Evaluating the Effects of Transient Purge Flow on Stator-Rotor Seal Performance

2020 ◽  
pp. 1-55
Author(s):  
Reid A. Berdanier ◽  
Eric DeShong ◽  
Karen A. Thole ◽  
Christopher Robak
Keyword(s):  
Measurement Techniques ◽  
Operating Conditions ◽  
Pressure Measurements ◽  
Physical Mechanisms ◽  
Melting Temperatures ◽  
Thermally Driven ◽  
Purge Flow ◽  
Transient Events ◽  
Critical Components ◽  
The Relationship

Abstract As engine designs target higher efficiencies through increased turbine inlet temperatures, critical components are at risk of damage from conditions exceeding material melting temperatures. In particular, improperly designed underplatform hardware are susceptible to damage when hot gas is ingested into the stator-rotor cavity. While all turbines inherently experience transients during operation, a majority of publicly available turbine studies have been executed using steady operating conditions or transient “blowdown” rigs. For this reason, routine transient events are not well understood. To address this need, this study utilized a combined experimental and computational approach. The test article is a continuous-duration, one-stage turbine operating with true-scale engine hardware and seal geometries at engine-representative flow conditions. The nature of the continuous-duration facility supports assessment of transient events through its ability to transition between steady-state operating conditions. The effects of transient purge flow were investigated to identify general trends for transient events in a full-scale engine. Results from multiple measurement techniques in the wheelspace region show an interdependence of transient purge flow with thermal lag of the underplatform hardware. Through experiments conducted at different coolant-to-main gas path temperature ratios, the use of pressure measurements as an indicator of fully-purged behavior was introduced, and a thermally-driven influence on rim seal performance was quantified. The computational results show good agreement with experimental pressure measurements and provide insight into the physical mechanisms that drive the relationship between pressure and sealing effectiveness observed in the experiments.

Evaluating the Effects of Transient Purge Flow on Stator-Rotor Seal Performance

2019 ◽  
Author(s):  
Reid A. Berdanier ◽  
Eric T. DeShong ◽  
Karen A. Thole
Keyword(s):  
Measurement Techniques ◽  
Operating Conditions ◽  
Pressure Measurements ◽  
Flow Conditions ◽  
Melting Temperatures ◽  
Increased Risk ◽  
Thermally Driven ◽  
Purge Flow ◽  
Transient Events ◽  
Thermal Lag

Abstract As modern engine designs target higher efficiencies through increased turbine inlet temperatures, critical turbine components are at increased risk of damage from conditions exceeding material melting temperatures. In particular, improperly designed underplatform hardware components are susceptible to damage when hot main gas path flow is ingested into the stator-rotor cavity. While all turbines inherently experience transients during operation, a majority of turbine tests have been executed using steady operating conditions, and routine transient events are not well understood. To address this need, the present study utilizes a continuous-duration, one-stage test turbine operating with true-scale engine hardware and seal geometries at engine-representative flow conditions. The nature of the continuous-duration facility uniquely supports direct assessment of transient events through its ability to transition between steady-state operating conditions. Specifically, the effects of a transient purge flow were investigated in this study to identify general trends for transient events in a full-scale engine. Results from multiple measurement techniques in the wheelspace region show an interdependence of transient purge flow with a thermal lag of the underplatform hardware. Through experiments conducted at different coolant-to-main gas path temperature ratios, the use of pressure measurements as an indicator of fully-purged behavior was introduced, and a thermally-driven influence on rim seal performance was quantified.

The Effect of Vanes and Blades on Ingress in Gas Turbines

2019 ◽  
Author(s):  
Fabian P. T. Hualca ◽  
Josh T. M. Horwood ◽  
Carl M. Sangan ◽  
Gary D. Lock ◽  
James A. Scobie
Keyword(s):  
Flow Rate ◽  
Gas Turbines ◽  
Large Scale ◽  
Strong Influence ◽  
Rotor Blades ◽  
Pressure Measurements ◽  
Test Rig ◽  
Purge Flow ◽  
Unsteady Pressure Measurements ◽  
The Relationship

Abstract This paper presents experimental and computational results using a 1.5-stage test rig designed to investigate the effects of ingress through a double radial overlap rim-seal. The effect of the vanes and blades on ingress was investigated by a series of carefully-controlled experiments: firstly, the position of the vane relative to the rim seal was varied; secondly, the effect of the rotor blades was isolated using a disc with and without blades. Measurements of steady pressure in the annulus show a strong influence of the vane position. The relationship between sealing effectiveness and purge flow-rate exhibited a pronounced inflexion for intermediate levels of purge; the inflexion did not occur for experiments with a bladeless rotor. Shifting the vane closer to the rim-seal, and therefore the blade, caused a local increase in ingress in the inflexion region; again this effect was not observed for the bladeless experiments. Unsteady pressure measurements at the periphery of the wheel-space revealed the existence of large-scale pressure structures (or instabilities) which depended weakly on the vane position and sealing flow rate. These were measured with and without the blades on the rotor disc. In all cases these structures rotated close to the disc speed.

Correlating Time-Resolved Pressure Measurements with Rim Sealing Effectiveness for Real-Time Turbine Health Monitoring

2021 ◽  
pp. 1-40
Author(s):  
Eric DeShong ◽  
Benjamin Peters ◽  
Reid A. Berdanier ◽  
Karen A. Thole ◽  
Kamran Paynabar ◽  
...  
Keyword(s):  
Real Time ◽  
Performance Feedback ◽  
Domain Knowledge ◽  
Performance Monitoring ◽  
Operating Conditions ◽  
Machine Learning Techniques ◽  
Pressure Measurements ◽  
Time Resolved ◽  
Learning Techniques ◽  
Purge Flow

Abstract Purge flow is bled from the upstream compressor and supplied to the under-platform region to prevent hot main gas path ingress that damages vulnerable under-platform hardware components. A majority of turbine rim seal research has sought to identify methods of improving sealing technologies and understanding the physical mechanisms that drive ingress. While these studies directly support the design and analysis of advanced rim seal geometries and purge flow systems, the studies are limited in their applicability to real-time monitoring required for condition-based operation and maintenance. As operational hours increase for in-service engines, this lack of rim seal performance feedback results in progressive degradation of sealing effectiveness, thereby leading to reduced hardware life. To address this need for rim seal performance monitoring, the present study utilizes measurements from a one-stage turbine research facility operating with true-scale engine hardware at engine-relevant conditions. Time-resolved pressure measurements collected from the rim seal region are regressed with sealing effectiveness through the use of common machine learning techniques to provide real-time feedback of sealing effectiveness. Two modelling approaches are presented that use a single sensor to predict sealing effectiveness accurately over a range of two turbine operating conditions. Results show that an initial purely data-driven model can be further improved using domain knowledge of relevant turbine operations, which yields sealing effectiveness predictions within three percent of measured values.

Correlating Time-Resolved Pressure Measurements With Rim Sealing Effectiveness for Real-Time Turbine Health Monitoring

2021 ◽  
Author(s):  
Eric T. DeShong ◽  
Benjamin Peters ◽  
Reid A. Berdanier ◽  
Karen A. Thole ◽  
Kamran Paynabar ◽  
...  
Keyword(s):  
Real Time ◽  
Performance Feedback ◽  
Domain Knowledge ◽  
Performance Monitoring ◽  
Operating Conditions ◽  
Machine Learning Techniques ◽  
Pressure Measurements ◽  
Time Resolved ◽  
Learning Techniques ◽  
Purge Flow

Abstract Purge flow is bled from the upstream compressor and supplied to the under-platform region to prevent hot main gas path ingress that damages vulnerable under-platform hardware components. A majority of turbine rim seal research has sought to identify methods of improving sealing technologies and understanding the physical mechanisms that drive ingress. While these studies directly support the design and analysis of advanced rim seal geometries and purge flow systems, the studies are limited in their applicability to real-time monitoring required for condition-based operation and maintenance. As operational hours increase for in-service engines, this lack of rim seal performance feedback results in progressive degradation of sealing effectiveness, thereby leading to reduced hardware life. To address this need for rim seal performance monitoring, the present study utilizes measurements from a one-stage turbine research facility operating with true-scale engine hardware at engine-relevant conditions. Time-resolved pressure measurements collected from the rim seal region are regressed with sealing effectiveness through the use of common machine learning techniques to provide real-time feedback of sealing effectiveness. Two modelling approaches are presented that use a single sensor to predict sealing effectiveness accurately over a range of two turbine operating conditions. Results show that an initial purely data-driven model can be further improved using domain knowledge of relevant turbine operations, which yields sealing effectiveness predictions within three percent of measured values.

A pilot web former designed to study retention-formation relationships

2010 ◽  
Vol 25 (2) ◽  
pp. 185-194
Author(s):  
Anna Svedberg ◽  
Tom Lindström
Keyword(s):  
Pilot Scale ◽  
Operating Conditions ◽  
Montmorillonite Clay ◽  
Speed Ratio ◽  
Good Reproducibility ◽  
Total Solids ◽  
Retention Aids ◽  
Solids Content ◽  
Relationship Of ◽  
The Relationship

Abstract A pilot-scale fourdrinier former has been developed for the purpose of investigating the relationship between retention and paper formation (features, retention aids, dosage points, etc.). The main objective of this publication was to present the R-F (Retention and formation)-machine and demonstrate some of its fields of applications. For a fine paper stock (90% hardwood and 10% softwood) with addition of 25% filler (based on total solids content), the relationship between retention and formation was investigated for a microparticulate retention aid (cationic polyacrylamide together with anionic montmorillonite clay). The retention-formation relationship of the retention aid system was investigated after choosing standardized machine operating conditions (e.g. the jet-to-wire speed ratio). As expected, the formation was impaired when the retention was increased. Since good reproducibility was attained, the R-F (Retention and formation)-machine was found to be a useful tool for studying the relationship between retention and paper formation.

scholarly journals Engine Malfunctioning Conditions Identification through Instantaneous Crankshaft Torque Measurement Analysis

2021 ◽  
Vol 11 (8) ◽  
pp. 3522
Author(s):  
Konstantinos-Marios Tsitsilonis ◽  
Gerasimos Theotokatos
Keyword(s):  
Operating Conditions ◽  
Cylinder Pressure ◽  
Dynamics Model ◽  
Engine Model ◽  
Measurement Analysis ◽  
Start Of Injection ◽  
Rate Of Heat Release ◽  
Relationship Of ◽  
Diagnostic Measurement ◽  
The Relationship

In this study a coupled thermodynamics and crankshaft dynamics model of a large two-stroke diesel engine was utilised, to map the relationship of the engine Instantaneous Crankshaft Torque (ICT) with the following frequently occurring malfunctioning conditions: (a) change in Start of Injection (SOI), (b) change in Rate of Heat Release (RHR), (c) change in scavenge air pressure, and (d) blowby. This was performed using frequency analysis on the engine ICT, which was obtained through a series of parametric runs of the coupled engine model, under the various malfunctioning and healthy operating conditions. This process demonstrated that engine ICT can be successfully utilised to identify the distinct effects of malfunctions (c) or (d), as they occur individually in any cylinder. Furthermore by using the same process, malfunctions (a) and (b) can be identified as they occur individually for any cylinder, however there is no distinct effect on the engine ICT among these malfunctions, since their effect on the in-cylinder pressure is similar. As a result, this study demonstrates the usefulness of the engine ICT as a non-intrusive diagnostic measurement, as well as the benefits of malfunctioning conditions mapping, which allows for quick and less resource intensive identification of engine malfunctions.

scholarly journals Improvement Effect of Green Remodeling and Building Value Assessment Criteria for Aging Public Buildings

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1200
Author(s):  
Yong-Joon Jun ◽  
Seung-ho Ahn ◽  
Kyung-Soon Park
Keyword(s):  
High Efficiency ◽  
Energy Performance ◽  
Operating Conditions ◽  
Energy Usage ◽  
Public Buildings ◽  
Value Judgment ◽  
Relationship Analysis ◽  
Improvement Effect ◽  
The Relationship ◽  
Usage Data

The Green Remodeling Project under South Korea’s Green New Deal policy is a government-led project intended to strengthen the performance sector directly correlated with energy performance among various elements of improvement applicable to building remodeling by replacing insulation materials, introducing new and renewable energy, introducing high-efficiency equipment, etc., with public buildings taking the lead in green remodeling in order to induce energy efficiency enhancement in private buildings. However, there is an ongoing policy that involves the application of a fragmentary value judgment criterion, i.e., whether to apply technical elements confined to the enhancement of the energy performance of target buildings and the prediction of improvement effects according thereto, thus resulting in the phenomenon of another important value criterion for green remodeling, i.e., the enhancement of the occupant (user) comfort performance of target buildings as one of its purposes, being neglected instead. In order to accurately grasp the current status of these problems and to promote ‘expansion of the value judgment criteria for green remodeling’ as an alternative, this study collected energy usage data of buildings actually used by public institutions and then conducted a total analysis. After that, the characteristics of energy usage were analyzed for each of the groups of buildings classified by year of completion, thereby carrying out an analysis of the correlation between the non-architectural elements affecting the actual energy usage and the actual energy usage data. The correlation between the improvement performance of each technical element and the actual improvement effect was also analyzed, thereby ascertaining the relationship between the direction of major policy strategies and the actual energy usage. As a result of the relationship analysis, it was confirmed that the actual energy usage is more affected by the operating conditions of the relevant building than the application of individual strategic elements such as the performance of the envelope insulation and the performance of the high-efficiency system. In addition, it was also confirmed that the usage of public buildings does not increase in proportion to their aging. The primary goal of reducing energy usage in target buildings can be achieved if public sector (government)-led green remodeling is pushed ahead with in accordance with biased value judgment criteria, just as in the case of a campaign to refrain from operating cooling facilities in aging public buildings. However, it was possible to grasp through the progress of this study that the remodeling may also result in the deterioration of environmental comfort and stability, such as the numerical value of the indoor thermal environment. The results of this study have the significance of providing basic data for pushing ahead with a green remodeling policy in which the value judgment criteria for aging existing public buildings are more expanded, and it is necessary to continue research in such a direction that the quantitative purpose of green remodeling, which is to reduce energy usage in aging public buildings, and its qualitative purpose, which is to enhance their environmental performance for occupants’ comfort, can be mutually balanced and secured at the same time.

Two-Stroke Marine Diesel Engine Variable Injection Timing System Performance Evaluation and Optimum Setting for Minimum Fuel Consumption at Acceptable NOx Levels

2014 ◽  
Author(s):  
Dimitrios T. Hountalas ◽  
Spiridon Raptotasios ◽  
Antonis Antonopoulos ◽  
Stavros Daniolos ◽  
Iosif Dolaptzis ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Engine Performance ◽  
Operating Conditions ◽  
Specific Fuel Consumption ◽  
Injection Timing ◽  
Nox Emissions ◽  
Pressure Measurements ◽  
Cylinder Pressure ◽  
Start Of Injection

Currently the most promising solution for marine propulsion is the two-stroke low-speed diesel engine. Start of Injection (SOI) is of significant importance for these engines due to its effect on firing pressure and specific fuel consumption. Therefore these engines are usually equipped with Variable Injection Timing (VIT) systems for variation of SOI with load. Proper operation of these systems is essential for both safe engine operation and performance since they are also used to control peak firing pressure. However, it is rather difficult to evaluate the operation of VIT system and determine the required rack settings for a specific SOI angle without using experimental techniques, which are extremely expensive and time consuming. For this reason in the present work it is examined the use of on-board monitoring and diagnosis techniques to overcome this difficulty. The application is conducted on a commercial vessel equipped with a two-stroke engine from which cylinder pressure measurements were acquired. From the processing of measurements acquired at various operating conditions it is determined the relation between VIT rack position and start of injection angle. This is used to evaluate the VIT system condition and determine the required settings to achieve the desired SOI angle. After VIT system tuning, new measurements were acquired from the processing of which results were derived for various operating parameters, i.e. brake power, specific fuel consumption, heat release rate, start of combustion etc. From the comparative evaluation of results before and after VIT adjustment it is revealed an improvement of specific fuel consumption while firing pressure remains within limits. It is thus revealed that the proposed method has the potential to overcome the disadvantages of purely experimental trial and error methods and that its use can result to fuel saving with minimum effort and time. To evaluate the corresponding effect on NOx emissions, as required by Marpol Annex-VI regulation a theoretical investigation is conducted using a multi-zone combustion model. Shop-test and NOx-file data are used to evaluate its ability to predict engine performance and NOx emissions before conducting the investigation. Moreover, the results derived from the on-board cylinder pressure measurements, after VIT system tuning, are used to evaluate the model’s ability to predict the effect of SOI variation on engine performance. Then the simulation model is applied to estimate the impact of SOI advance on NOx emissions. As revealed NOx emissions remain within limits despite the SOI variation (increase).

A Parametric Examination of the Factors Affecting the Performance of a Diffusion Absorption Refrigeration System

2021 ◽  
pp. 1-38
Author(s):  
Noman Yousuf ◽  
Timothy Anderson ◽  
Roy Nates
Keyword(s):  
Waste Heat ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Low Grade ◽  
Absorption Refrigeration ◽  
Factors Affecting ◽  
Thermally Driven ◽  
Mass Flowrate ◽  
Diffusion Absorption

Abstract Despite being identified nearly a century ago, the diffusion absorption refrigeration (DAR) cycle has received relatively little attention. One of the strongest attractions of the DAR cycle lies in the fact that it is thermally driven and does not require high value work. This makes it a prime candidate for harnessing low grade heat from solar collectors, or the waste heat from stationary generators, to produce cooling. However, to realize the benefits of the DAR cycle, there is a need to develop an improved understanding of how design parameters influence its performance. In this vein, this work developed a new parametric model that can be used to examine the performance of the DAR cycle for a range of operating conditions. The results showed that the cycle's performance was particularly sensitive to several factors: the rate of heat added and the temperature of the generator, the effectiveness of the gas and solution heat exchangers, the mass flowrate of the refrigerant and the type of the working fluid. It was shown that can deliver good performance at low generator temperatures if the refrigerant mass fraction in the strong solution is made as high as possible. Moreover, it was shown that a H2O-LiBr working pair could be useful for achieving cooling at low generator temperatures.

Characterization of the morning transition from downslope to upslope winds and its connection with the nocturnal inversion breakup at the foot of a gentle slope

2021 ◽  
Author(s):  
Sofia Farina ◽  
Dino Zardi ◽  
Silvana Di Sabatino ◽  
Mattia Marchio ◽  
Francesco Barbano
Keyword(s):  
Salt Lake ◽  
Vertical Direction ◽  
Blow Down ◽  
Physical Mechanisms ◽  
Morning Transition ◽  
Thermally Driven ◽  
Slope Wind ◽  
Slope Flow ◽  
Nocturnal Inversion

<p>Thermally driven winds observed in complex terrain are characterized by a daily cycle dominated by two main phases: a diurnal phase in which winds blow upslope (anabatic), and a nocturnal one in which they revert their direction and blow down slope (katabatic). This alternating pattern also implies two transition phases, following sunrise and sunset respectively. </p><p>Here we study the up-slope component of the slope wind with a focus on the morning transition based on from the MATERHORN experiment, performed in Salt Lake Desert (Utah) between Fall 2012 and Spring 2013. </p><p>The analysis develops along three main paths of investigation. The first one is the selection of the suitable conditions for the study of the diurnal component and the characterization of the morning transition. The second one focuses on the deep analysis of the erosion of the nocturnal inversion at the foot of the slope in order to investigate the physical mechanisms driving it. And the third one consists in the comparison between the experimental data and the results of an analytical model (Zardi and Serafin, 2015). The study of the morning transition in the selected case studies allowed its characterization in terms of the relation with the solar radiation cycle, in terms of its seasonality and in terms of its propagation along the slope and along the vertical direction. Most of the results of this investigation are related to the identification of the main mechanisms of erosion of the nocturnal inversion at the foot of the slope and to its role to the beginning of the transition itself. Finally, it is shown how the above model can fairly reproduce the cycle between anabatic and katabatic flow and their intensity.</p><p>Zardi, D. and S. Serafin, 2015: An analytic solution for daily-periodic thermally-driven slope flow. Quart. J. Roy. Meteor. Soc., 141, 1968–1974.</p>

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