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A muffler or silencer is an integral part of the exhaust system and is a device used to prevent sound from reaching the openings of the exhaust duct and radiating as far field noise. Different acoustical design and analysis techniques are used to predict the acoustical performance of exhaust systems. Flow noise from exhaust tail pipe is one of the major noise sources in a vehicle. Flow noise is generated mainly during fast acceleration operating condition due to complex flow behavior. In this paper, we have studied the detailed flow field and tried to establish an analyses procedure for flow...
Aerodynamic computational fluid dynamics analysis of a wing glove attached to one wing of a business jet is presented and discussed. A wing glove placed on only one wing will produce asymmetric aerodynamic effects that will result in overall changes in the forces and moments acting on the aircraft. These changes, referred to as deltas, need to be determined and quantified to ensure that the wing glove does not have a significant effect on the aircraft flight characteristics. TRANAIR (Calmar Research Corporation, Cato, New York), a nonlinear full potential solver, and Star-CCM+ (CD-adapco,...
Fuel cells are an appealing alternative to fossil fuels as they operate on hydrogen fuel without any toxic byproducts. A major drawback is the reliability and durability of the bipolar plates. In this project, the bipolar plates and the Gas Diffusion Layer (GDL) were studied and the flow fields optimized using Computational Fluid Dynamics. The flow geometries of the bipolar plate on the cathode side of the fuel cell were studied to understand the impact on fuel cell performance. Steadystate, three-dimensional, laminar, isothermal, and segregated models were chosen to study the designs, while...
In recent years the use of computational simulation tools for combustion research has appeared as a way to reduce time and cost in engine research. These tools face important challenges due to the complexity of the composition of the hydrocarbon petroleum fuels. One of the solutions to this problem is the use of surrogate fuels, with known physical and chemical properties and combustion characteristics similar to real fuels. This paper presents experimental and modelling studies of auto-ignition for long-chain hydrocarbon fuels such as dodecane and hexadecane. Results show a very good...
The use of energetic nanoparticles offers a promising means of adjusting the reactivity of liquid fuels for enhanced combustion stability in next generation propulsion systems. This work outlines the development of a novel aerosol rapid compression machine (RCM) for studying the impact of energetic nanoparticles on reducing the ignition delay of liquid fuels, and a proof-of-concept demonstration is presented using ethanol and JP-8. Fuel droplets are generated using an ultrasonic nozzle. The seeding of 50 nm aluminum nanoparticles in the liquid fuel is achieved by using a combination of...
Results from numerical simulations of the NASA trapezoidal wing geometry using the unstructured finite-volume-based solver STAR-CCM+ are presented. General polyhedral meshes are generated using automated techniques that are amenable to rapid grid generation for industrial use. A steady-state RANS approach is employed using the SST k-ω turbulence model coupled with a predictive laminar-to-turbulent transition model. Results are compared to experimental measurements provided as part of the 1st AIAA High-Lift Prediction Workshop (HiLiftPW-1), both with and without slat/flap support brackets.
Alenia Aeronautica is pursuing the virtual prototyping roadmap as a fundamental brick of the Product Lifecycle Management (PLM) approach. The key issues foreseen in this context are related to multi-disciplinary optimization, system engineering and experimental platform integration. The simulation architecture relies on Computer Aided Engineering technologies where CD-adapco provides the standard for internal fluid-dynamics and thermal transmission. This capability is enhanced by the links to the remaining environment, in order to build complex infrastructures and methodologies aimed at the...
The aim of this presentation is to show the ability of STAR-CCM+ to simulate unsteady aerodynamics, using both moving mesh and moving reference frame, in order to evaluate damping derivatives of the NACA 0012 airfoil. The simulations have been performed with STAR-CCM+ for 2D, unsteady, turbulent flow field and animating motions using a JAVA-macro written ad-hoc. The unsteady forces and moments acting on the airfoil have been directly compared with the exact theory of Theodorsen. The match between CFD end analytical data is very good. This lays the right foundation to calculate damping...
This paper presents the leakage performance of various stepped labyrinth seals. A stationary seal test rig was set up and the leakage characteristics of three seal configurations with different numbers of steps and teeth were investigated for wide operating ranges in terms of pressure ratio and tip clearance. Both the solid and honeycomb land structures were tested. In the honeycomb case, two different sizes were used. The seal was shaped, typical of labyrinth seals for gas turbine applications. The influences of seal configuration, and clearance and honeycomb sizes on the leakage performance...
The aerodynamics of a finite-span rectangular wing is investigated using a numerical method. A high-lift single element airfoil section is used. The study focuses on the effect of the ground clearance (the vertical distance between the leading edge of the wing and the ground). The study includes the effect on the overall characteristics of the flow around the wing and the generated aerodynamic forces (down force and drag). Two wings are used in the study with and without end plates. The CFD code “STAR CCM+” is used in the study. The study showed that there is a range of ground clearance where...

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