Out With the Old, in With the New: Pelton Hydro Turbine Performance Influence Utilizing Three Different Injector Geometries

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
S. Petley ◽  
A. Židonis ◽  
A. Panagiotopoulos ◽  
D. Benzon ◽  
G. A. Aggidis ◽  
...  
Keyword(s):  
Experimental Testing ◽  
Cfd Analysis ◽  
The Public ◽  
Hydro Turbine ◽  
Turbine Efficiency ◽  
Industry Standard ◽  
Turbine Performance ◽  
Upper Limit ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

In previous works, the authors presented computational fluid dynamics (CFD) results, which showed that injectors with noticeably steeper nozzle and needle tip angles 110 deg & 70 deg and 150 deg & 90 deg, respectively, attain higher efficiency than the industry standard, which, according to available literature on the public domain, ranges from 80 deg to 90 deg for nozzle and 50–60 deg for needle tip angles. Moreover, experimental testing of the entire Pelton system showed that gains of about 1% in efficiency can be achieved; however there appears to be an upper limit beyond which steeper designs are no longer optimal. This study aims at providing further insight by presenting additional CFD analysis of the runner, which has been coupled with the jet profile from the aforementioned injectors. The results are compared by examining the impact the jet shape has on the runner torque profile during the bucket cycle and the influence this has on turbine efficiency. It can be concluded that the secondary velocities, which contribute to the development of more significant free-surface degradations as the nozzle and needle tip angles are increased, result in a nonoptimal jet runner interaction.

scholarly journals Uncertainty Quantification of Leakages in a Multistage Simulation and Comparison With Experiments

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Cosimo Maria Mazzoni ◽  
Richard Ahlfeld ◽  
Budimir Rosic ◽  
Francesco Montomoli
Keyword(s):  
Uncertainty Quantification ◽  
Numerical Study ◽  
Turbine Blades ◽  
Industrial Practice ◽  
Turbine Efficiency ◽  
Simulation Based ◽  
Multistage Turbine ◽  
Computational Fluid Dynamics Cfd ◽  
Yaw Angle ◽  
The Impact

This paper presents a numerical study of the impact of tip gap uncertainties in a multistage turbine. It is well known that the rotor gap can change the gas turbine efficiency, but the impact of the random variation of the clearance height has not been investigated before. In this paper, the radial seals clearance of a datum shroud geometry, representative of steam turbine industrial practice, was systematically varied and numerically tested by means of unsteady computational fluid dynamics (CFD). By using a nonintrusive uncertainty quantification (UQ) simulation based on a sparse arbitrary moment-based approach, it is possible to predict the radial distribution of uncertainty in stagnation pressure and yaw angle at the exit of the turbine blades. This work shows that the impact of gap uncertainties propagates radially from the tip toward the hub of the turbine, and the complete span is affected by a variation of the rotor tip gap. This amplification of the uncertainty is mainly due to the low-aspect ratio of the turbine, and a similar behavior is expected in high pressure (HP) turbines.

scholarly journals Advancement of Turbine Aerodynamic Design Techniques

1993 ◽  
Author(s):  
Lisa W. Griffin ◽  
Frank W. Huber
Keyword(s):  
Fluid Dynamics ◽  
State Of The Art ◽  
Cfd Analysis ◽  
Aerodynamic Design ◽  
Turbine Efficiency ◽  
Component Design ◽  
Pump Stage ◽  
Computational Fluid Dynamics Cfd ◽  
The Government ◽  
And Performance

The Consortium for Computational Fluid Dynamics (CFD) Application in Propulsion Technology has been created at NASA/MSFC. Its purpose is to advance the state-of-the-art of CFD technology, to validate CFD codes and models, and to demonstrate the benefits attainable through the application of CFD in component design. Three teams are currently active within the Consortium: (1) the Turbine Technology Team, (2) the Pump Stage Technology Team, and (3) the Combustion Devices Technology Team. The goals, dynamics, and activities of the Turbine Team are the subjects of this paper. The Consortium is managed by NASA. The Turbine Team is co-coordinated by a NASA representative from the CFD area and an industry (Pratt & Whitney) representative from the area of turbine aerodynamic design. Membership of the Turbine Team includes experts in design, analysis, and testing from the government, industry, and academia. Each member brings a unique perspective, expertise, and experience to bear on the team’s goals of improving turbine efficiency and robustness while reducing the amount of developmental testing. To this end, an advanced turbine concept has been developed within the team using CFD as an integral part of the design process. This concept employs unconventionally high turning blades and is predicted to provide cost and performance benefits over traditional designs. This concept will be tested in the MSFC Turbine Airflow Facility to verify the design and to provide a unique set of data for CFD code validation. Currently, the team is developing and analyzing methods to reduce secondary and tip losses to further enhance turbine efficiency. The team has also targeted volute development as an area that could benefit from detailed CFD analysis.

scholarly journals Optimization of Radial Impulse Turbine for Oscillating Water Column Wave Renewable Energy

2019 ◽  
Vol 8 (12) ◽  
pp. 5699-5703
Keyword(s):  
Water Column ◽  
Oscillating Water Column ◽  
Peak Efficiency ◽  
Impulse Turbine ◽  
Trapped Air ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Radial Turbine ◽  
Wide Range ◽  
Computational Fluid Dynamics Cfd

An oscillating water column (OWC) extracts the power of waves by trapping air above a water column. This trapped air is compressed and decompressed by the wave action flow inside a turbine power to the mechanical power during process, and it is important as the turbines are expected to operate in oscillating and reversing flows over a wide range of conditions. The objectives of this study are to determine and analyze the type of radial impulse turbine of OWC and to optimize the performance of a radial impulse turbine for OWC by using Computational Fluid Dynamics (CFD). This requires a comprehensive investigation on turbine configuration, turbine efficiency, OWC integration, and turbine operation with respect to climate condition. The outcome of this study to settle the main drawbacks of radial turbine namely lower peak efficiency and damping on OWC can be considered. Later, these problems will be further study to identify the behavior of the airflow through the machine, sources of energy loss, and impact of different parameters on the turbine performance.

scholarly journals Caring for the future can turn tragedy into comedy for long-term collective action under risk of collapse

2020 ◽  
Vol 117 (23) ◽  
pp. 12915-12922 ◽  
Author(s):  
Wolfram Barfuss ◽  
Jonathan F. Donges ◽  
Vítor V. Vasconcelos ◽  
Jürgen Kurths ◽  
Simon A. Levin
Keyword(s):  
Climate Change ◽  
Collective Action ◽  
Experimental Testing ◽  
The Public ◽  
Regime Changes ◽  
The Future ◽  
The Commons ◽  
Future Outcomes ◽  
The Impact

We will need collective action to avoid catastrophic climate change, and this will require valuing the long term as well as the short term. Shortsightedness and uncertainty have hindered progress in resolving this collective action problem and have been recognized as important barriers to cooperation among humans. Here, we propose a coupled social–ecological dilemma to investigate the interdependence of three well-identified components of this cooperation problem: 1) timescales of collapse and recovery in relation to time preferences regarding future outcomes, 2) the magnitude of the impact of collapse, and 3) the number of actors in the collective. We find that, under a sufficiently severe and time-distant collapse, how much the actors care for the future can transform the game from a tragedy of the commons into one of coordination, and even into a comedy of the commons in which cooperation dominates. Conversely, we also find conditions under which even strong concern for the future still does not transform the problem from tragedy to comedy. For a large number of participating actors, we find that the critical collapse impact, at which these game regime changes happen, converges to a fixed value of collapse impact per actor that is independent of the enhancement factor of the public good, which is usually regarded as the driver of the dilemma. Our results not only call for experimental testing but also help explain why polarization in beliefs about human-caused climate change can threaten global cooperation agreements.

PHASE SHIFT METHODOLOGY ASSESSMENT OF AN AUTOMOTIVE MIXED FLOW TURBOCHARGER TURBINE UNDER PULSATING FLOW CONDITIONS

2015 ◽  
Vol 77 (8) ◽  
Author(s):  
M. H. Padzillah ◽  
S. Rajoo ◽  
R. F. Martinez-Botas
Keyword(s):  
Phase Shift ◽  
Flow Velocity ◽  
Combustion Engine ◽  
Bulk Flow ◽  
Phase Shifting ◽  
Power Matching ◽  
Cfd Models ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Computational Fluid Dynamics Cfd

The reciprocating nature of an Internal Combustion Engine (ICE) inevitably results in unsteady flow in the exhaust manifold. In a turbocharged engine, it means that the turbine is subjected to highly pulsating flows at its inlet. The finite time taken by the travelling pressure waves necessitates the need for phase-shifting method before any instantaneous parameter can be analyzed. In a turbocharger test-rig where the instantaneous isentropic power is evaluated upstream of the instantaneous actual power, one of the parameter has to be time-shifted in order to obtain meaningful instantaneous turbine efficiency. This research aims to compare two different methods of phase shifting which are by peak power matching and summation of sonic and bulk flow velocity. In achieving this aim, Computational Fluid Dynamics (CFD) models of full stage turbine operating at 20 Hz, 40 Hz, 60 Hz and 80 Hz have been developed and validated. Instantaneous efficiency was calculated at different locations and the order of calculated efficiency throughout the pulse is analyzed. Results have shown that phase shift using summation of sonic and bulk flow velocity indicated more reasonable efficiency values, thus the method could be used with high confidence for analysis involving unsteady turbine performance.

Multi-injection turbine housing for turbine performance improvement: A numerical and experimental analysis

2020 ◽  
pp. 095765092094300
Author(s):  
Hao Liu ◽  
Zheng Liu ◽  
Alessandro Romagnoli ◽  
Ricardo F Martinez-Botas ◽  
Srithar Rajoo ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Entropy Generation ◽  
Flow Injection ◽  
Cfd Simulation ◽  
Experimental Testing ◽  
Velocity Ratio ◽  
Suction Side ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Percentage Points

Secondary flow injection is a way which allows for the efficiency of a turbomachine to be increased further, after blade design optimizations have already been performed. In this paper, a novel method for improving turbine performance using secondary flow injection through an injection slot over the turbine shroud is investigated. Numerical simulations were conducted on a mixed-flow turbocharger turbine to test the effectiveness of secondary flow injection. An optimization was performed at peak efficiency at 50% turbine design speed to determine the injection setup which gives the highest turbine efficiency. Single-passage simulations for the optimized point showed an increase in efficiency of 2.6 percentage points compared to the baseline turbine. Flow analysis shows that injection partially blocks the flow passage near the blade tip, forcing turbine passage flow to migrate towards the hub. This apparently weakens the hub suction side separation vortex and reduces entropy generation from the vortex. Experimental testing was conducted and used for validation of full-stage turbine computational fluid dynamics (CFD) simulation results. Full-stage turbine CFD results show that with inlet nozzle vanes, secondary flow injection did not result in any visible improvement in the internal flow field and entropy generation, but overall efficiency can be improved by up to 2.28 percentage points at a velocity ratio of 0.75. Without nozzle vanes, however, secondary flow injection resulted in an efficiency improvement of up to 6.79 percentage points by weakening the hub suction side separation vortex and reducing its associated losses. Injection on the vaneless turbine configuration also resulted in a roughly 2 percentage point improvement in the peak turbine efficiency over the vaned turbine configuration. This might be due to more flow energy available to be extracted by the rotor from reduced losses due to the lack of nozzle vanes.

Strategies for Performance Enhancement of Tesla Turbines for Combined Heat and Power Applications

2010 ◽  
Author(s):  
Vince Romanin ◽  
Van P. Carey ◽  
Zack Norwood
Keyword(s):  
Experimental Testing ◽  
Rankine Cycle ◽  
High Energy ◽  
Combined Heat And Power ◽  
Model Analysis ◽  
Maintenance Cost ◽  
Small Scale ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Turbine Design

A small, efficient, and robust turbine is essential to the development of a small-scale (∼10 kWe) Combined Heat and Power (CHP) Rankine cycle system. While the Tesla turbine design offers a versatile solution with a low manufacturing and maintenance cost, its successful use in systems of this type hinges on development of a design that also offers high energy conversion efficiency. The investigation summarized here explored the parametric trends in Tesla turbine efficiency using model analysis of the turbine performance in tandem with experimental testing of a small scale Tesla turbine. The experimental data were used to evaluate the accuracy of trends predicted by the model analysis. Results of this evaluation show agreement between calculated and experiential efficiency. To further test the model, several non-dimensional parameters that arise from the model analysis were used to predict design modifications to the existing turbine that would improve turbine performance. Several of these modifications were fabricated and tested. Results show that the model is able to accurately predict efficiency variations that result from changes in turbine design. The model is then used to project new turbine designs that will maximize the efficiency of the turbine and recommendations are made for further improving Tesla turbine efficiency. Lastly, improved Tesla turbine designs are discussed in terms of their appropriateness for use in CHP Rankine cycle systems.

scholarly journals Investigation of the effect of gaps between the blades of open flume Pico hydro turbine runners

2019 ◽  
Vol 13 (3) ◽  
pp. 5493-5512
Author(s):  
D. Adanta ◽  
Budiarso . ◽  
Warjito . ◽  
Emanuele Quaranta ◽  
T. M. I. Mahlia
Keyword(s):  
Swirling Flow ◽  
Draft Tube ◽  
Water Pressure ◽  
Turbine Performance ◽  
Design And Manufacturing ◽  
Computational Fluid Dynamics Cfd ◽  
Velocity Triangle ◽  
Design And Manufacture ◽  
Physical Phenomena ◽  
The Impact

This study will analyze the impact of gap size in two different runners called runner A (five blades) and B (six blades) to provides recommendations in design and manufacture of open flume turbine runners so that maximize the conversion of kinetic and potential energy. There are three methods was used to investigate its: analytical method is used to design the turbine; experimental to determine the actual turbine performance; computational fluid dynamics (CFD) to study the physical phenomena and re-check the velocity triangle on the runner to validate the design and manufacturing process. Using the results obtained, gaps between the blades can alter the velocity vector on the outlet and unbalance the rotation of runner; this imbalance could cause cavitation. Then, the decreasing torque is assumed because water pressure in the draft tube is similar to atmospheric pressure. Two conditions must be satisfied to maximize the performance of the turbine: swirling flow is required after the water flows past the runner in order to minimize the radial velocity on the outlet so that the draft tube can function properly; the dimensions of the blade must be carefully selected to avoid the formation of gaps between the blades.

scholarly journals Analysing Hydraulic Efficiency of Water Vortex Pico-Hydro Turbine using Numerical Method

2020 ◽  
Vol 77 (2) ◽  
pp. 91-101
Author(s):  
Ridho Irwansyah ◽  
Warjito ◽  
Budiarso ◽  
Christopher Clement Rusli ◽  
Sanjaya BS Nasution
Keyword(s):  
Internal Flow ◽  
Computational Method ◽  
Hydraulic Efficiency ◽  
Optimum Location ◽  
Optimum Ratio ◽  
Hydro Turbine ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Low Head ◽  
Hydro Turbines

To overcome the lack of rural electricity in Indonesia vortex pico-hydro turbines are used as an option solution. This is due to the ability of the vortex turbine to work in low head conditions effectively. This study is conducted with comparison of curved and straight blade to obtain a more optimum turbine performance. Two methods are carried out in this study, analytical and computational method. Analytical methods are used to determine blade geometry and its performance while computational methods are used to analyse internal flow of turbine. As a result, the study concludes that hydraulic efficiency of vortex turbine in this study doesn’t affect much between straight and curved blades. The hydraulic efficiency for those blades is around 0.63. In addition, the study continued by analysing the optimum location of the blade in the basin. The results of the study show that the optimum ratio of depth and diameter of the blade is 0.33 with turbine efficiency is 0.84. Thus, the location of the blades is more important than the type of blades.

scholarly journals Assessment of wind heeling lever determined through CFD against the current naval stability standards

2018 ◽  
Author(s):  
J N Alderton
Keyword(s):  
Wind Tunnel Test ◽  
Cfd Analysis ◽  
Test Results ◽  
Fit For Purpose ◽  
Numerical Tools ◽  
Computational Fluid Dynamics Cfd ◽  
Potential Impact ◽  
The Uk ◽  
The Impact ◽  
Heeling Moment

Naval stability standards consider the impact of a number of different external factors, one of which is the effect of heeling caused by wind. With relatively large superstructures the wind heeling moment can be relatively significant but despite its potential impact, at present the calculation to determine the wind heeling moment is relatively simplistic. With increasing fidelity within computational tools, in particular Computational Fluid Dynamics (CFD), it questions whether the current standards are still considered fit for purpose or whether a more time consuming but comprehensive analysis should be used. This paper discusses work conducted by QinetiQ on behalf of the UK MoD, to explore this area. The work firstly benchmarks wind heeling moment derived by different CFD methods against existing model wind tunnel test results for a heeled patrol boat. The benchmarking compares the level of accuracy of the numerical tools and explores the impact of changing different parameters within the analysis. Following the benchmarking at model scale, CFD is used to calculate the wind heeling force on two ships at full scale.  The two selected ships represent very different types of hullform and ship particulars.  The results from the CFD analysis are then compared to the results determined using current naval standard wind heeling criteria. This paper discusses the different CFD methodology applied, the results from the benchmarking, the comparison between the CFD results and those determined by applying the current naval standard criteria and the implications on the applicability of a CFD analysis rather than the current criteria. 

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