A Novel Gas Generator Concept for Jet Engines Using a Rotating Combustion Chamber

2013 ◽  
Author(s):  
Peter Jeschke ◽  
Andreas Penkner
Keyword(s):  
Combustion Chamber ◽  
Weight Ratio ◽  
Thermodynamic Cycle ◽  
Ceramic Materials ◽  
Single Stage ◽  
Jet Engines ◽  
Gas Generator ◽  
Small Core ◽  
Efficiency Increase ◽  
Flow Compressor

A gas generator — consisting of a single-stage shrouded mixed-flow compressor without a diffusor, a rotating combustion chamber, and a vaneless single-stage shrouded centripetal turbine — is presented and analyzed here. All components comprise a coherent rotating device, which avoids most of the problems usually associated with small gas generators. In other words, the concept avoids all radial clearances, it is vaneless, shortens the combustion chamber, minimizes the wetted area and enables ceramic materials to be used, due to compressive blade stresses. However, the concept faces severe structural, thermal and chemical reaction challenges. All these features and their implications are discussed and their benefits for several jet engines are quantified, mainly by means of thermodynamic cycle calculations. An upfront CFD analysis identifies a polytropic compressor efficiency of around 95%. It is then demonstrated that the concept offers a thrust-to-weight ratio which is several times higher than the standard when incorporated into small UAV-type jet engines. It also enables an attractive multistage and dual-flow, but fully vaneless design option. Lastly, a thermal efficiency increase of several percentage points would be achieved, if the concept were to be realized in the (small) core of turbofans with highest overall pressure ratios and high bypass ratios. In summary, the paper presents a gas generator approach which may be considered by designers of small jet engines like those used in UAV applications and it might even be a (challenging) long-term option for the small core engines encountered in future turbofans and turboprops.

A Novel Gas Generator Concept for Jet Engines Using a Rotating Combustion Chamber

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Peter Jeschke ◽  
Andreas Penkner
Keyword(s):  
Combustion Chamber ◽  
High Efficiency ◽  
Weight Ratio ◽  
Thermodynamic Cycle ◽  
Ceramic Materials ◽  
Single Stage ◽  
Jet Engines ◽  
Gas Generator ◽  
Wetted Area ◽  
Flow Compressor

A gas generator—consisting of a single-stage shrouded mixed-flow compressor without a diffusor, a rotating combustion chamber, and a vaneless single-stage shrouded centripetal turbine—is presented and analyzed here. All components comprise a coherent rotating device, which avoids most of the problems usually associated with small gas generators. In other words, the concept avoids all radial clearances; it is vaneless, shortens the combustion chamber, minimizes the wetted area, and enables ceramic materials to be used, due to compressive blade stresses. However, the concept faces severe structural, thermal, and chemical reaction challenges and is associated with a large Rayleigh-type total pressure loss. All these features and their implications are discussed and their benefits and drawbacks for several jet engines are quantified, mainly by means of thermodynamic cycle calculations. As a result, it has been demonstrated that the concept offers a thrust-to-weight ratio which is higher than the standard when incorporated into small unmanned aerial vehicles (UAV)-type jet engines. It also enables an attractive multistage and dual-flow, but fully vaneless design option. However, the concept leads to a decrease in thermal efficiency if these were to be accomplished in the (small) core of turbofans with highest overall pressure ratios (OPRs) and high bypass ratios. In summary, the paper presents a gas generator approach, which may be considered by designers of small jet engines with high power density requirements, like those used in UAV applications. But this has been proven not to be an option for high-efficiency propulsion.

Numerical Efforts of Aerodynamic Re-Design in a Single-Stage Transonic Axial Compressor: Part 1 — Stator Design

2017 ◽  
Author(s):  
Justin (Jongsik) Oh
Keyword(s):  
Pressure Ratio ◽  
Axial Compressor ◽  
Axial Flow ◽  
Single Stage ◽  
Design Flow ◽  
Design Parameters ◽  
Original Design ◽  
Circular Arc ◽  
Surge Margin ◽  
Flow Compressor

In many aerodynamic design parameters for the axial-flow compressor, three variables of tailored blading, blade lean and sweep were considered in the re-design efforts of a transonic single stage which had been designed in 1960’s NASA public domains. As Part 1, the re-design was limited to the stator vane only. For the original MCA (Multiple Circular Arc) blading, which had been applied at all radii, the CDA (Controlled Diffusion Airfoil) blading was introduced at midspan as the first variant, and the endwalls of hub and casing (or tip) were replaced with the DCA (Double Circular Arc) blading for the second variant. Aerodynamic performance was predicted through a series of CFD analysis at design speed, and the best aerodynamic improvement, in terms of pressure ratio/efficiency and operability, was found in the first variant of tailored blading. It was selected as a baseline for the next design efforts with blade lean, sweep and both combined. Among 12 variants, a case of positively and mildly leaned blades was found the most attractive one, relative to the original design, providing benefits of an 1.0% increase of pressure ratio at design flow, an 1.7% increase of efficiency at design flow, a 10.5% increase of the surge margin and a 32.3% increase of the choke margin.

Design Aspects of Power Plants for V/STOL Aircraft

1967 ◽  
Author(s):  
J. F. Coplin
Keyword(s):  
Power Plants ◽  
Weight Ratio ◽  
Gas Generator ◽  
Extensive Experience ◽  
Thrust Vectoring ◽  
Two Generations ◽  
High Integrity ◽  
Integrated Concept ◽  
High Thrust ◽  
Efflux Velocity

Thrust in execess of that required for cruise and flight maneuvering is necessary to provide an aircraft with a VTOL capability. The extra thrust may be obtained by enlarged cruise engines with thrust vectoring or by retaining the optimum-size cruise engine possibly with thrust vectoring and adding a lift power plant in the form of lift jets or lift fans. A brief outline of extensive experience with lift jets, thrust vectoring, and lift fans is given and the importance of this background in making it possible to design more advanced engines which will satisfactorily meet practical operational requirements is brought out. Experience in two generations of lift-jet flight testing has shown many important areas where specal features must be incorporated in the design from the beginning to achieve high thrust for a compact volume, light weight, and high integrity in the relatively severe environment in which the lift jet has to operate. Examples are cited. The relative importance of thrust/volume and thrust/weight ratio is shown with reference to VTOL strike and transport aircraft. An integrated concept, using compact lift jets for VTOL strike aircraft and compact low-efflux-velocity lift fans using the same engine as a gas generator, is briefly noted.

scholarly journals Superalloy Technology - A Perspective on Critical Innovations for Turbine Engines

2008 ◽  
Vol 380 ◽  
pp. 113-134 ◽  
Author(s):  
Robert Schafrik ◽  
Robert Sprague
Keyword(s):  
High Temperature ◽  
Customer Value ◽  
Oil And Gas ◽  
Driving Forces ◽  
Ceramic Materials ◽  
Nickel Superalloy ◽  
Engineering Practice ◽  
Jet Engines ◽  
Societal Benefit ◽  
Development Paradigm

High temperature structural materials, such as nickel-based superalloys, have contributed immensely to societal benefit. These materials provide the backbone for many applications within key industries that include chemical and metallurgical processing, oil and gas extraction and refining, energy generation, and aerospace propulsion. Within this broad application space, the best known challenges tackled by these materials have arisen from the demand for large, efficient land-based power turbines and light-weight, highly durable aeronautical jet engines. So impressive has the success of these materials been that some have described the last half of the 20th century as the Superalloy Age. Many challenges, technical and otherwise, were overcome to achieve successful applications. This paper highlights some of the key developments in nickel superalloy technology, principally from the perspective of aeronautical applications. In the past, it was not unusual for development programs to stretch out 10 to 20 years as the materials technology was developed, followed by the development of engineering practice, and lengthy production scaleup. And many developments fell by the wayside. Today, there continue to be many demands for improved high temperature materials. New classes of materials, such as intermetallics and ceramic materials, are challenging superalloys for key applications, given the conventional wisdom that superalloys are reaching their natural entitlement level. Therefore, multiple driving forces are converging that motivate improvements in the superalloy development process. This paper concludes with a description of a new development paradigm that emphasizes creativity, development speed, and customer value that can provide superalloys that meet new needs.

Numerical Investigation of the Influence of Flow Parameters Nonuniformity at the Diffuser Inlet on Characteristics of the GTE Annular Combustion Chamber

2015 ◽  
Author(s):  
Sergey S. Matveev ◽  
Ivan A. Zubrilin ◽  
Mikhail Yu. Orlov ◽  
Sergey G. Matveev
Keyword(s):  
Combustion Chamber ◽  
Dynamic Pressure ◽  
Air Distribution ◽  
Gas Generator ◽  
Air Velocity ◽  
Degree Polynomial ◽  
Flow Dynamic ◽  
Ansys Fluent ◽  
Flow Parameters ◽  
Mode Of Operation

Parameters at a combustion chamber’s inlet significantly vary in an aircraft engine’s transient states of operation. At the same time, there is a significant spatial heterogeneity of flow parameters at a diffuser inlet of a combustion chamber, which is defined by nature of flow in a compressor and an individual for each mode of operation of a specific gas generator. In this paper presented a study of an influence of radial and circumferential nonuniformities of flow parameters on characteristics of a combustion chamber. Multi spray for annular combustion chamber with two rows of burner is considered. Z-shaped sector, which contains two nozzles of outer and two nozzles of inner row, was selected as the calculated domain. Calculations were carried out in ANSYS Fluent 14.5 software package with an implementation of cluster analysis. Nonuniformity at a diffuser inlet was set as fifth degree polynomial, which was derived from a numerical simulation of a compressor. As a result it was established, that radial nonuniformity of flow parameters at an inlet of a combustion chamber influences on characteristics of a combustion chamber. A stretched shape of velocity profile contributes to higher air flow dynamic pressure on dome than using uniform profile air velocity. At that, local equivalents ratio excess are changing, and consequently, sizes and location NOx production zones are changing as well. The residual rotation of flow from the compressor leads to a lesser effect on total pressure drop and air distribution in flame tube. The obtained results showed that, during a design of a combustion chamber, it is necessary to take into account nonuniformity of parameters’ distribution at its inlet.

scholarly journals Smart ceramic materials for homogeneous combustion in internal combustion engines: A review

2009 ◽  
Vol 13 (3) ◽  
pp. 153-163 ◽  
Author(s):  
Kannan Chidambaram ◽  
Tamilporai Packirisamy
Keyword(s):  
Combustion Chamber ◽  
Internal Combustion Engines ◽  
Porous Ceramic ◽  
Ceramic Materials ◽  
Combustion Engines ◽  
Emission Level ◽  
Engine Cylinder ◽  
Homogeneous Combustion ◽  
Zero Emission ◽  
Porous Ceramic Materials

The advantages of using ceramics in advanced heat engines include increased fuel efficiency due to higher engine operating temperatures, more compact designs with lower capacity cooling system. Future internal combustion engines will be characterized by near zero emission level along with low specific fuel consumption. Homogenous combustion which realized inside the engine cylinder has the potential of providing near zero emission level with better fuel economy. However, the accomplishment of homogeneous combustion depends on the air flow structure inside the combustion chamber, fuel injection conditions and turbulence as well as ignition conditions. Various methods and procedures are being adopted to establish the homogeneous combustion inside the engine cylinder. In recent days, porous ceramic materials are being introduced inside the combustion chamber to achieve the homogeneous combustion. This paper investigates the desirable structures, types, and properties of such porous ceramic materials and their positive influence on the combustion process.

Micro Machining of Nonconductive Al2O3 Ceramic on Developed TW-ECSM Setup

2012 ◽  
pp. 167-177
Author(s):  
Alakesh Manna ◽  
Amandeep Kundal
Keyword(s):  
Weight Ratio ◽  
High Hardness ◽  
High Strength ◽  
Ceramic Materials ◽  
Actual Condition ◽  
Test Results ◽  
Machining Performance ◽  
Machining Processes ◽  
Al2o3 Ceramic ◽  
Advanced Ceramic

Advanced ceramic materials are gradually becoming very important for their superior properties such as high hardness, wear resistance, chemical resistance, and high strength to weight ratio. But machining of advanced ceramic like Al2O3-ceramics is very difficult by any well known and common machining processes. Normally, cleavages and triangular fractures generate when machining of these materials is done by traditional machining methods. It is essential to develop an efficient and accurate machining method for processing advanced ceramic materials. For effective machining of Al2O3-ceramics, a traveling wire electrochemical spark machining (TW-ECSM) setup has been developed. The developed TW-ECSM setup has been utilized to machine Al2O3 ceramic materials and subsequently test results are utilized to analyze the machining performance characteristic. Different SEM photographs show the actual condition of the micro machined surfaces. The practical research analysis and test results on the machining of Al2O3 ceramics by developed TWECSM setup will provide a new guideline to the researchers and manufacturing engineers.

Micro Machining of Nonconductive Al2O3 Ceramic on Developed TW-ECSM Setup

2011 ◽  
Vol 1 (2) ◽  
pp. 46-55
Author(s):  
Alakesh Manna ◽  
Amandeep Kundal
Keyword(s):  
Weight Ratio ◽  
High Hardness ◽  
High Strength ◽  
Ceramic Materials ◽  
Actual Condition ◽  
Test Results ◽  
Machining Performance ◽  
Machining Processes ◽  
Al2o3 Ceramic ◽  
Advanced Ceramic

Advanced ceramic materials are gradually becoming very important for their superior properties such as high hardness, wear resistance, chemical resistance, and high strength to weight ratio. But machining of advanced ceramic like Al2O3-ceramics is very difficult by any well known and common machining processes. Normally, cleavages and triangular fractures generate when machining of these materials is done by traditional machining methods. It is essential to develop an efficient and accurate machining method for processing advanced ceramic materials. For effective machining of Al2O3-ceramics, a traveling wire electrochemical spark machining (TW-ECSM) setup has been developed. The developed TW-ECSM setup has been utilized to machine Al2O3 ceramic materials and subsequently test results are utilized to analyze the machining performance characteristic. Different SEM photographs show the actual condition of the micro machined surfaces. The practical research analysis and test results on the machining of Al2O3 ceramics by developed TWECSM setup will provide a new guideline to the researchers and manufacturing engineers.

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