Turbulent swirling flow in a model of a uniflow-scavenged two-stroke engine

Ingvorsen, Kristian Mark; Meyer, Knud Erik; Walther, Jens Honoré; Mayer, Stefan

doi:10.1007/s00348-013-1494-6

Cited by 25 publications

(30 citation statements)

References 27 publications

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“…It is found that none of the ensemble-averaged velocities display any significant change between the use of Method One or Method Two. This finding reveals that the wandering motion of vortex center has little effect on the ensemble-averaged velocity, which is consistent with the finding in the study of Ingvorsen et al 19 that ensemble-averaged velocity profiles of swirling flow obtained at a fixed frame could well represent the key flow features for a small wandering motion. Figure 6a shows normalized mean radial velocity ⟨u r ⟩/U j as a function of radial position for all four planes.…”

Section: ■ Results and Discussionsupporting

confidence: 92%

Flow Characteristics in a Scaled-up Multi-inlet Vortex Nanoprecipitation Reactor

Liu

Ramezani

Fox

et al. 2015

Ind. Eng. Chem. Res.

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The microscale multi-inlet vortex reactor (MIVR) has been developed for use in flash nanoprecipitation, a technique to generate functional nanoparticles. A scaled-up MIVR is motivated by the desire for a higher output of nanoparticles than the microscale reactor can provide. As the first step of this scaling process, the flow characteristics in a macro-scale MIVR have been investigated by stereoscopic particle image velocimetry. The studied Reynolds numbers based on the inlet geometry range from 3290 to 8225, resulting in a turbulent swirling flow within the reactor. The flow in the mixing chamber is found to be unstable with a wandering vortex center. The vortex wandering is constrained to a small area near the center of the reactor and has little effect on the mean velocity field. However, the measured turbulence kinetic energy and Reynolds stresses are found to be sensitive to the vortex wandering. The flow characteristics of the macro-scale MIVR are compared with the microscale MIVR in terms of swirl ratio and micromixing time. It is found that the swirl ratio and micromixing time of the flow increases as the MIVR is scaled up, indicating a flow with stronger swirl yet less mixing effectiveness in the scaled-up reactor. ■ INTRODUCTIONFunctional nanoparticles are of great scientific and industrial interest for their unique size-related properties and have a wide application in various areas, such as dyes, pesticides, and pharmaceuticals. 1 However, it is still challenging to produce functional nanoparticles in a relatively easy and inexpensive way. Flash nanoprecipitation (FNP) has been developed to produce functional nanoparticles with a narrow particle size distribution. 2 In the FNP technique, functional nanoparticles are formed by rapidly mixing a supersaturated organic active and a copolymer antisolvent, resulting in the organic active precipitation and particle growth where the growing particle size of the organic active is frozen by deposition of a block copolymer on its surface. 2 Mixing time in the FNP technique should be short enough to provide a uniform starting time for the precipitation. Two mixer geometries, the confined impinging jet reactor (CIJR) 3 and the multi-inlet vortex reactor (MIVR) 4 have been developed to meet the high demand of rapid mixing in FNP. While the CIJR is limited by the requirement of equal momenta of solvent and antisolvent streams, the MIVR is insensitive to the equality of the momentum from each stream, allowing the final fluid phase to be antisolvent dominant, which increases the stability of nanoparticles by depressing the rate of Ostwald Ripening. 4 Thus far, there have been many applications using the MIVR to produce functional nanoparticles. 5−9 To help understand the nanoprecipitation mechanism within the MIVR, mixing performance and flow characterization have been investigated in previous studies. Liu et al. 4 evaluated the mixing performance of a microscale MIVR by using a competitive reaction and computational fluid dynamics (CFD). Cheng et al. 10 measured fl...

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Section: ■ Results and Discussionsupporting

confidence: 92%

Flow Characteristics in a Scaled-up Multi-inlet Vortex Nanoprecipitation Reactor

Liu

Ramezani

Fox

et al. 2015

Ind. Eng. Chem. Res.

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“…The present work extends the work by Ingvorsen et al (2013) by considering the flow in the engine model under dynamic conditions, where the ports are opened and closed by the piston. The main purpose of the present work is to establish a database of reliable data that can be used in the development and validation of CFD models.…”

Section: Present Workmentioning

confidence: 73%

“…The swirling in-cylinder flow in uniflow-scavenged engines has been the subject of earlier works. Investigations have been based on both CFD (Sung and Patterson 1982;Diwakar 1987;Uzkan 1988;Goldsborough and Blarigan 2003;Obeidat et al 2014;Sigurdsson et al 2014) and experiments (Percival 1955;Nakagawa et al 1990;Sher et al 1991;Haider et al 2013;Ingvorsen et al 2012Ingvorsen et al , 2013. Due to the costs and limitations of experimental investigations on full-scale engines, the majority of the experimental work have been performed on simplified scale models, and often under steady-flow conditions.…”

Section: Previous Workmentioning

confidence: 99%

“…Due to the costs and limitations of experimental investigations on full-scale engines, the majority of the experimental work have been performed on simplified scale models, and often under steady-flow conditions. Ingvorsen et al (2013) developed a simplified experimental scale model of the MAN Diesel & Turbo 4T50ME-X research engine (Hult and Mayer 2013), which is a production-sized low-speed marine diesel engine. The flow in the model was investigated under steady-flow conditions, and the extensive measurements were performed using stereoscopic particle image velocimetry (PIV) and laser Doppler anemometry (LDA).…”

Section: Previous Workmentioning

confidence: 99%

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Turbulent swirling flow in a dynamic model of a uniflow-scavenged two-stroke engine

et al. 2014

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It is desirable to use computational fluid dynamics for optimization of the in-cylinder processes in low-speed two-stroke uniflow-scavenged marine diesel engines. However, the complex nature of the turbulent swirling in-cylinder flow necessitates experimental data for validation of the used turbulence models. In the present work, the flow in a dynamic scale model of a uniflowscavenged cylinder is investigated experimentally. The model has a transparent cylinder and a moving piston driven by a linear motor. The flow is investigated using phase-locked stereoscopic particle image velocimetry (PIV) and time-resolved laser Doppler anemometry (LDA). Radial profiles of the phase-locked mean and rms velocities are computed from the velocity fields recorded with PIV, and the accuracy of the obtained profiles is demonstrated by comparison with reference LDA measurements. Measurements are carried out at five axial positions for 15 different times during the engine cycle and show the temporal and spatial development of the swirling in-cylinder flow. The tangential velocity profiles in the bottom of Electronic supplementary material The online version of this article (

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“…24 CFD offers an expedient means for investigating the flow, gas exchange, and combustion processes under realistic engine operating conditions and identification of important features and major underlying interactions between them. 25 Although OP2S engine has already been commonly modeled and tested by many researchers, most of these researches focus on the basic engine performance; they are unable to identify details of the engine design and operating parameters. The article provides some insights into multi-dimensional gas flows in scavenging process of OP2S-GDI engine using commercial CFD software AVL-FIRE based on numerically simulated OP motion profiles and evaluates the scavenging performance using different design and operating parameters, namely, OP motion phase difference and crank-connecting rod ratio.…”

Section: Introductionmentioning

confidence: 99%

Scavenge flow analysis of opposed-piston two-stroke engine based on dynamic characteristics

Zhao

et al. 2015

Advances in Mechanical Engineering

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Opposed-piston two-stroke engine has been proposed by Beijing Institute of Technology to improve power density and complete machine balance relative to conventional engines. In order to study opposed-piston two-stroke engine scavenging flow, a scavenging system was configured using a three-dimensional computational fluid dynamics model effectively coupled to experiments. The boundary conditions are obtained through one-dimensional working process simulation results and experiments. As the opposed-piston relative dynamic characteristics of opposed-piston two-stroke engine depend on different design and operating parameters including the opposed-piston motion phase difference and crankconnecting rod ratio, a numerical simulation program was built using MATLAB/Simulink to define opposed-piston motion profiles based on equivalent crank angle of opposed crank-connecting rod mechanism. The opposed-piston motion phase difference only affects scavenging timing while crank-connecting rod ratio affects scavenging timing and duration. Scavenging timing and duration are the main factors which affect scavenging performance. The results indicate that a match of opposed-piston motion phase difference and crank-connecting rod ratio has the potential to achieve high scavenging and trapping efficiency with a right flow in cylinder.

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Turbulent swirling flow in a model of a uniflow-scavenged two-stroke engine

Cited by 25 publications

References 27 publications

Flow Characteristics in a Scaled-up Multi-inlet Vortex Nanoprecipitation Reactor

Flow Characteristics in a Scaled-up Multi-inlet Vortex Nanoprecipitation Reactor

Turbulent swirling flow in a dynamic model of a uniflow-scavenged two-stroke engine

Scavenge flow analysis of opposed-piston two-stroke engine based on dynamic characteristics

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