scholarly journals Analysis of the Quality Assessment of the Jet Engines Rotational Speed Signal from Set Value and Noise / Analiza Oceny Jakości Przebiegu Prędkości Obrotowej Silnika Odrzutowego Od Wartości Zadanej I Sygnału Zakłócenia

2012 ◽  
Vol 22 (1) ◽  
pp. 181-191
Author(s):  
Golak Karol ◽  
Lindstedt Paweł
Keyword(s):  
Noise Signal ◽  
Engine Control ◽  
Jet Engines ◽  
Technical Object ◽  
Engine Operation ◽  
Set Point ◽  
Ground Testing ◽  
Military Aviation ◽  
Ground Test ◽  
The Impact

Abstract Turbojet engine is a complex technical object. It fulfils an important role in the civil and military aviation. Its undesired operation can lead to tragic accidents. Hence the large role takes the proper preparation for work and adequate regulation. The correctness of the engine work is tested periodically during ground tests. During the ground tests the responses to set engine control lever (DSS) shift is examined, thus means that the engine is examined from the "set point". During ground testing is not possible to reflect the impact of changing conditions during engine operation in flight so the engine is not tested on the noise signal. It turns out that it is the properties of the noise signal often have a decisive effect on the engine operation correctness and by that on the safety of the flight. Hence there is a need to develop methods to assess the state of the engine control signal from noise on the basis of standard ground test from the set point (delivered by the DSS).

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

Turbine Blade Tip Clearance Measurement Instrumentation

2007 ◽  
Author(s):  
Eric B. Holmquist ◽  
Peter L. Jalbert
Keyword(s):  
Control System ◽  
Real Time ◽  
Tip Clearance ◽  
Engine Control ◽  
Operating Characteristics ◽  
Static Structure ◽  
Engine Operation ◽  
Area Of Interest ◽  
Blade Tip ◽  
Blade Tip Clearance

New and future gas turbine engines are being required to provide greater thrust with improved efficiency, while simultaneously reducing life cycle operating costs. Improved component capabilities enable active control methods to provide better control of engine operation with reduced margin. One area of interest is a means to assess the relative position of rotating machinery in real-time, in particular hot section turbo machinery. To this end, Hamilton Sundstrand is working to develop a real-time means to monitor blade position relative to the engine static structure. This approach may yield other engine operating characteristics useful in assessing component health, specifically measuring blade tip clearance, time-of-arrival, and other parameters. UTC is leveraging its many years of experience with engine control systems to develop a microwave-based sensing device, applicable to both military and commercial engines. The presentation will discuss a hot section engine demonstration of a blade position monitoring system and the control system implications posed by a microwave-based solution. Considerations necessary to implement such a system and the challenges associated with integrating a microwave-based sensor system into an engine control system are discussed.

Interaction of Shroud Leakage Flow and Main Flow in a Three-Stage LP Turbine

2003 ◽  
Vol 127 (4) ◽  
pp. 649-658 ◽  
Author(s):  
Jochen Gier ◽  
Bertram Stubert ◽  
Bernard Brouillet ◽  
Laurent de Vito
Keyword(s):  
Main Flow ◽  
Secondary Flows ◽  
Test Facility ◽  
Navier Stokes ◽  
Leakage Flow ◽  
Jet Engines ◽  
Flow Interactions ◽  
Lp Turbine ◽  
The Impact ◽  
The Ideal

Endwall losses significantly contribute to the overall losses in modern turbomachinery, especially when aerodynamic airfoil load and pressure ratios are increased. In turbines with shrouded airfoils a large portion of these losses are generated by the leakage flow across the shroud clearance. Generally the related losses can be grouped into losses of the leakage flow itself and losses caused by the interaction with the main flow in subsequent airfoil rows. In order to reduce the impact of the leakage flow and shroud design related losses a thorough understanding of the leakage losses and especially of the losses connected to enhancing secondary flows and other main flow interactions has to be understood. Therefore, a three stage LP turbine typical for jet engines is being investigated. For the three-stage test turbine 3D Navier-Stokes computations are performed simulating the turbine including the entire shroud cavity geometry in comparison with computations in the ideal flow path. Numerical results compare favorably against measurements carried out at the high altitude test facility at Stuttgart University. The differences of the simulations with and without shroud cavities are analyzed for several points of operation and a very detailed quantitative loss breakdown is presented.

scholarly journals The Impact of Central and Peripheral Cyclooxygenase Enzyme Inhibition on Exercise-Induced Elevations in Core Body Temperature

2017 ◽  
Vol 12 (5) ◽  
pp. 662-667 ◽  
Author(s):  
Matthijs T.W. Veltmeijer ◽  
Dineke Veeneman ◽  
Coen C.C.W. Bongers ◽  
Mihai G. Netea ◽  
Jos W. van der Meer ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Skin Temperature ◽  
Core Body Temperature ◽  
Exercise Tests ◽  
Hypothalamic Temperature ◽  
Set Point ◽  
Exercise Induced ◽  
Core Body ◽  
The Impact

Purpose:Exercise increases core body temperature (TC) due to metabolic heat production. However, the exercise-induced release of inflammatory cytokines including interleukin-6 (IL-6) may also contribute to the rise in TC by increasing the hypothalamic temperature set point. This study investigated whether the exercise-induced increase in TC is partly caused by an altered hypothalamic temperature set point.Methods:Fifteen healthy, active men age 36 ± 14 y were recruited. Subjects performed submaximal treadmill exercise in 3 randomized test conditions: (1) 400 mg ibuprofen and 1000 mg acetaminophen (IBU/APAP), (2) 1000 mg acetaminophen (APAP), and (3) a control condition (CTRL). Acetaminophen and ibuprofen were used to block the effect of IL-6 at a central and peripheral level, respectively. TC, skin temperature, and heart rate were measured continuously during the submaximal exercise tests.Results:Baseline values of TC, skin temperature, and heart rate did not differ across conditions. Serum IL-6 concentrations increased in all 3 conditions. A significantly lower peak TC was observed in IBU/APAP (38.8°C ± 0.4°C) vs CTRL (39.2°C ± 0.5°C, P = .02) but not in APAP (38.9°C ± 0.4°C) vs CTRL. Similarly, a lower ΔTC was observed in IBU/APAP (1.7°C ± 0.3°C) vs CTRL (2.0°C ± 0.5°C, P < .02) but not in APAP (1.7°C ± 0.5°C) vs CTRL. No differences were observed in skin temperature and heart-rate responses across conditions.Conclusions:The combined administration of acetaminophen and ibuprofen resulted in an attenuated increase in TC during exercise compared with a CTRL. This observation suggests that a prostaglandin-E2-induced elevated hypothalamic temperature set point may contribute to the exercise-induced rise in TC.

scholarly journals Analysis of wind impact on emission of selected exhaust compounds in jet engines of a business jet aircraft in cruise phase

2018 ◽  
Vol 173 (2) ◽  
pp. 55-60
Author(s):  
Małgorzata PAWLAK ◽  
Andrzej MAJKA ◽  
Michał KUŹNIAR ◽  
Jowita PAWLUCZY
Keyword(s):  
Wind Speed ◽  
Fuel Consumption ◽  
Wind Direction ◽  
Adverse Impact ◽  
Air Transport ◽  
Jet Engines ◽  
Business Jet ◽  
Condi Tions ◽  
Harmful Substances ◽  
The Impact

Among the most important problems currently faced by air transport, we can distinguish the adverse impact of aircrafts on the natu-ral environment, as well as the rising costs of transport. One of the possibilities to improve this situation is better adjustment of aircraft characteristics to the performed transport tasks, taking into account all the requirements and limitations that exist in air traffic and the adverse impact of air transport on the natural environment. It is reflected in the research tasks conducted under the SESAR program. The aspiration to minimize the adverse impact of aircrafts on the environment is executed, among others, through determining such trajectories that are characterized by minimal fuel consumption or minimal emission of harmful substances in the engines exhausts. These goals are corresponding with the research conducted and described in the paper. The main aim of the work was to analyse the impact of wind speed and direction on the emission of harmful substances of a jet aircraft performing a flight on a given route. For research purposes, the route between two Polish cities Gdansk and Rzeszow was considered. The distance between the two airports was divided into sections for which wind direction and strength were determined (read from the windy.com website). Next, the aircraft per-formance was determined and the fuel consumption and the amount of harmful compounds (CO2, NOx, CO and HC), emitted in the en-gines exhausts were determined for the route from Gdansk to Rzeszow (under favourable wind conditions) and on the return route – from Rzeszow to Gdansk (under unfavourable wind conditions). For comparative purposes, emission of these substances for windless condi-tions was also determined. The results are presented in tables and depicted in the graph, as well as discussed in the conclusions of the paper.

scholarly journals Thermodynamic cycles variability of TJI gas engine with different mixture preparation systems

2020 ◽  
Vol 181 (2) ◽  
pp. 46-52
Author(s):  
Filip SZWAJCA ◽  
Krzysztof WISŁOCKI
Keyword(s):  
Fuel Injection ◽  
Combustion Process ◽  
Engine Operation ◽  
Gas Engine ◽  
Part Load ◽  
Mixture Preparation ◽  
Key Factor ◽  
Test Engine ◽  
Operation Stability ◽  
The Impact

Gas engines are a viable source of propulsion due to the ecological indicators of gas fuels and the large amount of the needed natural resources. Combustion of lean homogeneous gas mixtures allows achieving higher thermal efficiency values, which is a key factor in current engine development trends. Using the spark-jet ignition system (also called as Turbulent Jet Ignition or Two-stage combustion) significantly improves the efficiency and stability of the combustion process, especially in the part-load operation on lean or very lean mixtures. This paper presents the impact of using two different fuel injection methods: Port Fuel Injection or Mixer on the operation stability of a gas engine designed for LDVs. Comparative studies of two different mixture preparation systems were carried out on a single-cylinder AVL 5804 test engine. By re-cording the cylinder pressure for a significant number of engine cycles, it became possible to determine the repeatability of engine operation and to correlate the results with the mixture formation system and the air-fuel ratio. In the performed research the beneficial effect of the mixer system application on the engine operation stability in the part-load conditions was found.

The impact of marine engine operation and maintenance on emissions

2012 ◽  
Vol 17 (1) ◽  
pp. 54-60 ◽  
Author(s):  
Vanessa Duran ◽  
Zigor Uriondo ◽  
Juan Moreno-Gutiérrez
Keyword(s):  
Engine Operation ◽  
Marine Engine ◽  
Operation And Maintenance ◽  
The Impact

scholarly journals Effect of Hot Water Setting Temperature on Performance of Solar Absorption-Subcooled Compression Hybrid Cooling Systems

2019 ◽  
Vol 10 (1) ◽  
pp. 258 ◽  
Author(s):  
Jinfang Zhang ◽  
Zeyu Li ◽  
Hongkai Chen ◽  
Yongrui Xu
Keyword(s):  
Cooling System ◽  
Hot Water ◽  
Operation Performance ◽  
Solar Absorption ◽  
Point Temperature ◽  
Set Point ◽  
Cooling Period ◽  
High Rise ◽  
Hybrid Cooling ◽  
The Impact

The solar absorption-subcooled compression hybrid cooling system (SASCHCS) displays outstanding advantages in high-rise buildings. Since the performance coupling of collectors and absorption subsystems is stronger due to the absence of backup heat and the effect of generator setting temperature has not been realized adequately, it is highly important to study the relationship of SASCHCS operation and the set point temperature of hot water to prevent performance deterioration by inappropriate settings. Therefore, the paper mainly deals with the effect of collector and generator setting temperature. The investigation was based on the entire cooling period of a typical high-rise office building in subtropical Guangzhou. The off-design model of hybrid systems was built at first. Subsequently, the impact mechanism of setting temperature in two hot water cycles on facility operation was analyzed. It was found that the excessive rise of collector setting temperature deteriorated the energy saving, while the appropriate improvement of generator set point temperature was beneficial for the solar cooling. Besides, global optimization by the genetic algorithm displayed that 71.6 °C for the collector setting temperature with 64.5 °C for the generator was optimal for annual operation. The paper is helpful in enhancing the operation performance of SASCHCS.

scholarly journals Optimization of gas turbine engine control using dynamic programming

2018 ◽  
Vol 220 ◽  
pp. 03002
Author(s):  
Venedikt Kuz’michev ◽  
Ilia Krupenich ◽  
Evgeny Filinov ◽  
Andrey Tkachenko
Keyword(s):  
Dynamic Programming ◽  
Differential Equations ◽  
Control Function ◽  
Minimax Principle ◽  
Engine Control ◽  
Engine Operation ◽  
Turbine Engine ◽  
Control Optimization ◽  
Aircraft Performance ◽  
Performance Calculation

The aim of engine control optimization is to derive the optimal control law for engine operation managing during the aircraft flight. For numerical modeling a continuous flight process defined by a system of differential equations is replaced by a discrete multi-step process. Values of engine control parameters in particular step uniquely identify a system transitions from one state to another. The algorithm is based on the numerical method of dynamic programming and the Bellman optimality principle. The task is represented as a sequence of nested optimization subtasks, so that control optimization at the first step is external to all others. The optimum control function can be determined using the minimax principle of optimality. Aircraft performance calculation is performed by numerical integration of differential equations of aircraft movement.

Control-Oriented Physics-Based NOX Emission Model for a Diesel Engine With Exhaust Gas Recirculation

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Saravanan Duraiarasan ◽  
Rasoul Salehi ◽  
Anna Stefanopoulou ◽  
Siddharth Mahesh ◽  
Marc Allain
Keyword(s):  
Diesel Engine ◽  
Test Procedure ◽  
Flame Temperature ◽  
Exhaust Gas Recirculation ◽  
Nox Emission ◽  
Injection Timing ◽  
Exhaust Gas ◽  
Engine Control ◽  
Gas Recirculation ◽  
The Impact

Abstract Stringent NOX emission norm for heavy duty vehicles motivates the use of predictive models to reduce emissions of diesel engines by coordinating engine parameters and aftertreatment. In this paper, a physics-based control-oriented NOX model is presented to estimate the feedgas NOX for a diesel engine. This cycle-averaged NOX model is able to capture the impact of all major diesel engine control variables including the fuel injection timing, injection pressure, and injection rate, as well as the effect of cylinder charge dilution and intake pressure on the emissions. The impact of the cylinder charge dilution controlled by the engine exhaust gas recirculation (EGR) in the highly diluted diesel engine of this work is modeled using an adiabatic flame temperature predictor. The model structure is developed such that it can be embedded in an engine control unit without any need for an in-cylinder pressure sensor. In addition, details of this physics-based NOX model are presented along with a step-by-step model parameter identification procedure and experimental validation at both steady-state and transient conditions. Over a complete federal test procedure (FTP) cycle, on a cumulative basis the model prediction was more than 93% accurate.

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