Two-Dimensional Heat Transfer Considerations for Thermoreflectance Measurements

2018 ◽  
Author(s):  
Dipta Sarkar ◽  
Partha Pratim Chakraborty ◽  
B. Terry Beck ◽  
Zayd C. Leseman
Keyword(s):  
Steady State ◽  
Heat Equation ◽  
Continuous Wave ◽  
Dirichlet Boundary Conditions ◽  
Transient Condition ◽  
Neumann Condition ◽  
Two Dimensional ◽  
Laser Beam Intensity ◽  
Steady State Condition ◽  
Dimensional Approximation

In the Suspended ThermoReflectance (STR) technique a microcantilever is heated with a laser power at the free end of the microcantilever and as heat propagates through it, another laser is used to measure the temperature along the beam.[1] In this paper, the heat equation is solved for two-dimensional heat flow in the microcantilever to determine the material’s thermal conductivity and heat capacity. Two of the dimensions of the microcantilever, width and length, are significantly greater than the third dimension, the thickness, leading to the two-dimensional approximation. Two boundaries along the length of the structure and one boundary along the width are assumed to be under Dirichlet boundary conditions, while the other boundary has Neumann condition. The Neumann or flux condition has a Gaussian profile due to the nature of laser beam intensity. The heat equation is solved using under 3 different flux conditions: (1) Steady-state, (2) Transient, and (3) Periodic. A steady-state condition mimics the experimental condition when a continuous wave laser is used to heat the microcantilever’s tip. A transient condition is possible when quickly removing or adding the continuous wave laser’s flux from the microcantilever’s tip using a chopper. Finally, a periodic condition can be achieved when an electro-optic modulator is utilized experimentally. Closed form analytical expressions are evaluated against the finite element model and experimental results for microcantilever beams and micro-structures of Si that have lengths on the order of a mm, width on the order of 100 microns, and thicknesses of 1 micron or less.

Experimental Validation of Towed Underwater Cable Model

2019 ◽  
Author(s):  
Jan Vidar Grindheim ◽  
Antonio Carlos Fernandes ◽  
Joel Sena Sales Junior ◽  
Inge Revhaug
Keyword(s):  
Steady State ◽  
Experimental Validation ◽  
Experimental Results ◽  
Experimental Setup ◽  
Two Dimensional ◽  
Cable Model ◽  
Governing Equations ◽  
Current Channel ◽  
Steady State Condition ◽  
Wet Weight

Abstract Towed underwater cable models have been validated using experimental results performed in the current channel at Laboratório de Ondas e Correntes (LOC) at COPPE/UFRJ, Rio de Janeiro. The numerical simulators utilize a Finite Difference Method to solve the Partial Differential Equations describing the dynamics of a towed underwater cable under tension. A non-dimensional analysis of the system dynamics for the two-dimensional case has been performed, with non-dimensional governing equations being presented. The experimental setup consists of two cable sections of ∼1.5 m length each, the first having 3 mm diameter and slightly positive wet weight while the second section has 2.5 mm diameter and slight negative wet weight. With the cable in steady-state condition, the towpoint is moved 0.50 m sideways and the time for the cable to return to straight tow is measured. Further, the cable depths at midpoint and tail are measured in steady-state. Experiments are performed at currents ranging from 0.17 to 0.47 m/s. The presented experimental results are compared to the numerical results. Reasonable agreements are obtained.

scholarly journals SENSITIVITY ANALYSIS ON THERMOHYDRAULIC CODE FOR MODIFIED PLATE-FUELED 2 MW TRIGA

2019 ◽  
Vol 25 (1) ◽  
Author(s):  
Endiah Puji Hastuti ◽  
Surip Widodo
Keyword(s):  
Sensitivity Analysis ◽  
Steady State ◽  
Flow Instability ◽  
State Condition ◽  
Coolant Temperature ◽  
Transient Condition ◽  
Steady State Condition ◽  
Uncertainty Factor ◽  
Calculation Results ◽  
Fuel Meat

SENSITIVITY ANALYSIS OF THERMOHYDRAULIC CODE FOR MODIFIED PLATE-FUELED 2 MW TRIGA. The plan to modify TRIGA 2000 Bandung from using regular TRIGA fuel to plate-type fuel should be supported by the use of appropriate computer codes. This research proposes three codes to design reactor thermohydraulics at transient condition. Analysis has been performed to identify code sensitivity using the same input and correlation. The codes used were COOLOD-N2, Heathyd, and PARET-ANL. The input was obtained from preliminary analysis of a flow rate calculation of 70 kg/s and a nominal power of 2 MW. The comparison of these three codes did not consider uncertainty factor for neutronic and technical aspects. The sensitivity analysis on thermohydraulic codes used to calculate heat transfer in the fuel plate of TRIGA reactor at steady state condition indicates similar temperature trend lines for the coolant, plate, and fuel meat. Temperature calculation results obtained from COOLOD-N2, Heathyd and PARET ANL give consistent sensitivity with the differences of coolant temperature from 2.83% to 12.5%; cladding temperature  from 2.14% to 31.30%; and fuel meat temperature  from 6.63% to 18.64%. The margins of flow instability were 5.03; 5.68 and 4.21, respectively for COOLOD-N2, Heathyd, and PARET-ANL. These values show that flow instability has not yet occurred. The results of the analysis show that the use of those three codes for steady state condition using the same input, in which uncertainty factor is neglected, give similar trend for coolant, cladding, and fuel meat temperature. As the modelling in each code is different, the values obtained are not exactly the same.Keywords: sensitivity analysis, TRIGA Plate, COOLOD-N2, Heathyd, PARET-ANL

scholarly journals A Percolative Approach to Reliability of Thin Film Interconnects and Ultra-thin Dielectrics

VLSI Design ◽  
2001 ◽  
Vol 13 (1-4) ◽  
pp. 363-367
Author(s):  
C. Pennetta ◽  
L. Reggiani ◽  
Gy. Trefán ◽  
R. Cataldo ◽  
G. De Nunzio
Keyword(s):  
Thin Film ◽  
Steady State ◽  
Stochastic Approach ◽  
Physical Parameters ◽  
Two Dimensional ◽  
Steady State Condition ◽  
Random Resistor Network ◽  
Resistor Network ◽  
Thin Dielectrics ◽  
Unified Description

Degradation of thin film interconnects and ultra-thin dielectrics is studied within a stochastic approach based on a percolation technique. The thin film is modelled as a two-dimensional random resistor network at a given temperature and its degradation is characterized by a breaking probability of the single resistor. A recovery of the damage is also allowed so that a steady-state condition can be achieved. The main features of experiments are reproduced. This approach provides a unified description of degradation and failure processes in terms of physical parameters.

Transient Thermal and Flow Field in a Turbine Disk Rotor-Stator System

2006 ◽  
Author(s):  
Yoji Okita
Keyword(s):  
Steady State ◽  
Flow Field ◽  
Turbine Disk ◽  
State Condition ◽  
Transient Condition ◽  
Detailed Measurement ◽  
Steady State Condition ◽  
Secondary Air ◽  
Transient Thermal ◽  
Heat And Fluid Flow

Thermal and flow field in a rotor-stator system around a single stage HP-turbine disk are investigated. In the previous work, the authors’ group applied a newly developed conjugate analysis method to the system at a steady-state condition, compared the thermal field with the measured data, and concluded that a satisfactory level of accuracy can be achieved with the proposed method at the steady-state condition. The present paper focuses on a heat and fluid flow in the same rotor-stator system, but at a transient condition which simulates a typical accelerating and decelerating schedule expected in actual aero-engine operations. First, detailed measurement of secondary-air and metal temperatures around the turbine disk is carried out in the transient condition. Then, the 3D fluid / solid conjugate analysis is applied to the whole accelerating and decelerating schedule. The results show that the transient thermal behavior of the rotor-stator system is well captured and reproduced with the present conjugate method.

Dynamic effects on the transition between two-dimensional regular and Mach reflection of shock waves in an ideal, steady supersonic free stream

2011 ◽  
Vol 676 ◽  
pp. 432-460 ◽  
Author(s):  
K. NAIDOO ◽  
B. W. SKEWS
Keyword(s):  
Steady State ◽  
Shock Waves ◽  
Experimental Evidence ◽  
High Speed ◽  
Mach Reflection ◽  
Neumann Condition ◽  
Two Dimensional ◽  
Reflection Transition ◽  
Strong Reflection ◽  
Transition Criteria

There have been numerous studies on the steady-state transition criteria between regular and Mach reflection of shock waves generated by a stationary, two-dimensional wedge in a steady supersonic flow, since the original shock-wave reflection research by Ernst Mach in 1878. The steady, two-dimensional transition criteria between regular and Mach reflection are well established. There has been little done to consider the dynamic effect of a rapidly rotating wedge on the transition between regular and Mach reflection. This paper presents the results of an investigation on the effect of rapid wedge rotation on regular to Mach reflection transition in the weak- and strong-reflection ranges with the aid of experiment and computational fluid dynamics. The experimental set-up includes a novel facility to rotate a pair of large aspect ratio wedges in a 450 mm × 450 mm supersonic wind tunnel at wedge rotation speeds up to 11000 deg s−1. High-speed images and measurements are presented. A numerical solution of the inviscid governing flow equations was used to mimic the experimental motion and to extend the investigation beyond the limits of the current facility to explore the influence of variables in the parameter space. There is good agreement between experimental measurements and numerical simulation. This paper includes the first experimental evidence of the regular to Mach reflection transition beyond the steady-state detachment condition in the weak- and strong-reflection ranges. It also presents results of simulations for the dynamic regular to the Mach reflection transition which show a difference between the sonic, length-scale and detachment conditions. This paper includes experimental evidence of the Mach to regular reflection transition below the steady-state von Neumann condition.

Design and Development on Full Scope V&V Simulator of Nuclear Power Plant

2014 ◽  
Vol 496-500 ◽  
pp. 1385-1389
Author(s):  
Qiang Gao ◽  
Ke Feng Zhou ◽  
Sen Gai Yang ◽  
Huan Mao ◽  
Jie Zhu
Keyword(s):  
Steady State ◽  
Power Plant ◽  
Nuclear Power ◽  
Program Verification ◽  
Management Program ◽  
Severe Accident ◽  
Transient Condition ◽  
Steady State Condition ◽  
Accident Management ◽  
Accident Condition

In order to strengthen the ability of nuclear safety regulatory and avoid nuclear accident, full scope V&V simulator is designed and developed. By using RELAP-3D and MELCOR procedures coupled with the simulation platform, it achieves a whole conditions simulation which contains steady-state condition, transient condition and severe accident condition. The full scope V&V simulator can be used to do the design verification, operation verification, nuclear emergency and severe accident management program verification.

Sign in / Sign up

Export Citation Format

Share Document