The Whole-Engine Model for Clearance Evaluation

2009 ◽  
Author(s):  
Alexander N. Arkhipov ◽  
Vladimir V. Karaban ◽  
Igor V. Putchkov ◽  
Guenter Filkorn ◽  
Andreas Kieninger
Keyword(s):  
Steady State ◽  
Transient Analysis ◽  
Operating Experience ◽  
Operating Conditions ◽  
Design Stage ◽  
Fe Model ◽  
Engine Operation ◽  
Engine Model ◽  
Operation Conditions ◽  
3D Effects

The evaluation of the blading clearance at the design stage is important for heavy duty gas turbine efficiency. The minimum clearance value at base load is limited by the pinch point clearance during startup and/or shutdown. Therefore, transient analysis is necessary for different operating conditions. 3D transient analysis of a whole engine is labor-intensive; however 2D axisymmetric analysis does not allow consideration of different 3D effects (e.g. twisting, bending, ovality, rotor alignment). In order to overcome these cost and time limitations, the combination of 2D, axisymmetric, whole-engine model results and the scaled deflections caused by different 3D effects is used for the axial and radial clearance engineering assessment during engine operation. The basic rotor and stator closures are taken from the transient analysis using a 2D finite element (FE) model composed of axisymmetric solid and plane stress elements. To take into account 3D effects of airfoil twisting and bending, the 3D FE displacements of the blade are included in the clearance evaluation process. The relative displacements of airfoil tip and reference point at the blade or vane hub are taken from 3D steady-state FE analyses. Then the steady-state displacements of the airfoils are scaled for transient conditions using the proposed technique. Different 3D rotor / stator effects (cold-build clearances and their tolerances, rotor position with respect to stator after assembly, casing bending, deformations of compressor and turbine vane carrier inducing of casing ovalization, exhaust gas housing movements, movements of the rotor in bearings and CVC and TVC support, etc.) are also included as a contributor to the clearances. The results of the calculations are analyzed and compared with good agreements to the clearances measured in engine testing under real operation conditions. The proposed methodology allows assessing the operating clearances between the stator and rotor during the design phase. Optimization of the running clearance is one key measure to upgrade and improve the engine performance during operating experience.

scholarly journals The Determination of Steady-State Movements Using Blade Tip Timing Data

2018 ◽  
Author(s):  
Mohamed Mohamed ◽  
Philip Bonello ◽  
Peter Russhard
Keyword(s):  
Steady State ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Fe Model ◽  
Measurement Point ◽  
Fe Modelling ◽  
Timing Data ◽  
Blade Tip ◽  
Dc Component ◽  
Change In Mean

One of the main challenges of the Blade Tip Timing (BTT) measurement method is to be able to determine the sensing position of the probe relative to the blade tip. It is highly important to identify the measurement point of BTT since each point of the blade tip may have a different vibration response. This means that a change in measurement position will affect the amplitude, phase and DC component of the results obtained from BTT data. This increases the uncertainty in the correlation between BTT measurements and Finite Element (FE) modelling. Also, the measurement point should ideally be located to measure as many modes as possible. This means that the probe’s position should not coincide with a node, or a position at which the sensor misses the blade tip. Changes in the sensing position usually arise from the steady state movements of the blades (change in mean displacement). Such movements are caused by changes to the static (thermal and pressure) loading conditions that result from changes in the rotational speed. Such movements usually have a constant direction at normal operating conditions, but the direction may fluctuate if the machine develops a fault. There are three main types of movements of the sensing position that are considered in this paper: (1) axial movement; (2) blade lean; (3) blade untwist. Ideally, the sensing position is known based on the geometries of both the blade and the probe, but due to different types of movements of the blade this position is lost. Very few works have researched the extraction of the sensing position. Such preliminary works have required a pre-knowledge of mode shapes and additional instrumentation. The aim of this paper is to present a novel method for the identification of the BTT sensing position of the probes relative to a blade tip, which can be used to quantify the above movements. The developed method works by extracting the steady state offset from measurements of blade tip displacements over a number of revolutions as the speed changes from zero to a certain value. Hence, that part of the offset that is due to the angular positioning error of the probes (outside the scope of this work) is cancelled out (since it is independent of speed). The change in steady state offset is then processed to identify the three possible movements. The new method is validated using a novel BTT simulator that is based on the modal model of the FE model of a bladed disk (“blisk”). The simulator generates BTT data for prescribed changes to the sensing position. The validation tests show that the novel algorithm can identify such movements within a 2% margin of error.

Startup and Steady-State Performance of a New Renewable Hydroprocessed Depolymerized Cellulosic Diesel Fuel in Multiple Diesel Engines

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Eric Bermudez ◽  
Andrew McDaniel ◽  
Terrence Dickerson ◽  
Dianne Luning Prak ◽  
Len Hamilton ◽  
...  
Keyword(s):  
Steady State ◽  
Diesel Engine ◽  
Cetane Number ◽  
Operating Conditions ◽  
Engine Operation ◽  
Start Of Injection ◽  
Ignition Quality ◽  
Engine Testing ◽  
Engine Start ◽  
Distillate Fuel

A new hydroprocessed depolymerized cellulosic diesel (HDCD) fuel has been developed using a process which takes biomass feedstock (principally cellulosic wood) to produce a synthetic fuel that has nominally ½ cycloparaffins and ½ aromatic hydrocarbons in content. This HDCD fuel with a low cetane value (derived cetane number from the ignition quality tester, DCN = 27) was blended with naval distillate fuel (NATO symbol F-76) in various quantities and tested in order to determine how much HDCD could be blended before diesel engine operation becomes problematic. Blends of 20% HDCD (DCN = 45), 30%, 40% (DCN = 41), and 60% HDCD (DCN = 37) by volume were tested with conventional naval distillate fuel (DCN = 49). Engine start performance was evaluated with a conventional mechanically direct injected (DI) Yanmar engine and a Waukesha mechanical indirect injected (IDI) Cooperative Fuels Research (CFR) diesel engine and showed that engine start times increased steadily with increasing HDCD content. Longer start times with increasing HDCD content were the result of some engine cycles with poor combustion leading to a slower rate of engine acceleration toward rated speed. A repeating sequence of alternating cycles which combust followed by a noncombustion cycle was common during engine run-up. Additionally, steady-state engine testing was also performed using both engines. HDCD has a significantly higher bulk modulus than F76 due to its very high aromatic content, and the engines showed earlier start of injection (SOI) timing with increasing HDCD content for equivalent operating conditions. Additionally, due to the lower DCN, the higher HDCD blends showed moderately longer ignition delay (IGD) with moderately shorter overall burn durations. Thus, the midcombustion metric (CA50: 50% burn duration crank angle position) was only modestly affected with increasing HDCD content. Increasing HDCD content beyond 40% leads to significantly longer start times.

scholarly journals Economizer Selection Method with Reference to its Reliability at Preliminary Design Stage of Seagoing Vessels

2009 ◽  
Vol 9-10 (1) ◽  
pp. 35-44
Author(s):  
Charchalis Adam ◽  
Krefft Jerzy
Keyword(s):  
Heat Exchange ◽  
Selection Method ◽  
Operating Conditions ◽  
Design Stage ◽  
Exhaust Gas ◽  
Preliminary Design ◽  
Incomplete Combustion ◽  
Operation Conditions ◽  
Preliminary Design Stage ◽  
Main Engine

Economizer Selection Method with Reference to its Reliability at Preliminary Design Stage of Seagoing Vessels The economizers are used for production of steam heating on en route ships. The economizers are producing steam in a heat exchange process from the ship's main engine exhaust gas. Products of the incomplete combustion of the heavy fuel oil remaining in engines, passing the boiler, collect on the heat exchange surface of the economizer. When the incorrect assumptions are made for the boiler operation conditions, the boiler steam capacity drops and fire and burning of the incomplete combustion products can occur in the economizer. To minimize combustion product quantity that collects on the boiler surface, the allowable exhaust gas pressure drop in the boiler should be taken into consideration, as well as the results from recommended exhaust gas flow velocity that is determined by main engine service load determined in the preliminary design phase of the ship. The remaining operating conditions are made in such a way to obtain high steam capacity of the boiler. It is essential at the design stage to take into consideration the future operating parameters of the combustion-steam-water installation, since these parameters depend on the choice of boiler and determined at the design stage production of steam. On the basis of operation parameters of contemporary container ships, an attempt was made to select economizer capacity in the preliminary design stage taking into consideration operation conditions of the propulsion system-steam installations unit in aspect of economizer reliability.

An Experimental Investigation of the Steady-State Response of a Noncontacting Flexibly Mounted Rotor Mechanical Face Seal

1995 ◽  
Vol 117 (1) ◽  
pp. 153-159 ◽  
Author(s):  
An Sung Lee ◽  
Itzhak Green
Keyword(s):  
Experimental Investigation ◽  
Steady State ◽  
Dynamic Behavior ◽  
Amplitude Ratio ◽  
Theoretical Work ◽  
Operating Conditions ◽  
Superior Performance ◽  
Steady State Response ◽  
State Response ◽  
Operation Conditions

Recent theoretical work on the dynamics of the noncontacting flexibly mounted rotor (FMR) seal has shown that it is superior in every aspect of dynamic behavior compared to the flexibly mounted stator (FMS) seal. The FMR seal is inherently stable regardless of the operating speed, the maximum relative misalignment response is smaller, and the critical stator misalignment is larger. All these are measures of superior performance. This work undertakes the experimental investigation of the dynamic behavior of a noncontacting FMR seal. The steady-state response of the FMR seal was measured at various operating conditions. The results are given in terms of dynamic and static transmissibilities, i.e., amplitude ratio of responses to two forcing inputs: the initial rotor and fixed stator misalignments. These are then compared to the analytical predictions. Further, operation maps are drawn for each set of operation conditions. The maps indicate how safely (away from contact) the seal operates. It is shown that the combination of the seal parameters that maximize the fluid film stiffness is optimal for safe noncontacting operation.

Transient Analysis for Contained-Cold-Aisle Data Center

2012 ◽  
Author(s):  
Sami A. Alkharabsheh ◽  
Mahmoud Ibrahim ◽  
Saurabh Shrivastava ◽  
Roger Schmidt ◽  
Bahgat Sammakia
Keyword(s):  
Steady State ◽  
Temperature Distribution ◽  
Data Center ◽  
Transient Analysis ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Base Case ◽  
Air Temperatures ◽  
Air Supply ◽  
Final Steady State

The objective of this paper is to conduct a transient analysis for a contained-cold-aisle data center using Computational Fluid Dynamics (CFD) modeling. Containing the cold aisle reduces the inherent challenges of predictability and energy consumption of data center cooling systems by separating the hot and cold air streams. Transient analysis is crucial to further show the benefits of this methodology and investigate the potential drawbacks. In this work, we investigate the effect of variable power and flow rate in time on a raised-floor data center with specific geometry. First, a base case numerical model is established. Then, we conduct a transient analysis for the uncontained base case and the three containment configurations. The containment configurations under consideration are ceiling-only, doors-only, and fully-contained cold aisle. We hold a comparison between different geometrical configurations of the containment system under certain transient operating conditions. Computer Room Air Conditioning (CRAC) failure and change in IT-demand are chosen to represent conventional transient scenarios in a data center. The transient analysis shows overshoots of cabinet inlet air temperatures beyond the final steady state, which cannot predicted through a simple steady state analysis. In addition, the uniform temperature distribution inside the cold aisle is affected by the change in air supply and level of containment. The temperature distribution in the cold aisle changes with time. Guidelines can be recommended based on the conclusion of this study.

Developments and Experiences With Pulsation Measurements for Heavy-Duty Gas Turbines

2007 ◽  
Author(s):  
Hanspeter Zinn ◽  
Michael Habermann
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Dynamic Pressure ◽  
Optimal Operation ◽  
Operating Conditions ◽  
Probe Design ◽  
Heavy Duty ◽  
Engine Operation ◽  
Accuracy Measurement ◽  
Operation Conditions

The dynamical combustion processes (pulsations) of heavy-duty gas turbines must be supervised by suitable instrumentation for optimal operation of the engine regarding emissions and component life. But the hostile environment of the combustor makes it difficult to perform the measurements. There are two possible approaches to measure the combustor pulsations. Either a high temperature sensor is placed as close as possible to the combustion chamber to measure the acoustics directly (Cavity Type Probe), or the acoustic signal is led to the outside of the engine by means of a reflection free waveguide, where a dynamic pressure sensor picks up the passing signal (Long Line Probe). Both approaches were developed and investigated in detail. This paper describes the past and current efforts in refining the probe designs for use in the harsh operational environment while maintaining sensor accuracy, measurement range and lifetime as a rugged probe. Theoretical and laboratory investigations were undertaken to increase the useable frequency range of the Cavity Type Probe up to 8kHz under engine operation conditions. This was made possible with a smaller high temperature transducer, which is the result of a cooperative development project with a sensor manufacturer. Experiences with both probe concepts on Alstom’s GT26 Test Power Plant in Birr and on field engines provided clear confirmation that the Cavity Type Probe design with an advanced sensor now fulfils all initially defined requirements of acoustic combustion measurements on heavy-duty gas turbines. On the contrary, the waveguide design principle has fundamental limitations in the direct measurement of the combustion acoustics at gas turbine operating conditions.

scholarly journals Application of a Constant Gain Extended Kalman Filter for In-Flight Estimation of Aircraft Engine Performance Parameters

2005 ◽  
Author(s):  
Takahisa Kobayashi ◽  
Donald L. Simon ◽  
Jonathan S. Litt
Keyword(s):  
Kalman Filter ◽  
Extended Kalman Filter ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Accurate Estimation ◽  
Aircraft Engines ◽  
Performance Parameters ◽  
Efficient Manner ◽  
Engine Operation ◽  
Engine Model

An approach based on the Constant Gain Extended Kalman Filter (CGEKF) technique is investigated for the in-flight estimation of non-measurable performance parameters of aircraft engines. Performance parameters, such as thrust and stall margins, provide crucial information for operating an aircraft engine in a safe and efficient manner, but they can not be directly measured during flight. A technique to accurately estimate these parameters is, therefore, essential for further enhancement of engine operation. In this paper, a CGEKF is developed by combining an on-board engine model and a single Kalman gain matrix. In order to make the on-board engine model adaptive to the real engine’s performance variations due to degradation or anomalies, the CGEKF is designed with the ability to adjust its performance through the adjustment of artificial parameters called “tuning parameters.” With this design approach, the CGEKF can maintain accurate estimation performance when it is applied to aircraft engines at off-nominal conditions. The performance of the CGEKF is evaluated in a simulation environment using numerous component degradation and fault scenarios at multiple operating conditions.

Transient “Single-Fuel” RCCI Operation With Customized Pistons in a Light-Duty Multicylinder Engine

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Christopher W. Gross ◽  
Rolf D. Reitz
Keyword(s):  
Steady State ◽  
Compression Ratio ◽  
Fuel Injection ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Maximum Pressure ◽  
Engine Operation ◽  
Volume Percentage ◽  
Light Duty ◽  
Brake Mean Effective Pressure

Reactivity controlled compression ignition (RCCI) combustion in a light-duty multicylinder engine (MCE) over transient operating conditions using fast response exhaust unburned hydrocarbon (UHC1), nitric oxide (NO), and particulate matter (PM) measurement instruments was investigated. RCCI has demonstrated improvements in efficiency along with low NOx and PM emissions by utilizing in-cylinder fuel blending, generally using two fuels with different reactivity in order to optimize stratification. In the present work, a “single-fuel” approach for RCCI combustion using port-injected gasoline and direct-injected gasoline mixed with a small amount of the cetane improver 2-ethylhexyl nitrate (EHN) was studied with custom designed, compression ratio (CR) of 13.75:1, pistons under transient conditions. The EHN volume percentage in the mixture for the direct-injected fuel was set at 3%. In an experimental investigation, comparisons were made to transient RCCI combustion operation with gasoline/diesel. The experiments were performed over a step load change from 1 to 4 bar brake mean effective pressure (BMEP) at constant 1500 rev/min on a General Motors (GM) Z19DTH 1.9-L diesel engine. The transients were conducted by changing the accelerator pedal command to provide a desired torque output with a DRIVVEN engine control unit (ECU) that replaced the original Bosch ECU. All relevant engine parameters are adjusted accordingly, based on 2D-tables. Previous to the transient engine operation, four steady-state points were used to obtain performance and emission values. Engine calibration at these four points, as well as the interpolation of the intermediate points, allowed for smooth operation during the instantaneous step changes. Differences between the steady-state and transient results indicate the complexity of transient operation and show the need for additional controls to minimize undesirable effects. The steady-state points were calibrated by modifying the fuel injection strategy (actual start of injection (aSOI) timing, port-fuel injection (PFI) fraction, etc.), exhaust gas recirculation (EGR), and rail pressure in order to obtain predefined values for the crank-angle at 50% of total heat release (CA50). Furthermore, emission targets (HC1 < 1500 ppmC3, NO < 10 ppm, filter smoke number (FSN)<0.1 with a maximum pressure rise rate (MPRR) < 10 bar/deg) and noise level targets (<95 dB) for RCCI combustion were maintained during the calibration and mapping. The tests were performed with a closed-loop (CL) calibration by using a next-cycle (NC) controller to adjust the PFI ratio of each cycle in order to reach the steady-state CA50 values in the table. The results show that single-fuel RCCI operation can be achieved, but requires significant alteration of the operating conditions, and NOx emissions were significantly elevated for gasoline/gasoline–EHN operation. While combustion phasing could not be matched, UHC1 emissions were at a similar level as for gasoline/diesel combustion. It is expected that the implementation of different injection strategies and boosted operation, combined with use of higher compression ratio pistons in order to compensate for the lower reactivity direct injection (DI) fuel, could raise the potential for improved performance.

Assessment of Lateral Buckles in a HP/HT Pipeline Using Sidescan Sonar Data

2011 ◽  
Author(s):  
Alexandre Santos Hansen ◽  
Bruno Reis Antunes ◽  
Rafael Familiar Solano ◽  
Graeme Roberts ◽  
Arek Bedrossian
Keyword(s):  
Operating Conditions ◽  
Sensitivity Analyses ◽  
Design Stage ◽  
Sidescan Sonar ◽  
Fe Model ◽  
High Pressure High Temperature ◽  
Oil Export ◽  
Using Data ◽  
Fe Model Calibration ◽  
Initial Heat

During design stage of high pressure/high temperature pipelines, some conservative parameters are adopted along with sensitivity analyses to assure safe operation in the presence of uncertainties that influence buckle formation, e.g. pipe-soil interaction, as-laid out-of-straightness and initial heat-up. After operation starts and lateral buckles appeared along the line, a survey may provide valuable information regarding confirmation of the design assumptions, evaluation of actual behaviour and the possibility of increase the operating conditions. This work presents the methodology applied to analyse the configuration of the P-53/PRA-1 12″ oil export pipeline in operation using data from a sidescan sonar survey. The aim of such analyses was to gather information for an FE model calibration as well as to obtain preliminary estimates for the bending strains at lateral buckling locations. Special attention was dedicated to smoothing and interpolation of the pipeline coordinates extracted from sonar imagery in order to avoid unrealistic strains estimates.

Transient “Single-Fuel” RCCI Operation With Customized Pistons in a Light Duty Multi-Cylinder Engine

2015 ◽  
Author(s):  
Christopher W. Gross ◽  
Rolf D. Reitz
Keyword(s):  
Steady State ◽  
Compression Ratio ◽  
Fuel Injection ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Maximum Pressure ◽  
Engine Operation ◽  
Volume Percentage ◽  
Light Duty ◽  
Brake Mean Effective Pressure

Reactivity Controlled Compression Ignition (RCCI) combustion in a light-duty multi-cylinder engine over transient operating conditions using fast response exhaust UHC1, NO and PM measurement instruments was investigated. RCCI has demonstrated improvements in efficiency along with low NOx and PM emissions by utilizing in-cylinder fuel blending, generally using two fuels with different reactivity in order to optimize stratification. In the present work, a “single-fuel” approach for RCCI combustion using port-injected gasoline and direct-injected gasoline mixed with a small amount of the cetane improver 2-ethylhexyl nitrate (EHN) was studied with custom designed, compression ratio of 13.75:1, pistons under transient conditions. The EHN volume percentage in the mixture for the direct-injected fuel was set at 3%. In an experimental investigation, comparisons were made to transient RCCI combustion operation with gasoline/diesel. The experiments were performed over a step load change from 1 to 4 bar brake mean effective pressure (BMEP) at constant 1,500 rev/min on a General Motors Z19DTH 1.9 liter diesel engine The transients were conducted by changing the accelerator pedal command to provide a desired torque output with a DRIVVEN engine control unit (ECU) that replaced the original Bosch ECU. All relevant engine parameters are adjusted accordingly, based on 2D-tables. Previous to the transient engine operation, 4 steady-state points were used to obtain performance and emission values. Engine calibration at these 4 points, as well as the interpolation of the intermediate points, allowed for smooth operation during the instantaneous step changes. Differences between the steady-state and transient results indicate the complexity of transient operation and show the need for additional controls to minimize undesirable effects. The steady-state points were calibrated by modifying the fuel injection strategy (actual Start of Injection (aSOI) timing, port-fuel injection (PFI) fraction, etc.), EGR and rail pressure in order to obtain predefined values for the crank angle at 50% of total heat release (CA50). Furthermore, emission targets (HC1 < 1500ppmC3, NO < 10ppm, FSN < 0.1 with a maximum pressure rise rate < 10bar/deg) and noise level targets (<95dB) for RCCI combustion were maintained during the calibration and mapping. The tests were performed with a closed-loop (CL) calibration by using a next-cycle (NC) controller to adjust the PFI ratio of each cycle in order to reach the steady-state CA50 values in the table. The results show that single-fuel RCCI operation can be achieved, but requires significant alteration of the operating conditions, and NOx emissions were significantly elevated for gasoline/gasoline-EHN operation. While combustion phasing could not be matched, UHC1 emissions were at a similar level as for gasoline/diesel combustion. It is expected that the implementation of different injection strategies and boosted operation, combined with use of higher compression ratio pistons in order to compensate for the lower reactivity direct injection (DI) fuel, could raise the potential for improved performance.

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