Design and Testing of a Micromix Combustor With Recuperative Wall Cooling for a Hydrogen Fuelled μ-Scale Gas Turbine

2010 ◽  
Author(s):  
A. E. Robinson ◽  
H. H.-W. Funke ◽  
P. Hendrick ◽  
R. Wagemakers
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Mass Flow ◽  
Gas Turbines ◽  
High Energy ◽  
High Energy Density ◽  
Energy Output ◽  
Experimental Investigations ◽  
Small Scale ◽  
Micro Scale

For more than a decade up to now there is an ongoing interest in small gas turbines downsized to micro-scale. With their high energy density they offer a great potential as a substitute for today’s unwieldy accumulators, found in a variety of applications like laptops, small tools etc. But micro-scale gas turbines could not only be used for generating electricity, they could also produce thrust for powering small unmanned aerial vehicles (UAVs) or similar devices. Beneath all the great design challenges with the rotating parts of the turbomachinery at this small scale, another crucial item is in fact the combustion chamber needed for a safe and reliable operation. With the so called regular micromix burning principle for hydrogen successfully downscaled in an initial combustion chamber prototype of 10 kW energy output, this paper describes a new design attempt aimed at the integration possibilities in a μ-scale gas turbine. For manufacturing the combustion chamber completely out of stainless steel components, a recuperative wall cooling was introduced to keep the temperatures in an acceptable range. Also a new way of an integrated ignition was developed. The detailed description of the prototype’s design is followed by an in depth report about the test results. The experimental investigations comprise a set of mass flow variations, coupled with a variation of the equivalence ratio for each mass flow at different inlet temperatures and pressures. With the data obtained by an exhaust gas analysis, a full characterisation concerning combustion efficiency and stability of the prototype chamber is possible. Furthermore the data show a full compliance with the expected operating requirements of the designated μ-scale gas turbine.

Design and Testing of a Micromix Combustor With Recuperative Wall Cooling for a Hydrogen Fueled μ-Scale Gas Turbine

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
A. E. Robinson ◽  
H. H.-W. Funke ◽  
P. Hendrick ◽  
R. Wagemakers
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Mass Flow ◽  
Gas Turbines ◽  
High Energy ◽  
Gas Analysis ◽  
High Energy Density ◽  
Energy Output ◽  
Experimental Investigations ◽  
Small Scale

For more than 1 decade up to now, there is an ongoing interest in small gas turbines downsized to microscale. With their high energy density, they offer a great potential as a substitute for today’s unwieldy accumulators found in a variety of applications such as laptops, small tools, etc. But microscale gas turbines could not only be used for generating electricity, they could also produce thrust for powering small unmanned aerial vehicles or similar devices. Beneath all the great design challenges with the rotating parts of the turbomachinery at this small scale, another crucial item is in fact the combustion chamber needed for a safe and reliable operation. With the so-called regular micromix burning principle for hydrogen successfully downscaled in an initial combustion chamber prototype of 10 kW energy output, this paper describes a new design attempt aimed at the integration possibilities in a μ-scale gas turbine. For manufacturing the combustion chamber completely out of stainless steel components, a recuperative wall cooling was introduced to keep the temperatures in an acceptable range. Also a new way of an integrated ignition was developed. The detailed description of the prototype’s design is followed by an in depth report about the test results. The experimental investigations comprise a set of mass flow variations, coupled with a variation of the equivalence ratio for each mass flow at different inlet temperatures and pressures. With the data obtained by an exhaust gas analysis, a full characterization concerning combustion efficiency and stability of the prototype chamber is possible. Furthermore, the data show full compliance with the expected operating requirements of the designated μ-scale gas turbine.

Numerical and Experimental Investigation of a Micromix Combustor for a Hydrogen Fuelled µ-Scale Gas Turbine

2009 ◽  
Author(s):  
A. E. Robinson ◽  
H. H.-W. Funke ◽  
R. Wagemakers ◽  
J. Grossen ◽  
W. Bosschaerts ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Mass Flow ◽  
Gas Turbines ◽  
Ambient Pressure ◽  
High Energy ◽  
High Energy Density ◽  
Design Parameters ◽  
Small Scale ◽  
Symmetric Model ◽  
Cfd Model

This last decade has shown an increased interest in the downsizing of gas turbines to micro-scale. Their potential for high energy density makes them extremely attractive for small scale high power units as alternative to traditional unwieldy accumulators or as thrust systems in small robots and unmanned aerial vehicles (UAVs). Beneath great challenges with the rotating parts at this small scale, another crucial item is in fact the combustion chamber needed for a safe and reliable operation. This paper presents a study to an alternative approach in μ-scale hydrogen combustion. The burning principle is based upon the so-called inverse micromix injection. In this non-premixed design, hydrogen fuel is introduced through a porous metal and injected in the axial direction into the combustion chamber. A CFD-model has been implemented to parameterise the different geometrical aspects of the combustion chamber and is set up as a 2D axis-symmetric model to allow for a rapid optimisation of the parameters. The flow calculations are done with a commercial CFD-software. The final optimised geometry showed stable combustion, a well suited temperature profile and acceptable wall temperatures. An overview on the influence of the critical design parameters for the different geometries is presented. Experimental investigations comprise a set of mass flow variations coupled with a variation of the equivalence ratio for each mass flow but always at ambient pressure conditions. With the data obtained by an exhaust gas analysis, a full characterisation concerning combustion efficiency and stability of the burning principle is possible. Combined with the wall temperature measurements, these results lead to a further validation of the CFD model.

Experimental Investigations of Pressure Drop in the Combustion Chamber of Gas Turbine

1989 ◽  
Author(s):  
Marek Dzida ◽  
Krzysztof Kosowski
Keyword(s):  
Pressure Drop ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Relative Pressure ◽  
Wide Range ◽  
Few Data

In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results. This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.

scholarly journals A Unique Small Gas Turbine Test Facility for Low-Cost Investigations of Ceramic Rotor Materials and Thermal Barrier Coatings

1998 ◽  
Author(s):  
Björn Schenk ◽  
Torsten Eggert ◽  
Helmut Pucher
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Low Cost ◽  
Temperature Gradients ◽  
Test Facility ◽  
Small Scale ◽  
Transient Temperature ◽  
Turbine Inlet ◽  
Turbine Rotors

The paper describes a test facility for small-scale gas turbines, which basically has been designed and assembled at the Institute of Combustion Engines of the Technical University Berlin. The facility exposes ceramic rotor components to the most significant loads that occur during real gas turbine operation in a clearly predefined manner (high circumferential velocities and highest turbine inlet temperatures). The test facility allows the investigation of bladed radial inflow turbine rotors, as well as — in a preceding step — geometrically simplified ceramic or coated metallic rotors. A newly designed, ceramically lined, variable geometry combustion chamber allows turbine inlet temperatures up to 1450°C (2640 F). A fast thermal shock unit (switching time of about 1s), which is integrated into the test facility between the combustion chamber and the turbine scroll, can be used to create, for example, severe transient temperature gradients within the rotor components to simulate gas turbine trip conditions. In order to generate steady state temperature gradients, especially during disk testing, the rotor components can be subjected to an impingement cooling of the rotor back face (uncoated in case of TBC-testing). The test facility is additionally equipped with a non-contact transient temperature measurement system (turbine radiation pyrometry) to determine the test rotor surface temperature distribution during operation. Apart from the possibilities of basic rotor material investigations, the test facility can also be used to automatically generate compressor and turbine performance characteristics maps. The latter might be used to assess the aerodynamic performance of bladed ceramic radial inflow or mixed flow turbine rotors with respect to manufacturing tolerances due to near-net-shape forming processes (e.g., gelcasting or injection molding).

A Thermal Mixing Scheme for Portable Gas Turbines

2010 ◽  
Author(s):  
S. Tanaka ◽  
Z. Spakovszky
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Gas Turbines ◽  
High Speed ◽  
Small Scale ◽  
Exhaust Gas ◽  
Mixing Length ◽  
Flow Ratio ◽  
Flow Mixing ◽  
Mass Flow Ratio

To meet the increasing demand for advanced portable power units, for example for use in personal electronics and robotics, a number of studies have recently focused on small gas turbine units in the 500 W to 1 kW range. The majority of the work to date is concerned with the design of efficient high-speed rotating machinery and electric components. An important aspect, especially critical for portable operation, is the cooling of the gas turbine and the exhaust gas. This is the focus of the present paper. The compact and small-scale architecture of such gas turbine engines poses major challenges in the thermal management as the required cooling mass flow for portable operation is relatively large and the flow mixing length is short and constrained by package size considerations. Previously, a mixer/ejector based cooling scheme was proposed and vortex generator rings and multi-walled ejector configurations were experimentally investigated with the goal to enhance the mixing of the exhaust gas with cooling flow [1]. Although the augmentations achieved a satisfactory cooling mass flow ratio of 16.8:1, hot spots still existed at the exit of the relatively long mixer duct due to the high area-ratio of the ejector configuration. To overcome this mixing challenge, an alternative cooling scheme was conceived. In this scheme, the hot exhaust gas flow is forced radially outward through a perforated cylindrical liner into the cooling air flow surrounding the exhaust duct. The concept resembles that of an inverted dilution liner where the hot exhaust gas is injected into the much larger cooling mass flow. The hypothesis is that the array of streamwise vortices formed by the hot jets reduces the mixing length and significantly mitigates the temperature non-uniformity. The design space was first explored using a control volume (CV) analysis and the performance of the proposed device and the detailed flow features were investigated using three-dimensional Computational Fluid Dynamics (CFD) simulations. The computations demonstrate enhanced mixing which reduces the turbine exhaust gas temperature of 630°C to a temperature distribution below 75°C at the mixer exit, comparable to the temperature levels and non-uniformity of a commercial hand dryer. The cooling mass flow ratio and required cooling fan power were 15.4 and 1.9% of engine power output respectively. Flow mixing guidelines were established together with a concept mixer configuration, generally applicable to small scale gas turbine devices.

Optimal Design of Micro-Turbine Cogeneration Systems for the Portuguese Buildings Sector

2011 ◽  
Author(s):  
Lui´s B. Martins ◽  
Ana C. M. Ferreira ◽  
Manuel L. Nunes ◽  
Celina P. Lea˜o ◽  
Senhorinha F. C. F. Teixeira ◽  
...  
Keyword(s):  
Optimal Design ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Thermal Power ◽  
High Energy ◽  
Medium Size ◽  
Small Scale ◽  
Inlet Temperature ◽  
Energy Prices ◽  
Cogeneration System

The use of combined heat and power (CHP) systems to produce both electric and thermal energies for medium-size buildings is on the increase, due to their high overall efficiency, high energy prices and political and social awareness. In this paper, an energy-economic study is presented. The main objective is to implement an analysis that will lead to the optimal design of a small cogeneration system, given the thermal power duration curve of a multi-family residential building. A methodology was developed to obtain this curve for a reference B-class building located in the North of Portugal. The CHP unit is based on a micro gas-turbine and includes an Internal Pre-Heater (IPH), typical of these types of small-scale units, and an external Water Heater (WH). A numerical optimization method was applied to solve the thermo-economic model. The mathematical model yields an objective function defined as the maximization of the annual worth of the cogeneration system. A purchase cost equation was used for each major plant component that takes into account size and performance variables. Seven decision variables were selected for the optimization algorithm, including performance of internal gas-turbine components and electrical and thermal powers. The results show that, the revenue from selling electricity to the grid and fuel costs have the greatest impact on the annual worth of the system. The optimal solution for the small CHP is sensitive to fuel price, electricity feed-in-tariff, capital cost and to the thermal load profile of the building. High European energy prices point towards future micro gas-turbines with better electrical efficiencies, achieved via a higher pressure-ratio compressor and turbine inlet temperature.

scholarly journals Numerical Study on the Characteristics of Methane Hedging Combustion in a Heat Cycle Porous Media Burner

Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1733
Author(s):  
Fei Wang ◽  
Xueming Li ◽  
Shuai Feng ◽  
Yunfei Yan
Keyword(s):  
Porous Media ◽  
Temperature Distribution ◽  
Energy Density ◽  
Wall Temperature ◽  
High Energy ◽  
High Energy Density ◽  
Small Scale ◽  
Cycle Structure ◽  
Heat Cycle ◽  
Micro Scale

With the rapid development of portable devices and micro-small sensors, the demand for small-scale power supplies and high-energy-density energy supply systems is increasing. Comparing with the current popular lithium batteries, micro-scale burners based on micro-thermal photoelectric systems have features of high power density and high energy density, the micro-scale burner is the most critical part of the micro-thermal photovoltaic system. In this paper, the combustor was designed as a heat cycle structure and filled with porous media to improve the combustion characteristics of the micro combustor. In addition, the influence of the porous media distribution on the burner center temperature and wall temperature distribution were studied through numerical simulation. Furthermore, the temperature distribution of the combustor was studied by changing the porous media parameters and the wall parameters. The research results show that the heat cycle structure can reduce heat loss and improve combustion efficiency. When the combustion chamber is filled with porous media, it makes the radial center temperature rise by about 50 K and the temperature distribution more uniform. When filling the heat cycle channel with porous media the wall temperature can be increased. Finally, the study also found that as methane is combusted in the combustor, the temperature of the outer wall gradually increases as the intake air velocity increases. The results of this study provide a theoretical and practical basis for the further design of high-efficiency combustion micro-scale burners in the future.

New Insights From Conceptual Design of an Additive Manufactured 300 W Micro Gas Turbine Towards UAV Applications

2020 ◽  
Author(s):  
Lukas Badum ◽  
Boris Leizeronok ◽  
Beni Cukurel
Keyword(s):  
Heat Transfer ◽  
Energy Density ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Energy ◽  
High Energy Density ◽  
Heat Transfer Analysis ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Micro Gas Turbine

Abstract Owing to high energy density of hydrocarbon fuels, ultra-micro gas turbines with power outputs below 1 kW have potential as battery replacement in drones. To overcome the obstacles observed in previous works on gas turbines of this scale, novel gas turbine architecture is proposed based on conventional roller bearing technology that operates at up to 500,000 RPM and additively manufactured monolithic rotor in cantilevered configuration, equipped with internal cooling blades. The optimum turbomachinery design is elaborated using diabatic cycle calculation, coupled with turbomachinery meanline design. This approach provides new insights on interdependencies of heat transfer, component efficiency and system electric efficiency. Thereby, reduced design pressure ratio of 2.5 with 1200 K turbine inlet temperature is identified as most suitable for 300 W electric power output. In following, material properties and design constraints for the monolithic rotor are obtained from available additive manufacturing technologies. Rotordynamic simulations are then conducted for four available materials using simplified rotor model. CFD simulations are conducted to quantify compressor efficiency and conjugate heat transfer analysis is performed to assess the benefit of internal cooling cavity and vanes for different rotor materials. It is demonstrated that the cavity flow absorbs large heat flux from turbine to compressor, thus cooling the rotor structure and improving the diabatic cycle efficiency. Finally, results of this conceptual study show that ultra-micro gas turbine with electric efficiency of up to 5% is feasible, while energy density is increased by factor of 3.6, compared to lithium-ion batteries.

scholarly journals Design and Numerical Analysis of a Micro Gas Turbine Combustion Chamber

2020 ◽  
Vol 10 (6) ◽  
pp. 6422-6426
Author(s):  
A. C. Mangra
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Transport Model ◽  
Droplet Diameter ◽  
Central Area ◽  
Numerical Results ◽  
Cfd Modeling ◽  
Small Scale ◽  
Micro Gas Turbine

The interest in micro gas turbines has been steadily increasing. As a result, attention has been focused on obtaining optimal configurations for micro gas turbines depending on the applications in which they are used. This paper presents the CFD modeling results regarding an annular type combustion chamber, part of an 800N micro gas turbine, predestined to equip a small scale multifunctional airplane. Two configurations have been taken into consideration and 3D RANS numerical simulations have been conducted with the use of the commercial software ANSYS CFX. The liquid fuel droplets were modeled by the particle transport model, which tracks the particles in a Lagrangian way. An initial fuel droplet diameter of 500µm has been imposed. The numerical results obtained are encouraging. The flame was developed in the central area of the fire tube, its walls thus not being subjected to high temperatures. Also, the maximum temperatures were obtained in the primary zone of the fire tube. The temperature then decreased in the fire tube's secondary zone and dilution zone. The numerical results will be validated by conducting combustion tests on a testing rig which will be developed inside the institute's Combustion Chamber Laboratory.

New Insights From Conceptual Design of an Additive Manufactured 300 W Micro Gas Turbine Towards UAV Applications

2020 ◽  
Author(s):  
L. Badum ◽  
B. Leizeronok ◽  
B. Cukurel
Keyword(s):  
Heat Transfer ◽  
Energy Density ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Energy ◽  
High Energy Density ◽  
Heat Transfer Analysis ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Micro Gas Turbine

Abstract Owing to the high energy density of hydrocarbon fuels, ultra-micro gas turbines with power outputs below 1 kW have clear potential as battery replacement in drones. However, previous works on gas turbines of this scale revealed severe challenges due to air bearing failures, heat transfer from turbine to compressor, rotordynamic instability and manufacturing limitations. To overcome these obstacles, a novel gas turbine architecture is proposed based on conventional roller bearing technology that operates at up to 500,000 RPM and an additively manufactured monolithic rotor in cantilevered configuration, equipped with internal cooling blades. The optimum turbomachinery design is elaborated using diabatic cycle calculation, coupled with turbomachinery meanline design code. This approach provides new insights on the interdependencies of heat transfer, component efficiency and system electric efficiency. Thereby, a reduced design pressure ratio of 2.5 with 1200 K turbine inlet temperature is identified as most suitable for 300 W electric power output. In following, a review of available additive manufacturing technologies yields material properties, surface roughness and design constraints for the monolithic rotor. Rotordynamic simulations are then conducted for four available materials using a simplified rotor model to identify valid permanent magnet dimensions that would avoid operation close to bending modes. To complete the baseline engine architecture, a novel radial inflow combustor concept is proposed based on porous inert media combustion. CFD simulations are conducted to quantify compressor efficiency and conjugate heat transfer analysis of the monolithic rotor is performed to assess the benefit of the internal cooling cavity and vanes for different rotor materials. It is demonstrated that the cavity flow absorbs large amount of heat flux from turbine to compressor, thus cooling the rotor structure and improving the diabatic cycle efficiency. Finally, the results of this conceptual study show that ultra-micro gas turbine with electric efficiency of up to 5% is feasible, while energy density is increased by factor of 3.6, compared to lithium-ion batteries.

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