Numerical Simulation of Flow in Dynamically Loaded Journal-Bearing by Vorticity-Stream Function and Moving Grid Method.

The flow around rotor is numerical simulated in hover and forward flight based on multi-structured grid. In hover the flow field can be transformed into a steady-state flow field in the rotating coordinate system. The experimental data of Caradonna and Tung rotor is used to verify the numerical simulation result. The numerical results compare well with the experimental data for both non-lifting and lifting cases. Non-lifting forward flight is simulated and the prediction capabilities have been validated through the ONERA two-blade rotor. The pressure distributions of different positions under different azimuth angles are compared, which is in good agreement with the experimental data. There is unsteady shock wave when forward flight. Dual-time method is used to obtain unsteady flow field with rigid moving grid in the inertial system.

Download Full-text

Utilization of Cold-Flow Numerical Simulation With Overset Grid Method in Development Process of Aeroengine Combustor

Volume 2: Combustion, Fuels and Emissions, Parts A and B ◽

10.1115/gt2010-23089 ◽

2010 ◽

Cited By ~ 1

Author(s):

Mitsumasa Makida ◽

Naoki Nakamura ◽

Osamu Nozaki

Keyword(s):

Numerical Simulation ◽

Development Process ◽

Grid Method ◽

Simulation Method ◽

Simulation Methods ◽

Overset Grid ◽

Simulation Code ◽

Screening Process ◽

Cold Flow ◽

Overset Grid Method

In the TechCLEAN project of JAXA, a combustor for a small aircraft engine has been developed. The combustor was tuned to show the behavior of the Rich-Lean combustion through combustion tests under atmospheric and practical conditions. In the development process of the combustor, numerical simulation methods were also utilized as analysis tools to accelerate the development of the combustor. To use in the screening process of the combustor design, we focused on cost-effective simulation methods and adopted the cold-flow RANS simulation code UPACS which has been developed in JAXA. And to simplify the treatment of calculation grids of the combustor with complicated configuration, we also utilized combination of the overset grid method with the attached multi-block grid method. This simulation method was applied to three phases in the combustor development process; first to the analysis of the combustor configuration to adjust the overall pressure loss, secondly to the analysis of flame stability, and thirdly to the tuning of air flow ratio to optimize emission characteristics of full annular combustors. Finally, the full annular combustor was successively tuned to reduce NOx emissions to 38.1% of the ICAO CAEP4 standard under ICAO LTO cycles, also sustaining basic performances as an aircraft combustor.

Download Full-text

Rapid and globally convergent method for dynamically loaded journal bearing design

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1243/1350650981542010 ◽

1998 ◽

Vol 212 (3) ◽

pp. 207-214 ◽

Cited By ~ 14

Author(s):

H Hirani ◽

K Athre ◽

S Biswas

Keyword(s):

Journal Bearing ◽

Pressure Curve ◽

Algebraic Equations ◽

Connecting Rod ◽

Main Bearing ◽

Element Analysis ◽

Globally Convergent ◽

Dynamically Loaded ◽

Convergent Method ◽

Bearing Design

An approximate analytical pressure expression for dynamically loaded journal bearings is proposed. This approximation is applied to the solution of the finite journal bearing with a π-extent film. The starting and ending angular positions of the pressure curve are predicted by simple algebraic equations. The journal orbit is determined by treating it as an ‘inverse problem’ and evaluated by using the globally convergent Newton-Raphson method. To illustrate the validity of the present study, the Ruston and Hornsby big-end connecting rod bearing and an engine main bearing are analysed. The accuracy of the minimum film thickness and maximum film pressure values obtained by the proposed methodology is comparable to the more elaborate and time consuming finite element analysis, while the execution time is comparable to that required for the short bearing approximation.

Download Full-text