamber (150 – 275 MPa). 2. Spring forces (40 – 140 N) with a stiffness of 40 N /mm, depending on its compression up to 3.5 mm. 3. The forces of the electromagnet (140 – 20 N) depending on the gap between the anchor and the core (0.2 – 0.5 mm).The method of restoring the required (rated) cyclic fuel supply when it changes as a result of replacing the control valve or adjusting is considered. The calculated values of fuel supply per cycle (mm3/cycle) from the activation time are given.Conclusion. The results of the study are intended for organizations and enterprises engaged in diagnostics, restoration, adjustment and coding of injectors with electro hydraulic control for the needle stroke of sprayers. The results of computational studies can be used to refine the methodology of maintenance of fuel systems with electronic control (Common Rail).

Proposed cardio-pulmonary model to investigate the effects of COVID-19 on the cardiovascular system

In this paper, we propose a new mathematical model of cardiovascular system coupled with a respiratory system to study the effects of COVID-19 on global blood circulation parameters using the lumped parameters model. We use the fourth-order Runge-Kutta method for solving the sets of equations of motion. We validate our model by showing that the simulated flows in pulmonary and aortic valves corroborate, respectively, the results established by Smith et al. [IFAC Proceedings Volumes, 39 (2006) 453–458]. Then we examine the effects of the new coronavirus (covid-19) on the cardiopulmonary system through the impact of the high respiratory frequency and the variation of the alveoli volume. To achieve this aim, we propose a new exponential law for the time varying of the pulmonary resistance. It appears that when the respiratory frequency grows, the delay between the systemic artery flow and the flow in the pulmonary artery diminishes. Therefore, the efficiency of the cardiac pump is reduced. Moreover, our results also show that variations of the alveoli volume cause the increment of the pleural pressure in the vascular cavities that induces an exponential growth of the pulmonary resistance. Furthermore, this growth of the pulmonary resistance provokes the augmentation of pressure in some organs and its reduction in others. We found that patient with covid-19 having a prior history of cardiovascular diseases is exposed to a severe case of inflammation/damage of certain organs than those with no history of cardiovascular disease.

Design and Simulation of a New Type of Speed-ratio Bladeless Supercharger Mechanism

Aiming at the problems of complex machining and impeller structural strength of traditional centrifugal compressors, a new speed-ratio bladeless supercharging mechanism is proposed. The results show that the system pressure of the new structure increases with the increase of the rotating speed of the disk; while the maximum pressure of the outer cavity and the maximum pressure of the system change in a curve with the difference of the disk wall clearance, the diameter of the disk and the number of pipes in the disk. Based on the results of theoretical and simulation analysis, a bladeless pressurized structure test platform was established. The test results show that the working medium pressurization measured at the outlet of the mechanism is 0.1Mpa, and the experimental results have a high degree of agreement with the theoretical analysis.

Analysis of cavity shedding around the twisted hydrofoil

In order to understand the mechanism of cavity shedding and evolution, turbulent cavitating flows of the twisted hydrofoil were numerically investigated using the k-? turbulence model and the ZGB cavitation model. The results of the numerical calculation and the experimental method are basically consistent, which confirms the feasibility of the numerical calculation model. This study has obtained the following conclusions. Firstly, the cavity shedding can be summarized into six stages, and the cavity shape, pressure and velocity field at different stages are displayed, analyzed and compared in detail. Secondly, the shedding of cavity and its evolution are mainly caused by the re-entrant jet and side-entrant jet, in which the former provides the kinetic energy and the latter plays the role of guiding the direction. Thirdly, under the convective shearing action of the re-entrant jet and the main flow, a strong vortex located in the mid-back edge of the hydrofoil is formed, which promotes the transformation of the cavity shape into a U-shaped structure.

水稻直播排种器扰流叶片的设计与性能试验

In order to improve air pressure utilization and working performance, the direct seed-metering device for rice was designed with spoiler blades embedded in the air cavity. The study was carried out using theoretical analysis and hydrodynamic methods to obtain the optimum structure of the spoiler blades. Taking the rotating speed of the air cavity, the negative pressure of the air cavity, and the filling height as the test factors, the multiple regression analysis and the response surface analysis were carried out to obtain the best working parameters of the seed-metering device with spoiler blades. The results showed that when the rotating speed of the air cavity was 23.56 r/min, the negative pressure of the air cavity was 4.97 kPa and the filling height was 12.82 cm, the qualified index was 95.21%, the missing index was 3.28% and the multiple index was 1.51%, which was the best seeding performance. Comparing the test with the seed-metering device without spoiler blades, the results showed that the installation of spoiler blades can improve the performance of the seed-metering device under the best working parameters. This study provide a reference for the design of direct seed-metering device for rice.

Internal leakage rate prediction and failure diagnosis of buried pipeline ball valve based on valve cavity pressure detection

— Ball valve is a key fluid control equipment used extensively in oil and gas pipelines. The online detection and failure diagnosis of the internal leakage of the ball valve is of great significance to ensure the safety operation of natural gas transmission pipelines. This paper proposes a prediction method of the internal leakage rate and a diagnosis method of the failure mode of the buried pipeline ball valve based on valve cavity pressure detection. Firstly, the valve cavity pressure signal generated by the internal leakage of the ball valve is detected by the pressure sensor, and the valve cavity pressure signal is denoised by wavelet threshold denoising. Then, the back propagation (BP) neural network has the disadvantage of unstable learning ability, so the BP neural network is optimized by chaos sparrow search optimization algorithm (CSSOA-BP). Finally, the prediction model of the ball valve internal leakage rate and the diagnosis model of the ball valve failure mode are established by using CSSOA-BP neural network and the characteristic parameters of the valve cavity pressure signal. To verify the performance of the prediction model and the diagnosis model of CSSOA-BP neural network, the predictive results and diagnostic results are compared with those of the sparrow search algorithm optimization BP (SSA-BP) neural network and BP neural network. The experimental results show that the maximum prediction error of CSSOA-BP neural network is the smallest, which is 13.6%. The accuracy of the diagnostic results of CSSOA-BP neural network is the highest, which is 83.3%. It indicates that the proposed method can achieve better predictive results of the ball valve internal leakage rate and more accurate diagnostic results of the ball valve failure mode.

Bottle-feeding techniques for children with cleft lip and palate experiencing feeding difficulties

ObjectiveThis study aimed to identify clinical bottle-feeding techniques practiced by nurses for children with cleft lip and palate experiencing feeding difficulties. MethodsA qualitative descriptive design was used. Five anonymous questionnaires were distributed to each hospital, and 1,109 hospitals with obstetrics, neonatology, or pediatric dentistry wards in Japan were enrolled in the survey between December 2021 and January 2022. Participants were nurses working for over 5 years providing nursing care for children with cleft lip and palate. The questionnaire comprised open-ended questions about the feeding techniques across four dimensions: preparation before bottle-feeding, nipple insertion methods, sucking assistance, and criteria for stopping bottle-feeding. The qualitative data obtained were categorized according to meaning similarity and analyzed. ResultsA total of 410 valid responses were obtained. The findings regarding the feeding techniques in each dimension were as follows: seven categories (e.g., improving child’s mouth movement, keeping child’s breath calm), 27 sub-categories in preparation before bottle-feeding; four categories (e.g., closing the cleft using the nipple to create negative pressure in oral cavity, inserting the nipple to not touch the cleft), 11 sub-categories in nipple insertion methods; five categories (e.g., facilitating awakening, creating negative pressure in oral cavity), 13 sub-categories in sucking assistance; and four categories (e.g., reduced awakening level, worsening vital signs), 16 sub-categories in criteria for stopping bottle-feeding. Most participants responded that they would like to learn bottle-feeding techniques for children with cleft lip and palate who have feeding difficulties. ConclusionMany bottle-feeding techniques were identified to address disease-characterized conditions. However, the techniques were found to be conflicting: some inserted the nipple to close the cleft to create negative pressure in the child’s oral cavity, while others inserted it without touching the cleft to prevent ulceration on the nasal septum. Although these techniques were used by nurses, the effectiveness of the methods has not been assessed. Future intervention studies are needed to determine each technique’s benefit or potential harm.

A graphical method for undrained analysis of cavity expansion in Mohr–Coulomb soil

A rigorous analytical solution is developed for undrained cavity expansion problems in non-associated Mohr–Coulomb soil, based on a novel graphical analysis approach and on the Lagrangian description through tracking only the responses of a soil particle at the cavity surface. The mathematical difficulties involved with the flow rate calculation when the stress state lies on the corner/edge of two adjacent (Mohr–Coulomb) yield surfaces, for both cylindrical and spherical cases, are tackled by using the generalised Koiter theory for non-associated plasticity. In particular, through the unique geometrical formulation, the effective stress path pertaining to the cylindrical cavity problem can be very conveniently directly determined, and is found to consist of simple, piecewise straight lines in the deviatoric stress plane with the orientations dependent of the relative magnitude of Poisson's ratio and the friction angle. This thus renders possible the removal of the stringent intermediacy assumption for the vertical stress that is commonly adopted in previous formulations, and hence the development of a complete cylindrical cavity expansion solution in Mohr–Coulomb soil under undrained loading conditions. The stress and deformation responses of the cavity, including the typical pressure–expansion curves and limiting cavity pressure, are finally analytically obtained along with the Lagrangian form of the radial equilibrium equation in completely explicit forms. The closed-form solution provided in this paper is the first rigorous one of its kind, thus completing the analytical analysis of the cavity expansion problem with the classical Mohr–Coulomb model; this is deemed to be essential for the interpretation of in situ test results pertaining to cohesive-frictional soils.

Simulation research on the outlet cavity features in the underwater launching process

This paper analyzes the evolution of cavity features and pressure characteristics during the underwater launching process. The improved delayed eddy simulation (IDDES), energy equation, and overlapping grid technique are adopted. In addition, validation of the numerical approach and grid independence is carried out. The evolution of the multiphase flow field and pressure fluctuations near the launcher outlet are studied. Results show that the gas mass escaping from the tube expands and contracts, eventually breaking off with a jet that acts on the tail of the vehicle after the vehicle leaves the tube. Four major pressure fluctuations occurred near the launcher outlet, the first two of which are generated by the alternate expansion and contraction of the high-pressure gas mass, while the subsequent fluctuations mainly originate from the intermittent escape of the remaining gas mass inside the tube, the magnitude of the pressure fluctuations decreases gradually. As the Froude number increases, the scale of the escaping high-pressure gas mass expands significantly, while the dissipation rate of the fused gas mass at the launch tube outlet also increases, the evolution mechanism of multiphase is more complex.