Computational Analysis of the Dynamics Flow in the Duct System of an Continuous Positive Airways Pressure Device

2020 ◽  
Author(s):  
Tung Xuan Vuong ◽  
Ahmed Al-Jumaily ◽  
Robert Paxton
Keyword(s):  
Noise Source ◽  
Hybrid Approach ◽  
Internal Flow ◽  
Broadband Noise ◽  
Product Development Process ◽  
Duct System ◽  
Software Environment ◽  
Cfd Simulations ◽  
Duct Systems ◽  
High Level

Abstract In this paper, 3-D duct models of Continuous Positive Airway Pressure (CPAP) device are developed to investigate the internal airflow behaviours and to identify potential noise source locations. The Computational Aeroacoustics (CAA) with a hybrid approach is conducted in the ANSYS software environment. CFD simulations were used to investigate the internal flow behaviours of the duct systems. The predicted results have shown the internal flow characteristics as circulation and separation behaviours. Those behaviours were found at several locations such as 90-degree corners, restricted cross-sectional areas, etc. High levels of turbulent energy are also found in those locations indicated they are likely to have a high level of noise. Further investigation to predict the noise generated from the duct system to validate the findings in CFD simulations. The results showed that there is a high level of noise generated at the identified locations in the CFD simulations. The noise experiments were also conducted to compare with the predicted noise results. It was found the predicted models can be used to evaluate the flow behaviours inside the duct system. In summary, the CAA with a hybrid approach is used to investigate the internal flow behaviours and the potential noise source locations of the duct systems in the studied CPAP device. The predicted results have explained and identified some potential noise source locations. These findings will be used as guidelines to optimize the internal flow and therefore improve the noise generated from ducts. The broadband noise source models are potential tools that can be used to determine the loudness at the source locations in the early product development process for reducing noise level and better sound quality as well as a cost-effective tool for noise prediction.

Physics-informed Broadband Noise Source Identification and Prediction of an Ideally Twisted Rotor

2021 ◽  
Author(s):  
Christopher Thurman ◽  
Nikolas S. Zawodny ◽  
Nicole A. Pettingill ◽  
Leonard V. Lopes ◽  
James D. Baeder
Keyword(s):  
Source Identification ◽  
Noise Source ◽  
Broadband Noise ◽  
Noise Source Identification

Design of a 0.1~18GHz High-Power Broadband Noise Source

2020 ◽  
Author(s):  
Rikang Zhao ◽  
Tingming Yao ◽  
Xidong Duan ◽  
Guoqing Fan ◽  
Shoumei Cheng ◽  
...  
Keyword(s):  
High Power ◽  
Noise Source ◽  
Broadband Noise

scholarly journals Enhanced Cognitive Walkthrough: Development of the Cognitive Walkthrough Method to Better Predict, Identify, and Present Usability Problems

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Lars-Ola Bligård ◽  
Anna-Lisa Osvalder
Keyword(s):  
Medical Equipment ◽  
Development Process ◽  
Product Development Process ◽  
Infusion Pumps ◽  
Usability Problems ◽  
Cognitive Walkthrough ◽  
High Level ◽  
High Degree ◽  
Further Development ◽  
Potential Use

To avoid use errors when handling medical equipment, it is important to develop products with a high degree of usability. This can be achieved by performing usability evaluations in the product development process to detect and mitigate potential usability problems. A commonly used method is cognitive walkthrough (CW), but this method shows three weaknesses: poor high-level perspective, insufficient categorisation of detected usability problems, and difficulties in overviewing the analytical results. This paper presents a further development of CW with the aim of overcoming its weaknesses. The new method is called enhanced cognitive walkthrough (ECW). ECW is a proactive analytical method for analysis of potential usability problems. The ECW method has been employed to evaluate user interface designs of medical equipment such as home-care ventilators, infusion pumps, dialysis machines, and insulin pumps. The method has proved capable of identifying several potential use problems in designs.

Dynamics of the Internal Flow in Swirl Atomizers by CFD Simulations

2018 ◽  
pp. 100-132
Author(s):  
Roman Ivanovitch Savonov
Keyword(s):  
Numerical Simulation ◽  
Homogeneous Model ◽  
Internal Flow ◽  
Surface Model ◽  
Cfd Simulations ◽  
Two Phase ◽  
Two Phases ◽  
Swirl Atomizer ◽  
Free Surface Model ◽  
Two Fluid

This work presents the simulation of the internal flow in a swirl atomizer. The geometry of the atomizer is calculated by analytical equations used in engineering. The numerical simulation of the two-phase flow is performed by using two equations k-ε turbulence model. The fluids are presented as two-fluid homogeneous model. The interface between two phases is calculated by free surface model. The distribution fields of the axial and tangential velocities, pressures and air core are obtained. The aim of this work is to compare the results obtained by numerical simulation with ones obtained analytically. Also, to study the internal fluids flow inside the atomizer.

scholarly journals Compact Modeling Framework v3.0 for high-resolution global ocean–ice–atmosphere models

2018 ◽  
Vol 11 (10) ◽  
pp. 3983-3997 ◽  
Author(s):  
Vladimir V. Kalmykov ◽  
Rashit A. Ibrayev ◽  
Maxim N. Kaurkin ◽  
Konstantin V. Ushakov
Keyword(s):  
Message Passing ◽  
Message Passing Interface ◽  
Global Ocean ◽  
Optimal Interpolation ◽  
Compact Modeling ◽  
Software Environment ◽  
Modeling Framework ◽  
Partitioned Global Address Space ◽  
Version 2.0 ◽  
High Level

Abstract. We present a new version of the Compact Modeling Framework (CMF3.0) developed for the software environment of stand-alone and coupled global geophysical fluid models. The CMF3.0 is designed for use on high- and ultrahigh-resolution models on massively parallel supercomputers.The key features of the previous CMF, version 2.0, are mentioned to reflect progress in our research. In CMF3.0, the message passing interface (MPI) approach with a high-level abstract driver, optimized coupler interpolation and I/O algorithms is replaced with the Partitioned Global Address Space (PGAS) paradigm communications scheme, while the central hub architecture evolves into a set of simultaneously working services. Performance tests for both versions are carried out. As an addition, some information about the parallel realization of the EnOI (Ensemble Optimal Interpolation) data assimilation method and the nesting technology, as program services of the CMF3.0, is presented.

Transient CFD Visualization of Fossil Fuel Combustion Simulations

2003 ◽  
Author(s):  
Brian Dotson ◽  
Kent Eshenberg ◽  
Chris Guenther ◽  
Thomas O’Brien
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Cfd Simulation ◽  
Low Cost ◽  
Three Dimensional ◽  
Cfd Simulations ◽  
Projection System ◽  
Computational Fluid Dynamics Cfd ◽  
High Level ◽  
Wall System

The design of high-efficiency lower-emission coal-fed power plants is facilitated by the extensive use of computational fluid dynamics (CFD) simulations. This paper describes work conducted at the National Energy Technology Laboratory (NETL) and Pittsburgh Supercomputing Center (PSC) to provide an environment for the immersive three-dimensional visualization of CFD simulation results. A low-cost high-resolution projection system has been developed in the visualization lab at NETL. This multi-wall system consists of four projection screens, three of which are tiled into four quadrants. The graphics for the multi-wall system are rendered using a cluster of eight personal computers. A high-level visualization interface named Mavis has also been developed to combine the powerful 3D modules of OpenDX with methods developed at NETL for studying multiphase CFD data. With Python, a completely new OpenDX user interface was built that extends and simplifies the features of a basic graphics library.

scholarly journals Compact Modeling Framework v3.0 for high-resolution global ocean-ice-atmosphere models

2018 ◽  
Author(s):  
Vladimir V. Kalmykov ◽  
Rashit A. Ibrayev ◽  
Maxim N. Kaurkin ◽  
Konstantin V. Ushakov
Keyword(s):  
High Resolution ◽  
Global Ocean ◽  
Optimal Interpolation ◽  
Compact Modeling ◽  
Software Environment ◽  
Modeling Framework ◽  
Coupled Models ◽  
High Resolution Models ◽  
High Level ◽  
Parallel Supercomputers

Abstract. We present new version of the Compact Modeling Framework (CMF3.0) developed for providing the software environment for stand-alone and coupled models of the Global geophysical fluids. The CMF3.0 designed for implementation high and ultra-high resolution models at massive-parallel supercomputers. The key features of the previous CMF version (2.0) are mentioned for reflecting progress in our researches. In the CMF3.0 pure MPI approach with high-level abstract driver, optimized coupler interpolation and I/O algorithms is replaced with PGAS paradigm communications scheme, while central hub architecture evolves to the set of simultaneously working services. Performance tests for both versions are carried out. As addition a parallel realisation of the EnOI (Ensemble Optimal Interpolation) data assimilation method as program service of CMF3.0 is presented.

Development of an Adaptive Helmholtz Resonator for Broadband Noise Control

2004 ◽  
Author(s):  
Simon J. Este`ve ◽  
Marty E. Johnson
Keyword(s):  
Helmholtz Resonator ◽  
Broadband Noise ◽  
Experimental Result ◽  
Helmholtz Resonators ◽  
Large Cylinder ◽  
Payload Fairing ◽  
Compact Design ◽  
High Level ◽  
Design Options ◽  
Control Application

This paper presents the development of adaptive Helmholtz resonators aimed at controlling broadband disturbance for the reduction of noise transmission into rocket payload fairing. Helmholtz resonators are commonly used for narrow band control application and so are designed to present the lowest amount of damping yielding maximum impedance. For this particular application however, optimal damping ratios usually superior to 4% are required. This relatively high level of damping permits more lightweight and compact design options to be considered that are not possible for low damping applications. Two design solutions are presented. The first tunes the resonator by varying the length of an accordion neck. The second varies the HR opening using an iris diaphragm. The characteristics of these two devices are measured, and a solution to maintain the damping level relatively constant is also proposed. Finally, experimental result obtained in a large cylinder representative of a payload fairing using 8 adaptive resonators is presented.

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