Thrust Load Measurement on Aero-Engine Bearing

1985 ◽  
Vol 107 (1) ◽  
pp. 181-186
Author(s):  
K. Jimboh ◽  
H. Aono ◽  
T. Chikata ◽  
Y. Hagiwara ◽  
K. Nakasu ◽  
...  
Keyword(s):  
High Speed ◽  
Open Space ◽  
Transient Condition ◽  
Load Cells ◽  
Aero Engine ◽  
Unit Cells ◽  
Thrust Measurement ◽  
Thrust Load ◽  
Engine Development ◽  
Engine Bearing

Aero-engine bearings operate in an extraordinarily high speed range (high DN number) and severe conditions. It is especially necessary to measure and adjust the bearing thrust load in the engine development phase, but it is very difficult to measure the thrust load accurately, because bearings and bearing housings are subjected to elevated temperature and oil environment. Open space permitted for installation of thrust measurement transducers is small and limited around the bearing housing. We tried to measure the thrust load by applying “Unit Cells,” which are installed between bearing and bearing housing. “Unit Cells” which have been specially designed to measure the bearing thrust load are very small and temperature-compensated load cells. We have been successful in measuring the actual thrust load using the above “Unit Cells,” both in the steady-state and transient condition. Repeatability and hysteresis of the data have been satisfactory. We have established the effect of seal clearance on the thrust load by the measurement. We also have obtained the dynamic characteristics of the thrust load versus rotor speed in low bypass fan engines. Procedure and obtained data are presented in detail.

Computational Study of a Customised Shallow-Sump Aero-Engine Bearing Chamber With Inserts to Improve Oil Residence Volume

2017 ◽  
Author(s):  
Akinola A. Adeniyi ◽  
Budi Chandra ◽  
Kathy Simmons
Keyword(s):  
High Speed ◽  
Cfd Simulation ◽  
Computational Study ◽  
Perforated Plate ◽  
Flow Characteristics ◽  
Positive Pressure ◽  
High Speed Engine ◽  
Aero Engine ◽  
Computational Fluid Dynamics Cfd ◽  
Engine Bearing

An aero-engine bearing chamber is a structure that is used to contain and collect oil used in lubricating and cooling the bearings supporting the high-speed engine shafts. There are various bearings in an aero-engine. Within the bearing chambers, there are typically the bearings, rotating shafts, seals and gears (in some designs). The walls of the bearing chamber are stationary and there are vents and sumps to take out the oil, via an offtake pipe, and the sealing air. The oil collected via the sump and vents is recycled and used again in the loop. To prevent oil degradation and reduce chance of coking in the chamber, it is desired that all of the oil goes through the recycling loop, with no oil staying longer than necessary in the chamber. The sealing air is used to maintain a positive pressure to keep the oil within the chamber. The flow inside a bearing chamber is highly turbulent and consists of a rotating mixture of oil and air. A smaller amount of the oil, mostly as oil-droplets, exits at the vents and is separated from the air using de-aerators [1]. It is expected that by gravity, most of the oil collects at the sump and can be easily scavenged. This is provided the sump can be large enough. The geometry of a bearing chamber is, however, complex largely because of space limitations. It is very important that oil is not resident longer than necessary to prevent over-heating and therefore deterioration or coking. Experimental observations by Chandra & Simmons [2], have shown that bearing chambers with deep sumps perform better that those with shallow sumps. Since shallow sumps are inevitable, a number of innovative studies have been done to improve bearing chamber designs. The presence of air in the oil (e.g. as bubbles) reduces the efficiency of the scavenging pump. Other factors such as oil momentum and windage can take oil away from the off-take pipe potentially increasing oil residence volume. Chandra & Simmons [2] placed inserts such as grille cover, perforated plate, etc, on a side of the bearing wall and improvements in the residence volume were seen. In this work, we are looking at a detailed computational fluid dynamics (CFD) simulation of one of the inserts that performed well. This will aid understanding of the flow characteristics of using an insert to improve oil residence in a bearing chamber.

Factors Affecting the Behaviour and Efficiency of a Targeted Jet Delivering Oil to a Bearing Lubrication System

2004 ◽  
Author(s):  
C. W. Lee ◽  
G. R. Johnson ◽  
P. C. Palma ◽  
K. Simmons ◽  
S. J. Pickering
Keyword(s):  
High Speed ◽  
Test Rig ◽  
Rotating Shaft ◽  
Factors Affecting ◽  
Oil Distribution ◽  
Jet Impact ◽  
Aero Engine ◽  
Visualization Techniques ◽  
Jet Structure ◽  
Engine Bearing

In this study oil delivery to an aero-engine bearing via a targeted jet was investigated using a bearing chamber test rig. The rig contains a high-speed rotating shaft of engine representative geometry within a stationary Perspex housing. Oil is collected from feedholes leading from scoops (scallops) on the shaft. The efficiency of this oil delivery system is dependent on jet structure and trajectory as it interacts with the rotating chamber flow. Flow visualization techniques and parametric tests are used to assess the influence of shaft speed and jet flowrate on oil collected through the feedholes. Detailed pictures of the structure of the jet in quiescent air are presented and compared with those from the rig, where there is a gas crossflow. As expected, jet break-up is accentuated in the rig. This influences jet impact behaviour at the scallop, and a consequent variation of oil distribution in the system is observed.

Reducing cost, time and risk in aero-engine compressor testing

1997 ◽  
Vol 211 (6) ◽  
pp. 395-402 ◽  
Author(s):  
R Backhouse ◽  
P Ivey
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Development Program ◽  
Cost Effective ◽  
Test Analysis ◽  
Low Speed ◽  
Aero Engine ◽  
Engine Compressor ◽  
Advanced Development ◽  
Engine Development

There is constant pressure to reduce engine development cycles to minimize costs and bring forward the revenue earning part of the engine's life. As cost and time are designed out, the risk of performance shortfall must be minimized by bidding efficiencies from demonstrated technology. This requires a large-scale ongoing advanced development program. In compressor development, high-speed tests are unavoidable but are expensive; low-speed rigs are easier to instrument and provide a cost-effective filter for the high-speed designs. The large-scale, low- speed compressor at Cranfield is one of only four worldwide. Recent investment in data reduction software has greatly reduced the test/analysis cycle time.

Analysis of Inter-Satellite Optical Wireless Communication System

2017 ◽  
Vol 7 (10) ◽  
pp. 10
Author(s):  
Rajbir Singh
Keyword(s):  
Wireless Communication ◽  
Optical Networks ◽  
Data Transmission ◽  
High Speed ◽  
Open Space ◽  
Communication Link ◽  
Optical Wireless Communication ◽  
Optical Wireless ◽  
High Speed Data ◽  
Speed Data Transmission

Optical networks are bandwidth efficient networks are used for long haul communication providing seamless data transfer. For high speed data transmission in open space between different satellites, Inter-satellite Optical wireless communication (IsOWC) is widely used .In this paper we have evaluated the performance of IsOWC communication link for high speed data transmission .The performance of the system is evaluated on the basis of qualitative parameters such as Q-factor and BER using optisystem simulator.

Further Computational Investigations Into Aero-Engine Bearing Chamber Off-Take Flows

2010 ◽  
Author(s):  
Adam Robinson ◽  
Carol Eastwick ◽  
Herve´ Morvan
Keyword(s):  
Experimental Work ◽  
Symmetry Plane ◽  
Two Phase ◽  
Pipe System ◽  
Aero Engine ◽  
Gravity Driven ◽  
Computational Fluid Dynamics Cfd ◽  
Modelling Assumptions ◽  
Static Head ◽  
Engine Bearing

Within an aero-engine bearing chamber oil is provided to components to lubricate and cool. This oil must be efficiently removed (scavenged) from the chamber to ensure it does not overheat and degrade. Bearing chambers typically contain a sump section with an exit pipe leading to a scavenge pump. In this paper a simplified geometry of a sump section, here simply made of a radial off-take port on a walled inclined plane, is analysed computationally. This paper follows on work presented within GT2008-50634. In the previous paper it was shown that simple gravity draining from a static head of liquid cold be modelled accurately, for what was akin to a deep sump situation fond in integrated gear boxes for example. The work within this paper will show that the draining of flow perpendicular to a moving film can be modelled. This situation is similar to the arrangements found in transmission bearing chambers. The case modelled is of a walled gravity driven film running down a plane with a circular off-take port, this replicates experimental work similar to that reported in GT2008-50632. The commercial computational fluid dynamics (CFD) code, Fluent 6 [1] has been employed for modelling, sing the Volume of Fluid (VOF) approach of Hirt and Nichols [2, 3] to capture the physics of both the film motion and the two phase flow in the scavenge pipe system. Surface tension [4] and a sharpening algorithm [5] are used to complement the representation of the free surface and associated effects. This initial CFD investigation is supported and validated with experimental work, which is only depicted briefly here as it is mainly sued to support the CFD methodology. The case has been modelled in full as well as with the use of a symmetry plane running down the centre of the plane parallel to the channel walls. This paper includes details of the meshing methodology, the boundary conditions sued, which will be shown to be of critical importance to accurate modelling, and the modelling assumptions. Finally, insight into the flow patterns observed for the cases modelled are summarised. The paper further reinforces that CFD is a promising approach to analysing bearing chamber scavenge flows although it can still be relatively costly.

scholarly journals The Influence of the Axial Rub Added in the Radial Rub on the Wear of the Seal Fins during the High Speed Rub of Labyrinth-Honeycomb Seal

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1997
Author(s):  
Bin Lu ◽  
Haijun Xuan ◽  
Xiaojian Ma ◽  
Fangjun Han ◽  
Weirong Hong ◽  
...  
Keyword(s):  
Wear Rate ◽  
High Speed ◽  
State Of The Art ◽  
Negative Influence ◽  
Axial Thrust ◽  
Cross Sectional ◽  
Honeycomb Seal ◽  
Aero Engine ◽  
Honeycomb Seals ◽  
Clearance Change

Labyrinth-honeycomb seals are a state-of-the-art sealing technology commonly used in aero-engine interstage seal. The undesirable severe rub between the seal fins and the honeycomb due to the clearance change may induce the cracking of the seal fins. A pervious study investigated the wear of the seal fins at different radial incursion rates. However, due to the axial thrust and mounting clearance, the axial rub between the seal fins and the honeycomb may occur. Hence, this paper focuses on the influence of the axial rub added in the radial rub on the wear of the seal fins. The rub tests results, including rubbing forces and temperature, wear rate, worn morphology, cross-sectional morphology and energy dispersive spectroscopy results, are presented and discussed. Overall, the participation of the axial rub leads to higher rubbing forces, temperature, and wear rate. The tribo-layer on the seal fin is thicker and the cracks are more obvious at high axial incursion rate. These phenomena indicate the axial rub has a negative influence on the wear of the seal fins and should be avoided.

scholarly journals Feasibility Study on Oil Droplet Flow Investigations Inside Aero Engine Bearing Chambers: PDPA Techniques in Combination With Numerical Approaches

1995 ◽  
Author(s):  
A. Glahn ◽  
M. Kurreck ◽  
M. Willmann ◽  
S. Wittig
Keyword(s):  
Numerical Methods ◽  
Flow Field ◽  
Flow Analysis ◽  
Field Analysis ◽  
Oil Droplet ◽  
Droplet Flow ◽  
Aero Engine ◽  
Secondary Air ◽  
Numerical Approaches ◽  
Engine Bearing

The present paper deals with oil droplet now phenomena in aero engine bearing chambers. An experimental investigation of droplet sizes and velocities utilizing a Phase Doppler Particle Analyzer (PDPA) has been performed for the first time in bearing chamber atmospheres under real engine conditions. Influences of high rotational speeds are discussed for individual droplet size classes. Although this is an important contribution to a better understanding of the droplet flow impact on secondary air/oil system performance, an analysis of the droplet flow behaviour requires an incorporation of numerical methods because detailed measurements as performed here suffer from both strong spatial limitations with respect to the optical accessibility in real engine applications and constraints due to the extremely time consuming nature of an experimental flow field analysis. Therefore, further analysis is based on numerical methods. Droplets characterized within the experiments are exposed to the flow field of the gaseous phase predicted by use of our well-known CFD code EPOS. The droplet trajectories and velocities are calculated within a Lagrangian frame of reference by forward numerical integration of the particle momentum equation. This paper has been initiated rather to show a successful method of bearing chamber droplet flow analysis by a combination of droplet sizing techniques and numerical approaches than to present field values as a function of all operating parameters. However, a first insight into the complex droplet flow phenomena is given and specific problems in bearing chamber heat transfer are related to the droplet flow.

Endurance and Failure Characteristic of Main-Shaft Jet Engine Bearing at 3 × 106 DN

1976 ◽  
Vol 98 (4) ◽  
pp. 580-585 ◽  
Author(s):  
E. N. Bamberger ◽  
E. V. Zaretsky ◽  
H. Signer
Keyword(s):  
Ball Bearings ◽  
Main Shaft ◽  
Test Results ◽  
Jet Engine ◽  
Material Life ◽  
Thrust Load ◽  
Inner Race ◽  
Continuous Running ◽  
Life Factor ◽  
Engine Bearing

Groups of thirty 120-mm bore angular-contact ball bearings were endurance tested at a speed of 12 000 and 25 000 rpm (1.44 × 106 and 3.0 × 106 DN) and a thrust load of 66 721 N (5000 lb). The bearings were manufactured from a single heat of VIM-VAR AISI M-50 steel. At 1.44 × 106 and 3.0 × 106 DN, 84 483 and 74 800 bearing test hours were accumulated, respectively. Test results were compared with similar bearings made from CVM AISI M-50 steel run under the same conditions. Bearing lives at speeds of 3 × 106 DN with the VIM-VAR AISI M-50 steel were nearly equivalent to those obtained at lower speeds. A combined processing and material life factor of 44 was found for VIM-VAR AISI M-50 steel. Continuous running after a spall has occurred at 3.0 × 106 DN can result in a destructive fracture of the bearing inner race.

A reconfigurable membrane-type acoustic metasurface for low-frequency and broadband wave front modulation

2019 ◽  
Vol 33 (19) ◽  
pp. 1950208
Author(s):  
Xinpei Song ◽  
Tianning Chen ◽  
Jian Zhu ◽  
Yanbin He
Keyword(s):  
Wave Front ◽  
High Speed ◽  
Power Transmission ◽  
Design Method ◽  
Real Life ◽  
Low Frequency ◽  
Pumping System ◽  
Unit Cells ◽  
Membrane Type ◽  
Structure Complexity

Low-frequency and broadband are the critical challenges in real-life applications. Here, we try to tackle the challenges by proposing a reconfigurable acoustic metasurface (AM) composed of the membrane-type metamaterial (MAM) structure of deep sub-wavelength scale. By employing the external air pumping system into each individual unit cell of the AM, the tension of the membrane can be readily tailored by the system with little interference from other unit cells. Two strategies of the constant pressure method (CPM) and constant volume method (CVM) are reported to design the MAM. And the CVM is adopted as the ultimate design strategy by comparing both methods from aspects of the dimension, operating frequency, and structure complexity. In order to validate the low-frequency and broadband performances of the AM, the Airy-like beams and the acoustic converging based on two identical Airy-like beams are introduced and proof-of-concept simulations are performed with the finite element method. The simulated results agree well with the theoretical predictions. Our design provides the little-interference active design method for the low-frequency and broadband AM to manipulate the wave front, and may have practical engineering applications in areas of the aerospace, high-speed train, marine vessel, and power transmission and transformation project.

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