Disintegration of Oil Jets Emerging From Axial Passages at the Face of a Rotating Cylinder

2003 ◽  
Vol 125 (4) ◽  
pp. 1003-1010 ◽  
Author(s):  
A. Glahn ◽  
M. F. Blair ◽  
K. L. Allard ◽  
S. Busam ◽  
O. Scha¨fer ◽  
...  
Keyword(s):  
Droplet Diameter ◽  
Rotating Disk ◽  
Rotating Cylinder ◽  
Operating Conditions ◽  
Droplet Generation ◽  
Fundamental Study ◽  
The Face ◽  
Near Term ◽  
Oil Films ◽  
Asme Paper

A fundamental study has been performed to examine the disintegration of oil films emerging from axial passages at the face of a rotating cylinder. The investigation has been conducted in parallel to a similar study on atomization processes at rotating radial holes (Glahn, A. et al., 2001, “Disintegration of Oil Films Emerging From Radial Holes Inside a Cylinder,” ASME Paper No. 2001-GT-0202) and has used the same approaches in simulating one of the droplet generation sources in aeroengine lubrication systems. Both papers aim to contribute to the establishment of a database that can be used for the development of droplet generation models directly applicable to engine conditions. As with the parallel investigation, the near-term objectives of fundamental oil film disintegration studies are (i) to determine droplet sizes under relevant aeroengine bearing compartment operating conditions, and (ii) to measure individual droplet diameter/velocity relationships. The long-term objective is to incorporate this information into advanced design systems such as CFD-based tools. In the present study, flow visualization has been used to identify the dominant disintegration processes. Droplet diameters and velocities have been obtained for relevant engine operating conditions. Data are presented in terms of both characteristic diameters and size-class resolved droplet velocities and flow angles. A comparison of droplet sprays measured in the present study with those generated by disintegration of oil films at the rim of a rotating disk (Glahn, A. et al., 2000, “Droplet Generation by Disintegration of Oil Films at the Rim of a Rotating Disk,” ASME Paper No. 2000-GT-0279) has been enabled by introducing nondimensional parameters for atomization products and operating conditions.

Disintegration of Oil Jets Emerging From Axial Passages at the Face of a Rotating Cylinder

2001 ◽  
Author(s):  
A. Glahn ◽  
M. F. Blair ◽  
K. L. Allard ◽  
S. Busam ◽  
O. Schäfer ◽  
...  
Keyword(s):  
Droplet Diameter ◽  
Rotating Disk ◽  
Rotating Cylinder ◽  
Operating Conditions ◽  
Droplet Generation ◽  
Fundamental Study ◽  
Aero Engine ◽  
The Face ◽  
Near Term ◽  
Oil Films

A fundamental study has been performed to examine the disintegration of oil films emerging from axial passages at the face of a rotating cylinder. The investigation has been conducted in parallel to a similar study on atomization processes at rotating radial holes (Glahn et al. 2001) and has used the same approaches in simulating one of the droplet generation sources in aero-engine lubrication systems. Both papers aim to contribute to the establishment of a database that can be used for the development of droplet generation models directly applicable to engine conditions. As with the parallel investigation, the near-term objectives of fundamental oil film disintegration studies are (i) to determine droplet sizes under relevant aero-engine bearing compartment operating conditions, and (ii) to measure individual droplet diameter/velocity relationships. The long-term objective is to incorporate this information into advanced design systems such as CFD-based tools. In the present study, flow visualization has been used to identify the dominant disintegration processes. Droplet diameters and velocities have been obtained for relevant engine operating conditions. Data are presented in terms of both characteristic diameters and size-class resolved droplet velocities and flow angles. A comparison of droplet sprays measured in the present study with those generated by disintegration of oil films at the rim of a rotating disk (Glahn at al. 2000) has been enabled by introducing non-dimensional parameters for atomization products and operating conditions.

Droplet Generation by Disintegration of Oil Films at the Rim of a Rotating Disk

2000 ◽  
Vol 124 (1) ◽  
pp. 117-124 ◽  
Author(s):  
A. Glahn ◽  
S. Busam ◽  
M. F. Blair ◽  
K. L. Allard ◽  
S. Wittig
Keyword(s):  
Volume Flow Rate ◽  
Droplet Diameter ◽  
Rotating Disk ◽  
Operating Conditions ◽  
Droplet Generation ◽  
Droplet Velocity ◽  
Fundamental Study ◽  
Flow Angle ◽  
Near Term ◽  
Oil Films

A fundamental study has been performed to examine oil film disintegration mechanisms at the rim of a rotating disk. The configuration investigated is an abstraction of one of the droplet generation sources in an aeroengine bearing compartment. The paper aims to contribute to both the determination of directly applicable droplet characteristics and the establishment of a database that can be used for the development of droplet generation models. The near-term objectives of the study are (i) to identify disintegration modes relevant with respect to aeroengine bearing compartment operating conditions, (ii) to determine droplet sizes under those operating conditions, and (iii) to measure individual droplet diameter/velocity relationships. The long-term objective is to incorporate this information into advanced CFD-based design tools. The disintegration modes identified here were similar to previously reported flow regimes generated by rotary atomizers. However, slightly different transition characteristics are documented for the turbine oil considered here, indicating a transition occurring at either higher speeds or higher flow rates. Droplet diameters and velocities are presented for relevant bearing compartment conditions. In this mode, droplet diameters appear to be insensitive to the volume flow rate, but show a finer atomization for increasing rotational speeds. Eventually a speed is reached beyond which no further droplet diameter reduction is obtained. For the first time, size class resolved droplet velocities are presented. A variation of operating parameters at a constant radial location does not have a significant impact on either the normalized droplet velocity or the flow angle. Radial traverses show a decrease of the droplet velocity with increasing distance from the rim of the disk and a transition from a more tangentially oriented droplet trajectory to a more radial motion.

Disintegration of Oil Films Emerging From Radial Holes in a Rotating Cylinder

2003 ◽  
Vol 125 (4) ◽  
pp. 1011-1020 ◽  
Author(s):  
A. Glahn ◽  
M. F. Blair ◽  
K. L. Allard ◽  
S. Busam ◽  
O. Scha¨fer ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Droplet Diameter ◽  
Rotating Disk ◽  
Operating Conditions ◽  
Droplet Generation ◽  
Diameter Distribution ◽  
Oil Droplets ◽  
Flow Angle ◽  
Oil Films

A fundamental study has been performed to examine the disintegration of oil films emerging from radial holes in a rotating hollow cylinder. The configuration investigated is an abstraction of one of the droplet generation sources in an aeroengine bearing compartment; similar configurations may also occur inside gearboxes. The paper aims to contribute to both the determination of directly applicable droplet characteristics and the establishment of a database that can be used for the development of droplet generation models. Similar to a prior paper on droplet generation processes at the rim of a rotating disk (Glahn, A. et al., 2000, “Droplet Generation by Disintegration of Oil Films at the Rim of a Rotating Disk,” ASME Paper No. 2000-GT-0279.) the near-term objectives of the study are (i) to determine droplet sizes under relevant aeroengine bearing compartment operating conditions, and (ii) to measure individual droplet diameter/velocity relationships. The long-term objective is to incorporate this information into advanced CFD-based design tools. Therefore, special emphasis has been directed towards a correlation of test results that enables determination of boundary conditions for a two-phase (oil droplets/air) simulation of lubrication system components. Based on the results of the present paper, droplet flow boundary conditions in terms of mean diameter, standard deviation of the diameter distribution, starting velocity, and flow angle are available for oil droplets generated by disintegration of oil films emerging from rotating radial holes and rotating disks.

Droplet Generation by Disintegration of Oil Films at the Rim of a Rotating Disk

2000 ◽  
Author(s):  
A. Glahn ◽  
S. Busam ◽  
M. F. Blair ◽  
K. L. Allard ◽  
S. Wittig
Keyword(s):  
Volume Flow Rate ◽  
Droplet Diameter ◽  
Rotating Disk ◽  
Operating Conditions ◽  
Droplet Generation ◽  
Droplet Velocity ◽  
Fundamental Study ◽  
Flow Angle ◽  
Aero Engine ◽  
Engine Bearing

A fundamental study has been performed to examine oil film disintegration mechanisms at the rim of a rotating disk. The configuration investigated is an abstraction of one of the droplet generation sources in an aero-engine bearing compartment. The paper aims to contribute to both the determination of directly applicable droplet characteristics and the establishment of a data-base that can be used for the development of droplet generation models. The near-term objectives of the study are (i) to identify disintegration modes relevant with respect to aero-engine bearing compartment operating conditions, (ii) to determine droplet sizes under those operating conditions, and (iii) to measure individual droplet diameter/velocity relationships. The long-term objective is to incorporate this information into advanced CFD-based design tools. The disintegration modes identified here were similar to previously reported flow regimes generated by rotary atomizers (Lefebvre, 1989). However, slightly different transition characteristics are documented for the turbine oil considered here, indicating a transition occurring at either higher speeds or higher flow rates. Droplet diameters and velocities are presented for relevant bearing compartment conditions. In this mode, droplet diameters appear to be insensitive to the volume flow rate, but show a finer atomization for increasing rotational speeds. Eventually a speed is reached beyond which no further droplet diameter reduction is obtained. For the first time, size class resolved droplet velocities are presented. A variation of operating parameters at a constant radial location does not have a significant impact on either the normalized droplet velocity or the flow angle. Radial traverses show a decrease of the droplet velocity with increasing distance from the rim of the disk and a transition from a more tangentially orientated droplet trajectory to a more radial motion.

Disintegration of Oil Films Emerging From Radial Holes in a Rotating Cylinder

2001 ◽  
Author(s):  
A. Glahn ◽  
M. F. Blair ◽  
K. L. Allard ◽  
S. Busam ◽  
O. Schäfer ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Operating Conditions ◽  
Droplet Generation ◽  
Diameter Distribution ◽  
Oil Droplets ◽  
Flow Angle ◽  
Aero Engine ◽  
Oil Films ◽  
Engine Bearing

A fundamental study has been performed to examine the disintegration of oil films emerging from radial holes in a rotating hollow cylinder. The configuration investigated is an abstraction of one of the droplet generation sources in an aero-engine bearing compartment; similar configurations may also occur inside gearboxes. The paper aims to contribute to both the determination of directly applicable droplet characteristics and the establishment of a data-base that can be used for the development of droplet generation models. Similar to a prior paper on droplet generation processes at the rim of a rotating disk (Glahn et al, 2000), the near-term objectives of the study are (i) to determine droplet sizes under relevant aero-engine bearing compartment operating conditions, and (ii) to measure individual droplet diameter/velocity relationships. The long-term objective is to incorporate this information into advanced CFD-based design tools. Therefore, special emphasis has been directed towards a correlation of test results that enables determination of boundary conditions for a two-phase (oil droplets/air) simulation of lubrication system components. Based on the results of the present paper, droplet flow boundary conditions in terms of mean diameter, standard deviation of the diameter distribution, starting velocity, and flow angle are available for oil droplets generated by disintegration of oil films emerging from rotating radial holes and rotating disks.

Conflict of international and regional strategies and the future of wars in the Arab region "Political stability or political chaos"

2019 ◽  
pp. 190
Author(s):  
Ahmed Fadel Jassim Dawood
Keyword(s):  
Political Stability ◽  
Arab Countries ◽  
Arab Region ◽  
Regional Powers ◽  
Regional Strategies ◽  
Regional Competition ◽  
The Future ◽  
The Face ◽  
Near Term ◽  
Political Differences

The Arab region is of great importance as an important part of the Middle East for both international and regional powers.This importance has placed it and its peoples in the suffering of international and regional interventions and has placed it in a state of permanent instability as it witnessed international and regional competition that increased significantly after the US intervention in Iraq in 2003. Accordingly, the research aims to shed light on the strategic directions of the global and regional powers by knowing their objectives separately, such as American, Russian, Turkish, Israeli and Iranian. The course aims at determining the future of this region in terms of political stability and lack thereof. Therefore, the hypothesis of the research comes from [that the different strategic visions and political and economic interests between the international and regional powers have exacerbated the conflicts between those forces and their alliances within the Arab region.. The third deals with the future of the Arab region in light of the conflict of these strategies. Accordingly, the research reached a number of conclusions confirming the continuation of international and regional competition within the Arab region, as well as the continuation of the state of conflict, tension, instability and chaos in the near term, as a result of the inability of Arab countries to overcome their political differences on the one hand and also their inability to advance their Arab reality. In the face of external challenges on the other.

Efficient Simulation of Gear Contacts Including Transient Elastohydrodynamic Effects

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Peter Fietkau ◽  
Bernd Bertsche
Keyword(s):  
Three Dimensional ◽  
Direct Determination ◽  
Simulation Method ◽  
Elastic Half Space ◽  
Operating Conditions ◽  
Multibody Simulation ◽  
Multibody Model ◽  
Gear Contact ◽  
Oil Films ◽  
Lubrication Conditions

This paper describes an efficient transient elastohydrodynamic simulation method for gear contacts. The model uses oil films and elastic deformations directly in the multibody simulation, and is based on the Reynolds equation including squeeze and wedge terms as well as an elastic half-space. Two transient solutions to this problem, an analytical and a numerical one, were developed. The analytical solution is accomplished using assumptions for the gap shape and the pressure in the middle of the gap. The numerical problem is solved using multilevel multi-integration algorithms. With this approach, tooth impacts during gear rattling as well as highly loaded power-transmitting gear contacts can be investigated and lubrication conditions like gap heights or type of friction may be determined. The method was implemented in the multibody simulation environment SIMPACK. Therefore it is easy to transfer the developed element to other models and use it for a multitude of different engineering problems. A detailed three-dimensional elastic multibody model of an experimental transmission is used to validate the developed method. Important values of the gear contact like normal and tangential forces, proportion of dry friction, and minimum gap heights are calculated and studied for different conditions. In addition, pressure distributions on tooth flanks as well as gap forms are determined based on the numerical solution method. Finally, the simulation approach is validated with measurements and shows good consistency. The simulation model is therefore capable of predicting transient gear contact under different operating conditions such as load vibrations or gear rattling. Simulations of complete transmissions are possible and therefore a direct determination of transmission vibration behavior and structure-borne noise as well as of forces and lubrication conditions can be done.

Bullwhip Effect – Logistic Stability Examination in Serial and Arborescent Topologies with Demand Uncertainty and Delay

2021 ◽  
Vol 1 (1) ◽  
pp. 68-80
Author(s):  
Adam Dziomdziora ◽  
Przemysław Ignaciuk
Keyword(s):  
Distribution System ◽  
Demand Uncertainty ◽  
Bullwhip Effect ◽  
Operating Conditions ◽  
Practical Significance ◽  
Transport Delay ◽  
Numerical Tests ◽  
The Face ◽  
Stability Examination ◽  
Basic Configuration

The paper analyzes the formation of the bullwhip effect in logistic systems as a significant threat to preserving stability in the face of non-negligible goods transport delay and uncertainty of demand and stock records. The popular order-up-to policy is selected as the method governing the goods flow. A dynamic model of entity interaction is constructed and examined, first, analytically, then in numerical tests for various scenarios of practical significance, e.g., a supply chain with external and local demand signals or real-world European goods distribution system. It has been found that the order-up-to policy does not trigger the bullwhip effect despite the delays in the goods delivery in the nominal operating conditions in supply chains. However, in networked environments, even the basic configuration triggers the bullwhip effect.

Does Investment-Related Pressure Lead to Misreporting? An Analysis of Reporting Following M&A Transactions

2012 ◽  
Vol 87 (3) ◽  
pp. 839-865 ◽  
Author(s):  
Daniel A. Bens ◽  
Theodore H. Goodman ◽  
Monica Neamtiu
Keyword(s):  
Financial Reporting ◽  
Large Body ◽  
Financial Statements ◽  
Probability Of Detection ◽  
Data Availability ◽  
The Public ◽  
Announcement Returns ◽  
Reporting Decisions ◽  
The Face ◽  
Near Term

ABSTRACT This study examines whether managers alter their financial reporting decisions in the face of investment-related pressure. We define investment-related pressure as the increased pressure managers feel to retain their job following an M&A poorly received by the market. We hypothesize that managers attempt to assuage pressure by delivering strong performance post-merger, creating incentives for misreporting. Our findings indicate that acquirers with more negative M&A announcement returns are more likely to misstate financial statements in the post-investment period and the issuance of misstated financials mitigates this pressure, at least in the near term. Our study contributes to the literature on the relation between corporate investing and financial reporting by showing how investment-related pressure leads to misreporting, even in a setting where the costs (e.g., greater probability of detection) are high. Our study also has implications for the large body of research that evaluates various consequences of M&As using post-merger performance. Specifically, researchers should be careful to distinguish real from misstated financial performance in the post-investment period. Data Availability: Data are available from the public sources indicated in the text.

scholarly journals The Effect of Surface Roughness on Diffusion and Chemical Reaction Controlled Limiting Currents on a Rotating Cylinder Electrode in Deaerated Solutions with and Without CO2

CORROSION ◽  
10.5006/2552 ◽  
2018 ◽  
Vol 74 (9) ◽  
pp. 971-983 ◽  
Author(s):  
M. Al-Khateeb ◽  
R. Barker ◽  
A. Neville ◽  
H.M. Thompson
Keyword(s):  
Mass Transfer ◽  
Surface Roughness ◽  
Sherwood Number ◽  
Schmidt Number ◽  
Rotating Cylinder ◽  
Operating Conditions ◽  
Limiting Current ◽  
Surface Roughening ◽  
Rotating Cylinder Electrode ◽  
Effect Of Surface

The influence of surface roughness on mass transfer on a rotating cylinder electrode apparatus is investigated experimentally for a roughness pattern consisting of grooves parallel to the direction of fluid flow. Mass transfer from four different samples, with roughness values of 0.5 μm, 6 μm, 20 μm, and 34 μm, is measured using the limiting current technique for a range of rotational speeds in NaCl solutions saturated with N2 at pH = 3 and 4. Comparison with available correlations for the Sherwood number in literature (which are independent of surface roughness and are either for specific or arbitrary roughness patterns) shows that H+ mass transfer only correlates well for particular levels of roughness and that their accuracy can be increased if a correlation is utilized which is a function of surface roughening. A new correlation for Sherwood number as a function of the Reynolds number, Schmidt number, and surface roughness is proposed which agrees well with the mass transfer observed from all of the rough surface cases considered for this particular roughness pattern. Complementary experiments in CO2 environments were used to assess the combined limiting current associated with H+ and H2CO3 reduction (with the latter occurring via the buffering effect and being associated with the slow CO2 hydration step). Although the increase in sample roughness clearly leads to an increase in the rate of H+ mass transfer, in the CO2 environments considered, surface roughness is found to have no significant influence on the limiting current contribution from H2CO3, which can therefore be determined from Vetter’s equation across this range of operating conditions.

Sign in / Sign up

Export Citation Format

Share Document