Francisco Eduardo Mourão Saboya Graduate Program in Mechanical Engineering

Research

Research Projects

2021

Evaluation of thermo-hydraulic parameters during boiling and convective condensation inside channels under forced vibration

Concentration area:
Nature of the Project: Research

Start date:

Research line:

Project situation: In progress

Description:
The proposed project main objective is the theoretical and experimental evaluation of thermal and hydraulic parameters during boiling and convective condensation in horizontal circular channels, of conventional and reduced dimensions, subjected to forced vibration. Considering that the circulation of fluid in refrigeration systems is generally carried out through compressors, which eventually transmit vibrations to the system's heat exchangers, this intensification mechanism is intrinsic to many systems. In the case of convective condensation inside horizontal channels, it is expected that the vibration of the channel favors the rupture or reduction of the liquid film thickness along the wall, thus implying an increase in the heat transfer coefficient. As for convective boiling inside channels subject to forced vibration, the rupture of liquid films along the wall may imply a reduction in the heat transfer coefficient or even in anticipation of the wall drying. Therefore, the present research project aims to develop an apparatus for the experimental evaluation of the heat transfer coefficient, pressure loss and flow patterns during boiling and convective condensation inside horizontal channels subjected to forced vibration. It is intended to evaluate circular channels with internal diameters between 3 and 10 mm, flows of refrigerant fluids R134a, R410A, R600a and R290, and saturation temperatures between -5 and 40 °C. Additionally, it is intended to use an actuator to impose vibration frequencies between 20 and 60 Hz, in order to cover the operating range of compressors driven by frequency inverters, with vertical, horizontal, axial and mixed vibration modes.

Team: Students: Master: (2)
Coordinator: Fabio Toshio Kanizawa
Members: Leandro Alcoforado Sphaier / Rian Maurício Santana / Jaqueline Diniz da Silva / Matheus Coitinho Constantino / Brunno Abreu da Fonseca Vargas.

Financiers: Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro - Financial assistance.

Novel Concepts for Transition Delay in Hypersonic Boundary Layers and their Optimization

Concentration area:
Nature of the Project: Research

Start date:

Research line:

Project situation: In progress

Description:
Use the solver developed at UFF under the AFOSR award FA9550-18-1-0419 to generate three- dimensional, disturbance-free, steady-states for the hypersonic laminar flow around a circular cone at an angle of attack. The method developed by the Research Collaborator have been successful in achieving convergence of one- and two-dimensional problems without spurious convectively unstable disturbances. The application to three-dimensional lifting bodies of interest to the Air Force will be studied during the visit. Previously designed three-dimensional grids will be used to calculate the solution with the new methods. The solution will be compared with previously computed and published solutions using the NASA solver VULCAN-CFD. Also, both linear and nonlinear stability analyses will be performed with these disturbance-free base flow solutions using stability solver developed by the PI. The main goal is to uncover the mechanisms that lead to the appearance of stationary and convectively unstable modes in three-dimensional steady-state solutions, usually in form of stationary crossflow vortices. The prediction of boundary layer transition with base flow solutions contaminated with spurious disturbances is not reliable. The calculation of the true basic state solutions without the spurious, grid-dependent disturbances will allow a reliable boundary-layer transition prediction with stability analysis techniques and facilitate the development of control strategies for such configurations. Orçamento: U$ 22,650.00

Team: Students: Undergraduate: (0) / Specialization: (0) / Academic Master: (1) / Professiconal Master: (0) / Doctorate: (0).
Coordinator: Leonardo Santos de Brito Alves
Members: Rodrigo Tavares Veloso / Pedro Paredes / Meelan Choudhari

Financiers: Air Force Office of Scientific Research - Grant.

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