Study on the reliability of paddle-wheel tumble flow meters for high-speed engines (original) (raw)
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International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/investigations-on-in-cylinder-tumble-flows-of-internal-combustion-engine-using-shear-stress-transport-model https://www.ijert.org/research/investigations-on-in-cylinder-tumble-flows-of-internal-combustion-engine-using-shear-stress-transport-model-IJERTV2IS70688.pdf The aim of this project is to investigate Intakegenerated tumble motion is proposed in this project work to enhance the turbulence level during compression stroke to promote the combustion rate and reduce operational parameter variations. Investigations of the in-cylinder tumble flows in an IC engine and its influence on different in-cylinder engine parameters like pressure, temperature, velocity and turbulence intensity can be carried out with flat and bowl-in-pistons[4]. Tumble flow analysis of IC engines is carried out by considering the combustion space on a vertical plane passing through cylinder axis. To characterize the tumble flow, tumble ratio has to be estimated and flow characteristics are analysed using commercially Computational Fluid Dynamics (CFD) software. The theoretical results obtained are validated against experimental values. Shear stress transport turbulence model is used to simulate in-cylinder flow dynamics. The variation in parameters like pressure, temperature, velocity etc. for tumble flow is studied. These results are useful to optimize the turbulence level [1,2]and hence to get better combustion characteristics to reduce the emissions[3]
Engineering Letters, 2009
This study deals with the investigations on the incylinder tumble flows of a single cylinder two-valve engine under motoring conditions with two pentroof pistons having different cavities at an engine speed of 1000 rev/min., during suction and compression strokes using particle image velocimetry (PIV). The two-dimensional velocity vector fields are analyzed on a vertical plane passing through the axis of the cylinder. To quantify the tumble flows, tumble ratio (TR) and average turbulent kinetic energy (ATKE) are estimated from the ensemble average velocity vectors obtained from PIV measurements. It is found that, the TR and ATKE are higher for pentroof-offset-cavity piston than pentroof-central-cavity piston. The present study will be useful in understanding the effect of piston-cavity and shape on the nature of the in-cylinder tumble flows in real engine conditions.
Energy Conversion and Management, 2017
The activity presented in the paper is focused on the development of a high-performance engine specifically dedicated to CNG fueling. The engine features a variable valve actuation system as well as different possible compression ratios ranging between 12 and 14. More specifically, the present work carries out an experimental and numerical characterization of the steady-state tumble flow from the engine head and deals with the development and assessment of a numerical model for the engine-cycle transient simulation. Experimental tests were carried out at Fiat Research Center (CRF) on a flow test rig equipped with two different devices for the tumble measurement, based on the Ricardo method and on the twodimensional HWA acquisition of the axial velocity, respectively. It is worth highlighting that the HWA technique was purposely developed by CRF for the tumble characterization. The experimental results were also used for the calibration of a 'virtual flow box' numerical model, which was in turn exploited to gain complimentary information about the characteristics of the tumbling flow and to define the requirements for the transient CFD model of the real engine, both in terms of discretization mesh and turbulence modeling. The results showed that the HWA technique represents a factual alternative to the integral techniques for tumble characterization. It also provides additional information about the unevenness of the flow distribution generated by the intake system. The 'virtual flow box' simulations pointed out that good results can be obtained by using the Realizable k-e model, whereas both the Realizable and the RNG k-e models proved to be appropriate for the engine transient simulations. Finally, the CFD models showed to be fairly accurate and reliable, especially when the relative changes from one engine geometry and/or valve actuation to another need to be accounted for.
Tumble Flow Analysis In An Unfired Engine Using Particle Image Velocimetry
2009
This paper deals with the experimental investigations of the in-cylinder tumble flows in an unfired internal combustion engine with a flat piston at the engine speeds ranging from 400 to 1000 rev/min., and also with the dome and dome-cavity pistons at an engine speed of 1000 rev/min., using particle image velocimetry. From the two-dimensional in-cylinder flow measurements, tumble flow analysis is carried out in the combustion space on a vertical plane passing through cylinder axis. To analyze the tumble flows, ensemble average velocity vectors are used and to characterize it, tumble ratio is estimated. From the results, generally, we have found that tumble ratio varies mainly with crank angle position. Also, at the end of compression stroke, average turbulent kinetic energy is more at higher engine speeds. We have also found that, at 330 crank angle position, flat piston shows an improvement of about 85 and 23% in tumble ratio, and about 24 and 2.5% in average turbulent kinetic ener...
Istanbul University - DergiPark, 2016
The turbulence is one of the most important parameters for internal combustion engines. Enough turbulence formations will result in a better mixing process of air and fuel and it will also enhance flame development. The desired turbulent character can be obtained with a well designed intake port. In this study, swirl and tumble motion investigations were performed for Ricardo E6 Research Engine. The CAD model of the engine cylinder with only intake port and intake valve was prepared and imported to STAR-CCM+ v6.04 software. The energy solver was frozen and segregated solver was used during the solutions. The turbulence model selection was a key point for such an analysis. So, three turbulence models (Realizable k-s, k-ro-SST and LES) were compared. The k-s model was found more suitable and stable for these cases. In our investigation, there were two case studies. One of them was effect of valve lift change on swirl and tumble number while the engine was operated constant speed. The second one was effect of engine speed on swirl and tumble number for a unique valve lift. As it is expected for a gasoline engine, the tumble numbers remain higher than swirl numbers. The valve lift change results showed that while increasing of valve lift increased the swirl numbers but decreased the tumble numbers. This inversely proportional result arises from the momentum transform between the angular and axial motions. Anyway, both dimensionless numbers were increased with the engine speed increasing and it was seen that the engine speed is the most effective parameter for incylinder flow formation.
Journal of Applied Fluid Mechanics, 2019
This paper describes an experimental study aimed at the characterization of the steady-state tumble motion in the cylinder of an engine using stereoscopic particle image velocimetry (Stereo-PIV). More specifically, a pentroof four valves gasoline direct injection (GDI) engine head was mounted on a modified FEV steady-state flow rig for applying Stereo-PIV at different measurement vertical tumble planes at mid cylinder, mid injector and mid valve. The flow field was described by the distribution of the ensemble average flow patterns for 1000 pairs of images for every case, vorticity contours, turbulent kinetic energy and tumble ratio. The results revealed that the higher velocities acquired at the mid valve plane improved the turbulent kinetic energy and tumble ratio compared to the other planes. There was a good level of agreement between direct and indirect methods used for calculating the tumble ratio.
Energy Procedia, 2015
Engine coherent flow structures such as swirl and tumble motions are key factors for the combustion process due to their capability to rise turbulence levels and enhance mixing which, in turns, severely influence both fuel efficiency and pollutant emissions. Automotive industry has therefore put great efforts over the last decades in evaluating air flow during induction stroke and air flow within the cylinder. Nowadays swirl and tumble motion characterizing a specific cylinder head are evaluated experimentally at design stage mainly using stationary flow benches. Such tests allow characterizing each head prototype using non-dimensional parameters like swirl and tumble ratios and, finally, to compare the different designs. In the present work the authors focused their attention on the swirl ratio characterization, firstly reviewing the two main methodologies for evaluating such parameter and more precisely the AVL and the Ricardo ones. A numerical method is then proposed in order to reproduce the stationary test bench with the final goal to develop a fast and accurate virtual test bench for cylinder head design. Simulations have been carried out on different VM Motori engine heads for which experimental data were available. The comparison between computational and experimental swirl ratios allowed to evaluate the suitability of using a virtual test bench as alternative or complementary to experiments. These results widened the understanding of the swirl fluid-dynamics and suggested that care must be taken when comparing duct designs having no geometrical similarity. Finally dynamic simulations have been performed for the head prototypes in order to compute the engine swirl in realistic conditions and to compare it with the steady bench results. This allowed evaluating the capability of the two different "static" swirl ratio definition (AVL/Ricardo) in correctly estimating real engine swirl.
Particle Image Velocimetry: Recent Improvements, 2004
With modern heavy-duty diesel engines the design of the inlet ports in the cylinder head is such that some degree of swirling motion is induced in the engine cylinders during intake. This swirling motion is mostly characterized using a stationary flow bench. In such a flow bench, a dummy cylinder is used instead of the cylinder in the engine. In this situation there is no moving piston, the air can flow out of the open end of the dummy cylinder. To measure the intensity of the swirling motion a swirl-torquemeter is used. This swirl-torquemeter is a flow rectifier, which is placed in the dummy cylinder. The restraining torque on the flow rectifier is a measure of the momentum in the flow. Simulations of the flow in the cylinder indicate that the flow is influenced by the flow-rectifier in such a way that the measured values can be questioned. One of the objectives in this research is to find out if this influence exists. To do this, the velocity field in the cylinder is measured using Particle Image Velocimetry (PIV). From the velocity measurements, the swirl was calculated and compared to the swirl measured using a swirl-torquemeter. The validity of the assumptions made when using a swirl-torquemeter was evaluated from the velocity fields. Last, turbulence characteristics were determined and a spectrum was made.
SAE Technical Paper Series, 2014
The objective of this paper is to simulate the air flow (cold run) inside a single cylinder research engine for different geometries of the piston crown and investigate the influence of them on the Tumble coefficient and Squish. The study was conducted through the software star-CD, with the module esice (Expert System -Internal Combustion Engine) and simulations of the air flow with the flat piston were carried out at the first time.