Numerical simulation of ship propulsion transients and full-scale validation

2003 ◽  
Vol 217 (1) ◽  
pp. 41-52 ◽  
Author(s):  
U Campora ◽  
M Figari
Keyword(s):  
Full Scale ◽  
Operating Conditions ◽  
Dynamics Simulation ◽  
Normal Operation ◽  
System Response ◽  
Prime Mover ◽  
Software Environment ◽  
Simulation Code ◽  
Ship Propulsion ◽  
Wide Range

The paper describes a mathematical model for the dynamics simulation of ship propulsion systems. The model, developed in a MATLAB-SIMULINK software environment, is structured in modular form; the various elements of the system are described as individuals blocks (hull, prime mover, gear, waterjet, etc.) and linked together to take their interactions into account. In this way it is possible to characterize the dynamic behaviour of both the single component and the whole propulsion plant. The model may be used to analyse the system response at off-design and transient conditions. In particular, the developed computer simulation code may be considered as a useful tool to facilitate the correct matching of the prime mover (diesel or gas turbine) to the propulsor (waterjet or propeller) in a wide range of operating conditions. The paper shows the application of the methodology to a cruise ferry used to validate the model results through a full-scale test campaign conducted by the authors during normal operation of the ship.

scholarly journals ЕНЕРГОСПОЖИВАННЯ НАВЧАЛЬНИХ КОРПУСІВ УНІВЕРСИТЕТУ В УМОВАХ КАРАНТИННИХ ОБМЕЖЕНЬ УКРАЇНИ

2021 ◽  
pp. 9-19
Author(s):  
VALERII DESHKO ◽  
INNA BILOUS ◽  
IRYNA SUKHODUB ◽  
TETYANA BOIKO
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Integrated Approach ◽  
Climatic Conditions ◽  
Operating Conditions ◽  
Normal Operation ◽  
Software Environment ◽  
Depth Analysis ◽  
Educational Buildings ◽  
Academic Building

Target. To analyze the features of energy consumption of the building of the educational building No. 17 of the National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute" in the conditions of quarantine restrictions in the implementation of energy-saving heating schemes.Methodology. Dynamic energetic modeling of a university academic building created in the DesignBuilder software environment under normal and quarantine modes.Results. Recommendations for the implementation of energy-saving modes of heating the building of the academic building of the university during the period of distance learning when introducing quarantine restrictions in Ukraine.Scientific novelty. An integrated approach has been developed to an in-depth analysis of energy consumption under conditions of partial use of the premises of educational buildings during the quarantine period. It is substantiated that the use of premises with partial operation of the building requires additional unit costs for heating needs.Practical significance. Simulation dynamic modeling of the building's energy consumption for heating for various modes of operation and employment / use of premises of educational buildings during the quarantine period in Ukraine, the results of the study will allow to obtain a set of energy characteristics of the building as a whole and its individual rooms / zones for hourly changes in internal operating conditions and external climatic conditions. The use of the proposed scheme of operation of the heating system of the building of the educational building allows to reduce energy consumption during the heating period by 8,5% compared to energy consumption during normal operation, which is economically feasible in conditions of partial occupancy of the building during quarantine restrictions (during lockdown) and an unpredictable macroeconomic situation on the energy market, causing a trend towards an increase in prices for basic energy resources.

scholarly journals A Wide-Range Axial-Flow Compressor Stage Performance Model

1992 ◽  
Author(s):  
Gregory S. Bloch ◽  
Walter F. O’Brien
Keyword(s):  
Axial Flow ◽  
Operating Conditions ◽  
System Response ◽  
Compressor Stage ◽  
Operating Characteristics ◽  
Compression System ◽  
Axial Flow Compressor ◽  
Multi Stage ◽  
Wide Range ◽  
Flow Compressor

Dynamic compression system response is a major concern in the operability of aircraft gas turbine engines. Multi-stage compression system computer models have been developed to predict compressor response to changing operating conditions. These models require a knowledge of the wide-range, steady-state operating characteristics as inputs, which has limited their use as predicting tools. The full range of dynamic axial-flow compressor operation spans forward and reversed flow conditions. A model for predicting the wide flow range characteristics of axial-flow compressor stages was developed and applied to a 3-stage, low-speed compressor with very favorable results and to a 10-stage, high-speed compressor with mixed results. Conclusions were made regarding the inception of stall and the effects associated with operating a stage in a multistage environment. It was also concluded that there are operating points of an isolated compressor stage that are not attainable when that stage is operated in a multi-stage environment.

scholarly journals Fingerprinting the ship propulsion system: low hanging fruit or mission impossible?

2018 ◽  
Author(s):  
A Vrijdag ◽  
Y Sang
Keyword(s):  
Transfer Functions ◽  
Full Scale ◽  
Propulsion System ◽  
Data Driven ◽  
Parameter Estimates ◽  
System Parameters ◽  
Ship Propulsion ◽  
Wide Range ◽  
System Input ◽  
Ship Operation

In this paper the concept of ship propulsion system “fingerprinting” is explored as an alternative for data driven models that require extensive measured datasets collected over long periods of ship operation. As a first exploratory step a model of a ship in bollard pull conditions is linearised and its transfer functions are determined. Subsequently limited experimental data, involving sinusoidal excitation of the system input at a wide range of frequencies, is used to determine the system parameters. The resulting parameter estimates compare well against previously determined values. Although the developed ideas are far from ready to be used on full scale, the authors believe that the approach is promising enough to be developed further towards full scale application. 

Auto-Ignition and Heat Release in a Gas Turbine Burner at Elevated Temperature

2004 ◽  
Author(s):  
Blazenko Ivancic ◽  
Peter Flohr ◽  
Bettina Paikert ◽  
Martin Brandt ◽  
Wolfgang Polifke
Keyword(s):  
Heat Release ◽  
Gas Turbine ◽  
Operating Conditions ◽  
Dynamics Simulation ◽  
Tuning Parameter ◽  
Ignition Process ◽  
Experimental Development ◽  
Auto Ignition ◽  
Processing Step ◽  
Wide Range

This paper reports on the validation of an advanced model for ignition and heat release of natural gas at elevated pressures and temperatures. The model comprises two sub-models: one for the auto-ignition process and the other to consider heat release. To describe the ignition process efficiently the model uses an intermediate species to represent the evolution of the radical pool. Once the radical pool has reached a critical concentration, the subsequent heat release process starts. Rates for both processes are determined by use of detailed chemistry; hence the model can also take into account effects of higher hydro-carbons without use of a tuning parameter. Turbulence-chemistry interactions are considered with a new Monte-Carlo formulation for the joint probability distribution. This approach is based on the description of the mixture statistics via particle ensembles and not via a function as traditional presumed PDF (Probability Density Function) methods do. The particle ensembles are generated for given means and (co-) variances of mixture fractions in a pre-processing step. To get information about the statistics in the CFD (Computed Fluid Dynamics) simulation, transport equations for means and variances are solved. Since the computation of turbulent mean reaction and heat release rates is performed in a pre-processing step, this approach is very efficient. Experimental results from a full-size burner of an industrial reheat gas turbine at atmospheric pressure was used as data for the model validation. It was found that this approach made possible the calculation of important physical characteristics, e.g. flame position and thickness for a wide range of operating conditions and burner geometries, with satisfying accuracy. Finally, it will be demonstrated how this numerical model is complementary to experimental development procedures and can be used as a burner design tool.

Design, Manufacturing and Testing of a New Family of Steam Turbine Low Pressure Stages

2007 ◽  
Author(s):  
Lorenzo Cosi ◽  
Jonathon Slepski ◽  
Steven DeLessio ◽  
Michele Taviani ◽  
Amir Mujezinovic´
Keyword(s):  
Power Generation ◽  
Steam Turbine ◽  
Low Pressure ◽  
Full Scale ◽  
Operating Conditions ◽  
Test Facility ◽  
Steam Turbines ◽  
Wide Range ◽  
The Family ◽  
Last Stage

New low pressure (LP), stages for variable speed, mechanical drive and geared power generation steam turbines have been developed. The new blade and nozzle designs can be applied to a wide range of turbine rotational speeds and last stage blade annulus areas, thus forming a family of low pressure stages—High Speed (HS) blades and nozzles. Different family members are exact scales of each other and the tip speeds of the corresponding blades within the family are identical. Thus the aeromechanical and aerodynamic characteristics of the individual stages within the family are identical as well. Last stage blades and nozzles have been developed concurrently with the three upstream stages, creating optimised, reusable low pressure turbine sections. These blades represent a step forward in improving speed, mass flow capability, reliability and aerodynamic efficiency of the low pressure stages for the industrial steam turbines. These four stages are designed as a system using the most modern design tools applied on Power Generation and Aircraft Engines turbo-machineries. The aerodynamic performance of the last three stage of the newly designed group will be verified in a full-scale test facility. The last stage blade construction incorporates a three hooks, axial entry dovetail with improved load carrying capability over other blade attachment methods. The next to the last stage blade also uses a three hooks axial entry dovetail, while the two front stage blades employ internal tangential entry dovetails. The last and next to the last stage blades utilize continuous tip coupling via implementation of integral snubber cover while a Z-lock integral cover is employed for the two upstream stages. Low dynamic strains at all operating conditions (off and on resonance speeds) will be validated via steam turbine testing at realistic steam conditions (steam flows, temperatures and pressures). Low load, high condenser pressure operation will also be verified using a three stage test turbine operated in the actual steam conditions as well. In addition, resonance speed margins of the four stages have been verified through full-scale wheel box tests in the vacuum spin cell, thus allowing the application of these stages to Power Generation applications. Stator blades are produced with a manufacturing technology, which combines full milling and electro-discharge machining. This process allows machining of the blades from an integral disc, and thus improving uniformity of the throat distribution. Accuracy of the throat distribution is also improved when compared to the assembled or welded stator blade technology. This paper will discuss the aerodynamic and aeromechanical design, development and testing program completed for this new low pressure stages family.

Transient Power Operation of a Supercritical Carbon Dioxide Brayton Cycle

2017 ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Martha A. King ◽  
Kevin D. Rahner
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Control Strategy ◽  
Power Level ◽  
Integrated System ◽  
Operating Conditions ◽  
System Response ◽  
Brayton Cycle ◽  
Wide Range ◽  
Supercritical Carbon

The Naval Nuclear Laboratory has been operating the Integrated System Test (IST) with the objective of demonstrating the ability to operate and control a supercritical carbon dioxide (sCO2) Brayton power cycle over a wide range of conditions. The IST is a two shaft recuperated closed sCO2 Brayton cycle with a variable speed turbine-driven compressor and a constant speed turbine-driven generator designed to output 100 kWe. This paper presents a thermal-hydraulic lead control strategy for operation of the cycle over a range of operating conditions along with predicted and actual IST system response to power level changes using this control strategy.

Effect of Sub-Freezing Temperature on a PEM Fuel Cell

2006 ◽  
Author(s):  
Q. G. Yan ◽  
H. Toghiani
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Cold Start ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Operating Conditions ◽  
Normal Operation ◽  
Subzero Temperatures ◽  
Wide Range ◽  
Backing Layer

The cold-start behavior and the effect of subzero temperatures on fuel cell performance were studied using a 25-cm2 PEMFC. The fuel cell system was housed in an environmental chamber that allowed the system to be subjected to temperatures ranging from sub-freezing to those encountered during normal operation. Fuel cell cold-start was investigated under a wide range of operating conditions. The cold-start measurements showed that the cell was capable of starting operation at −5 °C without irreversible performance loss when the cell was initially dry. The fuel cell was also able to operate at low environmental temperatures, down to −15 °C. However, irreversible performance losses were found if the cell cathode temperature fell below −5 °C during operation. Freezing of the water generated by fuel cell operation damaged fuel cell internal components. Several low temperature failure cases were investigated in PEM fuel cells that underwent sub-zero start and operation from −20 °C. Cell components were removed from the fuel cells and analyzed with scanning electron microscopy (SEM). Significant damage to the MEA and backing layer was observed in these components after operation below −5 °C. Catalyst layer delamination from both the membrane and the gas diffusion layer (GDL) was observed, as were cracks in the membrane, leading to hydrogen crossover. The membrane surface became rough and cracked and pinhole formation was observed in the membrane after operation at subzero temperatures. Some minor damage was observed to the backing layer coating Teflon and binder structure due to ice formation during operation.

Thermal Management for 6-Cylinder HCCI Engine: Low Cost, High Efficiency, Ultra-Low NOx Power Generation

2004 ◽  
Author(s):  
Joel Martinez-Frias ◽  
Daniel Flowers ◽  
Salvador M. Aceves ◽  
Francisco Espinos-Loza ◽  
Robert Dibble
Keyword(s):  
Thermal Efficiency ◽  
High Efficiency ◽  
Thermal Control ◽  
Operating Conditions ◽  
Simulation Code ◽  
Engine Operation ◽  
Brake Thermal Efficiency ◽  
Hcci Engine ◽  
Cycle Simulation ◽  
Wide Range

This paper investigates a purely thermal control system for a 6-cylinder HCCI engine. Thermal energy from exhaust gas and from compression is used to condition the charge for the desired engine output. HCCI engine operation is analyzed with a detailed chemical kinetics based engine cycle simulation code. This cycle simulation code is linked to an optimizer that determines the operating conditions that result in maximum brake thermal efficiency, while meeting the restrictions of low NOx, and peak cylinder pressure. The results show the values of the operating conditions that yield optimum efficiency as a function of brake power for a constant engine speed (1800 rpm). It has been determined that a thermally controlled HCCI engine can successfully operate at high efficiency and low emissions over a wide range of conditions from idle to full load. The results show that a 42% brake thermal efficiency can be reached while the NOx emissions are kept under 2 parts per million. The analytical results shown here are expected to guide the ongoing experimental effort of converting a heavy-duty stationary engine to HCCI mode. The experimental work has the goal of meeting the very aggressive efficiency and emissions targets set by the California Energy Commission (CEC) Advanced Reciprocating Internal Combustion Engine (ARICE) Program.

Progress in prediction of jet noise and quantification of aircraft/engine noise components

2018 ◽  
Vol 17 (4-5) ◽  
pp. 339-379 ◽  
Author(s):  
K Viswanathan
Keyword(s):  
Velocity Ratio ◽  
Jet Noise ◽  
Prediction Method ◽  
Full Scale ◽  
Operating Conditions ◽  
Noise Component ◽  
Turbofan Engines ◽  
Model Scale ◽  
Wide Range ◽  
Bypass Ratio

The bypass ratio of newer turbofan engines has been increasing steadily and has reached ∼10; even higher bypass ratios are being considered for improving aircraft fuel efficiency. An accurate method for the prediction of jet noise over a wide range of bypass ratio, from ∼5 to ultra-high bypass ratios (∼20), is required to address current and future needs. The main objective of the current study is the development of a procedure for real-world application that would permit the accurate prediction of jet noise, which in turn would enable the quantification of the non-jet noise component. A new empirical method for prediction of noise from realistic dual-stream jets is developed and validated against an extensive database acquired at model scale; the range of validity covers a velocity ratio ( Vs/Vp) ≥ ∼0.6, as this is the range of interest in real turbofan engines. Accurate absolute spectral predictions at all angles and all cycle conditions are first demonstrated at model scale. The same method is then extended to full-scale predictions, both from static engine tests and airplane flyover tests. The range of Strouhal number of interest in full-scale tests spans ∼0.1 to ∼100. Nearfield effects on the jet noise from dual-stream jets have been quantified and a simple and improved procedure for incorporating spectral effects has been developed. Accurate spectral predictions are obtained for noise from static engine tests and flyover tests, over a wide range of engine operating conditions and bypass ratio. Therefore, the good quality and accuracy of the new prediction method have been confirmed at both model scale and full scale, with and without forward flight. An absolute prediction takes ∼1 s on a workstation, as only a single scaling equation is utilized. The application of the new prediction method in gaining better quantification and understanding of the non-jet noise components, and their reduction, is described.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

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