A Robust Industrial Procedure for Measuring Modal Sound Fields in the Development of Radial Compressor Stages

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Peter Limacher ◽  
Carsten Spinder ◽  
Marius C. Banica ◽  
Heinz-Jürgen Feld
Keyword(s):  
Measurement System ◽  
Noise Source ◽  
Sound Field ◽  
Temperature Stability ◽  
Noise Emission ◽  
Radial Compressor ◽  
Sound Fields ◽  
Compressor Inlet ◽  
Time Required ◽  
The Impact

The turbocharger is a significant noise source in large diesel engines, such as those used in container vessels. Its main noise source is the radial compressor, where improvements in silencers and turbocharger insulation have led to a considerable reduction of compressor inlet noise emission over the past few years. As a result, compressor outlet noise is now becoming increasingly significant for large engines. Recently, an in-house compressor testbed was upgraded by adding an acoustic modal measurement system (MSMS) that allows detailed investigation of modal sound fields inside the piping. This forms part of an updated compressor acoustic qualification procedure. This paper is an in-depth treatise of the characteristics of this modal measurement system. The calculation approach for the modal decomposition and a simplified alternative that assumes axial propagation, as well as relevant considerations, such as spatial resolution, averaging, and the use of multiple reference sensors, are addressed. Various measurement parameters, such as repeatability, measurement time, required temperature stability, pressure scaling, flow noise and their impact on measurement uncertainty were investigated. A successful validation of the modal sound measurement system with a well-known modal sound field at the compressor inlet is also presented. Finally, the characteristics of the modal sound fields of the compressor outlet of a typical modern turbocharger are discussed. Modal decompositions at the first two blade passing frequencies (BPFs) are presented for selected operating points (OPs). The response of total sound power levels (PWLs) to compressor speed along the operating line (OL) is examined by means of both the present and the simplified algorithm. A sensitivity analysis shows the impact of volume flow and rotational speed on the modal sound distribution.

Synthetic Sound Source Generation for Acoustical Measurements in Turbomachines

2013 ◽  
Author(s):  
Michael Bartelt ◽  
Juan D. Laguna ◽  
Joerg R. Seume
Keyword(s):  
Wind Tunnel ◽  
Sound Source ◽  
Sound Propagation ◽  
Microphone Array ◽  
Sound Field ◽  
Acoustic Mode ◽  
Acoustic Excitation ◽  
Noise Emission ◽  
Noise Sources ◽  
Sound Fields

One of the greatest challenges in modern aircraft propulsion design is the reduction of the engine noise emission in order to develop quieter aircrafts. In the course of a current research project, the sound transport in low pressure turbines is investigated. For the corresponding experimental measurements, a specific acoustic excitation system is developed which can be implemented into the inlet of a turbine test rig and into an aeroacoustic wind tunnel. This allows for an acoustic mode generation and a synthesis of various sound source patterns to simulate typical turbomachinery noise sources such as rotor-stator interaction, etc. The paper presents the acoustical and technical design methodology in detail and addresses the experimental options of the system. Particular attention is paid to the design and the numerical optimization of the acoustic excitation units. To validate the sound generator during operation, measurements are performed in an aeroacoustic wind tunnel. For this purpose, an in-duct microphone array with a specific beamforming algorithm for hard-walled ducts is developed and applied to identify the source locations. The synthetically excited sound fields and the propagating acoustic modes are measured and analyzed by means of modal decomposition techniques. The measurement principles and the results are discussed in detail and it is shown that the intended sound source is produced and the intended sound field is excited. This paper shall contribute to help guide the development of excitation systems for aeroacoustic experiments to better understanding the physics of sound propagation within turbomachines.

Streamlining of the Radial Inlet Design Process for Centrifugal Compressors

2002 ◽  
Author(s):  
Anthony J. Saladino ◽  
Stephen J. Bielecki
Keyword(s):  
Optimization Techniques ◽  
Loss Coefficient ◽  
Efficiency Gain ◽  
Cfd Analysis ◽  
Production Environment ◽  
Radial Compressor ◽  
Optimization Parameter ◽  
Compressor Inlet ◽  
The Subject ◽  
The Impact

A radial compressor inlet represents an asymmetric and highly complex flow path, with high potential for flow disturbance. Due to the large computational resources and long lead times required for CFD analysis of such components, this resource has historically been reserved for conceptual or prototype designs. In the production environment, where compressor internals are often customized to a particular application, designers generally rely on geometric analysis of the flowpath. Low priority historically given to centrifugal inlet design is adequately illustrated in “mud etching” of the flow field in a retrofitted radial compressor inlet. An estimate of the potential for efficiency gain through inlet optimization, based on CFD predicted loss coefficient, is presented. It is noted that poor exit flow profiles can negatively impact performance, as well. Ill effects may include efficiency loss in downstream components, mechanical vibration, and compressor control issues. With continual improvement in CFD processing speed, the prospect of applying CFD based optimization techniques to production radial inlet designs becomes more feasible. In this investigation, CFD analysis is performed on an existing radial inlet design and validated with data from a flow visualization test rig. The subject inlet design is subsequently optimized through CFD analysis, with detailed attention being given to the impact of adjusting various geometric characteristics. A number of independent geometric parameters, which are determined to have significant impact on loss coefficient, are condensed into an optimization parameter. This optimization parameter serves as a preliminary indicator of design quality. Alternative brute force design methods are time prohibitive and may not provide the designer with feedback required to effectively alter geometry. Details of the CFD modeling and subsequent validation testing of the baseline inlet design are given. CFD results for a variety of modified inlet designs are presented. An overview of the optimization parameter and its application to a new radial inlet design are also presented. The potential for such an optimization parameter to limit design iteration is illustrated. Although additional refinement is suggested, the subject optimization parameter shows potential to direct the designer away from low efficiency designs.

Reconstruction of Interior Sound Fields of Vibrating Shells with an Open Spherical Microphone Array

2016 ◽  
Vol 24 (04) ◽  
pp. 1650013 ◽  
Author(s):  
Minzong Li ◽  
Huancai Lu
Keyword(s):  
Cross Validation ◽  
Microphone Array ◽  
Sound Field ◽  
Reconstruction Error ◽  
Wave Number ◽  
Tikhonov Regularization Method ◽  
Sound Fields ◽  
Noise Regularization ◽  
Enclosed Space ◽  
The Impact

Spherical acoustic holography was utilized to reconstruct the interior sound field of an enclosed space with vibrating boundaries using an open spherical microphone array. The interior sound fields of vibrating shells, including a pulsating shell, a [Formula: see text]-axis oriented oscillating shell, a partially vibrating shell and a point-excited vibrating shell, were reconstructed, and numerical simulations were carried out to examine the impact of reconstruction parameters, the radius of the microphone array, the number of microphones, the distribution of microphones on the array surface, the wave number, the number of basis functions used, and the radius of the reconstruction surface on the accuracy of reconstruction. In order to minimize the error of reconstruction caused by a variety of factors and uncertainties, such as the measurement noise, regularization treatments were introduced into the process of reconstructing, to suppress the divergent trends of the reconstruction error along with the increase of the wave number and the increase of the radius of the reconstruction surface. Results showed that a Tikhonov regularization method with generalized cross validation (GCV) could yield the least error of reconstruction among the investigated regularization methods.

scholarly journals Exoplanet mass estimation for a sample of targets for the Ariel mission

2021 ◽  
Author(s):  
J. R. Barnes ◽  
C. A. Haswell
Keyword(s):  
Radial Velocity ◽  
Input Parameter ◽  
Noise Sources ◽  
Time Commitment ◽  
Low Mass ◽  
Time Required ◽  
Fixed Input ◽  
The Impact ◽  
Quadrature Sampling

AbstractAriel’s ambitious goal to survey a quarter of known exoplanets will transform our knowledge of planetary atmospheres. Masses measured directly with the radial velocity technique are essential for well determined planetary bulk properties. Radial velocity masses will provide important checks of masses derived from atmospheric fits or alternatively can be treated as a fixed input parameter to reduce possible degeneracies in atmospheric retrievals. We quantify the impact of stellar activity on planet mass recovery for the Ariel mission sample using Sun-like spot models scaled for active stars combined with other noise sources. Planets with necessarily well-determined ephemerides will be selected for characterisation with Ariel. With this prior requirement, we simulate the derived planet mass precision as a function of the number of observations for a prospective sample of Ariel targets. We find that quadrature sampling can significantly reduce the time commitment required for follow-up RVs, and is most effective when the planetary RV signature is larger than the RV noise. For a typical radial velocity instrument operating on a 4 m class telescope and achieving 1 m s−1 precision, between ~17% and ~ 37% of the time commitment is spent on the 7% of planets with mass Mp < 10 M⊕. In many low activity cases, the time required is limited by asteroseismic and photon noise. For low mass or faint systems, we can recover masses with the same precision up to ~3 times more quickly with an instrumental precision of ~10 cm s−1.

Analysis and Reduction of the Waste in the Work Process Using Time Study Analysis: A Case Study

2014 ◽  
Vol 660 ◽  
pp. 971-975 ◽  
Author(s):  
Mohd Norzaim bin Che Ani ◽  
Siti Aisyah Binti Abdul Hamid
Keyword(s):  
Cycle Time ◽  
Lean Manufacturing ◽  
Value Added ◽  
Time Study ◽  
Study Approach ◽  
Root Cause ◽  
Wide Range ◽  
Unit Of Work ◽  
Time Required ◽  
The Impact

Time study is the process of observation which concerned with the determination of the amount of time required to perform a unit of work involves of internal, external and machine time elements. Originally, time study was first starting to be used in Europe since 1760s in manufacturing fields. It is the flexible technique in lean manufacturing and suitable for a wide range of situations. Time study approach that enable of reducing or minimizing ‘non-value added activities’ in the process cycle time which contribute to bottleneck time. The impact on improving process cycle time for organization that it was increasing the productivity and reduce cost. This project paper focusing on time study at selected processes with bottleneck time and identify the possible root cause which was contribute to high time required to perform a unit of work.

Laser-Based Measurement of Over Dimensional Freight Rail Shipments

2012 ◽  
Author(s):  
Bryan W. Schlake ◽  
Brian S. Daniel ◽  
Ron Voorheis
Keyword(s):  
Measurement System ◽  
Human Error ◽  
Cost Effective ◽  
Measuring System ◽  
Prototype System ◽  
Reference Target ◽  
Potential Benefits ◽  
Multiple Measurements ◽  
Current Measuring ◽  
Time Required

In pursuit of improved safety, Norfolk Southern Corp. (NS) has partnered with Amberg Technologies to explore the potential benefits of a laser-based measurement system for measuring over dimensional freight rail shipments. Shipments that do not fall within a standard geometric envelope, denoted as Plate B in the Association of American Railroads (AAR) Open Top Loading Rules [1], are considered to be over dimensional, or High-Wide Loads (HWLs). Extending beyond the limits of the Plate B diagram, these loads are not permitted in unrestricted interchange service. Instead, they must be measured both at points of origin and at interchange points. For US Class I Railroads, the de facto method for measuring HWLs requires mechanical personnel to either climb on the equipment or use a ladder and physically measure the overall height and width of the load. Using a tape measure, plumb line, and 6-foot level, car inspectors, or carmen, must often make multiple measurements to determine the height or width of a critical point on the load. The summation of these measurements can be subject to mathematical human error. In addition to the inherent limitations with regards to accuracy and efficiency, this method of measurement presents considerable safety challenges. The objective of the project was to develop a portable, cost-effective and accurate measurement system to improve the day-to-day operational process of measuring HWLs and reduce human exposure to railyard hazards. Norfolk Southern worked closely with Amberg Technologies to provide a clear overview of the current measuring methods, requirements, challenges and risks associated with HWLs. Amberg then developed a prototype system (with patent pending) and successful tests have been completed at both a point of origin for NS shipments and at a location where HWLs are received at interchange. The measuring system consists of a tripod mounted laser, a specially designed track reference target (TRT) and software designed specifically for HWL measurements. The system allows car inspectors to take measurements from a safe, strategic location away from the car. As a result, this system eliminates the need to climb on the equipment or a ladder and greatly reduces the amount of time spent on and around live tracks. In addition, initial tests indicate that this technology reduces the labor time required to measure HWLs by as much as one half while improving measurement accuracy. These tests have demonstrated that a laser-based system has the potential to greatly improve the safety, efficiency and accuracy associated with measuring HWLs.

Understanding Learning Environments, Personality, and Proctoring During Mandatory Remote Delivery

2021 ◽  
Vol 65 (1) ◽  
pp. 767-770
Author(s):  
Nancy J. Stone
Keyword(s):  
Online Learning ◽  
Online Education ◽  
Learning Environments ◽  
Online Survey ◽  
Campus Housing ◽  
Learning Success ◽  
Time Required ◽  
Relationship Of ◽  
The Impact ◽  
The Relationship

To evaluate students’ online learning environments, the relationship between personality and online learning success, and students’ perceptions about online proctoring during mandatory remote delivery due to the pandemic, students responded to an online survey. Learning environments generally included houses and rarely included on-campus housing. The specific room type was predominantly the bedroom. Only conscientiousness was related positively to anticipated semester GPA. The positive relationship between anticipated and overall GPA supports the notion that more conscientious students tend to be successful in online learning situations, as online education was rated as slightly ineffective. A majority of students did not see a need for online proctoring due to the inability or time required to search for materials, which would only harm one’s performance. There is a need to research further the impact of the study environment, relationship of the students’ personality to learning success, and consequences of online proctoring during remote learning.

Supplier performance measurement system use, relationship trust, and performance improvement: a dyadic perspective

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Vieri Maestrini ◽  
Andrea Stefano Patrucco ◽  
Davide Luzzini ◽  
Federico Caniato ◽  
Paolo Maccarrone
Keyword(s):  
Performance Measurement ◽  
Performance Improvement ◽  
Measurement System ◽  
Structural Equation ◽  
Performance Measurement System ◽  
Content Type ◽  
Performance Improvements ◽  
Supplier Performance ◽  
Performance Measurement Systems ◽  
The Impact

PurposeGrounding on resource orchestration theory, this paper aims to study the relationship between the way buying companies use their supplier performance measurement systems and the performance improvements obtained from suppliers, with relationship trust identified as a mediator in the previous link.Design/methodology/approachThe authors design a conceptual model and test it through structural equation modelling on a final sample of 147 buyer-supplier responses, collected by means of a dyadic survey.FindingsResults suggest that the buyer company may achieve the most by balancing a diagnostic and interactive use of the measurement system, as they are both positively related to supplier performance improvement. Furthermore, relationship trust acts as a mediator in case of the interactive use, but not for the diagnostic. This type of use negatively affects relationship trust, due to its mechanistic use in the buyer-supplier relationship.Originality/valueThe authors’ results contribute to the current academic debate about supplier performance measurement system design and use by analyzing the impact of different supplier performance measurement system uses, and highlighting their relative impact on relationship trust and supplier performance improvement. From a methodological perspective, adopting a dyadic data collection process increases the robustness of the findings.

Spreadsheet Tool for Quick-Turn 3D Numerical Modeling of Package Thermal Performance With Non-Uniform Die Heating

2001 ◽  
Author(s):  
Abhay A. Watwe ◽  
Ravi S. Prasher
Keyword(s):  
Finite Element ◽  
Numerical Modeling ◽  
Finite Volume ◽  
Thermal Performance ◽  
Three Dimensional ◽  
3D Numerical Modeling ◽  
Conventional Analysis ◽  
Time Required ◽  
The Impact ◽  
Fourier Equation

Abstract Traditional methods of estimating package thermal performance employ numerical modeling using commercially available finite-volume or finite-element tools. Use of these tools requires training and experience in thermal modeling. This methodology restricts the ability of die designers to quickly evaluate the thermal impact of their die architecture due to the added throughput time required to enlist the services of a thermal analyst. This paper describes the development of an easy to use spreadsheet tool, which performs quick-turn numerical evaluations of the impact of non-uniform die heating. The tool employs well-established finite-volume numerical techniques to solve the steady-state, three-dimensional Fourier equation of conduction in the package geometry. Minimal input data is required and the inputs are customized using visual basic pull-down menus to assist die designers who may not be thermal experts. Data showing comparison of the estimates from the spreadsheet tool with that obtained from a conventional analysis using the commercially available finite element code ANSYS™ is also presented.

scholarly journals A New Analysis Model for Potential Contamination of a Shallow Aquifer from a Hydraulically-Fractured Shale

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3010
Author(s):  
Weihong Peng ◽  
Menglin Du ◽  
Feng Gao ◽  
Xuan Dong ◽  
Hongmei Cheng
Keyword(s):  
Migration Time ◽  
Shallow Aquifer ◽  
Contaminant Migration ◽  
Analysis Model ◽  
Shallow Aquifers ◽  
Shale Formations ◽  
Migration Mechanism ◽  
Shale Reservoirs ◽  
Time Required ◽  
The Impact

Hydraulic fracturing (HF) is widely used in shale gas development, which may cause some heavy metals release from shale formations. These contaminants could transport from the fractured shale reservoirs to shallow aquifers. Thus, it is necessary to assess the impact of pollution in shallow aquifers. In this paper, a new analysis model, considering geological distributions, discrete natural fractures (NFs) and faults, is developed to analyze the migration mechanism of contaminants. Furthermore, the alkali erosion of rock caused by high-pH drilling of fluids, is considered in this paper. The numerical results suggest that both NFs and alkali erosion could reduce the time required for contaminants migrating to aquifers. When NFs and alkali erosion are both considered, the migration time will be shortened by 51 years. Alkali erosion makes the impact of NFs, on the contaminant migration, more significant. The migration time decreases with increasing pH values, while the accumulation is on the opposite side. Compared with pH 12.0, the migration time would be increased by 45 years and 29 years for pH 11.0 and 11.5, respectively. However, the migration time for pH 12.5 and 13.0 were found to be decreased by 82 years and 180 years, respectively. Alkali erosion could increase the rock permeability, and the elevated permeability would further enhance the migration velocity of the contaminants, which might play a major role in assessing the potential contamination of shallow aquifers.

Sign in / Sign up

Export Citation Format

Share Document