Integration of Computational Fluid-Particle Dynamics Techniques for the Instantaneous Estimation of Particle Erosion Damage on Axial Fan Blade Sections

2020 ◽  
Author(s):  
Alessio Castorrini ◽  
Paolo Venturini ◽  
Alessandro Corsini
Keyword(s):  
Working Condition ◽  
Characteristic Curve ◽  
Full Range ◽  
Operating Conditions ◽  
Fluid Particle ◽  
Single Element ◽  
Axial Fan ◽  
Erosion Damage ◽  
Blade Section ◽  
Numerical Tools

Abstract In the last decade, the authors focused their research in the development and implementation of accurate numerical tools and methods able to predict the erosion and deposit on turbomachinery blades operating with particle-laden flows. These models and methods give complete three-dimensional description of the phenomenon, but their application is limited to a single working condition of the blade. The present paper covers the first step in the definition of a general methodology to extend the applicability of these tools to a full range of the machines operating conditions. The method aims to obtain an instantaneous prediction of the expected damage pattern for a blade section, given its local working condition in terms of relative fluid-particle flow. The final result is based on a precomputed database associated to the blade section, where the single element is obtained by computing the erosion damage using the aforementioned numerical tools. This paper will show the methodology to obtain the database associated to the midspan section of an induced draft fan subjected to erosion due to coal ash particle. The final database is then used to predict the damage state of the section associated to a given point in the characteristic curve of the fan.

The behaviour of heavily loaded line contacts with transverse roughness

1999 ◽  
Vol 213 (4) ◽  
pp. 309-320 ◽  
Author(s):  
C. J. Hooke
Keyword(s):  
Surface Roughness ◽  
Full Range ◽  
Numerical Results ◽  
Operating Conditions ◽  
Entrainment Velocity ◽  
Original Surface ◽  
Line Contacts ◽  
Transverse Roughness ◽  
Inlet Length

In heavily loaded, piezoviscous contacts the surface roughness tends to be flattened inside the conjunction by any relative sliding of the surfaces. However, before it is flattened, the roughness affects the inlet to the contact, producing clearance variations there. These variations are then convected through the contact, at the entrainment velocity, producing a clearance distribution that differs from the original surface. The present paper explores this behaviour and establishes how the amplitude of the convected clearance varies with wavelength and operating conditions. It is shown that the primary influence is the ratio of the wavelength to the inlet length of the conjunction. Where this ratio is large, the roughness is smoothed and there is little variation in clearance under the conjunction. Where the ratio is small, significant variations in clearance may occur but the precise amplitude and phasing depend on the ratio of slide to roll velocities and on the value of a piezoviscous parameter, c. The numerical results agree closely with existing solutions but extend these to cover the full range of operating conditions.

Experimental and Numerical Investigation of Centrifugal Pump Performance When Handling Viscous Fluids

2005 ◽  
Author(s):  
M. H. Shojaee Fard ◽  
M. B. Ehghaghi ◽  
F. A. Boyaghchi
Keyword(s):  
Soviet Union ◽  
Centrifugal Pump ◽  
Turbulent Flows ◽  
Characteristic Curve ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Viscous Fluids ◽  
Test Bed ◽  
Flow Process ◽  
Pump Performance

On the test bed of centrifugal pump, the centrifugal pump performance has been investigated using water and viscous oil as Newtonian fluids, whose kinematic viscosities are 1 × 10−6, 43 × 10−6 and 62 × 10−6 m2/s, respectively. Also, the finite volume method is used to model the three dimensional viscous fluids for different operating conditions. For these numerical simulations the SIMPLEC algorithm is used for solving governing equations of incompressible viscous/turbulent flows through the pump. The κ-ε turbulence model is adopted to describe the turbulent flow process. These simulations have been made with a steady calculation and using the multiple reference frame (MRF) technique to take into account the impeller-volute interaction. Numerical results are compared with the experimental characteristic curve for each viscous fluid. The data obtained allow the analysis of the main phenomena existent in this pump, such as: head, efficiency, power and pressure field changes for different operating conditions. Also, the correction factors for oils are obtained from the experimental for part loading (PL), best efficiency point (BEP) and over loading (OL) and the results are compared with proposed factors by American Hydraulic Institute (HIS) and Soviet Union (USSR). The comparisons between the numerical and experimental results show a good agreement.

Experiments on an Axial Fan Stage: Time-Resolved Analysis of Rotating Instability Modes

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Benjamin Pardowitz ◽  
Ulf Tapken ◽  
Lars Neuhaus ◽  
Lars Enghardt
Keyword(s):  
Leading Edge ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Axial Fan ◽  
Time Resolved ◽  
Instability Waves ◽  
Instability Modes ◽  
Mode Decomposition ◽  
Rotating Instability ◽  
Annular Cascade

Rotating instability (RI) occurs at off-design conditions in axial compressors, predominantly in rotor configurations with large tip clearances. Characteristic spectral signatures with side-by-side peaks below the blade passing frequency (BPF) are typically referred to RI located in the clearance region next to the leading edge (LE). Each peak can be assigned to a dominant circumferential mode. RI is the source of the clearance noise (CN) and an indicator for critical operating conditions. Earlier studies at an annular cascade pointed out that RI modes of different circumferential orders occur stochastically distributed in time and independently from each other, which is contradictory to existing explanations of RI. Purpose of the present study is to verify this generally with regard to axial rotor configurations. Experiments were conducted on a laboratory axial fan stage mainly using unsteady pressure measurements in a sensor ring near the rotor LE. A mode decomposition based on cross spectral matrices was used to analyze the spectral and modal RI patterns upstream of the rotor. Additionally, a time-resolved analysis based on a spatial discrete-Fourier-transform (DFT) was applied to clarify the temporal characteristics of the RI modes and their potential interrelations. The results and a comparison with the previous findings on the annular cascade corroborate a new hypothesis about the basic RI mechanism. This hypothesis implies that instability waves of different wavelengths are generated stochastically in a shear layer resulting from a backflow in the tip clearance region.

scholarly journals Thermo-economic analysis and optimization of the steam absorption chiller network plant

2021 ◽  
pp. 58-58
Author(s):  
Farshad Panahizadeh ◽  
Mahdi Hamzehei ◽  
Mahmood Farzaneh-Gord ◽  
Villa Ochoa
Keyword(s):  
Economic Analysis ◽  
Working Condition ◽  
Search Algorithm ◽  
Deep Understanding ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Absorption Chiller ◽  
Absorption Chillers ◽  
Optimization Search

Absorption chillers are one of the most used equipment in industrial, commercial, and domestic applications. For the places where high cooling is required, they are utilized in a network to perform the cooling demand. The main objective of the current study was to find the optimum operating conditions of a network of steam absorption chillers according to energy and economic viewpoints. Firstly, energy and economic analysis and modeling of the absorption chiller network were carried out to have a deep understanding of the network and investigate the effects of operating conditions. Finally, the particle swarm optimization search algorithm was employed to find an optimum levelized total costs of the plant. The absorption chiller network plant of the Marun Petrochemical Complex in Iran was selected as a case study. To verify the simulation results, the outputs of energy modeling were compared with the measured values. The comparison with experimental results indicated that the developed model could predict the working condition of the absorption chiller network with high accuracy. The economic analysis results revealed that the levelized total costs of the plant is 1730 $/kW and the payback period is three years. The optimization findings indicated that working at optimal conditions reduces the levelized total costs of the plant by 8.5%, compared to the design condition.

scholarly journals Investigation of the Performances of a Diesel Engine Operating on Blended and Emulsified Biofuels from Rapeseed Oil

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6661
Author(s):  
Vladimir Anatolyevich Markov ◽  
Bowen Sa ◽  
Sergey Nikolaevich Devyanin ◽  
Anatoly Anatolyevich Zherdev ◽  
Pablo Ramon Vallejo Maldonado ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Rapeseed Oil ◽  
Characteristic Curve ◽  
Motor Fuel ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Test Results ◽  
Cfd Simulations ◽  
Brake Thermal Efficiency ◽  
Flow Simulations

The article discusses the possibility of using blended biofuels from rapeseed oil (RO) as fuel for a diesel engine. RO blended diesel fuel (DF) and emulsified multicomponent biofuels have been investigated. Fuel physicochemical properties have been analyzed. Experimental tests of a diesel engine D-245 in the operating conditions of the external characteristic curve and the 13-mode test cycle have been conducted to investigate the effect of these fuels on engine performances. CFD simulations of the nozzle inner flow were performed for DF and ethanol-emulsified RO. The possibility of a significant improvement in brake thermal efficiency of the engine has been noted. The efficiency of using blended biofuels from RO as a motor fuel for diesel engines has been evaluated based on the experimental test results. It was shown that in comparison with the presence of RO in emulsified multicomponent biofuel, the presence of water has a more significant effect on NOx emission reduction. The content of RO and the content of water in the investigated emulsified fuels have a comparable influence on exhaust smoke reduction. Nozzle inner flow simulations show that the emulsification of RO changes its flow behaviors and cavitation regime.

Optimization in Design of High-g Accelerometers

2007 ◽  
Author(s):  
Jun Liu ◽  
Xiaojin Qi ◽  
Yunbo Shi ◽  
Fai Ma
Keyword(s):  
Full Range ◽  
Operating Conditions ◽  
Fabrication Process ◽  
Optimized Design ◽  
Bridge Structure ◽  
Mass Center ◽  
Etch Stop ◽  
Impact Experiments

Under the operating conditions of high collision and strong vibration, a new high-g piezoresistive accelerometer (with a full range of 150000g) is designed. This design consists of 4-beams and 1-tower. This structure possesses superior anti-shock ability. In optimizing this piezoresistive bridge structure, a tower is etched directly from the back of the mass in KOH by using the (111) plane etch-stop technique. Since the distances between the mass center of the tower and the mass centers of the beams are shortened, anti-shock ability in transverse directions is improved. In addition, the fabrication process is relatively straightforward. Finally, it is found by impact experiments that the linearity of the optimized design lies within 9% for measurements in the range of 0–150000g.

Effect of Rotor-Stator Configuration in the Generation of Vortical Scales and Wake Mixing in Single Stage Axial Fans: Part II — Assessment of Vortex Sound Sources

2013 ◽  
Author(s):  
Mónica Galdo Vega ◽  
Jesus Manuel Fernandez Oro ◽  
Katia María Argüelles Díaz ◽  
Carlos Santolaria Morros
Keyword(s):  
Deep Understanding ◽  
Operating Conditions ◽  
Axial Fan ◽  
Noise Sources ◽  
Sound Sources ◽  
Time Resolved ◽  
Vortex Sound ◽  
Starting Point ◽  
Axial Fans ◽  
The Impact

This second part is devoted to the identification of vortex sound sources in low-speed turbomachinery. As a starting point, the time-resolved evolution of the vortical motions associated to the wake shear layers (reported in the first part of the present study) is employed to obtain vorticity distributions in both blade-to-blade and traverse locations throughout the axial fan stage. Following, the Powell analogy for generation of vortex sound is revisited to obtain the noise sources in the nearfield region of the fan. Both numerical and experimental databases presented previously are now post-processed to achieve a deep understanding of the aeroacoustic behavior of the vortical scales present in the flow. A LES simulation at midspan, using a 2.5D scheme, allows an accurate description of the turn-out time of the shedding vortices, within high-density meshes in the blades and vanes passages, and a correct modeling of the dynamics of turbulence. Besides, thermal anemometry has been employed with a two-wire probe to measure the planar flow in the midspan sections of the fan. Statistical procedures and signal conditioning of velocity traces have confirmed experimentally the unsteady flow patterns devised in the numerical model. The comparison of the rotor-stator and the stator-rotor configurations provides the influence of the wake mixing and the nucleation of turbulent spots in the distribution of the Powell source terms. Moreover, the relation between the turbomachine configuration and the generation of vortex sound can be established, including the impact of the operating conditions and the contributions of the interaction mechanisms.

A Shape Memory Alloy-Based Morphing Axial Fan Blade—Part I: Blade Structure Design and Functional Characterization

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Annalisa Fortini ◽  
Alessio Suman ◽  
Nicola Aldi ◽  
Mattia Merlin ◽  
Michele Pinelli
Keyword(s):  
Shape Memory ◽  
Solid Phase ◽  
Functional Characterization ◽  
Structure Design ◽  
Operating Conditions ◽  
Surface Pattern ◽  
Fluid Temperature ◽  
Axial Fan ◽  
Polymeric Matrices ◽  
Air Stream

The possibility to realize adaptive structures is of great interest in turbomachinery design, owing to the benefits related to enhanced performance and efficiency. To accomplish this, a challenging approach is the employment of shape memory alloys (SMAs), which can recover seemingly permanent strains by solid phase transformations whereby the so-called shape memory effect (SME) takes place. This paper presents the development of a heavy-duty automotive cooling axial fan with morphing blades activated by SMA strips that works as actuator elements in the polymeric blade structure. Concerning the fan performance, this new concept differs from a conventional viscous fan clutch solution especially during the nonstationary operating conditions. The blade design was performed in order to achieve the thermal activation of the strips by means of air stream flow. Two polymeric matrices were chosen to be tested in conjunction with a commercially available NiTi binary alloy, whose phase transformation temperatures (TTRs) were experimentally evaluated by imposing the actual operating thermal gradient. The SMA strips were then thermomechanically treated to memorize a bent shape and embedded in the polymeric blade. In a specifically designed wind tunnel, the different polymeric matrices equipped with the SMA strips were tested to assess the fluid temperature and surface pattern behavior of the blade. Upon heating, they tend to recover the memorized shape and the blade is forced to bend, leading to a camber variation and a trailing edge displacement. The recovery behavior of each composite structure (polymeric matrix with the SMA strips) was evaluated through digital image analysis techniques. The differences between the blade shape at the initial condition and at the maximum bending deformation were considered. According to these results, the best coupling of SMA strips and polymeric structure is assessed and its timewise behavior is compared to the traditional timewise behavior of a viscous fan clutch.

A Procedure to Reduce the Effects of Variable Fluid Temperatures in the Flow Direction: Application to the Design of a Rotary Regenerator

1988 ◽  
Author(s):  
Thomas P. Lewandowski ◽  
Tah-Teh Yang
Keyword(s):  
Heat Exchanger ◽  
Analytical Procedure ◽  
Flow Direction ◽  
Operating Conditions ◽  
Single Element ◽  
Temperature Dependent ◽  
Axial Temperature ◽  
Flow Length ◽  
Fluid Properties ◽  
Element Method

The purpose of this paper is to present results of an analytical procedure which accounts for variations in temperature dependent fluid properties in the flow direction of a heat exchanger. The procedure is called the multi-element method and is used in the performance calculations of a rotary regenerator subject to axial temperature variations greater than 2:1. The multi-element method partitions the flow length and evaluates the heat exchanger by combining the performances of each length. The results show graphically the differences between using the multi-element method and a more commonly used single-element method. The differences presented are between the predicted regenerator disk thickness and between the predicted core pressure drop for a variety of operating conditions.

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