Impact of Heat Transfer on Centrifugal Compressors of Micro Turbines

2012 ◽  
Author(s):  
Dries Verstraete ◽  
Yasitha Hewakuruppu
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
High Speed ◽  
Power Level ◽  
Centrifugal Compressors ◽  
Detail Design ◽  
Heavy Duty Diesel ◽  
And Performance ◽  
Competitive Efficiency ◽  
The Impact

Micro turbines are small, high-speed gas turbine engines. When designed for a power output of 5 to 15 kW, micro turbines could provide the power for a household or a small set of units, serve as a range extender for hybrid electrical vehicles, or an auxiliary power unit to meet anti-idling requirements for heavy-duty diesel truck engines. The smaller the gas turbine, the harder it however is to achieve a competitive efficiency. At the considered power level, manufacturing limitations become significant and heat transfer and fluid leaks start to dominate. Significant development in material science has enabled higher temperatures to be sustained, so that reasonable efficiencies could be obtained. Achieving these efficiencies however depends critically on limiting the effect of inter component heat transfer. In this paper the impact of heat losses on the performance of small centrifugal compressors are investigated. The paper presents the adaptation of a 1D design and performance analysis code to accommodate heat transfer effects. The modifications made to the code to account for heat transfer will be discussed and a validation of the adapted code will be given. After that the performance of several non-adiabatic compressor impellers will be discussed in detail. Design modifications will be presented that reduce the impact of heat transfer for the investigated compressors. The impact on heat transfer on the compressor maps will also be detailed.

scholarly journals Comprehensive Thermodynamic Analysis of the Humphrey Cycle for Gas Turbines with Pressure Gain Combustion

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3521 ◽  
Author(s):  
Panagiotis Stathopoulos
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Process ◽  
Ideal Gas ◽  
Point Of View ◽  
Pressure Gain Combustion ◽  
Combustion Technology ◽  
Secondary Air ◽  
And Performance ◽  
The Impact

Conventional gas turbines are approaching their efficiency limits and performance gains are becoming increasingly difficult to achieve. Pressure Gain Combustion (PGC) has emerged as a very promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine thermodynamic cycles. Up to date, only very simplified models of open cycle gas turbines with pressure gain combustion have been considered. However, the integration of a fundamentally different combustion technology will be inherently connected with additional losses. Entropy generation in the combustion process, combustor inlet pressure loss (a central issue for pressure gain combustors), and the impact of PGC on the secondary air system (especially blade cooling) are all very important parameters that have been neglected. The current work uses the Humphrey cycle in an attempt to address all these issues in order to provide gas turbine component designers with benchmark efficiency values for individual components of gas turbines with PGC. The analysis concludes with some recommendations for the best strategy to integrate turbine expanders with PGC combustors. This is done from a purely thermodynamic point of view, again with the goal to deliver design benchmark values for a more realistic interpretation of the cycle.

Map Width Enhancement Technique for a Turbocharger Compressor

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Subenuka Sivagnanasundaram ◽  
Stephen Spence ◽  
Juliana Early
Keyword(s):  
Performance Improvement ◽  
Peak Pressure ◽  
Pressure Ratio ◽  
Comparison Study ◽  
Heavy Duty ◽  
Recirculating Flow ◽  
Heavy Duty Diesel ◽  
And Performance ◽  
The Stability ◽  
The Impact

This paper presents an investigation of map width enhancement and the performance improvement of a turbocharger compressor using a series of static vanes in the annular cavity of a classical bleed slot system. The investigation has been carried out using both experimental and numerical analysis. The compressor stage used for this study is from a turbocharger unit used in heavy duty diesel engines of approximately 300 kW. Two types of vanes were designed and added to the annular cavity of the baseline classical bleed slot system. The purpose of the annular cavity vane technique is to remove some of the swirl that can be carried through the bleed slot system, which would influence the pressure ratio. In addition to this, the series of cavity vanes provides a better guidance to the slot recirculating flow before it mixes with the impeller main inlet flow. Better guidance of the flow improves the mixing at the inducer inlet in the circumferential direction. As a consequence, the stability of the compressor is improved at lower flow rates and a wider map can be achieved. The impact of two cavity vane designs on the map width and performance of the compressor was highlighted through a detailed analysis of the impeller flow field. The numerical and experimental study revealed that an effective vane design can improve the map width and pressure ratio characteristic without an efficiency penalty compared to the classical bleed slot system without vanes. The comparison study between the cavity vane and noncavity vane configurations presented in this paper showed that the map width was improved by 14.3% due to a significant reduction in surge flow and the peak pressure ratio was improved by 2.25% with the addition of a series of cavity vanes in the annular cavity of the bleed slot system.

Uncertainty Analysis of Inflow Conditions on an HPT Gas Turbine Nozzle: Effect on Particle Deposition

2020 ◽  
Author(s):  
R. Friso ◽  
N. Casari ◽  
M. Pinelli ◽  
A. Suman ◽  
F. Montomoli
Keyword(s):  
Gas Turbine ◽  
Energy Efficient ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Operating Conditions ◽  
Wide Range ◽  
And Performance ◽  
Gas Turbine Nozzle ◽  
The Impact ◽  
Inflow Conditions

Abstract Gas turbines (GT) are often forced to operate in harsh environmental conditions. Therefore, the presence of particles in their flow-path is expected. With this regard, deposition is a problem that severely affects gas turbine operation. Components’ lifetime and performance can dramatically vary as a consequence of this phenomenon. Unfortunately, the operating conditions of the machine can vary in a wide range, and they cannot be treated as deterministic. Their stochastic variations greatly affect the forecasting of life and performance of the components. In this work, the main parameters considered affected by the uncertainty are the circumferential hot core location and the turbulence level at the inlet of the domain. A stochastic analysis is used to predict the degradation of a high-pressure-turbine (HPT) nozzle due to particulate ingestion. The GT’s component analyzed as a reference is the HPT nozzle of the Energy-Efficient Engine (E3). The uncertainty quantification technique used is the probabilistic collocation method (PCM). This work shows the impact of the operating conditions uncertainties on the performance and lifetime reduction due to deposition. Sobol indices are used to identify the most important parameter and its contribution to life. The present analysis enables to build confidence intervals on the deposit profile and on the residual creep-life of the vane.

On the Feasibility of Nuclear Versus Combustion Gas Turbine Propulsion for High-Speed Cargo Ships

2004 ◽  
Author(s):  
H. Boonstra ◽  
A. C. Groot ◽  
C. A. Prins
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Gas Turbine ◽  
High Speed ◽  
Nuclear Power ◽  
Parametric Design ◽  
Pebble Bed ◽  
Pressurized Water ◽  
Combustion Gas ◽  
The Impact

This paper presents the outcome of a study on the feasibility of a nuclear powered High-Speed Pentamaran, initiated by Nigel Gee and Associates and the Delft University of Technology. It explores the competitiveness of a nuclear power plant for the critical characteristics of a marine propulsion plant. Three nuclear reactor types are selected: the Pressurized Water Reactor (PWR), the Pebble-bed and Prismatic-block HTGR. Their characteristics are estimated for a power range from 100 MWth to 1000 MWth in a parametric design, providing a level base for comparison with conventional gas turbine technology. The reactor scaling is based on reference reactors with an emphasis on marine application. This implies that preference is given to passive safety and simplicity, as they are key-factors for a marine power plant. A case study for a 60-knot Pentamaran shows the impact of a nuclear power plant on a ship designed with combustion gas turbine propulsion. The Prismatic-block HTGR is chosen as most suitable because of its low weight compared to the PWR, in spite of the proven technology of a PWR. The Pebble-bed HTGR is considered too voluminous for High-Speed craft. Conservative data and priority to simple systems and high safety leads to an unfavorable high weight of the nuclear plant in competition with the original gas turbine driven Pentamaran. The nuclear powered ship has some clear advantages at high sailing ranges.

On the Heat Transfer and Flow Structures’ Characteristics of the Turbine Blade Tip Underside With Dirt Purge Holes at Different Locations by Using Topological Analysis

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Lei Luo ◽  
Zhiqi Zhao ◽  
Xiaoxu Kan ◽  
Dandan Qiu ◽  
Songtao Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Topological Analysis ◽  
Internal Heat ◽  
Gas Turbine Blade ◽  
Transfer Enhancement ◽  
Cooling Passage ◽  
The Impact

This paper numerically investigated the impact of the holes and their location on the flow and tip internal heat transfer in a U-bend channel (aspect ratio = 1:2), which is applicable to the cooling passage with dirt purge holes in the mid-chord region of a typical gas turbine blade. Six different tip ejection configurations are calculated at Reynolds numbers from 25,000 to 200,000. The detailed three-dimensional flow and heat transfer over the tip wall are presented, and the overall thermal performances are evaluated. The topological methodology, which is first applied to the flow analysis in an internal cooling passage of the blade, is used to explore the mechanisms of heat transfer enhancement on the tip wall. This study concludes that the production of the counter-rotating vortex pair in the bend region provides a strong shear force and then increases the local heat transfer. The side-mounted single hole and center-mounted double holes can further enhance tip heat transfer, which is attributed to the enhanced shear effect and disturbed low-energy fluid. The overall thermal performance of the optimum hole location is a factor of 1.13 higher than that of the smooth tip. However, if double holes are placed on the upstream of a tip wall, the tip surface cannot be well protected. The results of this study are useful for understanding the mechanism of heat transfer enhancement in a realistic gas turbine blade and for efficient designing of blade tips for engine service.

Interfacial Heat Transfer During Droplet Impact on a Solid Surface: Comparison of High-Resolution Laser Measurements With Finite-Element Simulations

2007 ◽  
Author(s):  
Rajneesh Bhardwaj ◽  
Jon P. Longtin ◽  
Daniel Attinger
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Finite Element ◽  
High Speed ◽  
Element Model ◽  
Deposition Process ◽  
Interfacial Heat Transfer Coefficient ◽  
Interfacial Heat Transfer ◽  
Laser Measurements ◽  
The Impact

The objective of this work is to understand the coupling of fluid dynamics and heat transfer during the impact of a millimeter-size water droplet on a flat, solid glass substrate. In this work, a finite-element model is presented which simulates the transient fluid dynamics and heat transfer during the droplet deposition process, considering Laplace forces on the liquid-gas boundary, and the dynamics of wetting. A novel, experimental laser-based method is used to measure temperatures at the solid-liquid interface. This method is based on a thermoreflectance technique and provides unprecedented temporal and spatial resolutions of 1 microsecond and 20 micrometer, respectively. Matching between simulations, temperature measurements and high-speed visualization allows the determination of the interfacial heat transfer coefficient.

Through Flow Calculations for Convective Cooling Turbines

2014 ◽  
Author(s):  
Li Haibo ◽  
Chunwei Gu
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Calculation Method ◽  
Conjugate Heat Transfer ◽  
High Efficiency ◽  
Thermodynamic Efficiency ◽  
Inlet Temperature ◽  
Flow Calculation ◽  
Through Flow ◽  
The Impact

Conjugate heat transfer is a key feature of modern gas turbine, as cooling technology is widely applied to improve the turbine inlet temperature for high efficiency. Impact of conjugate heat transfer on heat loads and thermodynamic efficiency is a key issue in gas turbine design. This paper presented a through flow calculation method to predict the impact of heat transfer on the design process of a convective cooled turbine. A cooling model was applied in the through flow calculations to predict the coolant requirements, as well as a one-dimensional mixing model to evaluate some key parameters such as pressure losses, deviation angles and velocity triangles because of the injection cooling air. Numerical simulations were performed for verification of the method and investigation on conjugate heat transfer within the blades. By comparing these two calculations, it is shown that the through flow calculation method is a useful tool for the blade design of convective cooled turbines because of its simplicity and flexibility.

scholarly journals The Simultaneous Analysis of Droplets’ Impacts and Heat Transfer during Water Spray Cooling Using a Transparent Heater

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2730
Author(s):  
Vladimir Serdyukov ◽  
Nikolay Miskiv ◽  
Anton Surtaev
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
Spray Cooling ◽  
Capillary Waves ◽  
Heat Fluxes ◽  
Small Scale ◽  
Unsteady Temperature ◽  
The Impact

This paper demonstrates the advantages and prospects of transparent design of the heating surface for the simultaneous study of the hydrodynamic and thermal characteristics of spray cooling. It was shown that the high-speed recording from the reverse side of such heater allows to identify individual droplets before their impact on the forming liquid film, which makes it possible to measure their sizes with high spatial resolution. In addition, such format enables one to estimate the number of droplets falling onto the impact surface and to study the features of the interface evolution during the droplets’ impacts. In particular, the experiments showed various possible scenarios for this interaction, such as the formation of small-scale capillary waves during impacts of small droplets, as well as the appearance of “craters” and splashing crowns in the case of large ones. Moreover, the unsteady temperature field during spray cooling in regimes without boiling was investigated using high-speed infrared thermography. Based on the obtained data, the intensity of heat transfer during spray cooling for various liquid flow rates and heat fluxes was analyzed. It was shown that, for the studied regimes, the heat transfer coefficient weakly depends on the heat flux density and is primarily determined by the flow rate. In addition, the comparison of the processes of spray cooling and nucleate boiling was made, and an analogy was shown in the mechanisms that determine their intensity of heat transfer.

Advances in Gas Turbine Technology and the Digital Computer

1996 ◽  
Author(s):  
Melvin Platt
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Speed ◽  
Historical Context ◽  
Interactive Operation ◽  
Technology Advancement ◽  
Coherent Image ◽  
Key Technologies ◽  
The Impact ◽  
Digital Computers

Recent advances in gas turbine technology from computational fluid dynamics (CFD) to concurrent engineering are identified and discussed. These advances are placed in a historical context. Parallels are drawn between advances in gas turbine technology and digital computers. The advent of high-speed digital computers in the late 50s, followed by interactive operation and display graphics in the 70s. and orders-of-magnitude increases in affordable processing speed more recently, have each enabled key technologies for the gas turbine. Examples of such key technologies are given and their evolution is considered. Further, the impact of that technology on gas turbine development is discussed. Those perspectives provide a more coherent image of technology advancement, and thus a greater ability to identify new and future advances that will effect the evolution of gas turbines. The paper concludes with a look into the near future of gas turbine technology.

Lumped Capacitance and 3D CFD Conjugate Heat Transfer Modelling of an Automotive Turbocharger

2015 ◽  
Author(s):  
R. Burke ◽  
C. Copeland ◽  
T. Duda ◽  
M. A. Reyes-Belmonte
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Weak Link ◽  
Three Dimensional ◽  
Sensitivity Study ◽  
Heat Fluxes ◽  
Strategy Development ◽  
Inlet Temperature ◽  
Compression Process ◽  
The Impact

One dimensional wave-action engine models have become an essential tool within engine development including stages of component selection, understanding system interactions and control strategy development. Simple turbocharger models are seen as a weak link in the accuracy of these simulation tools and advanced models have been proposed to account for phenomena including heat transfer. In order to run within a full engine code, these models are necessarily simple in structure yet are required to describe a highly complex 3D problem. This paper aims to assess the validity of one of the key assumptions in simple heat transfer models, namely, that the heat transfer between the compressor casing and intake air occurs only after the compression process. Initially a sensitivity study was conducted on a simple lumped capacity thermal model of a turbocharger. A new partition parameter was introduced αA, which divides the internal wetted area of the compressor housing into pre and post compression. The sensitivity of heat fluxes to αA was quantified with respect to the sensitivity to turbine inlet temperature (TIT). At low speeds, the TIT was the dominant effect on compressor efficiency whereas at high speed αA had a similar influence to TIT. However, modelling of the conduction within the compressor housing using an additional thermal resistance caused changes in heat flows of less than 10%. Three dimensional CFD analysis was undertaken using a number of cases approximating different values of αA. It was seen that when considering a case similar to αA=0, meaning that heat transfer on the compressor side is considered to occur only after the compression process, significant temperature could build up in the impeller area of the compressor housing, indicating the importance of the pre-compression heat path. The 3D simulation was used to estimate a realistic value for αA which was suggested to be between 0.15 and 0.3. Using a value of this magnitude in the lumped capacitance model showed that at low speed there would be less than 1% point effect on apparent efficiency which would be negligible compared to the 8% point seen as a result of TIT. In contrast, at high speeds, the impact of αA was similar to that of TIT, both leading to approximately 1% point apparent efficiency error.

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