Flow Loss Mechanism and Modeling in a Centrifugal Compressor Casing

2016 ◽  
Author(s):  
Mingxu Qi ◽  
Leon Hu ◽  
Harold Sun ◽  
Margaret Wooldridge
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Main Flow ◽  
Air Flow Rate ◽  
Loss Mechanism ◽  
Computational Costs ◽  
Flow Losses ◽  
Flow Loss ◽  
Loss Models

The current work presents a simplified flow loss model of centrifugal compressor casing flow. The model can be used to estimate the flow losses and air flow rate through the casing under arbitrary casing geometry definitions. Numerical simulations of a turbocharger centrifugal compressor are presented and experimentally validated, with excellent agreement between the model and experimental data. The numerical results were used to investigate the different casing flow loss mechanisms, and the major sources of flow loss in the casing were identified. The simulations indicate the casing flow losses are due to a combination of dividing flow loss, expansion flow loss and friction loss. The dividing flow loss, caused by a portion of the main flow entering the casing slot, is the major source of flow loss, while the expansion flow loss, caused by the expansion flow returning from the slot to the casing cavity, is the second most important source of flow loss. By simplifying the casing into a 2-D configuration, the flow loss coefficient k in the dividing flow and expansion flow is simplified as a function of the casing geometric parameters and dividing flow loss and expansion flow loss models are developed and numerically validated. The results of this work are a valuable new tool to rapidly evaluate casing designs with low computational costs.

Investigation of Quench-16 Experiment With MELCOR Computer Code

2014 ◽  
Author(s):  
Petya Vryashkova ◽  
Pavlin Groudev ◽  
Antoaneta Stefanova
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Initial Temperature ◽  
Computer Code ◽  
Air Flow Rate ◽  
Fuel Rod ◽  
Fuel Bundle ◽  
Oxygen Starvation ◽  
Air Ingress ◽  
Good Agreement

This paper presents a comparison of MELCOR calculated results with experimental data for the QUENCH-16 experiment. The analysis for the air ingress experiment QUENCH-16 has been performed by INRNE. The calculations have been performed with MELCOR code. The QUENCH-16 experiment has been performed on 27-th of July 2011 in the frame of the EC-supported LACOMECO program. The experiments have focused on air ingress investigation into an overheated core following earlier partial oxidation in steam. QUENCH-16 has been performed with limited pre-oxidation and low air flow rate. One of the main objectives of QUENCH-16 was to examine the interaction between nitrogen and oxidized cladding during a prolonged period of oxygen starvation. The bundle is made from 20 heated fuel rod simulators arranged in two concentric rings and one unheated central fuel rod simulator, each about 2.5 m long. The tungsten heaters were surrounded by annular ZrO2 pellets to simulate the UO2 fuel. The geometry and most other bundle components are prototypical for Western-type PWRs. To improve the obtained results it has been made a series of calculations to select an appropriate initial temperature of the oxidation of the fuel bundle and modified correlation oxidation of Zircaloy with MELCOR computer code. The compared results have shown good agreement of calculated hydrogen and oxygen starvation in comparison with test data.

scholarly journals Extended Windage Loss Models for Gas Bearing Supported Spindles Operated in Dense Gases

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Kévin Rosset ◽  
Jürg Schiffmann
Keyword(s):  
Experimental Data ◽  
Turbulent Flow ◽  
High Speed ◽  
Skin Friction Coefficient ◽  
Air Gap ◽  
Operating Pressure ◽  
Rotating Disks ◽  
Loss Model ◽  
Flow Loss ◽  
Loss Models

Abstract Generic models are proposed to evaluate the skin friction coefficient acting on enclosed rotating disks and cylinders under various flow regimes. In particular, a model taking into account the inner radius of the disk is developed. The models are compared with experimental data obtained from coast-down tests of a high-speed spindle supported on gas lubricated bearings, operated in air and in halocarbon R245fa at various pressures. The windage losses are first computed considering state-of-the-art laminar flow loss models in the gas bearings and an experimentally validated laminar-turbulent flow loss model in the air gap. This reference approach predicts the air data with a good accuracy (deviation less than 5%) but underestimates the organic fluid data by up to 36%. This deviation is considerably reduced (max 6.8%) when applying the proposed multiflow regime loss model for enclosed rotating disks to the thrust bearing. Finally, the proposed laminar-turbulent flow loss model for enclosed rotating cylinders is simultaneously applied to the journal bearings and the air gap. A peak deviation of 6.5% is maintained among all test cases when setting the critical Taylor number to an artificial value (67) instead of the theoretical value (41.1) characterizing the onset of growth of Taylor vortices. Taking into account the uncertainties on the bearing clearances, as well as on the operating pressure and temperature, a ±10% agreement with the experimental data is obtained.

Design of a Gas Turbine Based Air Start Unit for Larger Aircraft Engine

2004 ◽  
Author(s):  
Li-Chieh Hsu ◽  
Wu-Chi Ho ◽  
Chien-Ching Hsueh
Keyword(s):  
Control System ◽  
Gas Turbine ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Aircraft Engine ◽  
Aircraft Engines ◽  
Air Flow Rate ◽  
Turbine Engine ◽  
Engine Control System ◽  
Compact Design

A novel Air Start Unit powered by gas turbine engine is developed. The feature of this unit is that it can start various aircraft engines, including the hundred thousand pound thrust class engine like GE90, with different air flow rate in a compact design. This paper introduces the complete design and development of large centrifugal compressor, digital engine control system, testing of gas turbine system.

Numerical Investigation of the Nonreacting Swirling Flow Structure Downstream of Industrial Gas Turbine Burner With the Central Body

2015 ◽  
Author(s):  
Ivan A. Zubrilin ◽  
Dmitriy N. Dmitriev ◽  
Sergey S. Matveev ◽  
Sergey G. Matveev
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Flow Structure ◽  
Flow Rate ◽  
Central Body ◽  
Swirling Flow ◽  
Air Flow ◽  
Air Flow Rate ◽  
Piv Measurements ◽  
Good Agreement

This paper will discuss the investigation of the nonreacting swirling flow downstream of the burner with the central body. This burner is designed for burning partially prepared fuel-air mixture. The burner consists of the axial swirler and the central body. The swirler plays the role of the premixer, and the central body is used to stabilize the flame. The simulation was conducted with the commercial software ANSYS Fluent 15.0. At present, the most widespread CFD approaches to the swirling flow investigation are URANS and LES. In this study URANS is used for obtaining flow charts and LES is used for detailed research of swirling flow structures. The influences of the model parameters (turbulence models, geometry simplification) and numerical parameters (the number of grid elements) on the burner pressure drop are shown in the simulation results. The LES results were compared with the experimental data on the flow structure downstream of the burner. The measurements were provided by 2D PIV with the imaging frequency of 500 Hz and 1000 Hz. It was found that in the investigated range of parameters the burner pressure drop changes slightly and is in good agreement with the experimental data. It was shown that the results of the PIV measurements with the different imaging frequency are in good agreement. The results show that flow behavior achieved in simulation is in accordance with the PIV measurements. It is shown that the flow separation from the central body trailing edge results in formation of large eddies and high velocity fluctuations. On the one hand it can contribute to the mixing of pilot fuel with air, but on the other hand it can lead to high amplitude pressure oscillations during combustion. The form and the frequency of the precessing vortex core were discovered. It was found that the maximum air flow rate through the recirculation zone is about 12% of the total air flow rate through the burner.

Performance Evaluation for SCO2 Compressor With Loss Models Consideration

2020 ◽  
Author(s):  
Yiting Huang ◽  
Tong Wang
Keyword(s):  
Numerical Simulation ◽  
Performance Evaluation ◽  
Centrifugal Compressor ◽  
Performance Prediction ◽  
Loss Factor ◽  
Prediction Method ◽  
Numerical Results ◽  
Flow Loss ◽  
Loss Models ◽  
Theoretical Performance

Abstract Centrifugal compressor is one of the key components in the Super-critical carbon dioxide (SCO2) Brayton cycle process, its performance prediction under variable operating conditions are concerned a lot with consideration of the unique of SCO2 properties. At the same time, the general techniques, including numerical simulation, test, and theoretical analysis with the loss models, are applied to evaluate the compressor performance. In addition with numerical analysis on the performance of the compressor, the flow loss models from air compressor were studied and extended the application to the SCO2 compressors, including incidence loss, blade loading loss, passage flow loss, tip clearance loss, mixing loss, disk friction loss, vaneless diffuser loss. All of these models were investigated to get the performance of a SCO2 compressor. The CO2 quality was got from the multipurpose NIST REFPROP 9.0 (NiST) which is based on Span and Wagner equation of state. The quality was added in the numerical simulation process. Besides, the passage flow loss factor has been modified to get more accurate theoretical performance prediction method for SCO2 compressor. The predicted performance map was compared to the numerical results, and the comparison results proved that, the combination of the loss models provided the similar results as those from the numerical simulation. For the SCO2 centrifugal compressor, the passage flow loss covers the most part among all the compressor flow losses. The value of the passage flow loss factor applied in the theoretical performance prediction method ranges between 0.008∼0.025, which is higher than that for air. Finally, the performance evaluation by improved loss models at different compression starting points were compared with that by the numerical results, it was found that, closer to the critical point would make the passage flow loss increase a lot, which may even exceed its rational range and the produced loss would be beyond expectation. This might be the reason for the low efficiency of SCO2 compressor in the practical working conditions.

Utilization of Waste of Enzymes Biomass as Biosorbent for the Removal of Dyes from Aqueous Solution in Batch and Fluidized Bed Column

2020 ◽  
Vol 71 (1) ◽  
pp. 1-12
Author(s):  
Salman H. Abbas ◽  
Younis M. Younis ◽  
Mohammed K. Hussain ◽  
Firas Hashim Kamar ◽  
Gheorghe Nechifor ◽  
...  
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Particle Size ◽  
Adsorption Capacity ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Fungal Biomass ◽  
Solution Flow Rate ◽  
Maximum Adsorption Capacity ◽  
Solution Flow

The biosorption performance of both batch and liquid-solid fluidized bed operations of dead fungal biomass type (Agaricusbisporus ) for removal of methylene blue from aqueous solution was investigated. In batch system, the adsorption capacity and removal efficiency of dead fungal biomass were evaluated. In fluidized bed system, the experiments were conducted to study the effects of important parameters such as particle size (701-1400�m), initial dye concentration(10-100 mg/L), bed depth (5-15 cm) and solution flow rate (5-20 ml/min) on breakthrough curves. In batch method, the experimental data was modeled using several models (Langmuir,Freundlich, Temkin and Dubinin-Radushkviechmodels) to study equilibrium isotherms, the experimental data followed Langmuir model and the results showed that the maximum adsorption capacity obtained was (28.90, 24.15, 21.23 mg/g) at mean particle size (0.786, 0.935, 1.280 mm) respectively. In Fluidized-bed method, the results show that the total ion uptake and the overall capacity will be decreased with increasing flow rate and increased with increasing initial concentrations, bed depth and decreasing particle size.

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