Adaptation of an Existing Impeller Design to Large Bore Requirements: Aerodynamic Considerations

2019 ◽  
Author(s):  
Vishal Jariwala ◽  
Louis Larosiliere
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Cost Effective ◽  
Aerodynamic Performance ◽  
Vector Diagram ◽  
Multistage Process ◽  
Rotor Stiffness

Abstract Multistage process centrifugal compressor applications with single shaft rotors supported by only two bearings are quite common. It is sometimes desirable to operate impellers at higher rotational speeds, resulting in relatively compact and cost-effective machines. Such high-speed rotors can, however, pose rotordynamic challenges, and therefore require larger shaft or impeller bore diameters to increase rotor stiffness and rotordynamic stability. This work explores aerodynamically favorable ways to adapt an existing standard bore impeller design to large bore requirements. First, the stage aerodynamic performance and flow range implications of increasing bore diameter are discussed using meanline modeling and vector diagram arguments. Some strategies for adapting a standard bore design to large bore variant are then presented. Attempts are made to identify and clarify technical limitations to the degree of adaptability of an existing impeller to large bore requirements. Finally, a CFD-backed case study on a large-bore adaptation of a particular stage is presented to clarify practical considerations.

A Comprehensive Framework for Assessing Passenger Rail Services: A Case Study of the Hoosier State Line

2014 ◽  
Author(s):  
V. Dimitra Pyrialakou ◽  
Konstantina (Nadia) Gkritza
Keyword(s):  
High Speed ◽  
Systems Approach ◽  
Cost Effective ◽  
The United States ◽  
Economic Benefits ◽  
Fiscal Year ◽  
High Speed Rail ◽  
Passenger Rail ◽  
Rail Services

The development of a nationwide commuter and high-speed rail (HSR) network has been suggested as a promising and “greener” passenger transport solution with the potential to reduce energy consumption and greenhouse gas emissions, given efficient planning that will ensure sufficient ridership and sustainable investment. It is anticipated that passenger rail growth will bring regional economic benefits as well as promote energy independence, transportation safety, and livable communities with improved accessibility and inter-connectivity. Much research has been conducted to identify the benefits and costs associated with the operation, maintenance, and improvement of passenger rail services. However, previous studies supporting investment in passenger rail have generally considered one evaluation factor at a time. Additionally, studies suggesting that investment in passenger rail is not cost-effective give more weight to quantifiable benefits and current conditions, and rarely consider changes in public preferences influenced by policies and fostered conditions to encourage mode shifts. Thus, the literature lacks a comprehensive approach that would evaluate investments in passenger rail, accounting for quantifiable and other benefits, in light of environmental, resilience and sustainability, economic, demand, and feasibility factors. Using a case study of the Hoosier State line, this study illustrates a systems approach for comprehensively assessing passenger rail services in the United States in terms of the system’s existing opportunities and future directions. The Hoosier State line operates four days per week between Indianapolis, Indiana and Chicago, Illinois with four intermediate stops. As of October 1, 2013, the State of Indiana, local communities, and Amtrak reached an agreement to support the Hoosier State line for the next fiscal year (2013–2014).

Centrifugal Compressor Stage Efficiency and Rotor Stiffness Augmentation via Artificial Neural Networks

2021 ◽  
Author(s):  
Andrea Agnolucci ◽  
Michele Marconcini ◽  
Andrea Arnone ◽  
Lorenzo Toni ◽  
Angelo Grimaldi ◽  
...  
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Centrifugal Compressor ◽  
Aerodynamic Performance ◽  
Compressor Stage ◽  
Centrifugal Compressor Stage ◽  
High Stiffness ◽  
Low Stiffness ◽  
Artificial Neural ◽  
Rotor Stiffness

Abstract Centrifugal compressor stages with high rotor stiffness (i.e. impeller hub-to-outer-diameter ratio) may represent a crucial element to cope with tight rotordynamic requirements and constraints that are needed for certain applications. On the other hand, high-stiffness has a detrimental effect on the aerodynamic performance. Thus, an accurate design and optimization are required to minimize the performance gap with respect to low-stiffness stages. This paper shows a redesign and optimization procedure of a centrifugal compressor stage aimed at increasing the impeller stiffness while keeping high aerodynamic performance. Two different optimization steps are employed to consider a wide design space while keeping the computational cost as low as possible. At first the attention is focused on the impeller only, then the diffuser and the return channel are taken into account. The multi-objective and multi-operating point optimization makes use of artificial neural networks (ANNs) as a surrogate model to obtain the response surfaces. RANS calculations are carried out using the TRAF code and are employed to create the training dataset. Once the ANN has been trained, an optimization strategy is used to find the constrained optimum geometries for the impeller and the static components. The optimized high-stiffness stage is finally compared to the low-stiffness one to assess its applicability.

The aerodynamic performance of a high speed research centrifugal compressor facility

1994 ◽  
Author(s):  
Pat Shook ◽  
William Oakes ◽  
Ron McGuire ◽  
John Fagan ◽  
Sanford Fleeter
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Aerodynamic Performance

The Radio Probe™: A New Measurement Tool for High Speed Integrated Circuits

2005 ◽  
Author(s):  
Mark Kimball
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
High Speed ◽  
Attenuation Factor ◽  
Cost Effective ◽  
Frequency Measurement ◽  
Single Frequency ◽  
Measurement Tool ◽  
Probe Design ◽  
Differential Measurement

Abstract This article presents a novel tool designed to allow circuit node measurements in a radio frequency (RF) integrated circuit. The discussion covers RF circuit problems; provides details on the Radio Probe design, which achieves an input impedance of 50Kohms and an overall attenuation factor of 0 dB; and describes signal to noise issues in the output signal, along with their improvement techniques. This cost-effective solution incorporates features that make it well suited to the task of differential measurement of circuit nodes within an RF IC. The Radio Probe concept offers a number of advantages compared to active probes. It is a single frequency measurement tool, so it complements, rather than replaces, active probes.

Effect of the strip spacing on the aerodynamic performance of a high-speed double-strip pantograph

2021 ◽  
pp. 1-17
Author(s):  
Zhiyuan Dai ◽  
Tian Li ◽  
Jian Deng ◽  
Ning Zhou ◽  
Weihua Zhang
Keyword(s):  
High Speed ◽  
Aerodynamic Performance

The socio-spatial politics of royalties and their distribution: A case study of the Surat Basin, Queensland

2021 ◽  
pp. 0308518X2110266
Author(s):  
Neil Argent ◽  
Sean Markey ◽  
Greg Halseth ◽  
Laura Ryser ◽  
Fiona Haslam-McKenzie
Keyword(s):  
Cost Effective ◽  
Indigenous Communities ◽  
Energy Extraction ◽  
Grant Application ◽  
Coal Seam Gas ◽  
Spatial Politics ◽  
Developmental Needs ◽  
Development Fund ◽  
Effective Use

This paper is concerned with the socio-spatial and ethical politics of redistribution, specifically the allocation of natural resources rents from political and economic cores to the economic and geographical peripheries whence the resource originated. Based on a case study of the coal seam gas sector in Queensland's Surat Basin, this paper focuses on the operation of the Queensland State Government's regional development fund for mining and energy extraction-affected regions. Employing an environmental justice framework, we critically explore the operation of these funds in ostensibly helping constituent communities in becoming resilient to the worst effects of the ‘staples trap’. Drawing on secondary demographic and housing data for the region, as well as primary information collected from key respondents from mid-2018 to early 2019, we show that funds were distributed across all of the local government areas, and allocated to projects and places primarily on a perceived economic needs basis. However, concerns were raised with the probity of the funds’ administration. In terms of recognition justice, the participation of smaller and more remote towns and local Indigenous communities was hampered by their structural marginalisation. Procedurally, the funds were criticised for the lack of local consultation taken in the development and approval of projects. While spatially concentrated expenditure may be the most cost-effective use of public monies, we argue that grant application processes should be open, transparent and inclusive, and the outcomes cognisant of the developmental needs of smaller communities, together with the need to foster regional solidarity and coherence.

scholarly journals 2D-3D integration of hexagonal boron nitride and a high-κ dielectric for ultrafast graphene-based electro-absorption modulators

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hitesh Agarwal ◽  
Bernat Terrés ◽  
Lorenzo Orsini ◽  
Alberto Montanaro ◽  
Vito Sorianello ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Hafnium Oxide ◽  
High Speed ◽  
Hexagonal Boron Nitride ◽  
Temperature Stability ◽  
Cost Effective ◽  
Fold Increase ◽  
Building Blocks ◽  
High Quality ◽  
New Device

AbstractElectro-absorption (EA) waveguide-coupled modulators are essential building blocks for on-chip optical communications. Compared to state-of-the-art silicon (Si) devices, graphene-based EA modulators promise smaller footprints, larger temperature stability, cost-effective integration and high speeds. However, combining high speed and large modulation efficiencies in a single graphene-based device has remained elusive so far. In this work, we overcome this fundamental trade-off by demonstrating the 2D-3D dielectric integration in a high-quality encapsulated graphene device. We integrated hafnium oxide (HfO2) and two-dimensional hexagonal boron nitride (hBN) within the insulating section of a double-layer (DL) graphene EA modulator. This combination of materials allows for a high-quality modulator device with high performances: a ~39 GHz bandwidth (BW) with a three-fold increase in modulation efficiency compared to previously reported high-speed modulators. This 2D-3D dielectric integration paves the way to a plethora of electronic and opto-electronic devices with enhanced performance and stability, while expanding the freedom for new device designs.

scholarly journals Toward Decentralised Sanitary Sewage Collection Systems: A Multiobjective Approach for Cost-Effective and Resilient Designs

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1886
Author(s):  
Arezoo Zahediasl ◽  
Amin E. Bakhshipour ◽  
Ulrich Dittmer ◽  
Ali Haghighi
Keyword(s):  
Treatment Plant ◽  
Drainage System ◽  
Cost Effective ◽  
Optimization Approach ◽  
Hydraulic Design ◽  
Multiobjective Approach ◽  
Layout Generation ◽  
Plant Allocation ◽  
Problem Solving Process

In recent years, the concept of a centralized drainage system that connect an entire city to one single treatment plant is increasingly being questioned in terms of the costs, reliability, and environmental impacts. This study introduces an optimization approach based on decentralization in order to develop a cost-effective and sustainable sewage collection system. For this purpose, a new algorithm based on the growing spanning tree algorithm is developed for decentralized layout generation and treatment plant allocation. The trade-off between construction and operation costs, resilience, and the degree of centralization is a multiobjective problem that consists of two subproblems: the layout of the networks and the hydraulic design. The innovative characteristics of the proposed framework are that layout and hydraulic designs are solved simultaneously, three objectives are optimized together, and the entire problem solving process is self-adaptive. The model is then applied to a real case study. The results show that finding an optimum degree of centralization could reduce not only the network’s costs by 17.3%, but could also increase its structural resilience significantly compared to fully centralized networks.

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