Classification of Fluid Dynamic Loss in Aeroengine Transmission Gears: Experimental Analysis and CFD Validation

2017 ◽  
Author(s):  
Hidenori Arisawa ◽  
Yuji Shinoda ◽  
Mitsuaki Tanaka ◽  
Tatsuhiko Goi ◽  
Hirofumi Akahori ◽  
...  
Keyword(s):  
High Speed ◽  
Fluid Dynamic ◽  
Aircraft Engine ◽  
Momentum Conservation ◽  
Cfd Modeling ◽  
Management Technique ◽  
Cfd Validation ◽  
Computational Fluid Dynamics Cfd ◽  
Dynamic Loss ◽  
Oil Jet

Reducing fluid dynamic power loss as speed increases is crucial to developing highly efficient high-speed aircraft engine gearing. Therefore, in this study, experiments were conducted using a precise friction-loss management technique and a vacuum pump in the gearbox for experimentally classifying fluid dynamic loss. Consequently, it was found that fluid dynamic loss could be classified into “oil-jet acceleration loss and oil reacceleration loss based on the momentum conservation of point mass” and “oil churning loss and windage loss based on the momentum conservation of an incompressible continuum”. Furthermore, the simulation results obtained via appropriate computational fluid dynamics (CFD) modeling of the resultant mechanisms agreed with the experimental results. The results of the present study are expected to improve the efficiency of mechanical systems, e.g., the fan drive gear system of Geared Turbofan™ and the accessory gearbox.

Classification and Modeling of Fluid Dynamic Loss in Aeroengine Transmission Gears

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Hidenori Arisawa ◽  
Yuji Shinoda ◽  
Mitsuaki Tanaka ◽  
Tatsuhiko Goi ◽  
Hirofumi Akahori ◽  
...  
Keyword(s):  
Conservation Law ◽  
High Speed ◽  
Fluid Dynamic ◽  
Aircraft Engine ◽  
Management Technique ◽  
Proposed Model ◽  
Loss Prediction ◽  
Dynamic Loss ◽  
Oil Jet ◽  
Experimental Fluid

Reducing the fluid dynamic power loss for increasing speed is critical for the development of highly efficient high-speed aircraft engine gearing. In this study, the fluid dynamic loss was experimentally performed using a precise friction loss management technique along a vacuum being drawn on the gearbox. The experimental fluid dynamic loss could be classified as either “oil jet acceleration loss and oil reacceleration loss based on the conservation law of momentum for a point mass” or “oil churning loss and windage loss based on the conservation law of momentum for an incompressible continuum.” Windage loss and oil dynamic loss (i.e., the summation of oil jet acceleration loss, oil reacceleration loss, and oil churning loss) were modeled to develop equations for a loss prediction. The equations of the windage loss are pressure loss of flow passing through the side clearance of the gears and energy loss caused by the vortex generation in the cavity between tooth valleys. Oil dynamic loss was determined by multiplying the oil jet acceleration loss by an empirical coefficient. The results of the loss prediction equations agree with the experimental results, demonstrating the validity of the proposed model of the fluid dynamic loss.

Numerical Designed Experiment to Optimize a Ported Shroud to Extend the Operability Margin of a Centrifugal Compressor

2005 ◽  
Author(s):  
J. Slovisky ◽  
M. L. Mansour ◽  
M. T. Barton ◽  
D. L. Palmer
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Numerical Technique ◽  
Fluid Dynamic ◽  
Constant Width ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Stall Margin ◽  
Designed Experiment ◽  
Ported Shroud

This paper describes the Computational Fluid Dynamic (CFD) numerical optimization of a modern centrifugal compressor impeller with a ported shroud for increased surge margin. The vent configuration selected was a full circumference, constant-width slot. A multiblock, steady flow three dimensional (3D) viscous RANS model (ADPAC) is used with parallel processing capability to increase computational speed. Grid generation is performed in an automated fashion to enable the timely optimization of the ported shroud configuration. A designed experiment (DoE) approach is used to minimize the number of vent configurations to be modeled, to ensure that factor interaction effects are captured, and to facilitate the definition of an optimum vent configuration. The DoE is a 2 factor, 2 level full factorial experiment with a center point included to detect possible curvature in the solution surface. The factors optimized are slot width and the flow-wise location of the slot. The numerical technique verifies the ability of the ported shroud to extend compressor stall margin at the part-speed operating condition, while maintaining acceptable high speed performance, in good agreement with test data for a similar impeller with a ported shroud. The use of a DoE method coupled with CFD modeling identified an optimized vent configuration with a minimum of time and effort. The CFD results also provide enhanced understanding of the device physics.

scholarly journals Numerical Simulation of Oil Jet Lubrication for High Speed Gears

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Tommaso Fondelli ◽  
Antonio Andreini ◽  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Lorenzo Cipolla
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Low Pressure ◽  
Adaptive Meshing ◽  
Viscous Effects ◽  
Cfd Simulations ◽  
Oil Jet ◽  
Oil Injection ◽  
Bypass Ratio

The Geared Turbofan technology is one of the most promising engine configurations to significantly reduce the specific fuel consumption. In this architecture, a power epicyclical gearbox is interposed between the fan and the low pressure spool. Thanks to the gearbox, fan and low pressure spool can turn at different speed, leading to higher engine bypass ratio. Therefore the gearbox efficiency becomes a key parameter for such technology. Further improvement of efficiency can be achieved developing a physical understanding of fluid dynamic losses within the transmission system. These losses are mainly related to viscous effects and they are directly connected to the lubrication method. In this work, the oil injection losses have been studied by means of CFD simulations. A numerical study of a single oil jet impinging on a single high speed gear has been carried out using the VOF method. The aim of this analysis is to evaluate the resistant torque due to the oil jet lubrication, correlating the torque data with the oil-gear interaction phases. URANS calculations have been performed using an adaptive meshing approach, as a way of significantly reducing the simulation costs. A global sensitivity analysis of adopted models has been carried out and a numerical setup has been defined.

Windage Losses of a Meshing Gear Pair Measured at Different Working Conditions

2018 ◽  
Author(s):  
D. Massini ◽  
T. Fondelli ◽  
B. Facchini ◽  
L. Tarchi ◽  
F. Leonardi
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Volume Flow Rate ◽  
Fluid Dynamic ◽  
Lubrication System ◽  
Test Rig ◽  
Rotating Speed ◽  
Aero Engine ◽  
Speed Up ◽  
Oil Jet

In recent years the aero-engine community is looking towards the reduction of specific fuel consumption by increasing the efficiency of gearing systems. Considering their weight contribution, internal power losses and lubrication requirements, they have indeed a direct impact on the engine overall efficiency. Even though nowadays gears have reached very high efficiencies, over 99%, all the power dissipated through losses is converted into heat that must be removed by the lubrication system. Heat reduction is hence beneficial for minimizing lubrication system dimensions that is crucial in aero engine applications where it is mandatory to limit the weight of every component. Among the sources of loss, two main categories may be distinguished: load dependent and load independent losses. The first ones are due to the transmission of torque and have been deeply studied in the last years, the latter are related to fluid-dynamic interaction between gears and the surrounding environment, they are negligible at low pitch line velocities, but become very important in high speed applications, typical of turbomachinery. This work deals with an experimental investigation of the load independent losses due to a couple of spur meshing gears working at different conditions in presence of an oil-jet lubrication system. The test rig allows the gears to rotate, at different velocities up to 15000 rpm, in a controlled environment contained in a sealed box. Test rig pressure can be imposed (0.3–1.0 bar) and monitored as well as the oil jet conditions, in terms of mass flow rate (jet volume flow rate up to 1.65 litres per minute), temperature (80–140 °C) and inclination angle. A high precision bearing-less torque meter, equipped with a speedometer, was exploited to measure at the same time the torque losses and rotating speed. Results of the experimental survey allowed a better understanding of load independent losses at pitch line speed up to 100 m/s and in different environmental conditions.

Recovery boiler sootblowers: History and technological advances

TAPPI Journal ◽  
2015 ◽  
Vol 14 (1) ◽  
pp. 51-60
Author(s):  
HONGHI TRAN ◽  
DANNY TANDRA
Keyword(s):  
Cfd Modeling ◽  
Computing Systems ◽  
The Past ◽  
Technological Advances ◽  
Recovery Boilers ◽  
Computational Fluid Dynamics Cfd ◽  
Recovery Boiler ◽  
Steam Parameters ◽  
Insight Into ◽  
Deposit Removal

Sootblowing technology used in recovery boilers originated from that used in coal-fired boilers. It started with manual cleaning with hand lancing and hand blowing, and evolved slowly into online sootblowing using retractable sootblowers. Since 1991, intensive research and development has focused on sootblowing jet fundamentals and deposit removal in recovery boilers. The results have provided much insight into sootblower jet hydrodynamics, how a sootblower jet interacts with tubes and deposits, and factors influencing its deposit removal efficiency, and have led to two important innovations: fully-expanded sootblower nozzles that are used in virtually all recovery boilers today, and the low pressure sootblowing technology that has been implemented in several new recovery boilers. The availability of powerful computing systems, superfast microprocessors and data acquisition systems, and versatile computational fluid dynamics (CFD) modeling capability in the past two decades has also contributed greatly to the advancement of sootblowing technology. High quality infrared inspection cameras have enabled mills to inspect the deposit buildup conditions in the boiler during operation, and helped identify problems with sootblower lance swinging and superheater platens and boiler bank tube vibrations. As the recovery boiler firing capacity and steam parameters have increased markedly in recent years, sootblowers have become larger and longer, and this can present a challenge in terms of both sootblower design and operation.

Yaw Galloping of a TLWP Platform Under High Speed Currents by Analytical Methods and its Comparison With Experimental Results

2017 ◽  
Author(s):  
Francisco Lamas ◽  
Miguel A. M. Ramirez ◽  
Antonio Carlos Fernandes
Keyword(s):  
High Speed ◽  
Production Systems ◽  
Experimental Tests ◽  
Experimental Results ◽  
Analytical Methodology ◽  
New Approach ◽  
Laboratory Facilities ◽  
Polynomial Curve ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses

Flow Induced Motions are always an important subject during both design and operational phases of an offshore platform life. These motions could significantly affect the performance of the platform, including its mooring and oil production systems. These kind of analyses are performed using basically two different approaches: experimental tests with reduced models and, more recently, with Computational Fluid Dynamics (CFD) dynamic analysis. The main objective of this work is to present a new approach, based on an analytical methodology using static CFD analyses to estimate the response on yaw motions of a Tension Leg Wellhead Platform on one of the several types of motions that can be classified as flow-induced motions, known as galloping. The first step is to review the equations that govern the yaw motions of an ocean platform when subjected to currents from different angles of attack. The yaw moment coefficients will be obtained using CFD steady-state analysis, on which the yaw moments will be calculated for several angles of attack, placed around the central angle where the analysis is being carried out. Having the force coefficients plotted against the angle values, we can adjust a polynomial curve around each analysis point in order to evaluate the amplitude of the yaw motion using a limit cycle approach. Other properties of the system which are flow-dependent, such as damping and added mass, will also be estimated using CFD. The last part of this work consists in comparing the analytical results with experimental results obtained at the LOC/COPPE-UFRJ laboratory facilities.

scholarly journals Computational Investigation of Inclusion Removal in the Steel-Refining Ladle Process

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1048
Author(s):  
Xipeng Guo ◽  
Joel Godinez ◽  
Nicholas J. Walla ◽  
Armin K. Silaen ◽  
Helmut Oltmann ◽  
...  
Keyword(s):  
Multiphase Flow ◽  
Porous Plug ◽  
Cfd Modeling ◽  
Balance Model ◽  
Computational Investigation ◽  
Inclusion Removal ◽  
Inclusion Interaction ◽  
Computational Fluid Dynamics Cfd ◽  
Steel Refining ◽  
Transient Multiphase Flow

In a steel-refining ladle, the properties of manufactured steel can be notably degraded due to the presence of excessive inclusions. Stirring via gas injection through a porous plug is often used as part of the steel-refining process to reduce these inclusions. In this paper, 3D computational fluid dynamics (CFD) modeling is used to analyze transient multiphase flow and inclusion removal in a gas-stirred ladle. The effects of gas stirring with bubble-inclusion interaction are analyzed using the Euler–Euler approach for multiphase flow modeling, while the effects of inclusions aggregation and removal are modeled via a population balance model (PBM).

scholarly journals Risk Analysis of Road Tunnels: A Computational Fluid Dynamic Model for Assessing the Effects of Natural Ventilation

2020 ◽  
Vol 11 (1) ◽  
pp. 32
Author(s):  
Ciro Caliendo ◽  
Gianluca Genovese ◽  
Isidoro Russo
Keyword(s):  
Natural Ventilation ◽  
Fluid Dynamic ◽  
Movement Time ◽  
Radiant Heat ◽  
Heat Fluxes ◽  
Maximum Heat ◽  
Road Tunnels ◽  
Maximum Heat Release ◽  
Computational Fluid Dynamics Cfd ◽  
Time Required

We have developed an appropriate Computational Fluid Dynamics (CFD) model for assessing the exposure to risk of tunnel users during their evacuation process in the event of fire. The effects on escaping users, which can be caused by fire from different types of vehicles located in various longitudinal positions within a one-way tunnel with natural ventilation only and length less than 1 km are shown. Simulated fires, in terms of maximum Heat Release Rate (HRR) are: 8, 30, 50, and 100 MW for two cars, a bus, and two types of Heavy Goods Vehicles (HGVs), respectively. With reference to environmental conditions (i.e., temperatures, radiant heat fluxes, visibility distances, and CO and CO2 concentrations) along the evacuation path, the results prove that these are always within the limits acceptable for user safety. The exposure to toxic gases and heat also confirms that the tunnel users can safely evacuate. The evacuation time was found to be higher when fire was related to the bus, which is due to a major pre-movement time required for leaving the vehicle. The findings show that mechanical ventilation is not necessary in the case of the tunnel investigated. It is to be emphasized that our modeling might represent a reference in investigating the effects of natural ventilation in tunnels.

scholarly journals Computational fluid dynamics (CFD) simulation analysis on retinal gas cover rates using computational eye models

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Makoto Gozawa ◽  
Yoshihiro Takamura ◽  
Tomoe Aoki ◽  
Kentaro Iwasaki ◽  
Masaru Inatani
Keyword(s):  
Cfd Simulation ◽  
Simulation Analysis ◽  
Fluid Dynamic ◽  
Fluid Analysis ◽  
Intraocular Gas ◽  
Pars Plana ◽  
Computational Fluid Dynamics Cfd ◽  
Multiple Breaks ◽  
Gas Volume ◽  
Wall Wettability

AbstractWe investigated the change in the retinal gas cover rates due to intraocular gas volume and positions using computational eye models and demonstrated the appropriate position after pars plana vitrectomy (PPV) with gas tamponade for rhegmatogenous retinal detachments (RRDs). Computational fluid dynamic (CFD) software was used to calculate the retinal wall wettability of a computational pseudophakic eye models using fluid analysis. The model utilized different gas volumes from 10 to 90%, in increments of 10% to the vitreous cavity in the supine, sitting, lateral, prone with closed eyes, and prone positions. Then, the gas cover rates of the retina were measured in each quadrant. When breaks are limited to the inferior retina anterior to the equator or multiple breaks are observed in two or more quadrants anterior to the equator, supine position maintained 100% gas cover rates in all breaks for the longest duration compared with other positions. When breaks are limited to either superior, nasal, or temporal retina, sitting, lower temporal, and lower nasal position were maintained at 100% gas cover rates for the longest duration, respectively. Our results may contribute to better surgical outcomes of RRDs and a reduction in the duration of the postoperative prone position.

Sign in / Sign up

Export Citation Format

Share Document