scholarly journals NUMERICAL STUDY OF DYNAMICS INTRACHAMBER PROCESSES IN SOLID PROPELLANT SUSTAINER TAKING INTO ACCOUNT FLIGHT OVERLOADS. PART 2. CALCULATION RESULTS

2021 ◽  
pp. 104-112
Author(s):  
Mikhail Egorov ◽  
◽  
Dmitry Egorov ◽  
Sergey Egorov ◽  
◽  
...  
Keyword(s):  
Solid Phase ◽  
Particle Density ◽  
Numerical Study ◽  
Rocket Engine ◽  
Large Diameter ◽  
Operating Mode ◽  
Combustion Products ◽  
Cruise Missile ◽  
Engine Operation ◽  
Back Plate

The article presents the results of numerical calculations of the dynamics of in-chamber processes in the cruise missile's second-stage cruise missile propulsion system, taking into account the distributed space-three-dimensional and time-varying flight overloads, obtained using the previously developed calculation method and the application software package created on its basis. The value of the flight overload of a cruise missile, in projections along the coordinate axes, is determined depending on the mass, speed and trajectory of the rocket, mass flow and thrust of the rocket engine. The external aerodynamic effect on the in-chamber process in the SRM is neglected. The results of the calculations are given in comparison-without taking into account and taking into account the effect of flight overload. Two main stages of the rocket engine operation are considered: entering the operating mode and the main operating mode. At the stage of entering the SRM operation mode, the overload affects the redistribution of the temperature of the gas phase of the combustion products in the area of the front bottom of the combustion chamber. On the March operation of the SRB as a result of the flight of an overload, an increase of the particle density (liquid drops) small and large diameter of the solid phase of the combustion products in the wall of the back plate and pre-exhaust gas flue, and the degree of change in the distribution density of the particles (liquid droplets) that are larger than large. The results of the numerical study are in good agreement with the experimental data – the results of bench tests of the rocket engine and the results of flight tests of the cruise missile, which includes the considered SRM.

Experimental and Numerical Study of Rotating Fluidized Beds in a Static Geometry

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Juray De Wilde ◽  
Ali Habibi ◽  
Axel de Broqueville
Keyword(s):  
Fluidized Bed ◽  
Solid Phase ◽  
Numerical Study ◽  
Large Diameter ◽  
Scale Up ◽  
Small Diameter ◽  
Polymer Particles ◽  
Bubbling Fluidized Bed ◽  
Particle Bed ◽  
Dynamics Simulations

The new concept of a rotating fluidized bed in a static geometry was numerically and experimentally studied. The particle bed can be both tangentially and radially fluidized by injecting the fluidization gas tangentially in the static fluidization chamber via multiple gas inlet slots located in its outer cylindrical wall. The tangential fluidization of the particles induces a rotating motion of the particle bed. As a result of the particle bed rotational motion, the solids experience a radially outwards centrifugal force. A radially inwards gas-solid drag force and radial fluidization of the particle bed can be introduced by forcing the fluidization gas to leave the fluidization chamber via a chimney with one or multiple gas outlet slots, positioned at the axis of the fluidization chamber. The solids can be continuously fed and removed in and out of the fluidization chamber via solids inlet and outlet holes in the front or back ends of the fluidization chamber.The fluidization patterns of low-density polymer particles with a large diameter and of high-density salt particles with a small diameter were experimentally studied in a 24-cm diameter, 13.5-cm long non-optimized static fluidization chamber at different solids loadings. Scale-up to a 36-cm diameter fluidization chamber was also studied. With both types of particles, a rotating fluidized bed and an acceptable gas-solid separation was obtained provided that the solids loading was sufficiently high. Slugging and channeling and a non-uniform distribution of the gas over the gas inlet slots to the fluidization chamber may occur at low solids loadings and can be detected via well-chosen pressure measurements. The fluidization patterns observed in the same fluidization chamber were completely different with the polymer particles and with the salt particles. The polymer particles tend to form a dense and uniform bed, its behavior being mainly characterized by tangential fluidization. The salt particles tend to form a less dense, bubbling fluidized bed that is both tangentially and radially fluidized.Computational fluid dynamics simulations give an improved insight in the gas and solid phase flow pattern.

Investigation of a Rotor Blade With Tip Cooling Subject to a Nonuniform Temperature Profile

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Harika S. Kahveci
Keyword(s):  
Temperature Profile ◽  
Turbine Blade ◽  
Numerical Study ◽  
Turbine Rotor ◽  
Inlet Temperature ◽  
Pressure Side ◽  
Engine Operation ◽  
Pressure Losses ◽  
Blade Tip ◽  
Temperature Levels

Abstract One of the challenges in the design of a high-pressure turbine blade is that a considerable amount of cooling is required so that the blade can survive high temperature levels during engine operation. Another challenge is that the addition of cooling should not adversely affect blade aerodynamic performance. The typical flat tips used in designs have evolved into squealer form that implements rims on the tip, which has been reported in several studies to achieve better heat transfer characteristics as well as to decrease pressure losses at the tip. This paper demonstrates a numerical study focusing on a squealer turbine blade tip that is operating in a turbine environment matching the typical design ratios of pressure, temperature, and coolant blowing. The blades rotate at a realistic rpm and are subjected to a turbine rotor inlet temperature profile that has a nonuniform shape. For comparison, a uniform profile is also considered as it is typically used in computational studies for simplicity. The effect of tip cooling is investigated by implementing seven holes on the tip near the blade pressure side. Results confirm that the temperature profile nonuniformity and the addition of cooling are the drivers for loss generation, and they further increase losses when combined. Temperature profile migration is not pronounced with a uniform profile but shows distinct features with a nonuniform profile for which hot gas migration toward the blade pressure side is observed. The blade tip also receives higher coolant coverage when subject to the nonuniform profile.

scholarly journals Destabilization of Immersed Dense Granular Material Submitted to Localized Fluidization: An Experimental and Numerical Study

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Aboubacar Sidiki Dramé ◽  
Li Wang ◽  
Yanping Zhang
Keyword(s):  
Granular Material ◽  
Granular Medium ◽  
Experimental Approach ◽  
Solid Phase ◽  
Numerical Study ◽  
Lighting System ◽  
Led Lighting ◽  
Hydrogel Beads ◽  
Static Regime ◽  
As Solid Phase

An alternative experimental approach and a numerical analysis for the study of destabilization by localized fluidization of an immersed dense granular material are presented. To visualize the evolutions of the internal structure of the granular medium, the hydrogel beads, composed of about 99% of water and having substantially the same refraction indexes, are used as solid phase. A LED lighting system is used in place of a laser lighting system. As a result, the optical access restriction of porous structure is removed. A real economic alternative for the experimental study of fluid-grain coupling during destabilization by localized fluidization of a granular material is created. The experimental phenomenology presented in the literature is verified: the system passes successively through three different stationary regimes: static regime, fluidized cavity regime, and fluidized chimney regime. Some restrictions of using hydrogel beads as particles in the study of liquid-solid interaction are also discussed.

scholarly journals Numerical Study of Plasmon Resonance Silver Nanoparticles Coated Polyvinyl Alcohol (PVA) using Bohren-Huffman-Mie Approximation

2016 ◽  
Vol 1 ◽  
Author(s):  
Dede Djuhana
Keyword(s):  
Silver Nanoparticles ◽  
Polyvinyl Alcohol ◽  
Numerical Study ◽  
Large Diameter ◽  
Small Diameter ◽  
Resonant Mode ◽  
Major Peak ◽  
Ag Nps ◽  
Quadrupole Mode ◽  
Minor Peak

<p class="TTPAbstract">In this study, we have investigated the LSPR spectra of the silver nanoparticles (Ag-NPs) coated by polyvinyl alcohol (PVA) by means of a numerical study using Bohren-Huffman-Mie (BHMie) approximation. The LSPR of Ag-NPs shifted to red-shift as the diameter size of Ag-NPs and the thickness of PVA increased. The peak of the LSPR spectra exponentially increased as the thickness increased. Interestingly, there have three characteristic of the LSPR spectra, small, intermediate, and large diameter. In small diameter, the dipole resonant mode contributed to the LSPR spectra while in large diameter, the LSPR spectra originated from the quadrupole resonant mode. In contrast to intermediate diameter, the LSPR spectra originated from the competition between the dipole and the quadrupole mode. For this reason, at small and large diameter the LSPR peak has one peak and increased then until a certain thickness showed constant. Different at intermediate diameter, the LSPR peak appeared more one peak with major peak increased then until a certain thickness trend to decrease and minor peak followed at small diameter behavior.</p>

Estimation of the Occurrence of Micro-Explosion for the Diesel-Biofuel Multi-Components Droplets

2012 ◽  
Author(s):  
Cai Shen ◽  
Chia-fon F. Lee ◽  
Way L. Cheng
Keyword(s):  
Surface Energy ◽  
Minimal Surface ◽  
Weber Number ◽  
Numerical Study ◽  
Engine Operation ◽  
Fuel Droplets ◽  
Fuel Blends ◽  
Operation Conditions ◽  
Simulation Results ◽  
Breakup Model

A numerical study of micro-explosion in multi-component bio-fuel droplets is presented. The onset of micro-explosion is characterized by the normalized onset radius (NOR). Bubble expansion is described by a modified Rayleigh equation. The final breakup is modeled from a surface energy approach by determining the minimal surface energy (MSE). After the breakup, the Sauter mean radius (SMR) for initially small size droplets can be estimated from a look-up table generated from the current breakup model. There exists an optimal droplet size for the onset of micro-explosion. The MSE approach reaches the same conclusion as previous model determining atomization by aerodynamic disturbances. The SMR of secondary droplets can be estimated by the possible void fraction, ε, at breakup and the corresponding surface Weber number, Wes, at the minimal surface energy ratio (MSER). Biodiesel can enhance micro-explosion in the fuel blends of ethanol and diesel (which is represented by a single composition tetradecane). The simulation results show that the secondary atomization of bio-fuel and diesel blends can be achieved by micro-explosion under typical diesel engine operation conditions.

APPLICATION OF THE IMPLICIT METHOD OF CHARACTERISTICS ON A REGULAR GRID FOR SOLVING THE GAS-DYNAMIC PROBLEMS

2021 ◽  
pp. 80-92
Author(s):  
A.M. Lipanov ◽  
Keyword(s):  
Solid Propellant ◽  
Method Of Characteristics ◽  
Rocket Engine ◽  
Second Order ◽  
Implicit Method ◽  
Dynamic Parameters ◽  
Time Layer ◽  
Engine Operation ◽  
Order Of Accuracy ◽  
Gas Dynamic

In this work, an implicit method is proposed to numerically solve a system of the onedimensional nonstationary equations of gas dynamics transformed by the method of characteristics. Internal points of the channel for a solid-propellant charge are considered at a preignition period of the solid-propellant rocket engine operation. The use of the implicit method makes it possible to calculate the values of gas-dynamic parameters at nodal points of the regular coordinate grid. Calculations of the gas-dynamic parameters both when integrating over time and along the spatial coordinate are performed with the second order of accuracy. Both subsonic and supersonic flows are studied. It is shown that, when predicting the expected pressure value during the transition from one time layer to another with the second order of accuracy, the twenty-fold efficiency of the implicit method is achieved in comparison with the explicit difference method. The trial calculation is performed.

A numerical study of the nucleation, growth and settling of crystals from a turbulent convecting fluid

2021 ◽  
Author(s):  
Vojtech Patocka ◽  
Nicola Tosi ◽  
Enrico Calzavarini
Keyword(s):  
Magma Chamber ◽  
Solid Fraction ◽  
Large Scale ◽  
Solid Phase ◽  
Numerical Study ◽  
Equilibrium Concentration ◽  
Solid Particles ◽  
Settling Rate ◽  
Carrier Fluid ◽  
Nucleation Growth

&lt;p&gt;We evaluate the equilibrium concentration of a thermally convecting suspension that is cooled from above and in which&lt;br&gt;solid crystals are self-consistently generated in the thermal boundary layer near the top. In a previous study (Patoc&amp;#780;ka et&lt;br&gt;al., 2020), we investigated the settling rate of solid particles suspended in a highly vigorous (Ra = 10&lt;sup&gt;8&lt;/sup&gt; , 10&lt;sup&gt;10&lt;/sup&gt;, and 10&lt;sup&gt;12&lt;/sup&gt; ),&lt;br&gt;finite Prandtl number (Pr = 10, 50) convection. In this follow-up study we additionally employ the model of crystal&lt;br&gt;generation and growth of Jarvis and Woods (1994), instead of using particles with a predefined size and density that are&lt;br&gt;uniformly injected into the carrier fluid.&lt;/p&gt;&lt;p&gt;We perform a series of numerical experiments of particle-laden thermal convection in 2D and 3D Cartesian geometry&lt;br&gt;using the freely available code CH4 (Calzavarini, 2019). Starting from a purely liquid phase, the solid fraction gradually&lt;br&gt;grows until an equilibrium is reached in which the generation of the solid phase balances the loss of crystals due to&lt;br&gt;sedimentation at the bottom of the fluid. For a range of predefined density contrasts of the solid phase with respect to&lt;br&gt;the density of the fluid (&amp;#961;&lt;sub&gt;p&lt;/sub&gt; /&amp;#961;&lt;sub&gt;f&lt;/sub&gt; = [0, 2]), we measure the time it takes to reach such equilibrium. Both this time and&lt;br&gt;the equilibrium concentration depend on the average settling rate of the particles and are thus non-trival to compute for&lt;br&gt;particle types that interact with the large-scale circulation of the fluid (see Patoc&amp;#780;ka et al., 2020).&lt;/p&gt;&lt;p&gt;We apply our results to the cooling of a large volume of magma, spanning from a large magma chamber up to a&lt;br&gt;global magma ocean. Preliminary results indicate that, as long as particle re-entrainment is not a dominant process, the&lt;br&gt;separation of crystals from the fluid is an efficient process. Fractional crystallization is thus expected and the suspended&lt;br&gt;solid fraction is typically small, prohibiting phenomena in which the feedback of crystals on the fluid begins to govern the&lt;br&gt;physics of the system (e.g. Sparks et al, 1993).&lt;/p&gt;&lt;p&gt;References&lt;br&gt;Patoc&amp;#780;ka V., Calzavarini E., and Tosi N.(2020). Settling of inertial particles in turbulent Rayleigh-Be&amp;#769;nard convection.&lt;br&gt;Physical Review Fluids, 26(4) 883-889.&lt;/p&gt;&lt;p&gt;Jarvis, R. A. and Woods, A. W.(1994). The nucleation, growth and settling of crystals from a turbulently convecting&lt;br&gt;fluid. J. Fluid. Mech, 273 83-107.&lt;/p&gt;&lt;p&gt;Sparks, R., Huppert, H., Koyaguchi, T. et al (1993). Origin of modal and rhythmic igneous layering by sedimentation in&lt;br&gt;a convecting magma chamber. Nature, 361, 246-249.&lt;/p&gt;&lt;p&gt;Calzavarini, E (2019). Eulerian&amp;#8211;Lagrangian fluid dynamics platform: The ch4-project. Software Impacts, 1, 100002.&lt;/p&gt;

Calculation of mass content of water vapour in car exhaust gas

2020 ◽  
pp. 91-97
Author(s):  
Nikita Igorevich Kuznetsov ◽  
◽  
Denis Viktorovich Kuznetsov ◽  
Keyword(s):  
Water Vapour ◽  
Combustion Products ◽  
Exhaust Gas ◽  
Mass Content ◽  
Engine Exhaust ◽  
Engine Operation ◽  
Ambient Temperatures ◽  
Car Exhaust ◽  
Car Exhaust Gas

The paper presents the dependence between mass content of water vapour and combustion products that are formed in result of combustion of 1 kg of hydrocarbon and air excess coefficient at different negative ambient temperatures during 60 minutes of car engine operation. As a result, the authors have determined conditions of formation of the greatest amount of water vapour in engine exhaust gas.

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