Experimental Investigation on Effusion Liner Geometries for Aero-Engine Combustors: Evaluation of Global Acoustic Parameters

2012 ◽  
Author(s):  
A. Andreini ◽  
B. Facchini ◽  
L. Ferrari ◽  
G. Lenzi ◽  
F. Simonetti ◽  
...  
Keyword(s):  
Cooling System ◽  
Fluid Dynamic ◽  
Pressure Fluctuations ◽  
Main Concern ◽  
Dynamic Features ◽  
Ambient Conditions ◽  
Test Rig ◽  
Acoustic Parameters ◽  
Field Range ◽  
Aero Engines

In new generation aero-engines based on the innovative lean combustion technology, thermoacoustic instabilities are one of the most important issues and their prevention and reduction are challenging goals. To achieve these targets, the use of multi-perforated liners, that have to primarily provide an efficient liner cooling, is very attractive because they are efficient passive dampers of pressure fluctuations, especially with bias flow. The design of multi-perforated liners for both thermal and acoustic purposes can be accomplished by selecting liner parameters, such as hole diameter, pattern and inclination, main and bias Mach numbers, fulfilling both requirements; this procedure requires to assess the effect of both geometrical and fluid-dynamic features. Thus, a specific research project is ongoing on the acoustic and thermal experimental characterization of selected multi-perforated liner geometries. In this paper, the complete experimental campaign on the acoustic behavior of the aforementioned liners has been carried out in the planar wave field range, that is of main concern in aero-engines. For this purpose, an innovative modular test rig has been designed to characterize test cases at ambient conditions, changing bias and main flows up to operating engine conditions. Liner geometries account for 3 different hole diameters, 5 different patterns and 2 hole inclinations, ranging within typical cooling system values; tests were performed with the two-source multi-microphone technique to evaluate global acoustic parameters independently from test rig boundary conditions. The acoustic performances of liners are discussed in terms of the energy dissipation coefficient.

scholarly journals Partial Redesign of an Accelerator Driven System Target for Optimizing the Heat Removal and Minimizing the Pressure Drops

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2090 ◽  
Author(s):  
Guglielmo Lomonaco ◽  
Giacomo Alessandroni ◽  
Walter Borreani
Keyword(s):  
Cooling System ◽  
Fluid Dynamic ◽  
Heat Removal ◽  
Dynamic Features ◽  
Pressure Drops ◽  
Driven System ◽  
Reference Design ◽  
Accelerator Driven Systems ◽  
Definition Of ◽  
Target Design

Accelerator Driven Systems (ADS) seem to be a good solution for safe nuclear waste transmutation. One of the most important challenges for this kind of machine is the target design, particularly for what concerning the target cooling system. In order to optimize this component a CFD-based approach has been chosen. After the definition of a reference design (Be target cooled by He), some parameters have been varied in order to optimize the thermal-fluid-dynamic features. The final optimized target design has an increased security margin for what regarding Be melting and reduces the maximum coolant velocity (and consequently even more the pressure drops).

Experimental and Numerical Investigation on Windage Power Losses in High Speed Gears

2017 ◽  
Author(s):  
D. Massini ◽  
T. Fondelli ◽  
A. Andreini ◽  
B. Facchini ◽  
L. Tarchi ◽  
...  
Keyword(s):  
High Speed ◽  
Power Transmission ◽  
Fluid Dynamic ◽  
Spur Gear ◽  
Cooling Capacity ◽  
Relative Magnitude ◽  
Power Losses ◽  
Test Rig ◽  
Aero Engines ◽  
Cooling And Lubrication

Enhancing the efficiency of gearing systems is an important topic for the development of future aero-engines with low specific fuel consumption. The transmission system in fact has a direct impact on the engine overall efficiency by means of its weight contribution, internal power losses and lubrication requirements. Thus, an evaluation of its structure and performance is mandatory in order to optimize the design as well as maximize its efficiency. Gears are among the most efficient power transmission systems, whose efficiencies can exceed 99 %, nevertheless in high speed applications power losses are anything but negligible. All power dissipated through losses is converted into heat that must be dissipated by the lubrication system. More heat leads to a larger cooling capacity, which results in more oil, larger heat exchangers which finally means more weight. Mechanical power losses are usually distinguished in two main categories: load-dependent and load-independent losses. The former are all those associated with the transmission of torque, while the latter are tied to the fluid-dynamics of the environment which surrounds the gears, namely windage, fluid trapping and squeezing between meshing gear teeth and inertial losses resulting by the impinging oil jets, usually adopted in high speed transmission for cooling and lubrication purposes. The relative magnitude of these phenomena is strongly dependent on the operative conditions of the transmission. While load-dependent losses are predominant at slow speeds and high torque conditions, load-independent mechanisms become prevailing in high speed applications, like in turbomachinery. Among fluid-dynamic losses, windage is extremely important and can dominate the other mechanisms. In this context, a new test rig was designed for investigating windage power losses resulting by a single spur gear rotating in a free oil environment. The test rig allows the gear to rotate at high speed within a box where pressure and temperature conditions can be set and monitored. An electric spindle, which drives the system, is connected to the gear through a high accuracy torque meter, equipped with a speedometer providing the rotating velocity. The test box is fitted with optical accesses in order to perform particle image velocimetry measurements for investigating the flow-field surrounding the rotating gear. The experiment has been computationally replicated, performing RANS simulations in the context of conventional eddy viscosity models. The numerical results were compared with experimental data in terms of resistant torque as well as PIV measurements, achieving a good agreement for all of the speed of rotations.

scholarly journals Progress on Measurement Techniques for Industrial Gas Turbine Technology

1988 ◽  
Author(s):  
E. Valentini ◽  
P. Lacitignola ◽  
M. Casini
Keyword(s):  
Gas Turbine ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Measurement Techniques ◽  
Experimental Program ◽  
Special Role ◽  
Load Testing ◽  
Ambient Conditions ◽  
Full Load ◽  
Industrial Gas Turbine

Instrumentation and measurements play a very special role in the advancement of gas turbine turbomachinery. In an industrial gas turbine experimental program, testing constantly flanks machine development and full-load testing of extensively instrumented units provides information on both overall and component performance. Rotordynamic testing is performed to determine, in ambient conditions, the optimum configuration for the rotor-bearing-casing assembly. Fluid-dynamic testing on models of the inlet duct, turbine casing and transition piece assembly and blade cooling system is carried out to minimize flow distortions or optimize cooling flows. Stress and modal analyses on turbine and compressor blades are performed, using 3D photoelasticity and holographic interferometry. In the full-load testing, the measurements include thermodynamic values, temperatures of the components, blade vibratory strains, blade tip clearances and axial displacements. Signals from rotating thermocouples and strain gages, installed on both turbine and compressor rotors, are transmitted using slip ring systems. HP blade temperature distribution is measured by means of the infrared pyrometer. Typical Campbell diagrams are derived from the blade strain gage measurements and are used for HCF verification. Radial and axial stator-to-rotor displacements are measured during transients.

scholarly journals Experimental Investigation and Comparison of the Thermal Performance of Additively and Conventionally Manufactured Heat Exchangers

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 574
Author(s):  
Ana Vafadar ◽  
Ferdinando Guzzomi ◽  
Kevin Hayward
Keyword(s):  
Surface Roughness ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Experimental Studies ◽  
Manufacturing Method ◽  
Industrial Sectors

Air heat exchangers (HXs) are applicable in many industrial sectors because they offer a simple, reliable, and cost-effective cooling system. Additive manufacturing (AM) systems have significant potential in the construction of high-efficiency, lightweight HXs; however, HXs still mainly rely on conventional manufacturing (CM) systems such as milling, and brazing. This is due to the fact that little is known regarding the effects of AM on the performance of AM fabricated HXs. In this research, three air HXs comprising of a single fin fabricated from stainless steel 316 L using AM and CM methods—i.e., the HXs were fabricated by both direct metal printing and milling. To evaluate the fabricated HXs, microstructure images of the HXs were investigated, and the surface roughness of the samples was measured. Furthermore, an experimental test rig was designed and manufactured to conduct the experimental studies, and the thermal performance was investigated using four characteristics: heat transfer coefficient, Nusselt number, thermal fluid dynamic performance, and friction factor. The results showed that the manufacturing method has a considerable effect on the HX thermal performance. Furthermore, the surface roughness and distribution, and quantity of internal voids, which might be created during and after the printing process, affect the performance of HXs.

Inlet Air Cooling Applied to Combined Cycle Power Plants: Influence of Site Climate and Thermal Storage Systems

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Nicola Palestra ◽  
Giovanna Barigozzi ◽  
Antonio Perdichizzi
Keyword(s):  
Power Output ◽  
Parametric Analysis ◽  
Power Plants ◽  
Cooling System ◽  
Thermal Storage ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Air Cooling ◽  
Ambient Conditions ◽  
Cooling Systems

The paper presents the results of an investigation on inlet air cooling systems based on cool thermal storage, applied to combined cycle power plants. Such systems provide a significant increase of electric energy production in the peak hours; the charge of the cool thermal storage is performed instead during the night time. The inlet air cooling system also allows the plant to reduce power output dependence on ambient conditions. A 127MW combined cycle power plant operating in the Italian scenario is the object of this investigation. Two different technologies for cool thermal storage have been considered: ice harvester and stratified chilled water. To evaluate the performance of the combined cycle under different operating conditions, inlet cooling systems have been simulated with an in-house developed computational code. An economical analysis has been then performed. Different plant location sites have been considered, with the purpose to weigh up the influence of climatic conditions. Finally, a parametric analysis has been carried out in order to investigate how a variation of the thermal storage size affects the combined cycle performances and the investment profitability. It was found that both cool thermal storage technologies considered perform similarly in terms of gross extra production of energy. Despite this, the ice harvester shows higher parasitic load due to chillers consumptions. Warmer climates of the plant site resulted in a greater increase in the amount of operational hours than power output augmentation; investment profitability is different as well. Results of parametric analysis showed how important the size of inlet cooling storage may be for economical results.

Development of an Anti-Interference Swirl Meter Based on Numerical Simulation of Hydrodynamic Vibration

2000 ◽  
Author(s):  
Xin Fu ◽  
Huayong Yang
Keyword(s):  
High Reliability ◽  
Fluid Dynamic ◽  
Pressure Oscillation ◽  
Measuring Error ◽  
Dynamic Features ◽  
Pressure Transducers ◽  
Vortex Precession ◽  
Eccentric Motion ◽  
Piezoelectric Pressure Sensor ◽  
Good Medium

Abstract Having the advantages of no motion elements, high reliability, undemanding maintenance and good medium flexibility, the swirl meter has been widely used to measure the gas, liquid and steam in chemical, petroleum as well as processing industries. For the current one-piezoelectric-pressure-sensor swirl meter, however, the measuring error caused by the interference pressure oscillation limits its application in the system where pressure is unsteady, or a noisemaker is nearby. In this paper, the fluid dynamic features inside the channel of the swirl meter are studied numerically and by experiment. The time dependent vortex motions as well as the hydrodynamic vibrations within the channel of the swirl meter are simulated using the CFD approaches of the RNG k-ε model. The computed flow fields indicate that the eccentric motion of vortexes initiates an axisymmetric pressure oscillation within the vortex precession area of the swirl meter. The frequency of the oscillation shifts linearly with volume flow rates. Both the calculated and the measured results prove that the hydrodynamic vibrations on the arbitrary axisymmetric points are equal in amplitude and frequency but with a 180 degree phase difference. By installing differential pressure transducers on such the axisymmetric points, the signals of the vortex pressure oscillations are enhanced, while the interferential signals are suppressed, enabling the anti-interference performance and low-flowrate sensibility of the swirmeter to be effectively improved.

Experimental Research on Steam Condensation on Cold Surface: Facility Design

2014 ◽  
Author(s):  
Li-Yong Han ◽  
Lin Yang ◽  
Shan Zhou ◽  
Shen Wang ◽  
Chun-Lai Tian ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Test Section ◽  
Cooling System ◽  
Theoretical Research ◽  
Test Facility ◽  
Measurement Technology ◽  
Ambient Conditions ◽  
Steam Condensation ◽  
Cold Surface ◽  
Process Gas

The passive containment cooling system (PCCS) of the 3rd generation APWR utilizes natural phenomena to transfer the heat released from the reactor to the environment during postulated designed basic accidents. Steam condensation on the inner surface of the containment shell is one of the most dominate mechanism to keep the ambient conditions within the design limits. Extensive experiment and theoretical research shows condensation is a complex process, gas pressure, film temperature and velocity of the gas have impact on the heat transfer coefficient. To span the expected range of conditions and provide proper model for evaluating the condensation heat transfer process, SCOPE test facility was designed by State Nuclear Power Technology Research & Development Centre (SNPTRD) in various conditions anticipated the operating range of CAP1400 in accident conditions. Pressurized test section with a rectangular flowing channel was used, with one of the walls cooled to maintain low temperature for condensing, supplying systems was designed for different pressures, gas temperatures, velocities and coolant water temperatures. Facility components, test section structure, supplying systems and measurement technology were described in this paper, also results of some pre-tests was introduce to show property of the facility.

A Novel Test Rig Using Air for Investigation of Vibration and Interaction of Two Steam Turbine Control Valves

2021 ◽  
Author(s):  
Stefan Wallat ◽  
Stefan Preibisch ◽  
Matthias Strauch ◽  
Dieter Brillert
Keyword(s):  
Material Selection ◽  
Pressure Fluctuations ◽  
Steam Turbines ◽  
Test Rig ◽  
Valve Seat ◽  
Scaling Method ◽  
Control Valves ◽  
Parallel Control ◽  
Selection For ◽  
Selection Of

Abstract The governing of steam turbines is often realised by a set of two or more valves, which control the amount of steam entering the turbine. During part-load operation forces caused by pressure fluctuations, turbulence etc. are acting on the throttling valve and lead to spindle vibrations. Besides these mechanisms, it is assumed that there is also an interaction between the control valves, which leads to another source of vibration. In this paper, the design of a new test rig using air with two parallel control valves is presented. One aspect of the design is the chosen scaling method, which includes material selection for the valve spindle, and ensures comparability and transferability of the vibrational behaviour to the full scale with steam. Another aspect is the selection of measurement equipment. The results show that the reasons for valve vibrations can be located both upstream and downstream of the valve seat. Forces caused by pressure fluctuations in and behind the valve gap lead to similar oscillations at both valves. In addition, the upstream valve causes disturbances that lead to partly differing behaviour of the second valve.

Optimization of fluid characteristics in the main nozzle of an air-jet loom

2021 ◽  
pp. 004051752110395
Author(s):  
Xinlei Huang ◽  
Lee Michael Clemon ◽  
Mohammad Saidul Islam ◽  
Suvash C. Saha
Keyword(s):  
Fluid Dynamic ◽  
Three Dimensional ◽  
Sudden Expansion ◽  
Dynamic Features ◽  
Original Design ◽  
Flow Models ◽  
Air Jet ◽  
Acceleration Tube ◽  
Air Jet Loom ◽  
Fluid Characteristics

As part of the propulsion system, the fluid dynamic features of the main nozzle can immediately affect the stability and efficiency of an air-jet loom. This study aims to optimize the fluid characteristics in the main nozzle of an air-jet loom. To investigate ways of weakening the effect of airflow congestion and backflow phenomenon occurring in the sudden expansion region, the computational fluid dynamics method is employed. Three-dimensional turbulence flow models for a regular main nozzle and 12 prototypes with different nozzle core tip geometry are built, simulated, and analyzed to get the optimum performance. Furthermore, a set of modified equations that consider the direction of airflow are proposed for better estimation of the friction force applied by the nozzle. The result shows that the nozzle core tip's geometry has a significant influence on the internal airflow, affecting the acceleration tube airflow velocity, turbulence intensity, and backflow strength of the sudden expansion region, and other critical fluid characteristics as well. Several proposed models have succeeded in reducing the backflow and outperforming the original design in many different aspects. Models A-60 and C-P, in particular, manage to increase the propulsion force by 37.6% and 20.2% in the acceleration tube while reducing the maximum backflow by 57.1% and 52.2%, respectively. These simulation results can provide invaluable information for the future optimization of the main nozzle.

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