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.

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 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.

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.

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.

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.

Assessment of the Loss Map of a Centrifugal Compressor’s External Volute

2020 ◽  
Author(s):  
Thomas Ceyrowsky ◽  
Andre Hildebrandt ◽  
Martin Heinrich ◽  
Rüdiger Schwarze
Keyword(s):  
Mach Number ◽  
Flow Rate ◽  
Numerical Approach ◽  
Operating Conditions ◽  
Circumferential Velocity ◽  
Flow Angle ◽  
Absolute Flow ◽  
Highly Sensitive ◽  
Geometrical Features ◽  
Comparison With Experimental Data

Abstract A volute’s loss coefficient is highly sensitive to Mach number, circumferential velocity and flow rate at volute inlet. In case of a backswept impeller, these parameters are coupled to each other. An increased flowrate leads to a steeper absolute flow angle at impeller exit and hence to a decrease of circumferential velocity. The absolute Mach number is also altered. Therefore, in order to investigate the effects of flowrate and flow angle separately, one would have to vary the diffuser width together with the flowrate, keeping the flow angle constant. This corresponds to coupling the volute with aerodynamically similar impellers, designed for higher and lower flowrates. Since this is elaborate, there is no adequate study available in open literature, assessing a volute’s global loss map. In this work, a new numerical approach for the prediction of a volute’s representative loss map is presented: The volute is calculated by means of steady CFD as a standalone component. The inlet boundary conditions are carefully selected by means of 1D and applied together with different diffuser widths. This allows for separate investigation of the impacts of flow angle, flow rate and Mach number. Validation against full stage CFD confirms the applicability of the standalone model. The results exhibit that minimum losses do not necessarily occur at the theoretical matching point but either when the volute is smaller or bigger, depending on the inlet flow angle. Investigations of the loss mechanisms at different operating conditions provide useful guidelines for volute design. Finally, the validity of these study’s findings for volutes with different geometrical features is examined by comparison with experimental data as well as with fullstage CFD.

Mass Transfer Enhancement for CO2 Absorption in Structured Packed Absorption Column

2019 ◽  
Vol 41 (5) ◽  
pp. 820-820
Author(s):  
Pongayi Ponnusamy Selvi and Rajoo Baskar Pongayi Ponnusamy Selvi and Rajoo Baskar
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Gas Flow ◽  
Aqueous Ammonia ◽  
Volume Flow Rate ◽  
Packed Column ◽  
Operating Conditions ◽  
Co2 Absorption ◽  
Absorption Column

The acidic gas, Carbon dioxide (CO2) absorption in aqueous ammonia solvent was carried as an example for industrial gaseous treatment. The packed column was provided with a novel structured BX-DX packing material. The overall mass transfer coefficient was calculated from the absorption efficiency of the various runs. Due to the high solubility of CO2, mass transfer was shown to be mainly controlled by gas side transfer rates. The effects of different operating parameters on KGav including CO2 partial pressure, total gas flow rates, volume flow rate of aqueous ammonia solution, aqueous ammonia concentration, and reaction temperature were investigated. For a particular system and operating conditions structured packing provides higher mass transfer coefficient than that of commercial random packing.

An Impact of Self-Recirculation Casing Treatment (SRCT) Configurations on Impeller Stall Margin and the Flow Field

2012 ◽  
Author(s):  
Yan Ma ◽  
Guang Xi ◽  
Guangkuan Wu
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Operating Conditions ◽  
Centrifugal Impeller ◽  
Flow Angle ◽  
Stall Margin ◽  
Casing Treatment ◽  
Swirl Velocity ◽  
Inlet Swirl ◽  
Unsteady Simulation

The present paper describes an investigation of stall margin enhancement and a detailed analysis of the impeller flow field due to self-recirculation casing treatment (SRCT) configuration of a high-speed small-size centrifugal impeller. The influence of different SRCT configurations on the impeller flow field at near-stall condition has been analyzed, highlighting the improvement in stall flow ability. This paper also discusses the influence of the SRCT configurations on the inlet flow angle, inlet swirl velocity and loss distribution in the impeller passage to understand the mechanism of the SRCT configurations in enhancing the stall margin of the impeller. The variation of the bleed flow rate at different operating conditions is also presented in this paper. Finally, the time-averaged unsteady simulation results at near-stall point are presented and compared with steady-state solutions.

The Effects of Spraying Parameters on Spray Cooling Heat Transfer Performance in the Non-Boiling Regime

2017 ◽  
Author(s):  
Azzam S. Salman ◽  
Jamil A. Khan
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Target Surface ◽  
Spray Cooling ◽  
Operating Conditions ◽  
Droplet Velocity ◽  
Inlet Pressure ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Spraying Parameters

Experiments were conducted in a closed loop spray cooling system working with deionized water as a working fluid. This study was performed to investigate the effect of the spraying parameters, such as Sauter mean diameter (SMD), the droplet velocity, and the residual velocity on the spray cooling heat transfer in the non-boiling region. Thermal effects on plain and modified surfaces with circular grooves were examined under different operating conditions. The inlet pressure of the working fluid was varied from 78.6 kPa to 183.515kPa, and the inlet temperature was kept between 21–22 °C. The distance between the nozzle and the target surface 10 mm. The results showed that increasing the coolant inlet pressure increases the droplet velocity and the number of droplets produced while decreasing the droplet size. As a consequence of these changes, increasing inlet pressure improved the heat transfer characteristics of both surfaces.

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