Development of Friction Drive Transmission

2005 ◽  
Vol 127 (4) ◽  
pp. 857-864 ◽  
Author(s):  
Xiaolan Ai ◽  
Matthew Wilmer ◽  
David Lawrentz
Keyword(s):  
Friction Coefficient ◽  
Performance Optimization ◽  
Operating Conditions ◽  
Elastic Support ◽  
Outer Ring ◽  
Design Parameters ◽  
Fe Model ◽  
Frictional Contacts ◽  
Actual Operating ◽  
Wide Range

A cylindrical friction drive was developed for electric oil pump applications. It was comprised of an outer ring, a sun roller, a loading planet, two supporting planets, and a stationary carrier. The sun roller was set eccentric to the outer ring to generate a wedge gap that facilitates a torque actuated loading mechanism for the friction drive. The loading planet was properly assembled in the wedge gap and elastically supported to the carrier. By altering the stiffness ratio of the elastic support to contact, the actual operating friction coefficient of the friction drive can be changed regardless of the wedge angle to suit for performance requirement. This provided a greater freedom for design and performance optimization. Design analysis was presented and a FE model was developed to quantify design parameters. Prototypes of the friction drive were fabricated and extensive testing was conducted to evaluate its performance. Results indicated the performance of the friction drive far exceeded the design specifications in speed, torque, and power ratings. The friction drive offered a consistent smooth and quiet performance over a wide range of operating conditions. It was capable of operating at an elevated speed of up to 12 000 rpm with adequate thermal characteristics. The friction drive demonstrated a peak efficiency above 97%. Results confirmed that the stiffness of the elastic support has an important impact on performance. The elastic support stiffness, in conjunction with the contact stiffness, determines the actual operating friction coefficient at the frictional contacts.

Ambient Condition Effects on NOx and CO Emissions From Process Heaters

2008 ◽  
Author(s):  
Wesley R. Bussman ◽  
Charles E. Baukal
Keyword(s):  
Atmospheric Pressure ◽  
Ambient Air ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Ambient Conditions ◽  
Fuel Gas ◽  
Natural Draft ◽  
Actual Operating ◽  
Wide Range ◽  
Pollution Emissions

Because process heaters are typically located outside, their operation is subject to the weather. Heaters are typically tuned at a given set of conditions; however, the actual operating conditions may vary dramatically from season to season and sometimes even within a given day. Wind, ambient air temperature, ambient air humidity, and atmospheric pressure can all significantly impact the O2 level, which impacts both the thermal efficiency and the pollution emissions from a process heater. Unfortunately, most natural draft process burners are manually controlled on an infrequent basis. This paper shows how changing ambient conditions can considerably impact both CO and NOx emissions if proper adjustments are not made as the ambient conditions change. Data will be presented for a wide range of operating conditions to show how much the CO and NOx emissions can be affected by changes in the ambient conditions for fuel gas fired natural draft process heaters, which are the most common type used in the hydrocarbon and petrochemical industries. Some type of automated burner control, which is virtually non-existent today in this application, is recommended to adjust for the variations in ambient conditions.

Development of Friction Drive Transmission

2005 ◽  
Author(s):  
Xiaolan Ai ◽  
Matthew Wilmer ◽  
David Lawrentz
Keyword(s):  
Friction Coefficient ◽  
Power Density ◽  
High Speed ◽  
Contact Stiffness ◽  
Outer Ring ◽  
The Sun ◽  
Input Shaft ◽  
Input And Output ◽  
Actual Operating ◽  
Output Torque

Friction drive is a mechanical device that utilizes friction force to transmit torque and power. Since the power is transferred through shearing a thin layer of highly pressurized lubricant film formed between the mating surfaces. Friction drive possesses desired performance attributes that pertain to its unique operating principles. These attributes include high mechanical efficiency, minimal backlash, low noise and vibration and high-speed capability. The power density of a friction drive can be very high when operated at elevated speeds. These performance features, in conjunction with its inherent manufacturing simplicity, make friction drives suitable candidates for a host of applications. The current global technology trend towards electrification and increasing use of electric machines in auxiliary drives for both automotive and industrial applications presents a good opportunity for friction drives as a cost-effective alternative to conventional gear drives. The smooth high-speed performance feature of friction drives allows the use of more efficient high-speed motors to reduce motor size and thus improve system power density. A novel cylindrical friction drive was developed [1,2] for electric oil pump applications. The friction drive is to be integrated with an electric motor to provide necessary speed reduction. The friction drive, as shown in Figure 1, is comprised of an outer ring, a sun roller, a loading planet, two supporting planets and a stationary carrier. The sun roller is set eccentric to the outer ring to generate a wedge gap that facilitates a torque actuated loading mechanism for the friction drive. The loading planet is properly assembled in the wedge gap with frictional contact with the sun roller and the outer ring and is elastically supported on the carrier. By altering the ratio of the support stiffness to contact stiffness, the actual operating friction coefficient of the friction drive can be changed to suit for desired performance regardless the wedge angle. This provides a grater freedom for design optimization. Design analysis was presented and a FE model was developed to quantify design parameters. Prototypes of the friction drive were fabricated for testing. Major geometry parameters are listed in Table 1. Extensive testing was conducted to evaluate its performance. Figure 2 shows the schematic of test apparatus. It is comprised of a drive motor, a high-speed spindle, and a hydraulic brake pump. The motor drives the spindle through a rubber belt and a pair of pulleys. The spindle shaft connects to the input shaft of the friction drive thought an input torque meter. The output shaft of the friction drive couples to the hydraulic pump through an output torque meter. The torque meters pick up both speed and torque signals at input and output shafts of the friction drive, respectively. Thermo-couples are mounted to monitor temperatures at planet support shafts and at bearings of input and output shafts. An accelerometer was placed on the back plate of a mounting bracket to which the friction drive was bolted. It monitors the vibration signals of the friction drive for reference and safety purposes. A data acquisition system was used to collect and process all signals at predetermined sampling rate. The friction drive offered a consistent smooth and quite performance over a wide range of operating conditions. It was capable of operating at an elevated speed of up to 12000 rpm with adequate thermal characteristics. Figure 3 shows the steady sate temperature contour map as function of input shaft speed and output shaft torque. Results demonstrated that the friction drive has high power transmission efficiency under various test conditions. The peak efficiency exceeded 97%. Figure 4 plots the overall system efficiency as a function of output torque for various input speeds. Results also confirmed that the stiffness of the elastic support has an important impact on performance. The elastic support stiffness, in conjunction with, the contact stiffness determines the actual operating friction coefficient at the frictional contacts.

scholarly journals A Computationally Efficient Multidiode Model for Optimizing the Front Grid of Multijunction Solar Cells under Concentration

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chris H. van de Stadt ◽  
Pilar Espinet Gonzalez ◽  
Harry A. Atwater ◽  
Rebecca Saive
Keyword(s):  
Solar Cells ◽  
Operating Conditions ◽  
Design Parameters ◽  
Computationally Efficient ◽  
Fast Determination ◽  
Wide Range ◽  
Multijunction Solar Cells ◽  
Efficiency Increase ◽  
Light Concentration

We have developed a computationally efficient simulation model for the optimization of redirecting electrical front contacts for multijunction solar cells under concentration, and we present its validation by comparison with experimental literature results. The model allows for fast determination of the maximum achievable efficiency under a wide range of operating conditions and design parameters such as the contact finger redirecting capability, period and width of the fingers, the light concentration, and the metal and emitter sheet resistivity. At the example of a state-of-the-art four-junction concentrator solar cell, we apply our model to determine ideal operating conditions for front contacts with different light redirection capabilities. We find a 7% relative efficiency increase when enhancing the redirecting capabilities from 0% to 100%.

Extension of the Friction Mastercurve to Limiting Shear Stress Models

2003 ◽  
Vol 125 (4) ◽  
pp. 739-746 ◽  
Author(s):  
B. Jacod ◽  
C. H. Venner ◽  
P. M. Lugt
Keyword(s):  
Shear Stress ◽  
Friction Coefficient ◽  
Numerical Simulations ◽  
Coefficient Of Friction ◽  
Rheological Model ◽  
Operating Conditions ◽  
Limiting Shear Stress ◽  
Wide Range ◽  
Two Parameters ◽  
Stress Models

A previous study of the behavior of friction in EHL contacts for the case of Eyring lubricant behavior resulted in a friction mastercurve. In this paper the same approach is applied to the case of limiting shear stress behavior. By means of numerical simulations the friction coefficient has been computed for a wide range of operating conditions and contact geometries. It is shown that the same two parameters that were found in the Eyring study, a characteristic shear stress, and a reduced coefficient of friction, also govern the behavior of the friction for the case of limiting shear stress models. When the calculated traction data is plotted as a function of these two parameters all results for different cases lie close to a single curve. Experimentally measured traction data is used to validate the observed behavior. Finally, the equations of the mastercurves for both types of rheological model are compared resulting in a relation between the Eyring stress τ0 and the limiting shear stress τL.

Analysis of Contact Mechanics for Rotor-Bristle Interference of Brush Seal

2003 ◽  
Vol 125 (2) ◽  
pp. 414-421 ◽  
Author(s):  
R. J. Stango ◽  
H. Zhao ◽  
C. Y. Shia
Keyword(s):  
Contact Force ◽  
Flexural Rigidity ◽  
Operating Conditions ◽  
Contact Forces ◽  
Design Parameters ◽  
Attractive Alternative ◽  
Seal Design ◽  
Brush Seal ◽  
Wide Range ◽  
Deformation Mechanics

Brush seals have proven to be an attractive alternative to labyrinth seals for turbomachinery applications. This innovation in seal technology utilizes both the high temperature capability of special-alloy wire and the flexural adaptability of fibers to accommodate a wide range of operating conditions that are encountered during service. The effectiveness of the seal is principally derived from the bristles ability to endure forces imparted by both the fluid and shaft, and yet maintain contact between the filament tips and the surface of the rotor. Consequently, contact forces generated along the interface of the fiber tip and rotor are an important consideration for both the design and performance of the rotor-seal assembly. This paper focuses on evaluating brush seal forces that arise along the surface of the rotor due to the dimensional disparity or interference between the rotor-fiber. Filament tip contact forces are computed on the basis of an in-plane, large deformation mechanics analysis of a cantilever beam, and validation of the model is assessed by using an electronic balance for measuring the shear and normal force exerted by a bristle tip onto a flat, hardened surface. Formulation of the mechanics problem is briefly reviewed, and includes the effect of Coulombic friction at the interface of the fiber tip and rotor. Filament contact force is used as a basis for computing bearing stress along the fiber-rotor interface. Results are reported for a range of brush seal design parameters in order to provide a better understanding of the role that seal geometry, friction, and bristle flexural rigidity play in generating rotor contact force.

Unsteady Simulations of a Low NOx LDI Combustor for Environmentally Responsible Aviation Engines

2015 ◽  
Author(s):  
Scott A. Drennan ◽  
Gaurav Kumar ◽  
Erlendur Steinthorsson ◽  
Adel Mansour
Keyword(s):  
Experimental Data ◽  
Complex Geometry ◽  
Mesh Refinement ◽  
Operating Conditions ◽  
Design Parameters ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Cfd Simulations ◽  
Wide Range ◽  
Environmentally Responsible

A key objective of NASA’s Environmentally Responsible Aviation (ERA) research program is to develop advanced technologies that enable 75% reduction of LTO NOx emissions of N+2 aviation gas turbine engines relative to the CAEP 6 standard. To meet this objective, a new advanced multi-point fuel injector was proposed and tested under the NASA ERA program. The new injector, called the three-zone injector, or 3ZI, uses fifteen spray cups arranged in three zones. Swirling air flows into each cup and fuel is introduced via pressure swirl atomizers within the cup. Multiple design parameters impact the performance of the injector, such as the location of the atomizer within the spray cup, the spray angle and cup-to-cup spacing. To fully understand the benefits and trade-offs of various injector design parameters and to optimize the performance of the injector, detailed CFD simulations are an essential tool. Furthermore, the CFD methodology must allow easy changes in design parameters and guarantee consistent and comparable accuracy from one design iteration to the next. This paper investigates the use of LES in reacting and non-reacting flows and compares against the NOx experimental data for the multi-point atomization strategy of the injector. The CFD simulations employ an automatically generated Cartesian cut-cell meshing approach with mesh refinement applied near complex geometry and spray regions. Adaptive Mesh Refinement (AMR) is used to refine mesh in regions of high gradients in velocity and temperature. The CFD simulations use boundary and operating conditions based on experimental data for air flow and spray atomization obtained from LDV and PDPA characterizations of the spray respectively. The results are extended to reacting flow using a detailed reaction mechanism and predictions of NOx emissions are compared to experimental data. Overall NOx predictions were consistently less than experimental values. However, the NOx prediction trends showed excellent agreement with experimental data across the wide range of equivalence ratios investigated.

scholarly journals GE ENERGY Jenbacher gas engine technology – preventive maintenance by means of highly sophisticated control systems

2006 ◽  
Vol 125 (2) ◽  
pp. 82-86
Author(s):  
Thomas ELSENBRUCH
Keyword(s):  
Control Systems ◽  
Data Transmission ◽  
Operating Conditions ◽  
Engine Operation ◽  
Actual Operating ◽  
Wide Range ◽  
Control Concept ◽  
On Line ◽  
Optimal Adjustment ◽  
And Control

Data collection and control concept of Jenbacher gas engines has been presented in the paper. Internet data transmission allow on-line control of the engine operation, early detection of defects and optimal adjustment to engine actual operating conditions. The system offers both customers and GE Jenbacher maintenance staff a wide range of functionalities for commissioning, monitoring and maintaining installations and for diagnostic purposes.

scholarly journals Modeling and assessment of the stress-strain state of above-ground pipelines at different types of compensation sections

2021 ◽  
Vol 266 ◽  
pp. 01022
Author(s):  
Z.A. Besheryan ◽  
I.F. Kantemirov
Keyword(s):  
Strain State ◽  
Complex Stress ◽  
Operating Conditions ◽  
The Arctic ◽  
Design Parameters ◽  
The Finite Element Method ◽  
Stress Strain ◽  
Stress Strain State ◽  
Actual Operating ◽  
Different Types

The development of Russian fuel and energy complex in the short term is connected with the development of new hydrocarbon field in the permafrost zone and the need to build Arctic pipelines north of the 60th parallel. The ground-based structural scheme of pipeline laying is the most optimal while constructing trunk pipelines in permafrost areas in the Arctic and subarctic latitudes. The actual operating conditions of these systems are insufficiently studied. The above-ground pipeline in permafrost is in an complex stress-strain state. This study presents the results of the assessment of the stress-strain state of linearly extended above-ground pipelines at different compensation sections (triangular compensator; trapezoidal compensator; U-shaped compensator) under actual operating conditions. Using the finite element method on mathematical models, the dependences of the transverse displacements of the pipeline on movable supports and stresses arising in dangerous sections of the typical pipeline section during self-compensation of deformations on the variable design parameters of the system for various load combinations were established (the simulation was carried out in the ANSYS software package).

Detailed Hydrodynamic Study for Performance Optimization of a Combined Lift and Drag-Based Modified Savonius Water Turbine

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Mithinga Basumatary ◽  
Agnimitra Biswas ◽  
Rahul Dev Misra
Keyword(s):  
Performance Optimization ◽  
Operating Conditions ◽  
Hydrodynamic Performance ◽  
Design Parameters ◽  
Ansys Fluent ◽  
Orthogonal Experiments ◽  
Water Turbine ◽  
Hydrodynamic Study ◽  
Lift And Drag ◽  
Power Curves

Abstract A combined lift and drag (CLD) Savonius water turbine is an advanced form of Savonius water turbine that has higher efficiency than the latter. However, its detailed hydrodynamic performance optimization is still unexplored, which is important for its possible future commercialization. The objective of the present work is to perform a detailed hydrodynamic study for performance optimization of the CLD Savonius water turbine at low water speed (characteristic of river stream current) under different design and operating conditions. A parametric optimization using orthogonal experiments is first done to obtain the optimized values of all the contributing design parameters. It is then followed by a detailed computational fluid dynamics (CFD) investigation using ansys fluent software to optimize the hydrodynamic performance of the turbine at the selected design conditions under different operating tip speed ratios (TSRs). Detailed fluidic behaviors including boundary layer features, blade loading, and vorticity structures of the turbine are explored to obtain important performance insights, and power curves of the improved CLD design are also obtained. It is found that the optimized CLD Savonius water turbine has higher hydrodynamic performance than the earlier design of this turbine with a maximum coefficient of power obtained as 0.29 at TSR 0.8.

An Investigation of Heat Generation Characteristics of Brush Seals

2007 ◽  
Author(s):  
Mehmet Demiroglu ◽  
John A. Tichy
Keyword(s):  
Contact Force ◽  
Heat Generation ◽  
Operating Conditions ◽  
Frictional Heat ◽  
Design Parameters ◽  
Frictional Heat Generation ◽  
Operation Conditions ◽  
Seal Design ◽  
Wide Range ◽  
Brush Seals

Brush seals are considered as a category of compliant seals, which tolerate a great high level of interference between the seal and the rotor or shaft. Their superior leakage characteristics have opened many application fields in the turbo-machinery world, ranging from industrial steam turbines to jet engines. However, brush seal designers have to find a trade-off between the lower parasitic leakage but higher heat generation properties of brush seals for given operation conditions. As brush seals can maintain contact with the rotor for a wide range of operating conditions, the contact force/pressure generated at the seal-rotor interface becomes an important design parameter for sustained seal performance and longevity of its service life. Furthermore, due to this contact force at the interface, frictional heat generation is inevitable and must be evaluated for various design and operating conditions. In this paper, frictional heat generation at the sealrotor interface is studied. To capture temperature rise at the interface, a thermal image of the seal and rotor is taken with an infrared camera under various operating conditions. The temperature map of the rotor is compared to results from thermal finite element analysis of the rotor to back calculate the heat flux to the rotor. A closed form equation for frictional heat generation is suggested as a function of seal design parameters, material properties, friction coefficient and empirical factors from testing.

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