Lumped parameter modelling for the thermal analysis of the launch vehicle Vega C

2018 ◽  
Vol 90 (3) ◽  
pp. 542-558
Author(s):  
Mattia Olivero ◽  
Matteo Ferrai ◽  
Piero Pantaleone ◽  
Ivan Perkovic ◽  
Antonella D’Amato ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Thermal Protection ◽  
Time Frame ◽  
Launch Vehicle ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
Content Type ◽  
Flight Phase ◽  
Second Stage ◽  
Lumped Parameter

Purpose This activity dealt with the thermal analysis of the launch vehicle Vega C through a lumped parameter model. The Vega C is the upgrade of the actual launch vehicle Vega within the Vega Consolidation and Evolution Program, whose objective is to develop a consolidated – hence the C – version of the Vega by 2020. The main aim of the study was verifying the thickness of the external thermal protection of the launch vehicle, such that the structure and equipment temperatures were kept within their operating ranges. Design/methodology/approach The analysis has been performed by means of ESATAN–TMS during a time-frame that included the stand-by on ground phase and a flight phase up to the separation of the second stage from the third one. Two operating conditions have been considered, i.e. the worst hot and worst cold cases. The study has been divided as follows: geometry definition through spatial discretization; application of materials and optical properties; application of thermal loads; thermal analysis; and post-processing of the results in ThermNV. Findings It was concluded that the calculated temperatures were within the supposed project specifications, while their trends reflected the expected behavior. Originality/value During the flight phase, the mutual separation of the investigated stages has been explicitly modelled through a routine specifically developed for this purpose. Therefore, the submodels of each stage have been disabled at the correct instant according to the known time-sheet.

Binge watching and college students: motivations and outcomes

2017 ◽  
Vol 18 (4) ◽  
pp. 425-438 ◽  
Author(s):  
Swati Panda ◽  
Satyendra C. Pandey
Keyword(s):  
College Students ◽  
Video Streaming ◽  
Research Question ◽  
Qualitative Interviews ◽  
Time Frame ◽  
Group Discussions ◽  
Content Type ◽  
Second Stage ◽  
Television Shows ◽  
Method Approach

Purpose The purpose of the paper is to explore various motivations that influence college students to spend more time binge watching and the subsequent gratifications. Video streaming websites such as Netflix and Amazon Video have changed the viewing habits of consumers. Viewers have more control and can enjoy on-demand content as per their convenience. This has resulted in viewers watching multiple episodes of television shows in a compressed time frame – a phenomenon termed as binge watching. College students engage in binge watching because of the various gratifications that it promises. This paper investigates the various triggers and consequences of binge watching. Design/methodology/approach Data were collected through a mixed method approach. The first stage involved qualitative interviews and focused group discussions with college students to understand the phenomenon of binge watching. The second stage involved administering a questionnaire to address our research question. Findings Findings indicate that social interaction, escape from reality, easy accessibility to TV content and advertising motivate college students to spend more time binge watching. If students are negatively gratified after binge watching, then they intend to spend more time doing it. Originality/value The findings have important implications on the overall wellbeing of college students and strategic implications for video streaming companies.

scholarly journals Induction Motor Thermal Analysis Based on Lumped Parameter Thermal Network

2020 ◽  
Author(s):  
Pedro Cabral ◽  
Amel Adouni
Keyword(s):  
Thermal Analysis ◽  
Induction Motor ◽  
Operating Conditions ◽  
Heat Sources ◽  
Thermal Network ◽  
Iron Losses ◽  
Lumped Parameter ◽  
Proposed Model ◽  
Industry Applications ◽  
Different Temperatures

Many industry applications required the use of the induction motors. In such envirenement the electrical machines are facing of many stressed operating conditions. One of the critical creteria which decide the choice of the induction motor is the thermal behaviour under different mode operation. In this paper a study of the thermal behavior of an induction motor is presented. In order to predict the temperature in the different machine components, a model based on the lumped parameter thermal network   has been developed. The geometry of the machine and the thermal properties of its various components are used to express the developed model. The joule and the iron losses are considering as the inputs. The proposed model is implemented and tested using MATLAB software. It is a simple model which could predict rapidly the different temperatures. Keywords: Induction motor, Thermal analysis, Lumped parameters thermal network, Modeling, Heat sources

Numerical investigation of multiphase blood flow coupled with lumped parameter model of outflow

2019 ◽  
Vol 30 (1) ◽  
pp. 228-244
Author(s):  
Bartlomiej Melka ◽  
Wojciech P. Adamczyk ◽  
Marek Rojczyk ◽  
Marcin L. Nowak ◽  
Maria Gracka ◽  
...  
Keyword(s):  
Blood Flow ◽  
Lumped Parameter Model ◽  
Coarctation Of Aorta ◽  
Multiphase Model ◽  
Computational Domain ◽  
Windkessel Model ◽  
Content Type ◽  
Model Based ◽  
Lumped Parameter ◽  
Euler Approach

Purpose The purpose of this paper is the application of the computational fluid dynamics model simulating the blood flow within the aorta of an eight-year-old patient with Coarctation of Aorta. Design/methodology/approach The numerical model, based on commercial code ANSYS Fluent, was built using the multifluid Euler–Euler approach with the interaction between the phases described by the kinetic theory of granular flow (KTGF). Findings A model of the blood flow in the arches of the main aorta branches has been presented. The model was built using the multifluid Euler–Euler approach with the interaction between the phases described by the KTGF. The flow and pressure patterns, as well as the volumetric concentration of the blood components, were calculated. The lumped parameter model was implemented to couple the interaction of the computational domain with the remaining portion of the vascular bed. Originality/value The multiphase model based on the Euler–Euler approach describing blood flow in the branched large vessel with a three-element Windkessel model in the coarcted geometry was not previously described in the literature.

Planetary Gear Modal Properties and Dynamic Response: Experiments and Analytical Simulation

2011 ◽  
Author(s):  
Tristan M. Ericson ◽  
Robert G. Parker
Keyword(s):  
Natural Frequencies ◽  
Planetary Gear ◽  
Forced Response ◽  
Operating Conditions ◽  
Modal Testing ◽  
Lumped Parameter Model ◽  
Lumped Parameter ◽  
Analytical Simulation ◽  
Analytical Research ◽  
Independent Motion

Planetary gear vibration is a major source of noise and may lead to fatigue-induced failures in bearings or other drivetrain components. Gear designers use mathematical models to analyze potential designs, but these models remain unverified by experimental data. This paper presents experiments that completely characterize the dynamic behavior of a spur planetary gear by modal testing and spinning tests under representative operating conditions, focusing on the independent motion of planetary components. Accelerometers are mounted directly to individual gear bodies. Rotational and translational accelerations obtained from the experiments are compared to the predictions of a lumped parameter model. Natural frequencies, modes, and forced response agree well between experiments and the model. Rotational, translational, and planet mode types presented in published analytical research are observed experimentally.

A Critical Examination of the Hysteresis in Wells Turbines Using Computational Fluid Dynamics and Lumped Parameter Models

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Tiziano Ghisu ◽  
Francesco Cambuli ◽  
Pierpaolo Puddu ◽  
Irene Virdis ◽  
Mario Carta ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbine Blades ◽  
Unsteady Aerodynamics ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
Hysteretic Behavior ◽  
Critical Examination ◽  
Wells Turbine ◽  
Lumped Parameter

Abstract The hysteretic behavior of oscillating water column (OWC)-installed Wells turbines has been known for decades. The common explanation invokes the presence of unsteady aerodynamics due to the continuously varying incidence of the flow on the turbine blades. This phenomenon is neither new nor unique to Wells turbines, as an aerodynamic hysteresis is present in rapidly oscillating airfoils and wings, as well as in different types of turbomachinery, such as wind turbines and helicopter rotors, which share significant similarities with a Wells turbine. An important difference is the non-dimensional frequency: the hysteresis appears in oscillating airfoils only at frequencies orders of magnitude larger than the ones Wells turbines operate at. This work contains a re-examination of the phenomenon, using both computational fluid dynamics (CFD) and a lumped parameter model, and shows how the aerodynamic hysteresis in Wells turbines is negligible and how the often measured differences in performance between acceleration and deceleration are caused by the capacitive behavior of the OWC system. Results have been verified with respect to both spatial and temporal discretization, for unstalled and stalled operating conditions.

Current Monitoring of Field Controlled DC Spindle Drives

1986 ◽  
Vol 108 (4) ◽  
pp. 289-295 ◽  
Author(s):  
J. L. Stein ◽  
Kyung-Chul Shin
Keyword(s):  
Signal To Noise Ratio ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
Cnc Machine ◽  
Spindle System ◽  
High Speeds ◽  
Lumped Parameter ◽  
Cnc Lathe ◽  
Speed Range ◽  
Current Monitoring

Unmanned machine tools as part of an automated factory require reliable inexpensive sensors to provide machine and process information. The electric current in the DC motor of a CNC machine tool can be inexpensively measured and used to calculate loads on the drive system. To characterize the bandwidth, sensitivity and accuracy of current monitoring on a DC field controlled spindle drive of a CNC lathe, a dynamic lumped parameter model of this sensor system is developed. The model is used to identify the system components that have a dominant effect on the behavior of the sensor when the spindle system is operated above the base speed. Tests were conducted to determine the model’s parameters and to verify the model. The bandwidth and sensitivity of this sensor are shown to be spindle speed dependent. High speeds improve sensitivity and reduce bandwidth. Sensitivity and bandwidth vary by factors of 4.3 and 18.5, respectively, over the speed range. The signal to noise ratio is limited by external load induced variations in the spindle system friction. Recommendations concerning machine designs and process operating conditions to improve current monitoring on spindle drives are presented.

Investigation on Thermal Loading of Disc Brakes: An Approach

2003 ◽  
Author(s):  
J. Jancirani ◽  
S. Chandrasekaran ◽  
P. Tamilporai
Keyword(s):  
Thermal Analysis ◽  
Thermal Loading ◽  
Three Dimensional ◽  
Lumped Parameter Model ◽  
Disc Brake ◽  
Thermal Distortion ◽  
Lumped Parameter ◽  
Wide Range ◽  
Disc Brakes ◽  
Three Dimensional Models

In the wide range of braking speed, the disc brakes are subjected to temperature variation and thermal loading. Different modelling approaches ranging from a simple lumped parameter model to complex three-dimensional models are available for the thermal analysis of the disc brakes. Based on the review of the above models, a model has been developed and formulated for the analysis of thermal loading of disc brake. The developed model is proposed to couple with a model for the thermal distortion of disc brake. It is also proposed to conduct the necessary experiments and thermal analysis to validate the results obtained from the synthesized analysis.

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