Waves in Reciprocating Compressors

Aigner, Roland; Steinrück, Herbert

doi:10.1002/pamm.200410239

Cited by 3 publications

(3 citation statements)

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“…[1][2][3][4] Unsteady flows often lead to poor level control and uneven solidification within the mould; which have been linked to the formation of defects such as deep oscillation marks, cracks, depressions, etc. [5][6][7] These defects are strongly linked to the mechanisms of initial shell solidification and growth in the mould. However, solidification itself is a complex combination of physical phenomena which include heat transfer, phase transformations and solid mechanics interacting simultaneously with the metal flow to form the solid shell within a time lapse of few seconds.…”

Section: Introductionmentioning

confidence: 99%

Recent Developments of a Numerical Model for Continuous Casting of Steel: Model Theory, Setup and Comparison to Physical Modelling with Liquid Metal

López¹,

Jalali²,

Björkvall³

et al. 2014

ISIJ Int.

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Recent developments of an advanced numerical model for Continuous Casting of steel unveiled at the previous 2010 CSSCR Conference in Sapporo, Japan are presented. These include coupling of the existing multiphase, heat transfer and solidification model to argon injection for tracking bubble trajectories in the SEN, metal bulk and across the slag bed after passing through the metal surface. Hence, description of a method for adding gas injection in combination with a multiphase model for tracking metal/slag interfaces (Discrete Phase Model + Volume Of Fluid, DPM+VOF) is given.Validation is supported by tests on a revamped Continuous Casting Simulator (CCS-1) based on a low melting point alloy, which can realistically replicate the flow conditions in the caster. Metal-slag-argon flow predictions were compared to observations in the physical model showing good agreement on features such as discharging jets, rolls, standing waves and argon distribution measured through a variety of techniques such as ultrasound, electromagnetic probes and video sequences. Ultimately, the model makes possible the prediction of stable or unstable flows within the mould as a function of different argon flow-rates and bubble sizes. Application to industrial practice is an ongoing task and preliminary results are illustrated. The robustness of the model combined with direct observations in CCS-1 make possible the description of phenomena difficult to observe in the caster (e.g. argon injection and metal flow), but critical for the stability of the process and the quality of cast products.

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Section: Introductionmentioning

confidence: 99%

Recent Developments of a Numerical Model for Continuous Casting of Steel: Model Theory, Setup and Comparison to Physical Modelling with Liquid Metal

López¹,

Jalali²,

Björkvall³

et al. 2014

ISIJ Int.

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“…Сложеност моделирања клипног компресора условила је да се на основу експерименталних резултата и за једноставна стационарна стања интегришу одвојени модели за проток вентила, пренос топлоте у цилиндру и губитке у лежајевима [61]. Аигнер (Aigner) и Стетенрук (Steteinruck) су моделирали кретање гаса у цилиндру које има таласну природу [2]. Линк (Link) и Дешамп (Deschamps) су моделирали процесе при пуштању у рад и заустављању компресора јер имају другачији облик од устаљених стања па их је неопходно и другачије моделирати [39].…”

Section: математички модел клипног компресораunclassified

“…Слично је и са фазом усисавања само што су ту варијације притиска мање. Динамика рада вентила и утицај на варијације притиска могу се видети у временском домену као што је приказано на Сл 2…”

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The test bench for non-standard testing of reciprocating compressors for motor vehicles

Taranović¹

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Докторска дисертација је резултат мојих вишегодишњих истраживачких активности и лутања па се захваљујем свим људима који су допринели њеном настанку. Докторска дисертација је резултат истраживања реализованих у оквиру пројекта ТР35041 па се захваљујем Министарству просвете, науке и технолошког развоја Републике Србије на финансијској помоћи. Много захвалности дугујем ментору проф. др Јованки Лукић за усмеравање и подршку током израде дисертације. Захваљујем се проф. др Радивоју Пешићу, на саветима и помоћи од непроцењиве вредности у свим фазама израде дисертације Захваљујем се колегама са Катедре за моторна возила и моторе на подршци, саветима и помоћи у свим фазама рада. И на крају сам захвалан својој породици на подршци, стрпљењу и вери у мој рад и мене. Аутор Кључне речи: мерна инсталација, клипни компресор, карактеристике компресора, моделирањеThe test bench for non-standard testing of reciprocating compressors for motor vehicles Abstract Reciprocating compressor in motor vehicles is a necessary component for the compressed air production system, used in motor vehicle's braking system and for operation of other devices. Continuous compressor improvements demand the measurement of compressor characteristics at corresponding, specific test benches, where standard and non-standard compressor parameters may be measured. Application of inadequate test bench, in addition to measurement errors, may preclude the measurements of parameter's dynamic variations and may even affect the operation of reciprocating compressors as test objects and induce the drawing of the wrong conclusions from the test results. In order to avoid the realization of inadequate test bench, an original mathematical model of the test bench and the reciprocating compressor as a test bench load was formed. By simulations using mathematical models, the test bench behaviour was investigated and, based on the simulation results and previously defined standard and non-standard compressor parameters, the test bench for testing of reciprocating compressors for motor vehicles was designed. The test bench was realized based on the project documentation. The results obtained by measurement on the compressor and on the test bench were compared to the results obtained by simulations using mathematical models. The test bench characteristics were verified separately from the reciprocating compressor characteristics, all by comparison with the simulation results. By comparison between the measurement and the simulation results, a good agreement of the results was established, thus verifying the test bench for non-standard testing of reciprocating compressors for motor vehicles. The realized test bench may be used for measurement of nominal parameters in stationary conditions, dynamic testing of compressor's working processes, tribological testing of the compressors, determination of the compressor's mechanical losses structure, comparative testing of lubricants for compressors, etc.

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Performance analysis of reciprocating compressors through computational fluid dynamics

Pereira

Deschamps

Ribas

2008

Proceedings of the Institution of Mechanical Engineers, Part E:

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An experimentally validated numerical analysis of reciprocating refrigeration compressors is presented. The finite-volume methodology is adopted to solve the flow field and a one-degree-of-freedom model is used to describe the valve dynamics. The variation of the computation domain, associated with the valve and piston displacements, is taken into account and the time-dependent flow field and the valve dynamics are coupled and solved simultaneously. The three-dimensional formulation considered in the analysis allowed the simulation of actual suction and discharge muffler geometries. Numerical results were validated with reference to experimental data for valve displacement and pressure in the suction and compression chambers obtained in a calorimeter facility. A study was carried out to identify the contributions of mufflers and valves to the compressor thermodynamic losses.

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Waves in Reciprocating Compressors

Abstract: In case of fast running reciprocating compressors an oscillating momentum on the piston has been observed. This oscillation has been attributed to internal waves. The aim of this paper is to present a simple model to show how such waves are initiated.

Cited by 3 publications

References 1 publication

Recent Developments of a Numerical Model for Continuous Casting of Steel: Model Theory, Setup and Comparison to Physical Modelling with Liquid Metal

Recent Developments of a Numerical Model for Continuous Casting of Steel: Model Theory, Setup and Comparison to Physical Modelling with Liquid Metal

The test bench for non-standard testing of reciprocating compressors for motor vehicles

Performance analysis of reciprocating compressors through computational fluid dynamics

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