Bubble breakup simulation in nozzle flows

2012 ◽  
Vol 710 ◽  
pp. 72-101 ◽  
Author(s):  
Oleg E. Ivashnyov ◽  
Marina N. Ivashneva
Keyword(s):  
High Pressure ◽  
Sharp Increase ◽  
Nozzle Flow ◽  
Constant Number ◽  
Interface Area ◽  
Bubble Breakup ◽  
Free Parameters ◽  
Nozzle Flows ◽  
Advanced Model ◽  
Bubble Fragmentation

AbstractExperiments on high-pressure vessel decompression have shown that vaporization occurs in ‘boiling shocks’ moving with a velocity of ${\ensuremath{\sim} }10~\mathrm{m} ~{\mathrm{s} }^{\ensuremath{-} 1} $. To explain this phenomenon, a model accounting for bubble breakup was suggested (Ivashnyov, Ivashneva & Smirnov, J. Fluid. Mech., vol. 413, 2000, pp. 149–180). It was shown that the explosive boiling was caused by chain bubble fragmentation, which led to a sharp increase in the interface area and instantaneous transformation of the mixture into an equilibrium state. In the present study, this model is used to simulate nozzle flows with no change in the free parameters chosen earlier for modelling a tube decompression. It is shown that an advanced model ensures the best correspondence to experiments for flashing flows in comparison with an equilibrium model and with a model of boiling at a constant number of centres. It is also shown that the formation of a boiling shock in a critical nozzle flow leads to autovibrations.

Nozzle Flow Model of High Pressure Variable-Rate Spraying Based on PWM Technology

2011 ◽  
Vol 422 ◽  
pp. 208-217 ◽  
Author(s):  
Chang Yuan Zhai ◽  
Xiu Wang ◽  
Da Yin Liu ◽  
Wei Ma ◽  
Yi Jin Mao
Keyword(s):  
High Pressure ◽  
Flow Model ◽  
Hypothesis Test ◽  
Test System ◽  
Nozzle Flow ◽  
Maximum Relative Error ◽  
Variable Rate ◽  
Flow Models ◽  
Pressure Variable ◽  
Variable Rate Spraying

Nozzle flow model for high pressure variable-rate spraying is indispensable when orchard sprayer is controlling liquid flow based on Pulse Width Modulation (PWM) technology. Three flow models for Teejet AITXA 8002, 8003 and 8004 nozzles are obtained by using nozzle flow model test system which is established in this paper. The results from equation hypothesis test and test for lack of fit of flow model shows that those three flow models work well. Nozzle flow model validation trials show that the relative errors of model flow and actual flow are small, while the maximum relative error is 6.50%; the flows characteristics of different nozzles with the same type are almost the same.

Computational Study on the Critical Nozzle Flow of High-Pressure Hydrogen Gas

2008 ◽  
Vol 24 (4) ◽  
pp. 715-721 ◽  
Author(s):  
Jae-hyung Kim ◽  
Heuy-dong Kim ◽  
Toshiaki Setoguchi ◽  
Sigeru Matsuo
Keyword(s):  
High Pressure ◽  
Computational Study ◽  
Hydrogen Gas ◽  
Nozzle Flow ◽  
Critical Nozzle ◽  
Pressure Hydrogen

scholarly journals Flows of ideal and real gases in channels of variable cross section with unsteady localized energy supply

2017 ◽  
pp. 20-40
Author(s):  
Н.А. Брыков ◽  
К.Н. Волков ◽  
В.Н. Емельянов ◽  
И.В. Тетерина
Keyword(s):  
Energy Supply ◽  
Variable Cross Section ◽  
Approximate Model ◽  
Nozzle Flow ◽  
Gas Flows ◽  
Variable Cross ◽  
Numerical Fluxes ◽  
Volume Method ◽  
Nozzle Flows ◽  
Thermodynamic Processes

Проводится моделирование течений газа в технических устройствах, в которых протекают процессы, связанные с нестационарным локализованным подводом энергии. Для численного моделирования нестационарных сопловых течений с интенсивным энергоподводом используется метод конечных объемов и векторизованный подход к расчету потоков. Для моделирования термодинамических процессов в высокотемпературных потоках воздуха применяется приближенная модель равновесной термодинамики воздуха. Приводятся результаты численного моделирования одномерных и двумерных сопловых течений с подвижной зоной энерогоподвода. На основе данных численного моделирования обсуждается качественная картина газодинамических и тепловых процессов в сопле при нестационарном подводе энергии. Устанавливается зависимость расходных характеристик сопла, а также смещение соплового скачка уплотнения при перерасширенном истечении газа из сопла от интенсивности и цикличности энергоподвода в дозвуковой части сопла. Gas flows are simulated in technical devices where processes associated with unsteady localized energy supply are proceeded. The finite volume method and the vectorized approach to the calculation of numerical fluxes are applied to the simulation of unsteady nozzle flows with intense energy supply. An approximate model of equilibrium thermodynamics of air is used to simulate thermodynamic processes in high-temperature air flows. The numerical results obtained for one-dimensional and two-dimensional nozzle flows with moving zones of energy supply are analyzed. A qualitative picture of gasdynamic and thermal processes in a nozzle with unsteady energy supply is discussed on the basis of the results of numerical simulation. A dependence of the nozzle flow rate and the displacement of nozzle shock wave on the intensity and cyclicity of energy supply is considered for overexpanded nozzle flow.

A transformation of the hodograph equation and the determination of certain fluid motions

1953 ◽  
Vol 245 (904) ◽  
pp. 583-624 ◽  
Keyword(s):  
Harmonic Functions ◽  
Gas Dynamics ◽  
Free Stream ◽  
Nozzle Flow ◽  
Type Ii ◽  
Sonic Nozzle ◽  
Free Stream Mach Number ◽  
Particular Solution ◽  
Nozzle Flows

A transformation is given of the hodograph equation of two-dimensional gas dynamics, from the usual variables q, 6t to q and a new variable (J). The transformation, which suits any gas for which pp~y = const, with y> 1, is so chosen that certain solutions, which in terms of q, 6 are multi valued, become single-valued functions of q, <j). Such a solution is represented, over the whole domain which is of interest, by a single series in q, which is rapidly convergent; whereas in terms of q, 6 different series would be required for different branches of the function, and these would be but slowly convergent. By this method we can construct (i) the nozzle flow for which the axial velocity is a prescribed analytic function of position, in particular trans-sonic nozzle flows; and (ii) various cases of flow past aerofoil-shaped cylinders placed in a uniform stream. Taking y = T4, complete numerical results are given for one case of trans-sonic nozzle flow, and from these other such flows can be obtained by superposition, and a family of flows of type (ii) is investigated, in which the trailing edge of the aerofoil is cusped; the aerofoil shape has been calculated for two representative values of the free- stream Mach number. A limiting flow of this family is found to consist of a set of Prandtl-Meyer flows, analytically distinct but joining continuously where they abut. These flows are related to a particular solution of the hodograph equation which is of funda­ mental analytic importance; it stands in the same relation to the set of 'Chaplygin solutions’ as the generating function for Legendre polynomials does to the harmonic functions rnPn(cos 6).

Injector nozzle flow model and its effects on the calculations of high pressure sprays

2004 ◽  
Vol 9 (4) ◽  
pp. 483-488
Author(s):  
Wei Ming-rui ◽  
Liu Yong-chang ◽  
Wen Hua ◽  
Zhang Yue-heng
Keyword(s):  
High Pressure ◽  
Flow Model ◽  
Nozzle Flow ◽  
Injector Nozzle
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