Swirl

One of the objectives of car manufacturers is to improve engine performance, reduce consumption and reduce emissions. To achieve this objective, it is important to understand the phenomena involved in the combustion chambers of engines. There are various factors that influence the engine performance such as compression ratio, atomization of fuel, fuel injection pressure, and quality of fuel, combustion rate, air fuel ratio, intake temperature and pressure and also based on piston design, inlet manifold, and combustion chamber designs etc. Geometrical design of intake manifold is one such method for the better performance of an I.C. Engine. Air swirl motion in CI engine influences the atomization and distribution of fuel injected in the combustion chamber. Intake manifolds provides Air motion to the chamber. So, to get the maximum output with the least input on Diesel engine researchers are experimentally and computationally working on construction of the intake manifold configurations for increase in engine performance and reduction of Exhaust Emissions. In this paper i have studied few papers and also gone through basics of my topic from various books to understand the phenomena.

In this present study, numerical modelling and experimental verification of heat transfer enhancement using compound technique of a concentric tube heat exchanger is done. Laminar flow is considered for both the numerical and experimental study. Among the active and passive technique, passive techniques were employed with surface roughened and insertion of twisted tape. A Computational Fluid Dynamics approach was used for numerical analysis which was further verified experimentally. The geometry of the concentric tube heat exchanger was designed in SolidWorks® and the discretization was carried out in ICEM CFD 14.5. The computational simulation was carried out by ANSYS CFX 14.5 solver. The experimental verification was conducted in the same Reynold's Number range used in the numerical analysis, of 500-5000. The heat transfer enhancement was calculated through Performance Evaluation Criteria (PEC) which was found to be 9.67 and 7.89 for CFD analysis and Experiment respectively.

En el siguiente documento se definirá y se describirán los aspectos más relevantes en el proceso de combustión para motores de combustión interna, ya sea motores de ignición por chispa, es decir motores que necesitan de una bujía para iniciar la combustión, o motores de ignición por compresión o auto encendido, a partir de conceptos termodinámicos y químicos.

A simple - yet plausible - model for B-type vortex breakdown flows is postulated; one that is based on the immersion of a pair of slender coaxial vortex rings in a swirling flow of an ideal fluid rotating around the axis of symmetry of the rings. It is shown that this model exhibits in the advection of passive fluid particles (kinematics) just about all of the characteristics that have been observed in what is now a substantial body of published research on the phenomenon of vortex breakdown. Moreover, it is demonstrated how the very nature of the fluid dynamics in axisymmetric breakdown flows can be predicted and controlled by the choice of the initial ring configurations and their vortex strengths. The dynamic intricacies produced by the two ring + swirl model are illustrated with several numerical experiments.

Fluid flow dynamics inside an engine combustion cylinder permits a better cylinder combustion, engine performance and efficiency. The In-Cylinder model of the software ANSYS Fluent is used in this paper to simulate 3D air motion with fuel combustion. The flow phantasm can create a 3D geometry andalso the numerical analysis by using CFD results. By doing like this, we have a chance to compare different designs and this comparisonhelps to determine the best suited optimal designs. The engine used for this combustion simulation is a simple straight valve engine with two intakeand two exhaustvalves.The piston moments can be visualized through the animation andvelocity magnitude curves are plotted for crank angle starting from 570 to 833. The engine is simulated for only working stroke/combustion stroke. The text file is written in working directory containing swirl, x-tumble, y-tumble and moment of inertia as a function of CA. This tool automatically creates animations for mesh on cut plane, temperature on ice cut plane and velocity magnitude on ice cut plane. These created counters and graphs can show the performance of the engine used.

The introduction of modern aftertreatment systems in marine diesel engines call for accurate prediction of exhaust gas temperature, since it significantly affects the performance of the aftertreatment system. The scavenging process establishes the initial conditions for combustion, directly affecting exhaust gas temperature, fuel economy, and emissions. In this paper, a semi-empirical zero-dimensional three zone scavenging model applicable to two-stroke uniflow scavenged diesel engines is updated using the results of CFD (computational fluid dynamics) simulations. In this 0-D model, the engine cylinders are divided in three zones (thermodynamic control volumes) namely, the pure air zone, mixing zone, and pure exhaust gas zone. The entrainment of air and exhaust gas in the mixing zone is specified by time varying mixing coefficients. The mixing coefficients were updated using results from CFD simulations based on the geometry of a modern 50 cm bore large two-stroke marine diesel engi...

Numerical and experimental analyse of the cavitation swirl in the inlet pipe of a radial pump is given in the contribution. The real radial pump impeller geometry was used for numerical simulation performed with CFX. Frozen rotor interface model, which requires the least amount of computational effort, was used, since the stationary pipe mesh is topological different than rotating impeller channel mesh. The measurement testing system was built for numerical results validation. The system was developed as a closed loop with possibility of inlet pressure variation. Modified housing of tested radial pump and inlet pipe are transparent which allows visualisation of cavitation swirl and measurement of pressure pulsations at three different pipe locations. Cavitation swirl length, diameter and rotating frequency were measured at different operating conditions (impeller rotating speed, inlet pressure, operating flow-rate …).

This work studied how in-cylinder flow structure is affected in a light-duty, swirl-supported diesel engine when equipped with three different piston geometries: the first two featuring a conventional re-entrant bowl, either with or without valve cut-outs on the piston surface and the third featuring a stepped-lip bowl. Particle image velocimetry experiments were conducted inside an optical engine to measure swirl vortex intensity and structure during the intake and compression strokes. A full computational model of the optical diesel engine was built using the FRESCO code, a recently developed object-oriented parallel computational fluid dynamics platform for engine simulations. The model was first validated against the measured swirl-plane velocity fields, and the simulation convergence for multiple cycles was assessed. Flow topology was studied by addressing bulk flow and turbulence quantities, including swirl structure, squish flux, plus geometric and operating parameters, such ...

Turbulent isothermal flow inside an axisymmetric dump diffuser and casing-liner annulus has been studied by using realizable k-ε model with and without swirl. Hemispherical, ellipsoidal and vertical ellipsoidal shapes of dome have been considered as liner heads in the simulation. The effects of different dome shapes on the flow pattern in the domain and pressure distributions along the casing and liner walls have been studied over a range of inlet swirl number. The static pressure recovery across the diffuser has been evaluated from the pressure distribution for each case. It is noticed that despite the variation in the size and intensity of the recirculating vortices, the pressure recovery remains nearly the same for all the three dome shapes for a particular swirl level in the inlet. However, swirl in the inlet flow considerably influences the pressure recovery. As the inlet swirl level increases, the size of the corner recirculation decreases, but a central reciculation is additi...

Abstract: Swirling flow generates rotating flows, turbulence and free jet wakes at the downstrean of swirler in combustion chamber. Swirling flow generates complex interaction between pressure gradients and fluid flow. To study the flow behavior and its effect in combustion chamber, experimental procedure is performed and recirculation zone is found out by using unsymetrical six vanes swirler.Here vanes used are of 45 ° at exit of swirler and 10 ° at inlet to the flow.To find out three dimentional velocities, five hole probe is used with multi tube manometer.To findout velocity at inlet duct anemometer is used. To validate experimental results, three dimentional flow within the flow geometry and through the swirler have been simulated by means of computational fluid dynamics(CFD) usind the code FLUENT Swirler applicable for producing CRZ (Central Recirculating Zone) to control length & stability of flame. Whole assembly design includes inlet pipes, Swirler, diffuser, expansion chamb...

In recent years, natural gas is attracted attention as alternative fuel for oil. This study focused on the dual fuel combustion system as a method to use natural gas for cogeneration engine. The purpose is construction of high power, high efficiency and low emission cogeneration engine by using lean burn and supercharged system. One of important parameters that affects on combustion is gas flow in cylinder. In this study, shrouds that are equipped near the intake valves were used to change the gas flow in cylinder. Combustion process was also observed by visualization. The engine performance and exhaust characteristics were compared to investigate effects of gas flow, that is, swirl, tumble and normal. This test engine has a single cylinder with bore of 96mm and stroke of 108mm. The compression ratio is 16:1. The engine was operated at 1000 rpm. Compressed natural gas was induced from an intake port and diesel fuel was injected into the cylinder near the compression TDC. After the d...

In current scenario, environmental concerns are posing a great challenge to DI Diesel engines. Control of emission limits requires a higher attention on combustion efficiency. A high efficiency Diesel engine can be developed only mastering all the parameters that can affect the combustion. Gas motion inside the engine cylinder, which depends on combustion chamber geometry is highly influences the performance of any internal combustion engine. Hence an attempt is made to study the performance, combustion parameters and emission particulates of diesel engine using varied piston bowl geometry in order to enhance the air swirl. Experiments are conducted on four stroke single cylinder water cooled diesel Engine at constant speed of 1500 rpm at different loads. The effect of varied piston bowl geometry on performance, combustion parameters viz. brake thermal efficiency, Brake specific fuel consumption, exhaust gas temperature, heat release rate& cylinder pressure and emission particulates have been investigated and presented in this paper. Results suggest that piston geometry has significant impact on performance, combustion characteristics and emission particulates inside the cylinder with varied piston bowl geometry shows that the squish flow affects the turbulence near the TDC during compression stroke.

Tujuan penelitian ini adalah mengamati kinerja Swirl pada saluran intake manifold untuk meningkatkan kinerja mesin dan membandingkan dengan kinerja mesin kondisi standar ranpa Swirl. Cara penelitian dengan menjalankan mesin selama kurang lebih 5 menit dan mengukur putaran, torsi, pemakaian bahan bakar, kemudian membandingkan hasilnya dengan mesin standar tanpa Swirl. Sebagai mesin uji digunakan sepeda motor merk Honda Karisma 125 D. Bentuk Swirl yang digunakan 6 kisi dengan sudut 15°, 30°, dan 60°. Pada penelitian ini lakukan dua kali pengujian yaitu pengujian kinerja mesin standar dan pengujian kinerja mesin dengan menggunakan Swirl. Dari hasil pengujian yang dilakukan dapat diketahui yaitu Swirl dengan sudut 15° menghasilkan torsi 11,53 Nm, daya rata-rata 3,6598 kW dan efisiensi bahan bakar rata-rata 10,85%. Swirl dengan sudut 30° menghasilkan torsi 12,59 Nm daya rata-rata 3,7303 kW dan efisiensi bahan bakar rata-rata 12,31%. Swirl dengan sudut 60° menghasilkan torsi 12,86 Nm, daya rata-rata 3,9641 kW dan efisiensi bahan bakar rata-rata 13,36%. Mesin standar tanpa Swirl menghasilkan torsi 11.25 Nm, daya rata-rata 3,5430 kW dan efisiensi bahan bakar rata-rata 10,97%.

This research was aimed to observe a swirl performance in manifold intake network to improve an engine performance and compare with non-swirl standard condition engine performance. The research way was by running engine during about 5 minutes and measure round, torsion, fuel usage, later compared the result with non-swirl standard engine. As a test engine was used a Honda Karisma 125 D motorcycle. The swirl shape used 6 grills with 15°, 30°, and 60° corners. In this research was conducted two testing i.e. standard engine performance testing and engine performance testing using a swirl. From the testing results conducted it was known swirl with 15° corner yielded torsion of 11.53 Nm, average power of 3.6598 kW and fuel efficiency of 10.58% in average. The swirl with 60° corner yielded torsion of 12.86 Nm, average power of 3.9641 and average fuel efficiency of 13.36%. The standard engine without swirl yielded torsion of 11,25 Nm, average power of 3.5430 kW and average fuel efficiency of 10.97%.

O mercado de equipamentos de pavimentação é extremamente competitivo e está em constante evolução na aplicação de novas tecnologias, fato que exige pesquisa dedicada a este segmento. É de conhecimento que o Brasil necessita grandes investimentos na área de infra-estrutura, em especial na construção rodoviária. Nesse cenário apresentam-se as usinas de asfalto de mistura a quente que produzem a massa asfáltica necessária para construção de rodovias. O objetivo básico dessas usinas de asfalto é proporcionar massa homogênea dentro de características previamente especificadas. A obtenção envolve a associação de agregados, aquecidos previamente para remoção de umidade e elevação de temperatura, de forma a garantir o envolvimento com um ligante asfáltico.
Dentre os sistemas que compõem uma usina de asfalto está o pré-coletor de particulados que é um componente importante no sistema de filtragem dos gases de exaustão provenientes do secador. Os gases de exaustão carregam pequenas quantidades de particulados de agregados. O pré-coletor tem a finalidade de separar os particulados maiores, de forma inercial, através de um conjunto fixo de aletas. Assim, ocorre a separação granulométrica dos materiais suspensos nos gases. Esta separação faz com que o coletor secundário, conhecido como filtro de mangas, seja preservado, pois o material mais abrasivo e maior é retirado. Estes particulados voltam para a composição da mistura asfáltica, o que corresponde à fração de 2,1% da produção nominal da usina de asfalto, aproximadamente, conforme Ciber Equipamentos Rodoviários Ltda[1].
O objetivo deste trabalho é avaliar o pré-coletor através de simulações numéricas. Para isso, verificam-se o ângulo de varredura e saída das aletas para obter alta eficiência do sistema. A utilização do Software CFX, comercializado pela empresa Ansys, Inc. é fundamental para as simulações com a Dinâmica dos Fluídos Computacional (“CFD - Computacional Fluid Dynamics”) do escoamento multifásico. Essa ferramenta realiza cálculos, através do método de volumes finitos baseado em elementos. Devido à dificuldade de avaliar o fenômeno de turbulência com base nas equações originais de Navier-Stokes opta-se por utilizar o modelo de turbulência 𝑘−𝜀 inseridos nas simulações numéricas via Equações Médias de Reynolds (“RANS – Reynolds-Averaged Navier-Stokes equations”). O modelo de turbulência 𝑘𝑘−𝜀𝜀, muito utilizado na indústria é baseado no modelo de viscosidade turbulenta. Após as simulações, os resultados obtidos de forma adimensionalizados foram comparados através da pressão total (perda de carga), Índice de Rotação (Swirl) e vazão mássica dos particulados na saída do pré-coletor. Com isso, foi possível apresentar soluções diferentes dos ângulos de varredura e saída que compõem as aletas e o local de coleta dos particulados. Os resultados mostram a possibilidade de melhoria da eficiência do sistema analisado.

The present paper work is directed to a device located at the intake port at the junction of the intake manifold and the engine head. This location allows the device to be used with any type of carburetor or fuel injection system. It is the object of the present device to utilize at least three fixed, helically twisted blades to impart additional swirl mixing of the fuel/air mixture. This fuel/air mixture has already been pre-heated by its travel through the intake manifold. The "violent swirl" created by the device provides a more uniform fuel/air mixture, thereby causing a more complete and efficient combustion. The overall result of using the device is better gas mileage, increased performance, easier starting, and less pollution. The object of the project work to improve the fuel/air mixture of the fuel injected engines, preventing valves from being burned or eroded by clogged injectors. As a result of forcing the air to enter the intake port in a high velocity swirl, there is disruption of any direct fuel streams upon the head of the cylinder intake valve which occur as a result of clogged injectors. Another object of the project work is to provide a device that improves the homogeneity of the fuel/air mixture delivered by the carburetor to the cylinders of an internal combustion engine with little or no obstruction in the mixture flow resulting in no starving of the engine. Another object to deliver the fuel/air mixture to the center of the cylinder for a uniform flame front. The swirling mixture delivered by the present invention results in cleaner, more-efficient combustion.

In this paper we present the modelled results of turbulence, scalar mixing and intermittency for three different basic fluid dynamical problems using large eddy simulation (LES). The modelled problems are a turbulent round jet, a bluff body stabilised jet, and a bluff body stabilised swirl jet in a co-flow environment. Both instantaneous and time averaged results along with the probability density functions (pdf) and intermittency of velocity and passive scalar are presented. Simulations well captured the flow features of jet, bluff body stabilised jet and bluff body stabilised swirl jet. The instantaneous and time averaged data show the differences in turbulence and mixing and also an improvement of mixing in the presence of a bluff body and swirl. The addition of bluff body and swirl affect the structure of pdfs for both velocity and passive scalar at different axial and radial locations. The radial variation of intermittency at locations close to the centreline indicates turbulent to non-turbulent phenomena with respect to bluff body and swirl at both upstream and downstream recirculation regions.

Keywords: jet; bluff body; swirl; mixing; intermittency; LES