scholarly journals Validation of a Radial Compressor CFD Analysis

2020 ◽  
Vol 3 (1) ◽  
pp. 85-90
Author(s):  
Süleyman Emre Ak ◽  
Sertaç Çadırcı
Keyword(s):  
High Speed ◽  
Pressure Ratio ◽  
Ideal Gas ◽  
Cfd Analysis ◽  
Test Results ◽  
Radial Compressor ◽  
Computational Fluid Dynamics Cfd ◽  
Relative Errors ◽  
Mesh Convergence ◽  
The Ideal

In this study, a radial compressor flow at a high speed is investigated by Computational Fluid Dynamics (CFD) methods. The radial compressor of interest consists of a rotor, diffuser, and exit guide vanes and has an operational rotational speed of 21789 rpm. The geometry of the compressor and its test results such as compression ratio and adiabatic efficiency are available in literature. After extensive mesh convergence tests, steady-state CFD analysis has been performed for compressible and turbulent flow using the ideal gas approach. The main motivation of the study is the determine the appropriate CFD approach and boundary conditions of the problem that will fit best to the measurements. The CFD analysis revealed that the maximum relative errors for the adiabatic efficiency and the pressure ratio were 3.6 % and 1.3 %, respectively.

Experimental Test Results for Four High-Speed, High-Pressure, Orifice-Compensated Hybrid Bearings

1994 ◽  
Vol 116 (1) ◽  
pp. 147-153 ◽  
Author(s):  
N. M. Franchek ◽  
D. W. Childs
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Pressure Ratio ◽  
Reynolds Numbers ◽  
Orifice Diameter ◽  
Test Results ◽  
Rotordynamic Coefficients ◽  
Geometric Configurations ◽  
Overall Performance ◽  
Mass Terms

In this study, four hybrid bearings having different geometric configurations were experimentally tested for their static and dynamic characteristics, including flowrate, load capacity, rotordynamic coefficients, and whirl frequency ratio. The four bearings included a square-recess, smooth-land, radial-orifice bearing (baseline), a circular-recess bearing, a triangular-recess bearing, and an angled-orifice bearing. Each bearing had the same orifice diameter rather than the same pressure ratio. Unique to these test results is the measurement of the added mass terms, which became significant in the present tests because of high operating Reynolds numbers. Comparisons of the results were made between bearings to determine which bearing had the best performance. Based on the parameters of interest, the angled-orifice bearing has the most favorable overall performance.

Pumping Loss of Shrouded Meshed Spur Gears

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Michael J. Hurrell ◽  
Jerzy T. Sawicki
Keyword(s):  
High Speed ◽  
Spur Gear ◽  
Test Facility ◽  
Spur Gears ◽  
Cfd Analysis ◽  
Total Load ◽  
New Approach ◽  
Computational Fluid Dynamics Cfd ◽  
Loss Component ◽  
Swept Volume

Abstract High speed rotorcraft transmissions are subject to load-independent power losses consisting of drag loss and pumping loss. Tightly conforming shrouds enclosing the transmission gears are often incorporated to reduce the drag component of the total load-independent losses. However, tightly conforming axial shrouds can result in an increase in the pumping loss component. Quantifying the pumping loss of shrouded gear transmissions has been the subject of many studies. This study presents a new approach for estimating pumping loss based on the concept of swept volume and examines the applicability of the approach to various shroud configurations. The drag loss and pumping loss of a shrouded spur gear pair have been determined through testing using the NASA Glenn Research Center (GRC) Gear Windage Test Facility. The results from this testing have been compared to theoretical results using the formulations presented in this study. In addition, computational fluid dynamics (CFD) analysis has been conducted for the various shroud configurations tested at NASA GRC. The results from the CFD analysis confirm the theoretical and empirical results and provide insight into the applicability of the swept volume approach for estimating pumping power loss of shrouded gear transmissions.

Design and Test Results of a Ultra High Loaded Single Stage High Pressure Turbine

2013 ◽  
Author(s):  
Harjit S. Hura ◽  
Scott Carson ◽  
Rob Saeidi ◽  
Hyoun-Woo Shin ◽  
Paul Giel
Keyword(s):  
High Pressure ◽  
Total Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Single Stage ◽  
Test Results ◽  
High Pressure Turbine ◽  
Technology Program ◽  
High Pressure Ratio ◽  
Expected Performance

This paper describes the engine and rig design, and test results of an ultra-highly loaded single stage high pressure turbine. In service aviation single stage HPTs typically operate at a total-to-total pressure ratio of less than 4.0. At higher pressure ratios or energy extraction the nozzle and blade both have regions of supersonic flow and shock structures which, if not mitigated, can result in a large loss in efficiency both in the turbine itself and due to interaction with the downstream component which may be a turbine center frame or a low pressure turbine. Extending the viability of the single stage HPT to higher pressure ratios is attractive as it enables a compact engine with less weight, and lower initial and maintenance costs as compared to a two stage HPT. The present work was performed as part of the NASA UEET (Ultra-Efficient Engine Technology) program from 2002 through 2005. The goal of the program was to design and rig test a cooled single stage HPT with a pressure ratio of 5.5 with an efficiency at least two points higher than the state of the art. Preliminary design tools and a design of experiments approach were used to design the flow path. Stage loading and through-flow were set at appropriate levels based on prior experience on high pressure ratio single stage turbines. Appropriate choices of blade aspect ratio, count, and reaction were made based on comparison with similar HPT designs. A low shock blading design approach was used to minimize the shock strength in the blade during design iterations. CFD calculations were made to assess performance. The HPT aerodynamics and cooling design was replicated and tested in a high speed rig at design point and off-design conditions. The turbine met or exceeded the expected performance level based on both steady state and radial/circumferential traverse data. High frequency dynamic total pressure measurements were made to understand the presence of unsteadiness that persists in the exhaust of a transonic turbine.

Polytropic Change of State Calculations

2014 ◽  
Author(s):  
Hans E. Wettstein
Keyword(s):  
Gas Turbines ◽  
Dissipation Rate ◽  
Pressure Ratio ◽  
Thermodynamic Cycle ◽  
Ideal Gas ◽  
Test Results ◽  
Stage Of Development ◽  
Change Of State ◽  
Calculation Algorithms ◽  
Polytropic Exponent

Polytropic change of state calculations are used within many thermodynamic cycle analysis tasks for turbomachinery like gas turbines or compressors. The typical approach is using formulas, which are theoretically valid for ideal gas conditions only. But often gases are used, which do certainly not behave like ideal gases. This is motivation to check how and which polytropic change of state algorithms can be used for real gases or corresponding mixtures. There is a vast experience on polytropic efficiencies achievable with existing turbomachinery. Manufacturers calibrate their performance analysis with real test results for compensating potential deviations from their analysis approach. But they normally do not disclose their approaches for the thermodynamic calculation and the corrections made based on their test results. But for investigations of new thermodynamic cycles before the stage of development with an available demonstrator a best possible prediction of the performance is desired. In this paper the assumptions and formulas for calculating polytropic changes of state and polytropic efficiencies are gathered from literature. The most fundamental assumption is based on a constant dissipation rate during the polytropic change of state. It could be tracked back to Zeuner, Stodola and Dzung. A numerically convenient approximation is the “polytropic exponent approach”. It fulfills the first assumption for an ideal gas but it is only an approximation for real gases. The temperature after a polytropic change of state is defined by its initial condition, the pressure ratio and the polytropic efficiency. Three different calculation algorithms are compared here: The recursive “constant dissipation rate algorithm” suggested by the author, the most used “ideal gas formula” and the “polytropic exponent formula” as the most used approximation for real gases. Numeric results for compression from 1bar to up to 100bar are shown for dry air, Argon, Neon, Nitrogen, Oxygen and CO2. The deviations of the different calculation approaches are considerable.

Piston-Lift Check Valve Flow Verification Using CFD

2018 ◽  
Author(s):  
Matthew Laney ◽  
Ronald Farrell
Keyword(s):  
Flow Characteristics ◽  
Check Valve ◽  
Valve Lift ◽  
Cfd Analysis ◽  
Test Results ◽  
Finite Element Software ◽  
Translational Movement ◽  
Wide Range ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Computational Fluid Dynamics (CFD) is increasingly being used as a reliable method for determining flow characteristics of a wide range of flow situations. This paper presents an extension of paper PVP2017-66269, “Check Valve Flow and Disk Lift Simulation Using CFD” [1], and utilizes some of the same concepts to characterize flow through piston-lift check valves. The previous example considered a swing check valve involving rotational movement; this example considers a vertical lift piston check valve involving translational movement. Specifically, CFD was used to determine valve flow coefficients (CV) as a function of disk lift position as well as to determine the flow rate required to achieve full open or predict intermediate disk lift positions. The CFX application, which is part of the ANSYS suite of finite element software, was used to determine the flow characteristics. As presented in PVP2017-66269, balancing flow-induced forces on the check element and considering the disk assembly weight, the valve lift behavior can be predicted. Results from the CFX analysis were compared to recent test results of a skirted disk-piston check valve and previous test results of a standard disk-piston check valve. The results showed good agreement in most cases. This validates that flow characteristics across valves with different types of check elements at different disk lift positions can be reliably predicted using CFD analysis. It is important to note that while the test results and CFD analysis showed good agreement, it was vital that actual testing be performed in order to validate the approach. This follows the recommendation outlined in the previous paper.

Adiabatic Analysis of Rotary Displacer Stirling Engine

2018 ◽  
Author(s):  
AmirHossein Bagheri ◽  
William C. Mullins ◽  
Phillip R. Foster ◽  
Huseyin Bostanci
Keyword(s):  
Ideal Gas ◽  
Stirling Engine ◽  
Analytical Models ◽  
Working Fluid ◽  
Power Cylinder ◽  
Significant Difference ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance ◽  
The Cost ◽  
The Ideal

Utilizing analytical models at the initial stages of Stirling engine (SE) development is a common approach since the cost could be excessive when experimental (i.e., building prototypes) or even numerical (i.e., using Computational Fluid Dynamics (CFD)) approaches are taken first. One of the well-known analyses in this area is the adiabatic analysis that assumes working fluid to be an ideal gas, and adiabatic expansion and compression processes in the power cylinder. Although adiabatic analysis neglects pressure loss in the cycle, it still predicts operating envelope and performance with a better accuracy compared to isothermal (Schmidt) analysis. This study considers the adiabatic analysis that was originally developed for conventional, reciprocating displacer SE configuration, and aims to adapt it for an innovative, rotary displacer SE configuration. The analysis enables to present pressure-volume diagrams, and estimates the amount of generated work and the efficiency. The results, when compared to that of the ideal Schmidt analysis, indicate up to 4.6% lower values of the generated work, suggesting a significant difference between the two ideal assumptions.

Noise Influence of High-Speed Train Based on Air Dynamics

2014 ◽  
Vol 687-691 ◽  
pp. 265-269
Author(s):  
Xiao Qin Wang
Keyword(s):  
High Speed ◽  
Pressure Ratio ◽  
Flow Distribution ◽  
Large Change ◽  
Aerodynamic Noise ◽  
Maximum Pressure ◽  
Air Conditioner ◽  
Test Results ◽  
Train Speed ◽  
Stable Flow

How to control aerodynamic noise of high speed motor train, this paper starts from the basic theory of hydrodynamics and acoustics, it adopts method of numerical simulation and applies Fluent and VirtuaUab Acousticsand software to make study on characteristics of aerodynamic noise for high speed motor train, the test results indicates that in the stable flow distribution, the baric gradient is relatively larger when its surface pressure is in area with large change in curve curvature, when it is in the area with even curve change, the baric gradient is relatively smaller. In different gradient, the train head, the maximum pressure and the maximum negative pressure ratio of air-conditioner air deflector predicate are in proportion to the square of train speed.

Development of a Direct Drive Servo Valve With Flow Force Compensated Spool

2003 ◽  
Author(s):  
Weongyu Shin ◽  
Hyunyoung Choi ◽  
Hyopil Shin ◽  
Euijoon Moon
Keyword(s):  
High Speed ◽  
Performance Test ◽  
Cfd Analysis ◽  
Test Results ◽  
Direct Drive ◽  
High Speed Flow ◽  
Simple Method ◽  
Servo Valve ◽  
Speed Flow ◽  
Force Compensation

This paper is on the development of a Direct Drive servo Valve (DDV) with flow force compensated spool. In valves with spool, flow force is caused by the unbalance of pressure exerted on each land of spool when high-speed flow passes through very narrow orifices. A simple method for flow force compensation using a stepped spool is presented in this paper. It is easy to manufacture the stepped spool of the presented method because the shape of it is simple. The method has another merit that the size of valve need not be increased. Actuating force required for driving the spool can be decreased through the compensation of flow force. The effectiveness of the proposed method is predicted through CFD analysis. The results of the CFD analysis are also utilized for the optimization of step shape. Prototypes of flow force compensated DDV are manufactured and the measurements of flow force are carried out. The measured effectiveness of flow force compensation is very similar to that from the CFD analysis. Performance test results of prototype DDV satisfy required specifications.

Multi-Dimensional CFD Analysis of Rotating Blades in a Lawnmower Deck

2002 ◽  
Author(s):  
P. A. Hagen ◽  
W. Chon ◽  
R. S. Amano
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Flow Patterns ◽  
Cfd Analysis ◽  
Rotating Blades ◽  
Cfd Models ◽  
High Speed Video Camera ◽  
Computational Fluid Dynamics Cfd ◽  
And Behavior ◽  
Blade Model

Aerodynamic experimentation and investigation of rotating blades has pioneered the research necessary for innovative lawnmower design. In this study, Computational Fluid Dynamics (CFD) models are generated for single and triple-blade arrangements to analyze their flow patterns and behavior. For the 2-D CFD analysis, blade profiles at several arbitrary radial sections have been selected for flow computations around the blade model. Likewise, the 3-D CFD analysis effectively simulates the flow patterns inside the entire triple-blade mower deck, as well as in single-blade enclosures. The accuracy of the attained CFD solutions was determined through comparison with experimental data. The flow behaviors were observed using both Laser Doppler Velocimetry (LDV) and a high-speed video camera recording at 2000 frames per second. Strain gage and pressure transducer analysis also aided in the correlative effort. It has been observed that both the mower deck configuration and blade profile share equal significance in the resultant flow profiles.

The Effect of Gas Models on Compressor Efficiency Including Uncertainty

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Fangyuan Lou ◽  
John Fabian ◽  
Nicole L. Key
Keyword(s):  
Pressure Ratio ◽  
Ideal Gas ◽  
Experimental Measurements ◽  
Perfect Gas ◽  
Real Gas ◽  
The Real ◽  
Compressor Efficiency ◽  
Ideal Gas Model ◽  
Isentropic Efficiency ◽  
The Ideal

Since isentropic efficiency is widely used in evaluating the performance of compressors, it is essential to accurately calculate this parameter from experimental measurements. Quantifying realistic bounds of uncertainty in experimental measurements are necessary to make meaningful comparisons to computational fluid dynamics simulations. This paper explores how the gas model utilized for air can impact not only the efficiency calculated in an experiment, but also the uncertainty associated with that calculation. In this paper, three different gas models are utilized: the perfect gas model, the ideal gas model, and the real gas model. A commonly employed assumption in calculating compressor efficiency is the perfect gas assumption, in which the specific heat, is treated as a constant and is independent of temperature and pressure. Results show significant differences in both calculated efficiency and the resulting uncertainty in efficiency between the perfect gas model and the real gas model. The calculated compressor efficiency from the perfect gas model is overestimated, while the resulting uncertainties from the perfect gas model are underestimated. The ideal gas model agrees well with the real gas model, however. Including the effect of uncertainty in gas properties results in very large uncertainties in isentropic efficiency, on the order of ten points, for low pressure ratio machines.

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