Unsteady Modeling of Turbochargers for Automotive Applications by Means of a Quasi-3D Approach

2020 ◽  
Author(s):  
Gianluca Montenegro ◽  
Matteo Tamborski ◽  
Augusto Della Torre ◽  
Angelo Onorati ◽  
Silvia Marelli
Keyword(s):  
Test Bench ◽  
Tangential Direction ◽  
Momentum Equation ◽  
Conservation Equation ◽  
Design Flow ◽  
Automotive Applications ◽  
Flow Conditions ◽  
Vaneless Diffuser ◽  
Energy Conservation Equation ◽  
The University

Abstract This work describes the development and the application of a quasi-3D method for the simulation of turbochargers for automotive applications under unsteady flow conditions. The quasi-3D approach is based on the solution of conservation equations for mass, momentum and energy for unsteady flows and applied to 0D and 1D elements arbitrarily oriented in the space. The compressor is divided into different regions, each one treated numerically in a different way. For the impeller region a relative reference system has been used and the presence of a centrifugal force field has been introduced both in the momentum and energy conservation equation. The direction of the ports at the inlet and outlet of the impeller are used to determine the design flow angles and therefore the deviation during off-design conditions. Conversely in the vaneless diffuser the conservation of the angular momentum of the flow stream has been imposed in the tangential direction and then combined with the solution of the momentum equation in the radial direction. The model has been validated against measurements carried out on the test bench of the University of Genoa both in diabatic and adiabatic conditions.

Unsteady Modeling of Turbochargers for Automotive Applications by Means of a Quasi-3D Approach

2020 ◽  
Author(s):  
Gianluca Montenegro ◽  
Matteo Tamborski ◽  
Augusto Della Torre ◽  
Angelo Onorati ◽  
Silvia Marelli
Keyword(s):  
Test Bench ◽  
Tangential Direction ◽  
Momentum Equation ◽  
Conservation Equation ◽  
Design Flow ◽  
Automotive Applications ◽  
Flow Conditions ◽  
Vaneless Diffuser ◽  
Energy Conservation Equation ◽  
The University

Abstract This work describes the development and the application of a quasi-3D method for the simulation of turbochargers for automotive applications under unsteady flow conditions. The quasi-3D approach is based on the solution of conservation equations for mass, momentum and energy for unsteady flows and applied to 0D and 1D elements arbitrarily oriented in the space. The compressor is divided into different regions, each one treated numerically in a different way. For the impeller region a relative reference system has been used and the presence of a centrifugal force field has been introduced both in the momentum and energy conservation equation. The direction of the ports at the inlet and outlet of the impeller are used to determine the design flow angles and therefore the deviation during off-design conditions. Conversely in the vaneless diffuser the conservation of the angular momentum of the flow stream has been imposed in the tangential direction and then combined with the solution of the momentum equation in the radial direction. The model has been validated against measurements carried out on the test bench of the University of Genoa both in diabatic and adiabatic conditions.

Heat Transfer Analysis of a Novel Pressurized Air Receiver for Concentrated Solar Power via Combined Cycles

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
I. Hischier ◽  
D. Hess ◽  
W. Lipiński ◽  
M. Modest ◽  
A. Steinfeld
Keyword(s):  
Heat Transfer ◽  
Thermal Efficiency ◽  
Porous Ceramic ◽  
Conservation Equation ◽  
Heat Transfer Analysis ◽  
Operational Parameters ◽  
Small Aperture ◽  
Solar Absorber ◽  
Energy Conservation Equation ◽  
Combined Cycles

A novel design of a high-temperature pressurized solar air receiver for power generation via combined Brayton–Rankine cycles is proposed. It consists of an annular reticulate porous ceramic (RPC) bounded by two concentric cylinders. The inner cylinder, which serves as the solar absorber, has a cavity-type configuration and a small aperture for the access of concentrated solar radiation. Absorbed heat is transferred by conduction, radiation, and convection to the pressurized air flowing across the RPC. A 2D steady-state energy conservation equation coupling the three modes of heat transfer is formulated and solved by the finite volume technique and by applying the Rosseland diffusion, P1, and Monte Carlo radiation methods. Key results include the temperature distribution and thermal efficiency as a function of the geometrical and operational parameters. For a solar concentration ratio of 3000 suns, the outlet air temperature reaches 1000°C at 10 bars, yielding a thermal efficiency of 78%.

Energy conservation, time-reversal invariance and reciprocity in ducts with flow

2001 ◽  
Vol 431 ◽  
pp. 223-237 ◽  
Author(s):  
WILLI MÖHRING
Keyword(s):  
Energy Conservation ◽  
Sound Wave ◽  
Conservation Equation ◽  
Smooth Transition ◽  
Rotational Flow ◽  
Flow Energy ◽  
Energy Conservation Equation ◽  
Reversal Invariance ◽  
Edge Conditions ◽  
Piecewise Continuous

A sound wave propagating in an inhomogeneous duct consisting of two semi-infinite uniform ducts with a smooth transition region in between and which carries a steady flow is considered. The duct walls may be rigid or compliant. For an irrotational sound wave it is shown that the three properties of the title are closely related, such that the validity of any two implies the validity of the third. Furthermore it is shown that the three properties are fulfilled for lossless locally reacting duct walls provided the impedance varies at most continuously. For piecewise-continuous wall properties edge conditions are essential. By an analytic continuation argument it is shown that reciprocity remains true for walls with loss. For rotational flow, energy conservation theorems have been derived only with the help of additional potential-like variables. The inter-relation between the three properties remains valid if one considers these additional variables to be known. If only the basic gasdynamic variables in both half-ducts are known, one cannot formulate an energy conservation equation; however, reciprocity is fulfilled.

Research of the flow procedures in a pressure sewer system

2003 ◽  
Vol 47 (7-8) ◽  
pp. 351-356
Author(s):  
C. Dohse ◽  
H. Eckstädt
Keyword(s):  
Land Reclamation ◽  
Flow Conditions ◽  
Sewer System ◽  
Flow Meters ◽  
Initial Information ◽  
Pressure Pipe ◽  
Pumping Stations ◽  
Hydraulic Conditions ◽  
Measuring Section ◽  
The University

At the Institute of Land Reclamation, Hydrology and Sanitary Engineering of the University at Rostock the pressure and flow ratios are examined within a measuring section in the pressure dewatering system on the Darfl peninsula. The objective of the research project is the knowledge upgrade about the highly unsteady hydraulic conditions in a pressure sewer system. This paper firstly presents the method and the dimensioning of pressure dewatering systems, which can be done using either the peak effluent method or the statistical method; the examination program will be explained. The examination includes pressure difference measuring with two pressure meters and flow data measuring via magnetic-inductive flow meters. Additionally the pump running times of 15 pumping stations, as well as the compressor action of the pressure pipe rinsing station are continuously and temporarily recorded and saved. Finally the measuring results which provide initial information about the pressure and flow conditions in a pressure dewatering system will be presented. The effects of the rinsing, the low pressure differences, the air cushions, the seasonal differences as well as the daily development graphs of the wastewater production are all clearly visible.

scholarly journals Investigation of the Flow In Cold Condition at the Exit of a Supersonic Combustor Test Bench

2020 ◽  
Author(s):  
Jefte da Silva Guimarães ◽  
Valéria Serrano Faillace Oliveira Leite ◽  
Dermeval Carinhana Junior ◽  
Marco Antônio Sala Minucci
Keyword(s):  
Nozzle Exit ◽  
Test Bench ◽  
Supersonic Combustion ◽  
Flow Conditions ◽  
Circular Section ◽  
Cold Flow ◽  
Ground Test ◽  
Cold Condition ◽  
Transition Piece ◽  
Generator Unit

For studies of hypersonic flows and supersonic combustion in ground test facilities, three devices can be used as ram accelerators, shock tunnels and supersonic combustor test benches. These devices can reproduce, on the ground, similar conditions to those in real flight at a certain altitude and speed. In the case of the supersonic combustor test bench (SCTB), it simulates the same flow conditions inside the combustor of a scramjet. The SCTB consists basically of a combustion chamber or vitiated air generator unit, where the air is heated, and a nozzle, where the air is accelerated to the desired test speed. The supersonic combustor to be tested is directly coupled to the nozzle exit of the SCTB. Ultimately, it was necessary to use a transition piece to connect the nozzle to the combustor to be tested, because the nozzle exit has a circular section and the combustor entrance has a rectangular one. This work aims to present the process of characterizing the cold flow along the SCTB of the Institute for Advanced Studies (IEAv) using the schlieren technique. The interference of the transition piece in obtaining the required flow conditions at the exit of the SCTB or the entrance of the combustor was mainly evaluated.

scholarly journals INDOOR AIR TEMPERATURE DISTRIBUTION – AN ALTERNATIVE APPROACH TO BUILDING SIMULATION

2003 ◽  
Vol 2 (1) ◽  
Author(s):  
A. T. Franco ◽  
C. O. R. Negrão
Keyword(s):  
Temperature Distribution ◽  
Air Temperature ◽  
Indoor Air ◽  
Linear Equations ◽  
Three Dimensional ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Algebraic Equations ◽  
Conservation Of Energy ◽  
Energy Conservation Equation

The current paper presents a model to predict indoor air temperature distribution. The approach is based on the energy conservation equation which is written for a certain number of finite volumes within the flow domain. The magnitude of the flow is estimated from a scale analysis of the momentum conservation equation. Discretized two or three-dimensional domains provide a set of algebraic equations. The resulting set of non-linear equations is iteratively solved using the line-by-line Thomas Algorithm. As long as the only equation to be solved is the conservation of energy and its coefficients are not strongly dependent on the temperature field, the solution is considerably fast. Therefore, the application of such model to a whole building system is quite reasonable. Two case studies involving buoyancy driven flows were carried out and comparisons with CFD solutions were performed. The results are quite promising for cases involving relatively strong couplings between heat and airflow.

scholarly journals A Two-Layer Model for Steady-Amplitude Gravity Waves and Convection Generated by a Thermal Forcing

2018 ◽  
Vol 75 (7) ◽  
pp. 2199-2216 ◽  
Author(s):  
A. A. M. Sayed ◽  
L. J. Campbell
Keyword(s):  
Gravity Waves ◽  
Lower Layer ◽  
Stable Stratification ◽  
Internal Gravity Waves ◽  
Conservation Equation ◽  
Lower Atmosphere ◽  
Thermal Forcing ◽  
Energy Conservation Equation ◽  
Vertical Location ◽  
Convective Cells

Abstract A two-dimensional two-layer mathematical model is described representing internal gravity waves and convection generated by a thermal forcing in the lower atmosphere. The model consists of an upper layer with stable stratification, a lower layer with unstable stratification, and a thermal forcing in the form of a nonhomogeneous term in the energy conservation equation. Exact analytical solutions are derived for some simple configurations. Depending on the vertical location and depth of the thermal forcing, the model can be used to represent different configurations in which gravity waves are generated by diabatic heating. When the thermal forcing is centered in the lower layer, convective cells are generated in the lower layer, and gravity waves are forced and propagate upward from the interface between the two layers. When the thermal forcing is centered at the interface, the convection in the lower layer is weaker, and gravity waves are forced by the direct effect of the thermal forcing in the upper layer and the influence of the convective cells below. Steady-amplitude solutions for the vertical profile of the gravity waves and convection are derived and generalized to include cases where there is a spectrum of horizontal wavenumbers or vertical wavenumbers or frequencies present.

Simulations of Transonic Diffuser-Volute System Using Hybrid Unstructured CFD

2000 ◽  
Author(s):  
A. Hosangadi ◽  
V. Ahuja ◽  
Y. T. Lee
Keyword(s):  
Transonic Flow ◽  
Numerical Stability ◽  
Efficient Solution ◽  
Solution Procedure ◽  
Flow Conditions ◽  
Vaneless Diffuser ◽  
Parallel Solution ◽  
Water Region ◽  
Good Comparison ◽  
Comparison With Experimental Data

Abstract Simulations for a vaneless diffuser-volute configuration at transonic flow conditions are presented using a multi-element unstructured CFD code CRUNCH. The unstructured framework permits the generation of a contiguous grid without internal boundaries between the diffuser-volute interface, and also provides good local resolution around the cut-water region. The increased numerical stability resulting from these factors coupled with the parallel solution framework yields an efficient solution procedure. Numerical results indicate good comparison with experimental data for the baseline geometry where the measured performance was below the design prediction.

Mathematical Model of In-Flight Oxidation of Metallic Particles in Thermal Spraying

2000 ◽  
Author(s):  
A.M. Ahmed ◽  
R.H. Rangel ◽  
V.V. Sobolev ◽  
J.M. Guilemany
Keyword(s):  
Mathematical Model ◽  
Thermal Behavior ◽  
Spray Deposition ◽  
Particle Surface ◽  
Thermal Spraying ◽  
Deposition Process ◽  
Conservation Equation ◽  
Spherical Particles ◽  
Energy Conservation Equation ◽  
Acceleration And Deceleration

Abstract This paper presents a mathematical model of the in-flight oxidation of spherical particles during thermal spray deposition process. The model includes analysis of the mechanical and thermal behavior of the powder particles. The former accounts for acceleration and deceleration of the particles at the spray distance under different fluid velocities. The thermal behavior takes into account heating, melting, cooling and possible solidification as the particle travel towards the substrate. A finite-difference method is used to solve the thermal energy conservation equation of the particles. The model includes nonequilibrium calculations of the phase change phenomena in the liquid-solid (mushy) zone. The growth of the oxide layer at the particle surface is represented by a modified boundary condition, which includes finite-rate oxidation. The results obtained give the interrelations between various process parameters and the oxidation phenomenon and agree with experimental observation.

Modeling of Oxidation of Plasma-Sprayed Molybdenum Coatings

2000 ◽  
Author(s):  
Y.P. Wan ◽  
X.Y. Jiang ◽  
H. Zhang ◽  
S. Sampath ◽  
V. Prasad ◽  
...  
Keyword(s):  
Spray Deposition ◽  
Mechanical Energy ◽  
Particle Surface ◽  
Conservation Equation ◽  
Type Model ◽  
Energy Conservation Equation ◽  
Thin Oxide Film ◽  
Molten Particle ◽  
Plasma Sprayed ◽  
Substrate Temperatures

Abstract A model for oxidation of molybdenum particles during plasma spray deposition is developed. The diffusion of metal an-ions or oxygen cat-ions through a thin oxidized film, chemical reactions on the surface, and diffusion of oxidant in gas phase are considered as possible rate-controlling mechanisms with controlling parameters as the temperature of the particle surface, and local oxygen concentration and flow field surrounding the particle. The deposition of molten particle and its rapid solidification and deformation is treated using a Madejski-type model, in which the mechanical energy conservation equation is solved to determine the splat deformation and one-dimensional heat conduction equation with phase change is solved to predict the solidification and temperature evolution. Calculations are performed for a single molybdenum particle sprayed under the Sulzer Metco-9MB spraying conditions. Results show that the mechanism that controls the oxidation of this droplet is the diffusion of metal/oxygen ions through a very thin oxide film. A higher substrate temperature results in a larger rate of oxidation at the splat surface, and hence, a larger oxygen content in the coating layer. Compared to the oxidation of droplet during m-flight, the oxidation during deposition is not weak and can become dominant at high substrate temperatures.

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