Journal articles on the topic 'Supersonic air inlet'
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1
TUDOSIE, Alexandru-Nicolae, Emanuel DUMITRU, and Marius-Alin ASPRA. "CONTROL LAW FOR AN AIRCRAFT SUPERSONIC AIR INLET WITH INTERNAL COMPRESSION." SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE 21, no. 1 (October 8, 2019): 199–208. http://dx.doi.org/10.19062/2247-3173.2019.21.27.
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Zhang, Yue, Hui-jun Tan, Yi Zhuang, and De-peng Wang. "Morphing Supersonic Inlet with Deforming Air Cell." Journal of Propulsion and Power 31, no. 2 (March 2015): 583–91. http://dx.doi.org/10.2514/1.b35425.
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Vnuchkov, D. A., V. I. Zvegintsev, and D. G. Nalivaychenko. "Investigation of Throttling Characteristics in Supersonic Polyclinic Inlet." Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no. 2 (125) (April 2019): 21–33. http://dx.doi.org/10.18698/0236-3941-2019-2-21-33.
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This paper presents an experimental investigation of throttling characteristics of a multi-wedge air inlet of a wind tunnel built for flat flow field at M = 2.5. The experiments were performed in a wind tunnel at M numbers of 2.55, 3.05 and 4.05. Results of numerical simulation of the flow in the air inlet, where air flow restriction was implemented by additional heating of the flow in the channel past the air inlet, are given for comparison. Experimental throttling characteristics are in good agreement with the values obtained from computations
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Vinogradov, Viacheslav A., Yurii M. Shikhman, and Corin Segal. "A Review of Fuel Pre-injection in Supersonic, Chemically Reacting Flows." Applied Mechanics Reviews 60, no. 4 (July 1, 2007): 139–48. http://dx.doi.org/10.1115/1.2750346.
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Developing an efficient, supersonic combustion-based, air breathing propulsion cycle operating above Mach 3.5, especially when conventional hydrocarbon fuels are sought and particularly when liquid fuels are preferred to increase density, requires mostly effective mechanisms to improve mixing efficiency. One way to extend the time available for mixing is to inject part of the fuel upstream of the vehicle’s combustion chamber. Injection from the wall remains one of the most challenging problems in supersonic aerodynamics, including the requirement to minimize impulse losses, improve fuel-air mixing, reduce inlet∕combustor interactions, and promote flame stability. This article presents a review of studies involving liquid and, in selected cases, gaseous fuel injected in supersonic inlets or in combustor’s insulators. In all these studies, the fuel was injected from a wall in a wake of thin swept pylons at low dynamic pressure ratios (qjet∕qair=0.6–1.5), including individual pylon∕injector geometries and combinations in the inlet and combustor’s isolator, a variety of injection conditions, different injectants, and evaluated their effects on fuel plume spray, impulse losses, and mixing efficiency. This review article cites 47 references.
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Chen, Haoying, Haibo Zhang, Zhihua Xi, and Qiangang Zheng. "Study on Inlet and Engine Integrated Model with Normal Shock Position Feedback." International Journal of Aerospace Engineering 2020 (January 4, 2020): 1–13. http://dx.doi.org/10.1155/2020/5313941.
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In order to consider the inlet and engine integrated model of supersonic airliner, the dynamic identification and control of inlet normal shock are studied. The research is based on the bleed air flow rate under supersonic conditions. With the two-dimensional CFD model of supersonic inlet, the dynamic and static effects of the bleeding flow rate on the normal shock position were investigated. The transfer function was identified, and simultaneously the paper carried out a comprehensive study of inlet and engine integrated model, which is established based on the inlet shock position model and engine component level model. The relationship between normal shock position and total pressure recovery coefficient has been taken into consideration in this model. Based on the inlet and engine integrated model, the closed-loop control simulation of normal shock position is carried out. The results show that the model could resist the disturbance of the inlet flow and keep the inlet and engine matching operation point stable near the optimal value.
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Freskos, G., and O. Penanhoat. "Numerical Simulation of the Flow Field Around Supersonic Air-Intakes." Journal of Engineering for Gas Turbines and Power 116, no. 1 (January 1, 1994): 116–23. http://dx.doi.org/10.1115/1.2906780.
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The demand for efficiency in today’s and in future civil aircraft is such that experimental studies alone do not suffice to optimize aircraft aerodynamics. In this context, much effort has been spent in the past decade to develop numerical methods capable of reproducing the phenomena that occur in the engine flow field. This paper presents some studies in Computational Fluid Dynamics related to supersonic inlets. Two approaches are considered. First, there is a need for a code capable of calculating in a cost-efficient way the entire flow field around a two-dimensional or three-dimensional inlet, e.g., to perform parametric studies. To this effect, a computing method based on grid construction by mesh generator dedicated to inlet shapes and on the discretization of the unsteady Euler equations with an explicit upwind scheme was developed. The treatment of complex geometries led us to adopt a multiblock grid approach. Therefore particular attention was paid to the treatment of the boundary conditions between the different domains. Second, there is a need for a code that can capture local phenomena in order to get a better understanding of inlet behavior (shock/shock, shock/boundary layer interactions, etc.). To this effect a two-dimensional turbulent Navier-Stokes code is used. The two-equation k-ε turbulence model included in the program seems to be one of the most successful models for calculating flow realistically. Correction of the near-wall influence extends its capability to complex flow configurations, e.g., those with separated zones.
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Cao, Da Min, Hong Yang Lv, Xing Yuan Zhang, and Sheng Bin Hu. "Numerical Simulation of the Supersonic Inlet Flow Field." Applied Mechanics and Materials 29-32 (August 2010): 2119–23. http://dx.doi.org/10.4028/www.scientific.net/amm.29-32.2119.
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The 2-D internal steady flow of the scramjet inlet-isolator was numerically simulated by the CFD method. The static pressure contours of the scramjet inlet-isolator under different boundary thickness and different back pressure were given. The numerical simulation results of two kinds of reasons which make the inlet un-start are obtained. One is the boundary layer thickness and another is the high back pressure at the exit of the isolator. When the boundary layer thickness increased, air can not smoothly flow into the inlet isolator and caused inlet un-start. Sameness along with the back pressure rise, have the phenomenon of inlet un-start, too. But the reason of un-start is disaffiliate. In the text analyzed the reasons of un-start phenomenon which from two different perspectives on the problem.
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Ferrero, Andrea. "Control of a Supersonic Inlet in Off-Design Conditions with Plasma Actuators and Bleed." Aerospace 7, no. 3 (March 19, 2020): 32. http://dx.doi.org/10.3390/aerospace7030032.
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Supersonic inlets are a key component of present and future air-breathing propulsion systems for high-speed flight. The inlet design is challenging because of several phenomena that must be taken under control: shock waves, boundary layer separation and unsteadiness. Furthermore, the intensity of these phenomena is strongly influenced by the working conditions and so active control systems can be particularly useful in off-design conditions. In this work, a mixed compression supersonic inlet with a double wedge ramp is considered. The flow field was numerically investigated at different values of Mach number. The simulations show that large separations appear at the higher Mach numbers on both the upper and lower walls of the duct. In order to improve the performances of the inlet two different control strategies were investigated: plasma actuators and bleed. Different locations of the plasma actuator are considered in order to also apply this technology to configurations with a diverter which prevents boundary layer ingestion. The potential of the proposed solutions is investigated in terms of total pressure recovery, flow distortion and power consumption.
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Utomo, Muhammad Adnan, and Romie Oktavianus Bura. "Design of Inward-Turning External Compression Supersonic Inlet for Supersonic Transport Aircraft." INSIST 2, no. 2 (January 25, 2019): 104. http://dx.doi.org/10.23960/ins.v2i2.90.
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Inward-turning external compression intake is one of the hybrid intakes that employs both external and internal compression intakes principle. This intake is commonly developed for hypersonic flight due to its efficiency and utilizing fewer shockwaves that generate heat. Since this intake employ less shockwaves, this design can be applied for low supersonic (Mach 1.4 - 2.5) intakes to reduce noise generated from the shockwaves while maintaining the efficiency. Other than developing the design method, a tool is written in MATLAB language to generate the intake shape automatically based on the desired design requirement. To investigate the intake design tool code and the performance of the generated intake shape, some CFD simulation were performed. The intake design tool code can be validated by comparing the shockwave location and the air properties in every intake's stations. The performance parameters that being observed are the intake efficiency, flow distortion level at the engine face, and the noise level generated by the shockwaves. The design tool written in MATLAB is working as intended. Two dimensional axisymmetric CFD simulations validation has been done and the design meets the minimum requirement. As for the 3D inlet geometry, with a little modification on diffuser and equipping vent to release the buildup pressure, the inlet has been successfully met the military standard on inlet performance (MIL-E-5007D). This design method also has feature to fit every possible throat cross sectional shapes and has been proven to work as designed.Keywords— Inward-turning, Supersonic, Engine Intakes, Low- noise, Design Method
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Ezrokhi, Yu A., and E. A. Khoreva. "Assessing the Impact of the Inlet Total Pressure Distortion on the Turbofan Thrust." Mechanical Engineering and Computer Science, no. 1 (March 3, 2018): 19–30. http://dx.doi.org/10.24108/0118.0001360.
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The paper considers techniques to develop a mathematical model using a method of «parallel compressors». The model is intended to estimate the impact of the air inlet distortion on the primary parameters of the aero-engine. The paper presents rated estimation results in the context of twin spool turbofan design for two typical cruiser modes of flight of the supersonic passenger jet. In estimation the base values σbase and the average values of the inlet ram recovery σave remained invariable. Thus, parametrical calculations were performed for each chosen relative value of the area of low-pressure region.The paper shows that an impact degree of the inlet distortion on the engine thrust for two modes under consideration is essentially different. In other words, if in the subsonic mode the impact assessment can be confined only to taking into account the influence of decreasing average values of the inlet total pressure, the use of such an assumption in the supersonic cruiser mode may result in considerable errors.With invariable values of the pressure recovery factor at the engine intake, which correspond to the speed of flight for a typical air inlet of external compression σbase, and average value σave, a parameter Δσuneven has the main effect on the engine thrust, and degree of this effect essentially depends on a difference between σave and σbase values.
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Gounko, Yu P., and I. I. Mazhul. "Experimental characteristics of a supersonic three-dimensional air inlet with adjustable throat." Thermophysics and Aeromechanics 20, no. 1 (February 2013): 49–64. http://dx.doi.org/10.1134/s0869864313010058.
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Vojta, Lukas, and Vaclav Dvorak. "Measurement and calculating of supersonic ejectors." EPJ Web of Conferences 213 (2019): 02097. http://dx.doi.org/10.1051/epjconf/201921302097.
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This paper deals with numerical and experimental investigation of the flow in an air to air supersonic ejector with constant area mixing chamber. The mixing chamber of previous ejector was completely repaired since a scratch from previous turning had been found. As a result, a new geometry of the mixing chamber was created. Several measurements were conducted with different nozzle position (NP): 1 mm, 2 mm and 3 mm. Furthermore, for a given NP, two different values of stagnation pressure of 200 kPa and 300 kPa at the primary air inlet were investigated in more detail. All numerical simulations were performed in the ANSYS Fluent software. It was found that the influence of the position of the nozzle influences the ejection factor only to a certain extent. For the other parameters of the ejector is also a need to find the optimum position of the nozzle. Repair of the mixing chamber has contributed to reduce the pressure difference at the wall of the mixing chamber.
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Ali, M., and T. Fujiwara. "A numerical study on the mixing of air and hydrogen in a scramjet combustor." Aeronautical Journal 109, no. 1097 (July 2005): 325–35. http://dx.doi.org/10.1017/s0001924000000774.
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Abstract A numerical study on mixing of air and hydrogen is performed by solving two-dimensional full Navier-Stokes equations. The main stream is air of Mach 5 entering through the configured inlet of the combustor and gaseous hydrogen is injected from the configured jet on the side wall. Supersonic mixing and diffusion mechanisms of a transverse hydrogen jet in two-dimensional finite air streams have been analyzed and discussed. The computed results are compared with the experimental data and show good agreement. For an otherwise fixed combustor geometry, the air inlet width and injection angle are varied to study the physics of mixing and flow field characteristics. On the effect of inlet width variation, two competing phenomena have been observed: (i) upstream of injector the strength of recirculation is higher for wider inlet and consequently the mixing increases, and (ii) downstream, the diffusion of hydrogen decreases with the increase of inlet width and eventually mixing decreases. As a result, in far downstream the mixing efficiency increases up to certain inlet width and then decreases for further increment of inlet width. For the variation of injection angle results show that upstream of injector the mixing is dominated by recirculation and downstream the mixing is dominated by mass concentration of hydrogen. Upstream recirculation is dominant for injecting angle 60° and 90°. Incorporating the various effects, perpendicular injection shows the maximum mixing efficiency and its large upstream recirculation region has a good flame holding capability.
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Wilk, Andrzej, and Slawomir Dykas. "Selected cases of heat transfer phenomena on the shock waves in atmospheric air." E3S Web of Conferences 128 (2019): 09005. http://dx.doi.org/10.1051/e3sconf/201912809005.
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The content of water vapour, liquid water or ice in a dispersed form in the atmospheric air is very common and it might affect the aerodynamic characteristics, especially in the transonic or supersonic flow regime. In the paper, special attention was paid to identifying the heat transfer phenomena appearing on a transition from sub- to supersonic, and vice versa flow regime. The in-house CFD code was employed for performing the numerical analysis. The CFD calculations were carried out for the geometry of the straight channel with a bump as well as blade-to-blade channel for different boundary conditions, ratio of outlet static pressure to inlet total pressure. The numerical results showed a clear dependence of the sonic region and wetness mass fraction formation.
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Levi, Reuben VR, and Amrutha Rajamani. "Study on Performance of Ramjet Intake by Changing the Cowl Angle." IOP Conference Series: Materials Science and Engineering 1258, no. 1 (October 1, 2022): 012042. http://dx.doi.org/10.1088/1757-899x/1258/1/012042.
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Most gas turbine engines require the Mach range on the engine face to be at a mild subsonic pace (around Mach 04). Therefore, for a supersonic plane with a gas turbine engine, the characteristic of the air inlet is to slow the supersonic unfastened flow to a subsonic pace and offer a matched air mass float charge to the engine. The gas turbine engine calls for the delivery of uniform excessive general stress restoration air for proper overall performance and operation because the quality of the airflow on the engine face substantially influences the overall performance of the engine, in particular, the total stress loss, which influences the engine thrust and therefore the gasoline consumption. A 2-D supersonic intake is designed for Mach No. 2.4 at an altitude of 11,000 m. The design of the mixed compression supersonic intake is done numerically, and the design with the k- turbulent module is done using CFD. Optimization of the intake is done by changing the cowl deflection in order to get maximum total pressure recovery. Results are compared to knowing the optimal design. The main advantage of mixed compression is that it gives the maximum total pressure recovery at any Mach number. The computation is done with the ANSYS software.
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Abedi, M., R. Askari, J. Sepahi-Younsi, and M. R. Soltani. "Axisymmetric and three-dimensional flow simulation of a mixed compression supersonic air inlet." Propulsion and Power Research 9, no. 1 (March 2020): 51–61. http://dx.doi.org/10.1016/j.jppr.2020.01.002.
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Alhassani, Abdulla Khamis, Mohanad Tarek Mohamed, Mohammed Fares, and Sharul Sham Dol. "Shock Waves Analysis of the Novel Intake Design System for a Scramjet Propulsion." WSEAS TRANSACTIONS ON SYSTEMS 20 (April 15, 2021): 67–75. http://dx.doi.org/10.37394/23202.2021.20.9.
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The supersonic combustion scramjet in the inlet applies the shock waves compression mechanism tosubstitute the actual compressor from a gas turbine engine. The scramjet works with combustion of fuel throughthe air stream in supersonic condition at least with Mach 5. Novel design of a scramjet intake system was madewith variations in the angle of the fins and entrance width. The best combination of diameter and inclinationangle was 1.75 m and 15 degrees, respectively. The findings were able to increase the oblique shock waveinteractions and supplicate effective combustion and reduce pressure losses for the effective application ofscramjet system, which can be significant for aerospace industry.
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Jermak, Czesław Janusz. "Discussion on Flow-Through Phenomena in the Air Gauge Cascade." Acta Mechanica et Automatica 11, no. 1 (March 1, 2017): 38–46. http://dx.doi.org/10.1515/ama-2017-0006.
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Abstract In the paper, the flow-through phenomena in the air gauge are under discussion form the thermodynamic and gasodynamic perspective. The main elements of the cascade are considered the inlet nozzle (restriction), measuring chamber and the measuring nozzle with the measuring slot (displacement between the nozzle head and measured surface). The purpose of the analysis was to point out the impact on the metrological characteristics of the air gauge. In particular, attention was paid to the airflow through the measuring slot. Here, the complex phenomena take place, among others the supersonic areas and a “bubble ring,” which cause discontinuity and hysteresis in the static characteristic. On the other hand, the air stream expansion after the restriction (inlet nozzle) is observed in the measuring chamber. The point of the above discussion was to work out some recommendation on the nozzles geometry and the localization of the back-pressure measuring point in the chamber.
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Egor Yakovlevich, BRAGUNTSOV, Dmitry Aleksandrovich VNUCHKOV, Vladislav Mikhailovich GALKIN, Igor Vladimirovich IVANOV, and Valery Ivanovich ZVEGINTSEV. "TEST OF THE ANNULAR SUPERSONIC AIR INLET WITH ISENTROPIC COMPRESSION IN THE WIND TUNNEL." Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mekhanika, no. 43(5) (October 1, 2016): 43–52. http://dx.doi.org/10.17223/19988621/43/5.
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Yoshimoto, Shigeka, Makoto Yamamoto, and Kazuyuki Toda. "Numerical Calculations of Pressure Distribution in the Bearing Clearance of Circular Aerostatic Thrust Bearings With a Single Air Supply Inlet." Journal of Tribology 129, no. 2 (December 11, 2006): 384–90. http://dx.doi.org/10.1115/1.2464135.
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This paper describes the pressure distribution in the bearing clearance of circular aerostatic thrust bearings with a single air supply inlet. For high air supply pressure, large bearing clearance, and a relatively small bearing outer radius, it was believed that shock waves are caused and that a complex fluid flow structure is formed in the bearing clearance. Accordingly, analytical models based on the occurrence of shock wave in the bearing clearance have been proposed. Recently, very small aerostatic bearings have been used in various machine devices where the pressure distribution near the air inlets has a large influence on the bearing characteristics due to a short distance between air inlets and the bearing edge. In order to predict various bearing characteristics accurately for these kinds of bearings, a proper analytical model has to be established. However, it is very difficult to obtain the detailed information about the flow structure from flow visualization because of a very thin bearing clearance. Therefore, we calculated the flow field using computational fluid dynamics, which can solve the Navier-Stokes equations directly. It was found that the airflow just after entering the bearing clearance becomes turbulent in a region where relatively rapid pressure recovery occurs and that no shock wave is generated at the boundary between subsonic and supersonic flow. In addition, the numerical results presented show good agreement with experimental data.
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Hamood, Hasson Shaban. "Performance Prediction of Internal Compression Supersonic Air Intake at Range of Mach Numbers (1.1-1.5)." Tikrit Journal of Engineering Sciences 23, no. 3 (August 31, 2016): 37–46. http://dx.doi.org/10.25130/tjes.23.3.04.
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In this research a numerical investigation on a supersonic air intake was done. The aim of this work is to investigate a variable geometry of cross-section area for supersonic air intake at range (1.1-1.5) Mach number, to get a maximum pressure recovery. In this work, the flow starts with a normal shock attached to the intake cowl lip. The flow is assumed compressible, inviscid, two-dimensional flow, unsteady, and axisymmetric. The equations (Continuity, Momentum, and Energy) were solved based on a finite volume method. The governing equations were solved iteratively using time marching technique. This part is analyzed for several Mach numbers, where the flow properties are determined from inlet of air intake to the diffuser exit. Results show that, the implementation of time marching scheme has succeeded in the prediction of the choked flow region, which is important in the study of the performance of convergent-divergent diffuser. Also the results indicated the absolute velocity increases along the convergent part and then start to decrease along divergent part independently on the values of free-stream Mach numbers.
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Shorinov, О., and S. Polyvianyi. "DETERMINATION OF ENERGY PARAMETERS OF Ni+Al2O3 POWDER PARTICLES IN A SUPERSONIC NOZZLE DURING COLD GAS-DYNAMIC SPRAYING USING THE ANALYTICAL METHOD." Innovative Materials and Technologies in Metallurgy and Mechanical Engineering, no. 2 (January 9, 2023): 64–70. http://dx.doi.org/10.15588/1607-6885-2022-2-11.
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Purpose. To calculate the temperature and velocity of nickel and aluminum oxide particles in the supersonic flow in the low-pressure cold gas-dynamic spraying nozzle. To investigate the effect of gas parameters at the nozzle inlet, in particular temperature and pressure, on the velocity and temperature of particles at the nozzle outlet.
Research methods. The calculation of the temperature-velocity characteristics of the powder particles is performed after determining the parameters of the gas flow in the supersonic nozzle channel using well known gas-dynamic dependencies. The initial data for the calculation are the following: the geometry of the nozzle, the temperature and pressure of the gas (air) at the nozzle inlet. The density of the material from which particles are obtained, as well as their diameter, were taken into account in the calculation of the energy parameters. Nickel particles with a diameter of 25 µm and aluminum oxide particles with a diameter of 22 µm were used.
Results. Based on the calculations results, graphs of changes in the velocities and temperatures of the particles of the investigated powders, as well as working gas, in the channel of the low-pressure cold gas-dynamic spraying supersonic nozzle were developed. The dependences of the temperature-velocity parameters of the particles at the nozzle exit in the range of initial values of temperature at the nozzle inlet from 300 to 600 C° and pressure from 0.6 to 1.0 MPa were also developed.
Scientific novelty. The influence of the initial parameters of the gas at the nozzle inlet in a wide range of values on the temperature and velocity of nickel and aluminum oxide particles during the low-pressure cold gas-dynamic spraying is shown.
Practical value. The obtained results can be used to determine rational spraying parameters in the development of technological processes of deposition of protective and restorative coatings from Ni+Al2O3 powder mixture.
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Zhang, Tian, Deji Jing, Shaocheng Ge, Jiren Wang, Xi Chen, and ShuaiShuai Ren. "Dust removal characteristics of a supersonic antigravity siphon atomization nozzle." Advances in Mechanical Engineering 12, no. 12 (December 2020): 168781402097768. http://dx.doi.org/10.1177/1687814020977689.
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To improve the trapping efficiency of respiratory dust by aerodynamic atomization, reduce the energy consumption and the requirements for the working conditions of nozzles and maintain the health and safety of workers, a comparative experiment evaluating aerodynamic atomization dust removal characteristics was conducted with a self-developed supersonic siphon atomization nozzle, which utilizes a Laval nozzle as the core, and an existing ultrasonic atomization nozzle. The experimental results showed that the new type of nozzle, from the perspectives of droplet speed, conservation of water and pressure, range, and attenuation view, completely surpasses the traditional pneumatic atomization nozzle. A supersonic antigravity siphon atomizer produces a cloud fog curtain composed of high-speed droplets and high-speed air. The particle size of the droplets is less than 10 µ. At the same flow rate of water, its dust removal rate is twice as high as that of ultrasonic nozzles. When the dust removal efficiency is the same, the water consumption of the supersonic siphon atomizer nozzle is 1/2, the air flow rate is 1/3, and the power consumption is 1/2 that of the ultrasonic atomizing nozzles. Siphon atomization can siphon at a total air pressure of 0.2 MPa, and the siphon pressure can reach 0.03 MPa at a total air pressure of 0.4 MPa, which increases with the increase in total inlet air pressure. For the first time, the process of siphoning and nozzle internal atomizing in the field of supersonic atomization dust removal is truly realized. The ultrafine sized droplets with high speeds produced by the new nozzle allow them to cover the limited working space in a shorter time, have a more effective trapping effect for a large number of fine dust particles, and quickly suppress the dust with greater kinetic energy. Therefore, the requirements for the working conditions are reduced, which will save more energy compared to the currently used nozzles available on the market.
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Dzido, Aleksandra, Piotr Krawczyk, and Michalina Kurkus-Gruszecka. "Numerical Analysis of Dry Ice Blasting Convergent-Divergent Supersonic Nozzle." Energies 12, no. 24 (December 16, 2019): 4787. http://dx.doi.org/10.3390/en12244787.
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There are several well-known and widely used industrial cleaning methods in the market today. One of them is dry ice blasting. In this method, moisture-free air is compressed, mixed with solid CO2 particles, and blasted though a nozzle; in the process, the gas expands, propelling its velocity. The high-speed, two-phase flow cleans by supercooling and crushing particles on the surface, causing dry ice sublimation. As the nozzle is a crucial component of the system, the authors conducted a numerical analysis of the geometry of the proposed convergent-divergent nozzle. A mathematical model of the supersonic, two-phase flow was developed and implemented in commercial Computational Fluid Dynamics (CFD) code. Various operating parameters, such as inlet pressure and dry ice mass flow, were taken into consideration.
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Makasheva, Altyn, Altynshash Naimanova, and Yerzhan Belyayev. "Numerical Study of the Particle Dispersion on a Supersonic Shear Layer." Applied Mechanics and Materials 798 (October 2015): 536–40. http://dx.doi.org/10.4028/www.scientific.net/amm.798.536.
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The numerical study of the two-dimensional supersonic hydrogen-air mixing in the free shear layer is performed. The system of the Favre-Averaged Navier-Stokes equations for multispecies flow is solved using the ENO scheme of the third order accuracy. The k-ε two-equation turbulence models with compressibility correction are applied to calculate the eddy viscosity coefficient. The dispersion of the particles is studied by following their trajectories in the shear layer by Euler method. In order to produce the roll-up and pairing vortex rings, an unsteady boundary condition is applied at the inlet plane. At the outflow, the non-reflecting boundary condition is taken. The influence of different Mach numbers on the formation of vorticity structures and shear layer growth rate are studied. The obtained results are compared with the available experimental data and the numerical results of other authors. The numerical simulation of the particle dispersion in the shear layer with large scale vortical structure is conducted.
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Timoshenko, V. I., and V. P. Halynskyi. "Methods and programs for comprehensive calculations of supersonic flow about ramjet flying vehicles." Technical mechanics 2022, no. 2 (June 30, 2022): 3–16. http://dx.doi.org/10.15407/itm2022.02.003.
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This paper discusses the use of the authors’ fast methods and programs for the calculation of 3D supersonic flow about a flying vehicle and thermogas dynamic processes in the components of an airframe-integrated ramjet. To conduct fast comprehensive calculations, use is made of marching methods, which are two to three orders of magnitude faster than pseudoviscosity methods. 3D supersonic flows about the airframe, in the inlet section of the air intake, and in the exhaust jet are calculated using a “viscous layer” model or Godunov’s scheme for the inviscid approximation. Subsonic flows in the outlet section of the air intake and in the combustion chamber are calculated using a “narrow channel” or a quasi-one-dimensional model. The elements of the presented methods and programs that complement a previously proposed fast comprehensive model are described in more detail. A method for assigning the spatial shape of the flying vehicle surface and the ramjet duct walls is described. A simplified approach to determining the critical area of the exit nozzle in the one-dimensional approximation is proposed. The paper substantiates the advantages of marching methods over pseudoviscosity ones in the predesigning of ramjets with direct account for flow choking, which may occur in the combustion chamber or the exit nozzle. The calculated 3D flows in the individual components and the full assembly of a stylized-shape flying vehicle are presented. The main advantages of the proposed methods and programs are their comprehensiveness and fast computation speed. Their use in the calculation of 3D supersonic flow about a ramjet flying vehicle shortens the ramjet component predesigning time.
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Prashana ANL, Kavin, Aldin Justin Sundararaj, and Mukit Azad Khan. "Investigation of nozzle flow in high altitude test facility." Advances in Mechanical Engineering 14, no. 5 (May 2022): 168781402110477. http://dx.doi.org/10.1177/16878140211047724.
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A high altitude test facility was developed for the experimental studies on nozzles for various levels of vacuum. The current study is focused on the performance of the nozzle under various altitude condition and to characterized the high altitude test facility. A supersonic nozzle designed for Mach 2.5 is used for the study. Compressed air is taped from the high pressure plenum having a pressure of 20 bar and is regulated and expanded through the nozzle. The inlet pressures for the study is varied from 4.5 to 10 bar. The nozzle is within the enclosure which is evacuated to 0.7–0.02 bar. Schlieren is used to view the flow condition at the end of the nozzle. A nozzle for 2.5 Mach is designed and tested in HAT facility. The nozzle design is validated with the CFD for various NPR. The high altitude test facility is characterized for various NPR and is found to be optimum flow at 14 NPR for 33 s at an inlet pressure of 4.5.
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Yu, Huafeng, Yingqing Guo, Xinghui Yan, and Jiamei Wang. "Flight/Propulsion Integrated Control of Over-Under TBCC Engine Based on GA-LQR Method." Aerospace 9, no. 10 (October 19, 2022): 621. http://dx.doi.org/10.3390/aerospace9100621.
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Turbine-based combined cycle (TBCC) engines are one of the ideal powers for reusable air-breathing supersonic aircraft, but the flight/propulsion integrated control and mode transition restricts its use. This paper takes the Mach 4 over-under TBCC engine as the research object. The inlet is established by the quasi-one-dimensional calculation theory, which can reflect the shock wave position. An iterative method is proposed, which points out that the flow rate in the mode transition depends on the flow capacity. By connecting the input and output that affect each other, the simulation of the coupling characteristics of the aircraft and engine are realized. A GA-LQR-based controller design method is proposed and verified through the aircraft’s climb and mode transition conditions. The simulation shows that the integrated control system can ensure the stability of the aircraft and the safe operation of the engine in the above two situations. During the mode transition process, the aircraft altitude and Mach number fluctuate less than 1%, and the normal shock wave of inlet is in a safe position.
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Wu, Hong, Peng Li, Dong Dong Liu, and Zhi Tao. "Improvement of One-Dimensional Analytical Model of Rotating Long Orifice with Chamfered or Radiused Inlet." Applied Mechanics and Materials 444-445 (October 2013): 320–31. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.320.
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In this paper, computational fluid dynamics calculations were conducted under various kinds of complex working conditions for rotating long orifice. As one of the most important structures of throttling and pressure limiting, orifice plays a significant role in flow control of the whole system. The existing empirical correlation was improved by correction on characteristics of low Reynolds number and compressibility. Then, improved one-dimensional analytical model of rotating long orifice with chamfered or radiused inlet was developed by programming. The model was verified against the results of commercial computational fluid dynamics codes. It turns out that the model has high precision, excellent convergence, and can predict the flow parameters under working conditions of low Reynolds number, supersonic and high pressure ratio with an acceptable error. And only geometric features, rotational speed and boundary conditions are required for one-dimensional modeling. Thus, it can be applied in the one-dimensional calculation and design of secondary air system widely.
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Laube, Tomasz, and Janusz Piechna. "Analytical and Numerical Feasibility Analysis of a Contra-Rotary Ramjet Engine." Energies 13, no. 1 (December 30, 2019): 163. http://dx.doi.org/10.3390/en13010163.
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A new idea for a contra-rotary ramjet engine is presented. To define the theoretical limits of the non-typical, contra-rotary ramjet engine configuration, its analytical model was developed. The results obtained from that model and the analytical results were compared with those received from numerical simulations. The main weakness of existing rotary ramjet engine projects is the very high rotational speed of the rotor required for achieving supersonic inlet flow. In this paper, a new idea for a contra-rotary ramjet engine (CORRE) is presented and analyzed. This paper presents the results of analytical analysis and numerical simulations of a jet engine system with two rotors rotating in opposite directions. Contra-rotating rotors generate a supersonic air velocity at the inlet to the compressor at two times slower rotor’s speed. To determine the flow characteristics, combustion process, and engine efficiency of the double-rotor engine, a numerical solution of the average Navier-Stokes equations was used with the k-eps turbulence model and the non-premixed combustion model. The results of numerical simulations of flow and the combustion process inside the contra-rotary jet engine achieving a shockwave compression are shown and compared with similar data for a single-rotor engine design and analytical data. This paper presents only the calculation results of the flow processes and the combustion process, indicating the advantages of the proposed double-rotor design. The results of the numerical analysis were presented on the contours and diagrams of the pressure and flow velocity, temperature distribution, and mass fraction of the fuel.
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Čarnogurská, Mária, Tomáš Brestovič, Miroslav Příhoda, Marián Lázár, and Natália Jasminská. "Analysis of the Subsonic and Supersonic Flow Using Analytical and Numerical Methods." Applied Mechanics and Materials 816 (November 2015): 16–26. http://dx.doi.org/10.4028/www.scientific.net/amm.816.16.
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The article presents the analysis of the 1D flow of compressible fluid by means of analytical and numerical methods. The results from the solution showed that the calculation of dimensionless velocity for particular flow conditions varies in the area of subsonic flow only a very little, when using both methods. It was found that the dependence of dimensionless velocity on the relative duration of the investigated tunnel applies universally. For any proportional value of the tunnel length x/L and the constant ratio of outlet and inlet cross section of the tunnel level equal to 0.6474, the course of the dimensionless velocity for each tunnel, which satisfies the above condition, will always be the same. This means that also the nature of flow in any such tunnel will exhibit the same properties. This finding provides new knowledge from the analysis of air flow through a channel with a variable flow cross section.
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Ihnatiev, O. D., N. S. Pryadko, G. O. Strelnikov, and K. V. Ternova. "Thrust characteristics of a truncated Laval nozzle with a bell-shaped tip." Technical mechanics 2022, no. 3 (October 3, 2022): 35–46. http://dx.doi.org/10.15407/itm2022.03.035.
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This paper presents the results of a thrust performance study of an unconventionally shaped supersonic nozzle in the form of a truncated Laval nozzle with a bell-shaped tip. This nozzle shape may be used in the development of compact layouts of multistage rockets. The study was carried out using the ANSYS software package in a 3D formulation. The methodological approaches to the numerical calculation of a complex separated gas flow used in this study were verified in a previous study of the flow pattern in similar nozzle. Some results of exact calculations were compared with the results of experimental studies carried out at the Institute of Technical mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine for a model of a similar truncated nozzle with a bell-shaped tip blown with a cold air. This study detailed the features of the separated gas flow in a spherical tip connected (at the corner point) to a truncated supersonic Laval nozzle of conical shape. It was found that the pattern of the separated flow in the tip depends on the nozzle flow expansion degree (nozzle inlet pressure). At a relatively low nozzle inlet pressure, a developed separation zone is observed in the nozzle tip (between the jet boundary and the nozzle wall) with a subsonic flow from the external environment, which forms an almost constant static pressure from the tip inlet cross-section to the tip exit. At a nozzle inlet pressure at which the free boundary of the jet flowing from the truncated nozzle adjoins the nozzle wall, the static pressure in the tip varies almost linearly along the tip length from the corner point with the minimum pressure to the tip exit. The dependence of the thrust of a tipped nozzle on the nozzle inlet pressure is nonlinear. As the pressure upstream of the nozzle increases (or the ambient pressure decreases), the effect of the external environment on the tipped-nozzle thrust diminishes. It is shown that under "terrestrial conditions" the thrust of a truncated nozzle with a tip exceeds the thrust of a profiled nozzle with the same geometric expansion degree (due to the atmosphere “entering” the tip). Under "vacuum” conditions, the former is 8% less than the latter.
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Chandra Bose, G., S. Thanigaiarasu, S. Elangovan, and E. Rathakrishnan. "Experimental Investigation of Shape Transition Effects on Isolator Performance." International Journal of Turbo & Jet-Engines 35, no. 4 (December 19, 2018): 331–38. http://dx.doi.org/10.1515/tjj-2015-0022.
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Abstract Isolator is a critical component in supersonic air breathing engine and it is usually situated between the inlet and the combustor of a dual-mode ramjet/scramjet engine. In the present study, shape transition effects on isolator performance have been studied by carrying out experimental investigations on square, square to circular and square to elliptical transition ducts. The length of the isolator chosen in this study is 180 mm and the cross-sectional area of 900 mm2 is maintained constant along the length for all the ducts. Experiments were carried out for isolator inlet Mach 2, using a contoured nozzle. Varying the pressure of the settling chamber varied the expansion level at the nozzle exit, which run the nozzle. The wall static pressure along the length of the isolator and the Pitot pressure at the exit plane of the isolator were measured for all the configurations. Shadowgraph technique was employed for visualizing the shock-train in the isolator. The square to circular transition isolator is found to be more efficient in achieving the static pressure rise across the isolator than the square and square to elliptical transition ducts.
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Veeran, Sasha, Apostolos Pesyridis, and Lionel Ganippa. "Ramjet Compression System for a Hypersonic Air Transportation Vehicle Combined Cycle Engine." Energies 11, no. 10 (September 25, 2018): 2558. http://dx.doi.org/10.3390/en11102558.
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This report assesses the performance characteristics of a ramjet compression system in the application of a hypersonic vehicle. The vehicle is required to be self-powered and perform a complete flight profile using a combination of turbojet, ramjet and scramjet propulsion systems. The ramjet has been designed to operate between Mach 2.5 to Mach 5 conditions, allowing for start-up of the scramjet engine. Multiple designs, including varying ramp configurations and turbo-ramjet combinations, were investigated to evaluate their merits and limitations. Challenges arose with attempting to maintain sufficient pressure recoveries and favourable flow characteristics into the ramjet combustor. The results provide an engine inlet design capable of propelling the vehicle between the turbojet and scramjet phase of flight, allowing for the completion of its mission profile. Compromises in the design, however, had to be made in order to allow for optimisation of other propulsion systems including the scramjet nozzle and aerodynamics of the vehicle; it was concluded that these compromises were justified as the vehicle uses the ramjet engine for a minority of the flight profile as it transitions between low supersonic to hypersonic conditions.
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Pandey, Krishna Murari, and Sukanta Roga. "CFD Analysis of Scramjet Combustor with Non-Premixed Turbulence Model Using Ramp Injector." Applied Mechanics and Materials 555 (June 2014): 18–25. http://dx.doi.org/10.4028/www.scientific.net/amm.555.18.
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This paper presents the supersonic combustion of hydrogen using strut injector along with two-dimensional turbulent non-premixed combustion model with air inlet temperature of 750 0k and vitiated Mach number of 2. In this process, a PDF approach is created and this method needs solution to a high dimensional PDF transport equation. As the combustion of hydrogen fuel is injected from the strut injector, it is successfully used to model the turbulent reacting flow field. It is observed from the present work that, the maximum temperature of 2096 0k occurred in the recirculation area which is produced due to shock wave-expansion and the fuel jet losses concentration and after passing successively through such areas, temperature decreased slightly along the axis. From the maximum mass fraction of OH, it is observed that there is very little amount of OH around 0.0017 were found out after combustion. By providing strut injector, expansion wave is created which causes the proper mixing between the fuel and air that results in complete combustion.
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Shorinov, Oleksandr, Anatoliy Dolmatov, and Serhii Polyvianyi. "Експериментальне дослідження впливу параметрів газодинамічного напилювання на коефіцієнт використання порошку." Aerospace technic and technology, no. 4sup2 (August 22, 2022): 123–28. http://dx.doi.org/10.32620/aktt.2022.4sup2.19.
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The effect of temperature and air pressure at the supersonic nozzle inlet, as well as the distance from the nozzle outlet to the surface of the substrate (stand-of-distance) on the powder usage rate of nickel-based powder in low pressure cold gas-dynamic spraying (inlet pressure up to 1.0 MPa) was analyzed. One of the most important parameters characterizing the deposition efficiency of the spraying process is the powder usage rate. This parameter is the ratio of the mass of the coating to the mass of the powder used to obtain this one. For the process of cold gas-dynamic spraying, implemented on the equipment using air pressure up to 1.0 MPa, the main disadvantage is the relatively low-powder usage rate. To increase it (but not limited to it), a ceramic component, such as alumina Al2O3, is added to pure metal powders. In this study a nickel-based powder mixture, in which the content of Al2O3 powder is about 10% mass., was used. Titanium alloy plates BT9 were used as the substrate material. Based on the multifactor planning of the experiment, the effect of the complex parameters of the low-pressure cold gas-dynamic spraying on the powder usage rate was studied. After the coating deposition according to the matrix of the experiment, the samples with coatings were weighed. According to the known mass of the samples before spraying and the increase in their mass, the powder usage rate was calculated. From the analysis of the obtained statistical data, the dependence of the effect of the complex parameters of the deposition process on the powder usage rate was developed. The maximum value of the powder usage rate were obtained up to 35 %. It was confirmed that the air temperature at the nozzle inlet has the greatest effect on the above-mentioned parameter. The explanation of this is the increase in gas flow temperature and velocity, and as a result, the increase in the velocity and temperature of the powder particles in this flow. Higher values of the velocity and temperature of the particles lead to more intense plastic deformation of particles during impact with the substrate and their adhesion to it.
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Yurchenko, Nina, and Pavlo Vynogradskyy. "Experimental optimization of the ejector design developed for a driver’s airbag." Mechanics and Advanced Technologies 6, no. 1 (May 31, 2022): 79–84. http://dx.doi.org/10.20535/2521-1943.2022.6.1.260933.
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Design modifications are tested experimentally of the compact supersonic ejector developed for the novel airbag inflation system. The base design resulting from combined numerical and experimental investigations showed itself potentially capable of inflating the 50 L airbag with three parts of entrained air volume together with one part produced by a gas generator. The base design work continues to study its technological flexibility and operational reliability by analyzing a complex flow structure within the inflator. For that, minor changes and supplements to the design were evaluated experimentally to avoid complicated numerical simulations. In particular, it was supposed that a vortex formed at the inflator inlet could significantly reduce its operational cross-section. The impact of this vortex on the airbag filling was investigated in the Laboratory for Advanced Aerodynamics using the developed pneumatic facility. The applied design improvement was found to affect the pressure distribution favorably in the inflator that increased the airbag filling by ~5%.
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Timoshenko, V. I., V. P. Halynskyi, and Yu V. Knyshenko. "Theoretical studies on rocket/space hardware aerogas dynamics." Technical mechanics 2021, no. 2 (June 29, 2021): 46–59. http://dx.doi.org/10.15407/itm2021.02.046.
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This paper presents the results of theoretical studies on rocket/space hardware aerogas dynamics obtained from 2016 to 2020 at the Department of Aerogas Dynamics and Technical Systems Dynamics of the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine along the following lines: rocket aerodynamics, mathematical simulation of the aerogas thermodynamics of a supersonic ramjet vehicle, jet flows, and the hydraulic gas dynamics of low-thrust control jet engines. As to rocket aerodynamics, computational methods and programs (CMPs) were developed to calculate supersonic flow past finned rockets. The chief advantage of the CMPs developed is computational promptness and ease of adding wings and control and stabilization elements to rocket configurations. A mathematical simulation of the aerogas thermodynamics of a supersonic ramjet vehicle yielded new results, which made it possible to develop a prompt technique for a comprehensive calculation of ramjet duct flows and generalize it to 3D flow past a ramjet vehicle. Based on marching methods, CMPs were developed to simulate ramjet duct flows with account for flow past the airframe upstream of the air inlet, the effect of the combustion product jet on the airframe tail part, and its interaction with a disturbed incident flow. The CMPs developed were recommended for use at the preliminary stage of ramjet component shape selection. For jet flows, CMPs were developed for the marching calculation of turbulent jets of rocket engine combustion products with water injection into the jet body. This made it possible to elucidate the basic mechanisms of the effect of water injection, jet–air mixing, and high-temperature rocket engine jet afterburning in atmospheric oxygen on the flow pattern and the thermogas dynamic and thermalphysic jet parameters. CMPs were developed to simulate the operation of liquid-propellant low-thrust engine systems. They were used in supporting the development and ground firing tryout of Yuzhnoye State Design Office’s radically new system of control jet engines fed from the sustainer engine pipelines of the Cyclone-4M launch vehicle upper stage. The computed results made it possible to increase the informativity of firing test data in flight simulation. The CMPs developed were transferred to Yuzhnoye State Design Office for use in design calculations.
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Mazhul, I. I. "Supersonic flow in the rectangular duct of an air inlet with the separation-induced interaction of the boundary layer with shock waves." Thermophysics and Aeromechanics 27, no. 4 (July 2020): 507–18. http://dx.doi.org/10.1134/s0869864320040046.
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Kaltayev, A., Ye Belyayev, and A. Naimanova. "2D-DNS and 2D-RANS Simulations of Supersonic QUASI-2D Turbulent Reacting Shear Flow." Eurasian Chemico-Technological Journal 16, no. 2-3 (April 8, 2014): 239. http://dx.doi.org/10.18321/ectj187.
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<p>Numerical studies of quasi-2D supersonic turbulent hydrogen-air mixing and combustion in free shear layer configuration are performed using 2D-DNS [1] and RANS equations. In order to produce the roll-up and pairing of vortex rings, an unsteady boundary condition is applied at the inlet plane. Frequencies of<br /> initial velocity perturbations have been taken in accordance with linear stability theory. The influences of different inflow perturbations on mixing layer structure are presented. At the outflow, the non-reflecting boundary condition is adopted. In the case of RANS simulation two-parameter k-e turbulence model is used. Thermal conduction is described by Fourier’s law, while diffusion of species by Fick’s law. Equation of state for thermally perfect multispecies gas is used. Thermodynamic parameters, such as specific heat, enthalpy, entropy and internal energy are determined by fourth order degree polynomial formula, which has dependence on temperature. Temperature is determined using Newton-Raphson iteration procedure. The Wilke’s formula is used to determine the mixture viscosity coefficient. Approximation of convection terms are performed by the ENO-scheme of third-order accuracy and approximation of diffusion terms – by second-order central-difference operators. For the description of reaction pathways of hydrogen, a seven species chemical reaction model by Jachimowski is adopted. Chemical reaction source term implicitly includes in mass fraction transport equations, where linearization is applied using Taylor decomposition. The hydrogen flow parameters are M<sub>0</sub> = 2.0, T<sub>0</sub> = 2000 K, P<sub>0</sub> = 101325 Pa, and air flow parameters are M<sub>¥</sub> = 2.1, T<sub>¥</sub> = 2000 K, p<sub>¥</sub> = 101325 Pa. Convective Mach number is M<sub>c</sub> = 0.38, where effect of compressibility is significant.</p>
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Bhide, Kalyani, and Shaaban Abdallah. "High-Order Accurate Numerical Simulation of Supersonic Flow Using RANS and LES Guided by Turbulence Anisotropy." Fluids 7, no. 12 (December 14, 2022): 385. http://dx.doi.org/10.3390/fluids7120385.
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This paper discusses accuracy improvements to Reynolds-Averaged Navier–Stokes (RANS) modeling of supersonic flow by assessing a wide range of factors for physics capture. Numerical simulations reveal complex flow behavior resulting from shock and expansion waves and so, a supersonic jet emanating from rectangular nozzle is considered. PIV based experimental data for the jet is available from literature and is used for validation purposes. Effect of various boundary conditions and turbulence modeling approaches is assessed qualitatively and quantitatively. Of particular interest are the inlet conditions considering the turbulence intensity and the effect of upstream air supply duct, the effect of nozzle wall surface roughness on nozzle internal flow and downstream, wall y+ sensitivity for boundary layer resolution and laminar to turbulent transition modeling. In addition to mesh sensitivity, domain dependency is conducted to evaluate the appropriate domain size to capture the kinetic energy dissipation downstream of the nozzle. To further improve the flow characteristics, accounting for the anisotropy of Reynolds stresses is also one of the focuses. Therefore, non-linear eddy viscosity-based two-equation model and Reynolds stress transport model are also investigated. Additionally, the results of baseline linear (Boussinesq) RANS are compared. Corresponding comparisons with high-fidelity LES are presented. Jet self-similar behavior resulting from all simulation fidelities is assessed and it appears that turbulent flow in LES becomes self-similar, but not in RANS. Finally, various factors such as the nozzle geometry and numerical modeling choices influencing the anisotropy in jet turbulence are discussed.
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Kovalchuk, O., O. Skorohvatov, A. Galkin, L. Gordishevski, and V. Liskovchuk. "ARMORED SHELLS WITH STRAIGHT AIR JET ENGINE." Collection of scientific works of Odesa Military Academy 1, no. 13 (December 30, 2020): 34–43. http://dx.doi.org/10.37129/2313-7509.2020.13.1.34-43.
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The article analyzes the problems of sub-caliber feathered projectile, offers a variant of equipping such a projectile with an air-jet engine, graphs of air resistance, calculations of the required thrust of the air-jet engine. Features of armor-piercing projectiles with a direct-flow air-jet engine are considered, the main calculations are performed using high-level Python programming language. Currently, as armor-piercing ammunition are widely used armor-piercing sub-caliber feathered shells (BPOS) with high penetrating ability This is achieved due to the high initial velocity of ammunition (1650-1840 m / s) and small cross section (d = 20-30 mm). To compensate for the force of air resistance, the provision of jet propulsion ammunition is used. But the main disadvantage of such shells is the dependence of the ability to pierce armor from a distance to the target. That is, due to the resistance of the air, the speed of the projectile is lost, namely its energy. What they are inferior to cumulative projectiles, for which the ability to pierce armor does not depend on the distance to the target. Modern armored vehicles have significant armor and BPOS lose their importance in the range of cumulative projectiles and anti-RPG. This situation can be corrected if the BPOS is equipped with direct-flow jet engines (PPD). Direct-flow air jet engine (PPD), simple in design, has a high efficiency at large Mach numbers, compact, because it does not require the presence of an oxidant in the fuel, as it uses oxygen from the environment. Compressed air entering the combustion chamber from the inlet device is heated by oxidation of the fuel supplied to it. Created from a mixture of air with combustion products gas mixture – the working fluid in the nozzle reaches the speed of sound, and at its output expanding to supersonic. The working fluid flows at a speed greater than the speed of the oncoming air flow, which creates a jet thrust. When the flight speed is much less than the speed of the jet, the thrust increases. As the speed of flight approaches the speed of the jet, the thrust decreases, passing some maximum corresponding to the optimal speed of flight. With the development of mixed solid fuel technology, it began to be used in PPRD. A fuel checker with a longitudinal Central channel is placed in the combustion chamber. The working fluid passing through the combustion chamber oxidizes the fuel from its surface and heats up. The use of solid fuel further simplifies the design of the PPRD as it does not require a combustion chamber. The main part of the filler of mixed fuel PPRD is a fine powder of aluminum, magnesium or beryllium, the heat of combustion, which is much higher than the heat of combustion of hydrocarbon fuels. With the development of mixed solid fuel technology, it began to be used in PPRD. A fuel checker with a longitudinal Central channel is placed in the combustion chamber. The working fluid passing through the combustion chamber oxidizes the fuel from its surface and heats up. The use of solid fuel further simplifies the design of the PPRD as it does not require a combustion chamber. The main part of the filler of mixed fuel PPRD is a fine powder of aluminum, magnesium or beryllium, the heat of combustion, which is much higher than the heat of combustion of hydrocarbon fuels. An example of a solid propellant PPRD can be the propulsion engine of the anti-ship missile P-270 Mosquito. Depending on the speed of flight PPRD are divided into subsonic, supersonic and hypersonic. This division is due to the design features of each of these groups. In the supersonic range PPRD is much more effective than in the subsonic. For example, at a speed of M = 3, the degree of pressure increase in the PPRD is 37, which can be compared with the most high-pressure compressors of turbojet engines. Keywords: armor-piercing sub-caliber feathered projectile, air-jet engine, external ballistics.
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Jing, Deji, Zhuo Jiang, Shuaishuai Ren, Xiangxi Meng, Shaocheng Ge, and Tian Zhang. "Study on Dust Migration Law and Spray Dust Suppression Technology in Fully Mechanized Mining Face." Eng 4, no. 1 (January 1, 2023): 121–35. http://dx.doi.org/10.3390/eng4010007.
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To effectively solve the problem of high dust concentration during coal cutting and frame shifting in fully mechanized mining faces, based on the theory of gas–solid two-phase flow, a geometric model of a fully mechanized mining face was established by using COMSOL numerical simulation software. Simulations were performed for the movement characteristics of wind flow and the law of dust diffusion. Results show that the air flow at the junction of the working face, the air inlet, the hydraulic support moving area, and the vicinity of the shearer has accelerated movement, and the maximum wind speed zone of about 3 m/s can be formed. Under the influence of wind flow, dust particles above 35 um settle faster, while dust particles below 35 um are very vulnerable to the influence of wind flow, and the settling speed is slower. Using a custom experimental platform, the atomization characteristics and wind resistance of a pressure fan nozzle, a supersonic nozzle, and an ultrasonic nozzle were tested, and the nozzle that was suitable for the scheme was selected and applied in the field. Comparing the dust concentration before and after the application of the dust removal scheme at the sampling point, results show that the dust removal efficiency of the proposed scheme exceeds 85%, and the treatment effect is good.
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Shi, Yalin, Lingling Chen, Pengfei Chen, Qingzhen Yang, Yongqiang Shi, and Hua Yang. "Numerical Study On Aerodynamic Characteristics Of Supersonic Nozzle In Presence Of Ground Effect." Journal of Physics: Conference Series 2252, no. 1 (April 1, 2022): 012013. http://dx.doi.org/10.1088/1742-6596/2252/1/012013.
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Abstract The aeroengine mobile test bench is well applied as it is convenient for outfield transportation and installation, and also it is suitable for different environments. When utilizing a mobile test bench, the distance between the center of the engine and the ground is normally within a range so that it can be manually operated. However, this limited distance will lead to the ground effect, which affects the test performance of the aeroengine. This paper numerically studies the aerodynamic characteristics of a supersonic nozzle in the presence of the ground effect. The work is conducted with the software package ANSYS Fluent 21, employing the unsteady large eddy simulation. The nozzle works in a supersonic condition, and the distance between the nozzle and the ground is 2Dj. Dj is the diameter of the nozzle outlet. The models with and without ground effect are investigated. The analysis of the flow field confirms that the ground effect enhances the mixing of the jet and the air, and enriches the coherent structure. With the ground effect, the Reynolds stress on the vertical centerline on each section plane is increased, and the shear layer on each section plane is expanded radially. The results show that the ground effect increases the ground temperature after x/Dj=9, shortens the length of the core area by about 12.5%, decreases the mean axial velocity on the centerline of the jet after x/Dj=10, and increases the dimensionless velocity on the near ground side of the vertical plane. Here, x is the distance between the inlet plane and the discussed cross section. The analysis of the thrust characteristics confirms that the ground effect has no influence on the thrust. Therefore, the mobile test bench can accurately evaluate the thrust performance of an aeroengine.
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Shi, Yalin, Lingling Chen, Pengfei Chen, Qingzhen Yang, Yongqiang Shi, and Hua Yang. "Numerical Study On Aerodynamic Characteristics Of Supersonic Nozzle In Presence Of Ground Effect." Journal of Physics: Conference Series 2252, no. 1 (April 1, 2022): 012013. http://dx.doi.org/10.1088/1742-6596/2252/1/012013.
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Abstract The aeroengine mobile test bench is well applied as it is convenient for outfield transportation and installation, and also it is suitable for different environments. When utilizing a mobile test bench, the distance between the center of the engine and the ground is normally within a range so that it can be manually operated. However, this limited distance will lead to the ground effect, which affects the test performance of the aeroengine. This paper numerically studies the aerodynamic characteristics of a supersonic nozzle in the presence of the ground effect. The work is conducted with the software package ANSYS Fluent 21, employing the unsteady large eddy simulation. The nozzle works in a supersonic condition, and the distance between the nozzle and the ground is 2Dj. Dj is the diameter of the nozzle outlet. The models with and without ground effect are investigated. The analysis of the flow field confirms that the ground effect enhances the mixing of the jet and the air, and enriches the coherent structure. With the ground effect, the Reynolds stress on the vertical centerline on each section plane is increased, and the shear layer on each section plane is expanded radially. The results show that the ground effect increases the ground temperature after x/Dj=9, shortens the length of the core area by about 12.5%, decreases the mean axial velocity on the centerline of the jet after x/Dj=10, and increases the dimensionless velocity on the near ground side of the vertical plane. Here, x is the distance between the inlet plane and the discussed cross section. The analysis of the thrust characteristics confirms that the ground effect has no influence on the thrust. Therefore, the mobile test bench can accurately evaluate the thrust performance of an aeroengine.
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Schweitzer, Thorge, Marla Hörmann, Benjamin Bühling, and Bernhard Bobusch. "Switching Action of a Bistable Fluidic Amplifier for Ultrasonic Testing." Fluids 6, no. 5 (April 25, 2021): 171. http://dx.doi.org/10.3390/fluids6050171.
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Air-coupled ultrasonic testing is widely used in the industry for the non-destructive testing of compound materials. It provides a fast and efficient way to inspect large concrete civil infrastructures for damage that might lead to catastrophic failure. Due to the large penetration depths required for concrete structures, the use of traditional piezoelectric transducer requires high power electric systems. In this study, a novel fluidic transducer based on a bistable fluidic amplifier is investigated. Previous experiments have shown that the switching action of the device produces a high-power broadband ultrasonic signal. This study will provide further insight into the switching behaviour of the fluidic switch. Therefore, parametric CFD simulations based on compressible supersonic RANS simulations were performed, varying the inlet pressure and velocity profiles for the control flow. Switching times are analyzed with different methods, and it was found that these are mostly independent of the slope of the velocity profile at the control port. Furthermore, it was found that an inversely proportional relationship exists between flow velocity in the throat and the switching time. The results agree with the theoretical background established by experimental studies that can be found in the literature.
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Жирков, Александр Григорьевич, Александр Павлович Усатый, Елена Петровна Авдеева, and Юрий Иванович Торба. "Структура потока в межлопаточном канале соплового аппарата с поворотной диафрагмой." Aerospace technic and technology, no. 4sup2 (August 27, 2021): 35–43. http://dx.doi.org/10.32620/aktt.2021.4sup2.05.
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In the process of developing a numerical study method of a flat flow around a snap line with a rotary diaphragm, calculations were made at various degrees of opening the rotary diaphragm δ and pressure drops on the grille. As a result of calculations, for small degrees, the opening of the rotary diaphragm, complex patterns of the flow were obtained, in the inter-tube channel of the nozzle apparatus. The article presents some results of a numerical study of the supersonic flow in the channel of the nozzle apparatus with the degree of opening the rotary diaphragm δ = (0.15 ÷ 0.3). Modeling and calculating the flow of the working fluid is made using the Fluent software package. The construction of the calculated areas bounded by one inter-tube channel, for varying degrees of opening the diaphragm of the nozzle apparatus. Grids are built for calculated areas. Calculations were carried out for δ = (0.15 ÷ 0.3) and with different degrees of pressure drop on the grille. As a result of the calculations performed, the flow patterns in the inter-tube canal were obtained and behind it, and the distribution of the coefficients of the kinetic energy loss on the lattice front at various degrees of the discovery of the diaphragm at the inlet in the nozzle apparatus. According to the results of the work carried out, the following conclusions can be drawn: the structure of the stream in the inter-tube channel, the nozzle apparatus at small detection of the discovery, is divided into two parts: a supersonic core of the spawth of the blade and a dialing, the vortex zone at the back of the blade; The supersonic thread kernel at certain values of the relative pressure drop on the lattice (or the air flow values through the grid) is separated by shock fronts into several areas; The coefficients of energy loss, for small degrees of discovery, decrease with a decrease in the relative pressure drops (with an increase in the rate of expiration of the flow from the nozzle lattice); The greatest contribution to the magnitude of the loss of kinetic energy is introduced by a vortex zone in the inter-tube channel, and not wave phenomena in the core of the flow; Optimization of the flow part of the nozzle apparatus must be carried out in order to reduce areas with vortex flow. The results obtained in this work will be used to develop a methodology for a numerical study of the spatial flow around the nozzle lattices with rotary diaphragms.
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Шорінов, Олександр Володимирович, Андрій Олегович Волков, Сергій Євгенійович Маркович, and Анатолій Іванович Долматов. "РОЗРАХУНОК ТЕМПЕРАТУРНО-ШВИДКІСНИХ ПАРАМЕТРІВ ЧАСТИНОК ПРИ ХОЛОДНОМУ ГАЗОДИНАМІЧНОМУ НАПИЛЮВАННІ." Aerospace technic and technology, no. 7 (August 31, 2019): 139–44. http://dx.doi.org/10.32620/aktt.2019.7.20.
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The method of computational fluid dynamics (CFD) for the supersonic nozzle SK-20 of the low-pressure cold gas-dynamic spraying equipment DYMET-405 was applied for calculation of particles impact temperature and velocity. The application of the CFD method is the one-dimensional isentropic gas-dynamic model considers the flow only along the nozzle axis, without taking into account the heat exchange with the nozzle and the friction losses on the internal walls, which leads to obtaining overestimated results of calculations. Previously it was found out that the difference in the values obtained by numerical simulation and the results of calculations of a one-dimensional isentropic model was less than 10%. Numerical simulation of the two-phase flow of the cold spray process has been performed using the Ansys Fluent Academic software package. The influence of the initial cold spray process parameters such as temperature and pressure at the nozzle inlet on the change in temperature and velocity of aluminum particles with a diameter of 25 μm at the moment of impact with the substrate has been studied. Also, the influence of the particle size on the above-mentioned parameters has been obtained. The numerical simulation results of the particle impact temperature with the substrate have been used to calculate the critical velocity of aluminum powder – the velocity needed for coating formation. It is known that the formation of cold spray coatings depends on the velocity of the powder particles. For each material, there is a critical velocity at which the process of forming the coating begins. At particle velocities above the critical one, their adhesion to the substrate and the formation of the coating, due to the plastic deformation of the particles, occurs, while at lower velocities the surface erosion or deposition with low efficiency under certain conditions is observed. As a result of simulation and calculations of the critical velocity, the window of spraying was developed, that is the region of values of velocities and temperatures of the particles of aluminum powder, depending on the temperature and pressure of the air at the nozzle inlet, at which the formation of coatings is possible.
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Srikrishnan, S., P. K. Dash, and V. Jayakumar. "Evaluation of critical blockage ratio and pulse length in a pulse detonation engine using CFD and MATLAB." MATEC Web of Conferences 172 (2018): 02006. http://dx.doi.org/10.1051/matecconf/201817202006.
Full textAbstract:
A Pulse Detonation Engine (PDE) is a new invented propulsion device that takes advantage of the pressure rise inherent to the efficient burning of fuel-air mixtures via detonations. Detonation initiation is a critical process that occurs in the cycle of a PDE. A practical method of detonation initiation is Deflagration-to-Detonation Transition (DDT), which describes the acceleration of a subsonic deflagration created using low initiation energies to a supersonic detonation. The DDT process is not well understood due to a wide range of time and length scales involving complex chemistry, turbulence and unsteady pressure waves. This paper discuss about the effects of blocking ratio in the augmentation of detonation pressure and velocity inside a cylindrical tube of diameter 0.0254m and a length of 1 m. The blockages are rectangular in shape placed at 2/3rd distances of the length of the tube and the heights of the blockages are varied in terms of the diameter of the tube as 1/4th, 1/3rd, ½, 2/3rd and 3/4th the diameter of the tube. The setup is then analyzed in MATLAB using the physics of Friedlander’s equation, which formulate the decay time duration of pressure across the tube length, with and without the blockage. Further, a 2D CFD analysis through ANSYS Workbench is conducted which gave the effective blocking ratio in a rectangular type of blockage placed at the 2/3rd position of the length of the tube and the results are compared. For variable pressures ranging from 1 MPa to 100 MPa input, the effective pulse length is around 0.25 seconds after which the decay of pressure and temperature attain the critical limit. Also it is found that the maximum feasible velocity occurs for an inlet pressure of 10 MPa and 2/3rd height of the blockage where the corresponding outlet velocity is 4692m/s and outlet total pressure being 10.542 MPa.
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Guan, Xiang Yi. "Verification of FLUENT in the Computation of Supersonic Inlet." Advanced Materials Research 591-593 (November 2012): 2064–67. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.2064.
Full textAbstract:
This paper analyzes the simulation results obtained by using FLUENT 6.1, simulation being carried out on supersonic inlet. A combination of turbulence models are adoptedsuch as k-RNG k- and S-A. The computation outcomes are checked by experiment results. Detailed analysis demonstrates that the numerical results obtained from the turbulence models can accurately forecast the pressure distribution trend in the inlet. However, for separation bubbles due to the mutual interference of the shock wave within the inlet boundary layer, the calculation predicts fewer bubbles than actually generated in the experiment. The RNG k- and SA turbulence models produces clearer wave structures in the channel.