Experimental Validation of a Numerical Model for the Simulation of Tramcar Vehicle Dynamics

2005 ◽  
Author(s):  
Federico Cheli ◽  
Roberto Corradi ◽  
Giorgio Diana ◽  
Alan Facchinetti
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Vehicle Dynamics ◽  
Experimental Validation ◽  
Dynamic Behaviour ◽  
Operating Conditions ◽  
Structural Configuration ◽  
Railway Vehicles ◽  
Design Solutions ◽  
Comparison With Experimental Data

Tramcar vehicles significantly differ from traditional railway vehicles both for the adopted structural configuration and design solutions and for the operating conditions. For this reason, a new numerical model specific for the analysis of tramcar dynamics has been developed by Politecnico di Milano. Before the numerical model can be adopted as a useful mean to analyse tramcar operational problems, the capability of the model to reproduce the actual tramcar dynamic behaviour has to be verified. The paper deals with the validation of the developed numerical model by means of comparison with experimental data.

Validation of a Numerical Model for the Simulation of Tramcar Vehicle Dynamics by Means of Comparison With Experimental Data

2007 ◽  
Vol 2 (4) ◽  
pp. 299-307 ◽  
Author(s):  
Federico Cheli ◽  
Roberto Corradi ◽  
Giorgio Diana ◽  
Alan Facchinetti
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Vehicle Dynamics ◽  
Operating Conditions ◽  
Structural Configuration ◽  
Railway Vehicles ◽  
Design Solutions ◽  
Comparison With Experimental Data

Tramcar vehicles significantly differ from traditional railway vehicles for both the adopted structural configuration and design solutions and the operating conditions. For this reason, a new numerical model specific for the analysis of tramcar dynamics has been developed at Politecnico di Milano. Before the numerical model can be adopted as a means to analyze tramcar dynamics in typical operating conditions, the capability of the model to reproduce the actual tramcar behavior has to be verified. This paper deals with the validation of the proposed numerical model by means of a comparison with experimental data.

scholarly journals A Quantitative Determination of Minimum Film Thickness in Elastohydrodynamic Circular Contacts

2021 ◽  
Author(s):  
Wassim Habchi ◽  
Philippe Vergne
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Numerical Model ◽  
Film Thickness ◽  
Quantitative Determination ◽  
Excellent Agreement ◽  
Operating Conditions ◽  
Pure Rolling ◽  
Minimum Film Thickness

Abstract The current work presents a quantitative approach for the prediction of minimum film thickness in elastohydrodynamic lubricated (EHL) circular contacts. In contrast to central film thickness, minimum film thickness can be hard to accurately measure, and it is usually poorly estimated by classical analytical film thickness formulae. For this, an advanced finite-element-based numerical model is used to quantify variations of the central-to-minimum film thickness ratio with operating conditions, under isothermal Newtonian pure-rolling conditions. An ensuing analytical expression is then derived and compared to classical film thickness formulae and to more recent similar expressions. The comparisons confirmed the inability of the former to predict the minimum film thickness, and the limitations of the latter, which tend to overestimate the ratio of central-to-minimum film thickness. The proposed approach is validated against numerical results as well as experimental data from the literature, revealing an excellent agreement with both. This framework can be used to predict minimum film thickness in circular elastohydrodynamic contacts from knowledge of central film thickness, which can be either accurately measured or rather well estimated using classical film thickness formulae.

Comparison of a Cavity Solar Receiver Numerical Model and Experimental Data

1990 ◽  
Vol 112 (3) ◽  
pp. 183-190 ◽  
Author(s):  
R. E. Hogan ◽  
R. B. Diver ◽  
Wm. B. Stine
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Convective Heat ◽  
Operating Conditions ◽  
Solar Furnace ◽  
Sensitivity Analyses ◽  
Test Bed ◽  
Transfer Rates ◽  
Solar Receiver ◽  
Solar Energy Input

Results from a numerical model of axisymmetric solar cavity receivers are compared with experimental data for tests of a novel test bed receiver in the Sandia National Laboratories solar furnace. The computed energy transfer rates and temperatures are compared with the experimental data for different receiver geometries, aperture sizes, and operating conditions. In general, the agreement between the numerical model and the experimental data is better for the small-to-midsized apertures than for the large apertures. The analysis indicates that for the larger apertures, the convective heat losses are over predicted. It also suggests that these losses could be better characterized. Sensitivity analyses show that both the total solar energy input rate and the convective heat-loss coefficient significantly affect the receiver thermal performance and that the distribution of the input solar flux significantly affects the temperature distribution in the receiver.

Turbulence Modeling and Simulation of Atmospheric Boundary Layers

1992 ◽  
Vol 114 (1) ◽  
pp. 40-44 ◽  
Author(s):  
T. W. Abou-Arab ◽  
M. A. Serag-Eldin
Keyword(s):  
Experimental Data ◽  
Surface Layer ◽  
Modeling And Simulation ◽  
Experimental Validation ◽  
Turbulence Modeling ◽  
Boundary Surface ◽  
Future Research ◽  
Surface Layers ◽  
Atmospheric Boundary Layers ◽  
Comparison With Experimental Data

The essence and shortcoming of turbulence modeling and simulation of atmospheric boundary/surface layers are discussed. The present approach rests on the extensively tested and widely used two-equation k-ε model to predict such flows. All features and constants of the standard version of the k-ε model as it is used for shear flows are retained here. This eliminates the requirement of rigorous experimental validation. However, the model with its set of boundary conditions features compatibility and realizability with the commonly reported stable, unstable and neutral atmospheric boundary/surface layer data. The paper presents also a comparison with experimental data and other models and the need for future research in this direction.

Assessment of the Loss Map of a Centrifugal Compressor's external Volute

2021 ◽  
pp. 1-63
Author(s):  
Thomas Ceyrowsky ◽  
Andre Hildebrandt ◽  
Martin Heinrich ◽  
Rüdiger Schwarze
Keyword(s):  
Experimental Data ◽  
Mach Number ◽  
Boundary Conditions ◽  
Flow Rate ◽  
Numerical Approach ◽  
Operating Conditions ◽  
Flow Angle ◽  
Highly Sensitive ◽  
Geometrical Features ◽  
Comparison With Experimental Data

Abstract A volute's loss coefficient is highly sensitive to Mach number, circumferential velocity and flow rate at volute inlet. In case of a backswept impeller, these parameters are coupled to each other. Therefore, in order to investigate the effects of flowrate and flow angle separately, one would have to vary the diffuser width together with the flowrate, keeping the flow angle constant. This corresponds to coupling the volute with aerodynamically similar impellers, designed for higher and lower flowrates. Since this is elaborate, there is no adequate study available in open literature, assessing a volute's global loss map. In this work, a new numerical approach for the prediction of a volute's representative loss map is presented: The volute is calculated by means of steady CFD as a standalone component. The inlet boundary conditions are carefully selected by means of 1D and applied together with different diffuser widths. This allows for separate investigation of the impacts of flow angle, flow rate and Mach number. Validation against full stage CFD confirms the applicability of the standalone model. The results exhibit that minimum losses do not necessarily occur at the theoretical matching point but either when the volute is smaller or bigger, depending on the inlet flow angle. Investigations of the loss mechanisms at different operating conditions provide useful guidelines for volute design. Finally, the validity of these study's findings for volutes with different geometrical features is examined by comparison with experimental data as well as with fullstage CFD.

Rail vehicle passing through a turnout: analysis of different turnout designs and wheel profiles

2012 ◽  
Vol 226 (6) ◽  
pp. 587-602 ◽  
Author(s):  
Rodrigo Fernando Lagos ◽  
Asier Alonso ◽  
Jordi Vinolas ◽  
Xabier Pérez
Keyword(s):  
Significant Influence ◽  
Vehicle Dynamics ◽  
Dynamic Behaviour ◽  
Geometrical Design ◽  
Railway Vehicles ◽  
Rail Vehicle ◽  
Wheel Profile

In recent years, different systems have been developed in order to improve the dynamic behaviour of railway vehicles when passing through turnouts. Some of these improvements consist in varying the geometry of the switch itself and including moveable crossing vees. It is worth mentioning that they are designed by taking a certain wheel profile into consideration, i.e. it is assumed that the wheel profile does not change. The objective of the current study is to determine the influence that the turnout design has on vehicle dynamics, as well as the influence that the variability in wheel profiles can have on the effectiveness of the different systems. In order to do this, the MBS software Simpack was used to model one vehicle with two different turnouts and four different profiles. The results show that the geometrical design of the turnout has a critical influence on the vehicle/turnout. We also concluded that the wheel profile does not have a significant influence when the vehicle passes through turnouts.

Comparison between an experimental study and a numerical model of the dynamic behaviour of machine-tool slideways

2003 ◽  
Vol 217 (8) ◽  
pp. 1111-1115 ◽  
Author(s):  
R Persianoff ◽  
P Ray ◽  
O Vidal
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Numerical Model ◽  
Machine Tool ◽  
High Speed ◽  
Dynamic Behaviour ◽  
Dynamic Performance ◽  
High Speed Machining ◽  
Dynamic Phenomenon ◽  
Weak Points

In this note work is presented that is used to obtain a numerical model of slideways. A numerical method is used for dynamic phenomenon processing with contact and friction problems. Then, an experimental study was carried out on a real slideway. This allows not only the law of friction to be obtained but also the behaviour of such a mechanism to be described in terms of various influences. These data are highly useful when validating models which include this kind of behaviour. Moreover, as this work is quoted in the context of high-speed machining, an opportunity is provided to increase the dynamic performance of these slideways by revealing their weak points. The machine-tool has a feature that takes into account the experimental law of friction which evolves according to the pressure of contact and the speed of sliding. For the real system considered, the results show good correlation between the numerical and experimental data.

Numerical-Based Comparison Among Critical Flow Properties of HFC-134a and its New Alternatives HFO-1234yf and HFO-1234ze Through Short-Tube Orifices

2015 ◽  
Author(s):  
Puya Javidmand ◽  
Klaus A. Koffmann
Keyword(s):  
Experimental Data ◽  
Global Warming ◽  
Numerical Model ◽  
Two Phase Flow ◽  
Operating Conditions ◽  
Phase Flow ◽  
Two Phase ◽  
Suitable Alternative ◽  
Hfc 134A ◽  
Short Tube

Although HFC-134a is a common refrigerant for residential and mobile refrigeration systems, investigators are dealing with replacing it with new alternatives because of its harmful environmental and global warming effects. Recently HFO-1234yf and HFO-1234ze have been introduced as suitable alternative refrigerants because they have zero ozone depletion potential (ODP) and low global warming potential (GWP) and possess thermophysical properties similar to those of HFC-134a. Because there is no experimental data on the performance of these new refrigerants in capillary tubes and short-tube orifices, a recently developed numerical model for analysis of critical two-phase flow through these tubes is used to predict the critical mass flow rate and pressure distribution of HFO-1234yf and HFO-1234ze under various operating conditions. The applied numerical model is based on a comprehensive two-fluid model including the effects of two-phase flow patterns and liquid-phase metastability. The numerical method has been validated by comparing numerical results of the critical flows of HFC-134a, R-410A, and HCFC-22 with available experimental data. The developed numerical simulation is applied in order to develop comparison and selection charts for short-tube orifices based on the common refrigerant HFC-134a and the alternative new refrigerants HFO-1234yf and HFO-1234ze.

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