scholarly journals Detailed Study on Stiffness and Load Characteristics of Film-Riding Groove Types Using Design of Experiments

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
S. M. Tibos ◽  
C. Georgakis ◽  
K. Harvey ◽  
J. A. Teixeira
Keyword(s):  
Design Of Experiments ◽  
Reynolds Equation ◽  
Design Space ◽  
Hydrodynamic Load ◽  
Pressure Drops ◽  
Seal Design ◽  
Hydrostatic Load ◽  
Simple Linear Relationship ◽  
Load Characteristics ◽  
The Relationship

In the application of film-riding sealing technology, there are various groove features that can be used to induce hydrodynamic lift. However, there is little guidance in selecting the relative parameter settings in order to maximize hydrodynamic load and fluid stiffness. In this study, two groove types are investigated—Rayleigh step and inclined groove. The study uses a design of experiments approach and a Reynolds equation solver to explore the design space. Key parameters have been identified that can be used to optimize a seal design. The results indicate that the relationship between parameters is not a simple linear relationship. It was also found that higher pressure drops hinder the hydrodynamic load and stiffness of the seal suggesting an advantage for using hydrostatic load support in such conditions.

scholarly journals The Role of Steps and Game Elements in Gamified Fitness Tracker Apps: A Systematic Review

2021 ◽  
Vol 5 (2) ◽  
pp. 5
Author(s):  
Aatish Neupane ◽  
Derek Hansen ◽  
Jerry Alan Fails ◽  
Anud Sharma
Keyword(s):  
Social Influence ◽  
Design Space ◽  
Real Life ◽  
Network Clustering ◽  
And Performance ◽  
Fitness Tracker ◽  
Game Elements ◽  
The Relationship ◽  
Contingent Rewards

This article reviews 103 gamified fitness tracker apps (Android and iOS) that incorporate step count data into gameplay. Games are labeled with a set of 13 game elements as well as meta-data from the app stores (e.g., avg rating, number of reviews). Network clustering and visualizations are used to identify the relationship between game elements that occur in the same games. A taxonomy of how steps are used as rewards is provided, along with example games. An existing taxonomy of how games use currency is also mapped to step-based games. We show that many games use the triad of Social Influence, Competition, and Challenges, with Social Influence being the most common game element. We also identify holes in the design space, such as games that include a Plot element (e.g., Collaboration and Plot only co-occur in one game). Games that use Real-Life Incentives (e.g., allow you to translate steps into dollars or discounts) were surprisingly common, but relatively simple in their gameplay. We differentiate between task-contingent rewards (including completion-contingent and engagement-contingent) and performance-contingent rewards, illustrating the differences with fitness apps. We also demonstrate the value of treating steps as currency by mapping an existing currency-based taxonomy onto step-based games and providing illustrations of nine different categories.

Design Parameters of Brush Seals and Their Impact on Seal Performance

2012 ◽  
Author(s):  
H. Schwarz ◽  
J. Friedrichs ◽  
J. Flegler
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Large Scale ◽  
Design Parameters ◽  
Test Rig ◽  
Pressure Drops ◽  
Seal Design ◽  
Brush Seal ◽  
Extreme Load ◽  
Brush Seals

Brush seals, which were originally designed for gas turbine applications, have been successfully applied to large-scale steam turbines within the past decade. From gas turbine applications, the fundamental behavior and designing levers are known. However, the application of brush seals to a steam turbine is still a challenge. This challenge is mainly due to the extreme load on the brush seal while operating under steam. Furthermore, it is difficult to test brush seals under realistic conditions, i.e. under live steam conditions with high pressure drops. Due to these insufficiencies, 2 test rigs were developed at the University of Technology Braunschweig, Germany. The first test rig is operated under pressurized air and allows testing specific brush seal characteristics concerning their general behavior. The knowledge gained from these tests can be validated in the second test rig, which is operated under steam at pressure drops of 45 bar and temperatures up to 450 °C. Using both the air test rig and the steam test rig helps keep the testing effort comparably small. Design variants can be pre-tested with air, and promising brush seal designs can consequently be tested in the steam seal test rig. The paper focuses on a clamped brush seal design which, amongst others, is used in steam turbine blade paths and shaft seals of current Siemens turbines. The consequences of the brush assembly on the brush appearance and brush performance are shown. The clamped brush seal design reveals several particularities compared to welded brushes. It could be shown that the clamped bristle pack tends to gape when clamping forces rise. Gapping results in an axially expanding bristle pack, where the bristle density per unit area and the leakage flow vary. Furthermore, the brush elements are usually assembled with an axial lay angle, i.e. the bristles are reclined against the backing plate. Hence, the axial lay angle is also part of the investigation.

Dimensions of Design in K-12 Telementoring Programs

2010 ◽  
pp. 15-30
Author(s):  
Kevin O’Neill
Keyword(s):  
Design Space ◽  
Research Findings ◽  
K 12 ◽  
Relationship Of ◽  
The Relationship ◽  
Made In

Teachers and researchers have been designing telementoring programs for more than fifteen years, yet there are many possible program designs that have not yet been attempted, and enormous potential yet to fulfill. An attempt is made to map out the “design space” of K-12 telementoring by discussing the major decisions made in designing a telementoring program, and the relationship of these decisions to one another. Where possible, research findings and examples of specific programs are cited in this discussion. By providing a look “under the hood” of telementoring programs, the chapter aims to help teachers become more equal partners in the effort to refine existing programs and develop new ones. Encouragement is offered to researchers to more fully articulate the rationale behind their designs in their writing, and to carry out more research on the efficacy of particular design choices, so that the field can develop cumulative literature on telementoring design.

scholarly journals From the Thirties to post-war reconstruction. The Land Reclamation Consortia and rural architecture in Italy.

2019 ◽  
Vol 63 ◽  
pp. 03001
Author(s):  
Luca Monica ◽  
Luca Bergamaschi
Keyword(s):  
Design Space ◽  
Land Reclamation ◽  
Rural Villages ◽  
Agrarian Economy ◽  
Rural Architecture ◽  
Post War ◽  
The Village ◽  
The Relationship ◽  
The City ◽  
Operational Aspects

This investigation highlights a new conception of design space in architecture, in the relationship between settlement and land, rooted in architectural historical studies and research on rural and agrarian economy and unlocks a potential regeneration and restoration of the rural villages of Italy’s cultural heritage. In Italy, the theme of rural architecture has gained momentum ever since the spread of the Modern Movement, reviving settlement and spatial principles as a moral lesson for the general development of new aesthetics and a new society. Innovative concepts inspired by Arrigo Serpieri such as “Integral Land Reclamation”, and long-standing institutions such as the Land Reclamation Consortia, became official law in 1933, and played a crucialrole in this process, particularly in consolidating new architectural thinking that was to endure up to post-war reconstruction and beyond, until our own times. Paradoxically, ideologically opposing phenomena, settlements related to the extensive land reclamation of the Fascist period and the rural redevelopment of the Fifties, were somehow based on comparable theoretical and operational aspects. We can recognize these ideas by looking at the most interesting experiments developed in these two periods: the city of Sabaudia designed by Piccinato, and the village of La Martella at Matera designed by Quaroni (and sponsored by Adriano Olivetti). The quest for a new “moral aesthetic” of architecture undertaken by leading representatives of Italian Rationalism was to re-emerge in the neorealism of post-war reconstruction.

Simple Recuperated s-CO2 Cycle Revisited: Optimization of Operating Parameters for Maximum Cycle Efficiency

2019 ◽  
Author(s):  
Anchit Dutta ◽  
Adhip Gupta ◽  
Sharath Sathish ◽  
Aman Bandooni ◽  
Pramod Kumar
Keyword(s):  
Design Of Experiments ◽  
Design Space ◽  
Pressure Ratio ◽  
Cycle Performance ◽  
Maximum Temperature ◽  
Brayton Cycle ◽  
High Side ◽  
Side Pressure ◽  
Cycle Efficiency ◽  
The Impact

Abstract The paper presents modeling and Design of Experiments (DOE) analysis for a simple recuperated s-CO2 closed loop Brayton cycle operating at a maximum temperature of 600°C and a compressor inlet temperature of 45°C. The analysis highlights the impact of isentropic efficiencies of the turbine and compressor, decoupled in this case, on other equipment such as recuperator, gas cooler and heater, all of which have a bearing on the overall performance of the s-CO2 Brayton cycle. A MATLAB program coupled with REFPROP is used to perform the thermodynamic analysis of the cycle. A design space exploration with a Design of Experiments (DOE) study is undertaken using I-sight™ (multi-objective optimization software), which is coupled with the MATLAB code. The outcome of the DOE study provides the optimal pressure ratios and high side pressures for maximum cycle efficiency in the design space. By varying pressure ratios along with a floating high side pressure, the analysis reveals that the cycle performance exhibits a peak around a pressure ratio of 2.5, with cycle efficiency being the objective function. A further interesting outcome of the DOE study reveals that the isentropic efficiencies of the compressor and turbine have a strong influence not only on the overall cycle efficiency, but also the optimum pressure ratio as well as the threshold pressures (low as well as high side pressure). An important outcome of this exercise shows that the isentropic efficiency of the turbine has a much greater impact on the overall cycle performance as compared to that of the compressor.

Squeeze Film Dampers: Amplitude Effects at Low Squeeze Numbers

1975 ◽  
Vol 97 (4) ◽  
pp. 1366-1370 ◽  
Author(s):  
Martin H. Sadd ◽  
A. Kent Stiffler
Keyword(s):  
Reynolds Equation ◽  
Dynamic Performance ◽  
Squeeze Film ◽  
Periodic Disturbance ◽  
Squeeze Film Dampers ◽  
Parallel Surfaces ◽  
Load Characteristics ◽  
Squeeze Number ◽  
Stiffness And Damping ◽  
Film Stiffness

Gaseous squeeze film dampers are analyzed to determine the effect of periodic disturbance amplitude on the dynamic performance. Both circular and rectangular parallel surfaces are investigated. A solution of the nonlinear Reynolds equation is obtained by expanding the pressure in powers of the squeeze number σ, retaining up to and including terms 0(σ2). The time dependent load characteristics are found. The effect of disturbance amplitude on the film stiffness and damping is given.

scholarly journals Hub clearance effect in the design space of the cantilevered stator embedded in a 4-stage low-speed research compressor

2021 ◽  
Vol 13 (8) ◽  
pp. 168781402110371
Author(s):  
Zhenzhou Ju ◽  
Jinfang Teng ◽  
Yuchen Ma ◽  
Mingmin Zhu ◽  
Xiaoqing Qiang
Keyword(s):  
Design Space ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Leakage Flow ◽  
Blade Loading ◽  
Low Speed ◽  
Entropy Variation ◽  
Total Leakage ◽  
Stage Matching ◽  
The Relationship

This paper focuses on the effect of hub clearance in the design space of the highly loaded cantilevered stator. The embedded 1.5 stages of a low-speed research compressor (LSRC) were conducted with Unsteady Reynolds Average Navier-Stokes (URANS) numerical investigation, and the cantilevered stator adopts positive bowed and fore-sweep three-dimensional design. The research details that with the hub clearance increasing from 1.1% to 4.5% span, the loss coefficient and the total leakage momentum of the cantilevered stator correspond to the change of the blade loading near the hub. When designing the inlet metal angle of the rotor downstream the cantilevered stator, emphasis should be given to considering the inter-stage matching below 15% span. The mixing of leakage flow in 1.1% span clearance and 2.5% span clearance is basically completed in the S3 passage, but the mixing of leakage flow in 3.5% span clearance and 4.5% span clearance is still relatively strong downstream of S3. When calculating the relative entropy variation based on Denton’s mixing model, attention should be paid to the relationship between the leakage flow velocity affected by the hub gap and the mainstream velocity, as well as whether the mixing has been completed in the blade passage.

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