Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

Design and Modeling of a 45kW, Switched Reluctance Starter-Generator for a Regional Jet Application

2014-09-16
2014-01-2158
Abstract A 45kW, switched reluctance type, starter-generator, having a 1:4 constant power speed range has been designed as a possible candidate for a regional jet application. In the first section of this paper, a review of the major starter-generator topologies considered for the aerospace application is provided, highlighting the advantages of choosing the Switched reluctance topology for such a safety critical application. Following this, the required torque speed characteristic of the machine, along with the imposed physical constraints, in terms of cooling and outer dimensions, are also detailed. Section III provides a description of the Electromagnetic design, and challenges encountered in meeting both the low speed, peak torque node, at 8000rpm, and the high speed, high power node, at 32000rpm. The induced mechanical stresses in the rotor at such high speeds have also been evaluated and used as a material selection criterion for such a design as presented in section III.
Technical Paper

Effects of Component Size and Cooling Air Flows on the Performance, Weight and Dimensions of High and Ultra-High Bypass Ratio Turbofan Engines

2013-10-07
2013-36-0511
The technical evolution of turbofan engines has been accomplished by increasing the engine thermal and propulsive efficiencies. The former is mainly a function of component efficiencies, cycle temperatures and pressures, while the latter is basically related to the engine BPR and FPR. However, several technological challenges are faced to increase those levels of efficiencies. In the thermal efficiency side, higher pressure ratios, for a given stage loading, are obtained by increasing the number of compressor stages, adding weight and size penalties to the engine, and increasing the compressor delivery temperature. Higher cycle temperatures, mainly those found in the burner exit and the stator outlet require higher cooling flows, for a given blade material technology level. Higher cooling flows lead to penalties in the engine efficiency, since the air used in the cooling is bled from the compressor.
Technical Paper

Numerical Simulation of Ice Accretion on the Rotor Blade of a Jet Engine Considering Splash and Bounce

2013-09-17
2013-01-2209
Ice accretion is a phenomenon in which supercooled water droplets impinge and accrete on a body. In the present study, we focus on a jet engine because it is well known that ice accretion on blades and vanes leads to performance degradation and has caused severe accidents. Although various anti-icing and deicing systems have been developed, such accidents still occur. Therefore, it is important to clarify the phenomenon of ice accretion in a jet engine. However, flight tests for ice accretion are very expensive, and in the wind tunnel it is difficult to reproduce every climate condition where ice accretion occurs. Therefore, it is expected that computational fluid dynamics (CFD), which can estimate ice accretion in various climate conditions, will be a useful way to predict the ice accretion phenomenon. The characteristic phenomena of supercooled large droplets (SLD) are splash and bounce.
Journal Article

HTF7000 Engine Design, Development and Uses

2013-09-17
2013-01-2228
Honeywell has developed a unique turbofan engine for application to the super mid-size business aviation market, the HTF7000. This paper will describe the design of this engine including aeromechanical design of its components. The unique design features of this engine will be described along with the technology growth path to keep the engine current. This paper will also describe several features which have been developed for this engine in response to new regulatory requirements. Some aspects of the engine to aircraft integration will also be described.
Journal Article

Investigation of Small Scale Pulsed Detonation Engines and Feasibility Study for Implementation with Disposable Unmanned Aerial Systems

2013-09-17
2013-01-2304
Significant efforts have been made in the research of Pulsed Detonation Engines (PDEs) to increase the reliability and longevity of detonation based propulsion systems for use in manned aircraft. However, the efficiency, durability, and low mechanical complexity of PDEs opens up potential for use in disposable unmanned-vehicles. This paper details the steps taken for producing a miniaturized pulse detonation engine at West Virginia University (WVU) to investigate the numerically generated constraining dimensions for Deflagration to Detonation Transition (DDT) cited in this paper. Initial dimensions for the WVU PDE Demonstrator were calculated using fuel specific DDT spatial properties featured in the work of Dr. Phillip Koshy Panicker, of The University of Texas at Arlington. The WVU demonstrator was powered using oxygen and acetylene mixed in stoichiometric proportions.
Journal Article

Conversion of a Spark-Ignited Aircraft Engine to JP-8 Heavy Fuel for Use in Unmanned Aerial Vehicles

2011-04-12
2011-01-0145
In order to satisfy a single-fuel mandate, the U.S. Department of Defense has a need for engines in the 20 to 50 hp range to power midsized Unmanned Aerial Vehicles (UAVs) and the ability to operate on JP-8 also known as “heavy” fuel. It is possible to convert two-stroke aircraft engines designed to operate on a gasoline-oil mixture to run on JP-8/oil using the Sonex Combustion System (SCS) developed by Sonex Research, Inc. Conversion of the engine involves replacing the cylinder heads with new components designed to accept a steel combustion ring insert. Also required are glow-plugs to preheat the cylinder head prior to engine start. The converted engine produces the same power output as the stock engine operating on gasoline. Conversion of both a 20 hp and 40 hp engine was successfully achieved using the SCS.
Journal Article

Numerical and Experimental Investigation of the Piezoelectric Flapping Wing Micro-Air-Vehicles Propulsion

2012-10-20
2012-01-2245
The flapping flight is advantageous for its superior maneuverability and much more aerodynamically efficiency for the small size UAV when compared to the conventional steady-state aerodynamics solution. Especially, it is appropriate for the Micro-air-vehicle (MAV) propulsion system, where the flapping wings can generate the required thrust. This paper investigated such solution, based on the piezoelectric patches, which are attached to the flexible plates, in combination with an appropriate amplification mechanisms. The numerical and experimental flow analyses have been carried out for the piezoelectric flapping plate, in order to characterize the fluid structure interaction induced by the swinging movement of the oscillating plate.
Technical Paper

Development of An Icing Tool For Aircraft Engines

2011-06-13
2011-38-0056
This paper describes a physics-based icing tool for aircraft engines, which have small components compared to the wing geometry of an aircraft. The tool consists of an icing code, viscous CFD software and mesh generator to build ice shapes incrementally to form the final shape. This multi-layered process was developed to predict ice shapes in components with high-pressure gradient flows as found inside engine flow passages. Good agreement was found between experimental and predicted ice shapes for engine inlet guide vanes and different wing geometries.
Technical Paper

An Analysis of Turbofan Inlet Water and Ice Concentration Effects in Icing Conditions

2011-06-13
2011-38-0050
This paper presents liquid water and ice crystal collection effects for a generic axisymmetric turbofan engine inlet over a range of flight Mach numbers, inlet mass flow ratios, droplet inertia parameters and droplet free stream Reynolds numbers. The ingested water mass flow is properly defined in the context of an Eulerean droplet trajectory calculation method to obtain the collection efficiency. Collection efficiency is then correlated against the mass flow ratio of the airflow rather than the velocity ratio as has been common practice. These results are also compared against published test results. The local concentration effect of liquid water content (LWC) is also described, which can be important in aircraft probe design and placement.
Technical Paper

Critical Point Evaluation of Ice Crystals in Turbofan Engines

2011-06-13
2011-38-0049
An integral part of a new engine certification process is the test verification of satisfactory operation in icing conditions. Icing conditions for this test, which is often conducted at sea level, need to meet or exceed conditions that would be experienced within the flight envelope. In order to assure this fact, manufacturers use analytical tools to conduct a critical point evaluation of engine over the range of flight operation for purposes of comparison to sea level testing. The recent concern for operating in ice crystals places new requirements on icing codes within the industry. One such code is used herein to describe these requirements and to illustrate the critical point evaluation procedure.
Technical Paper

Particle Trajectory and Icing Analysis of the E3 Turbofan Engine Using LEWICE3D Version 3

2011-06-13
2011-38-0048
Particle trajectory and ice shape calculations were made for the Energy Efficient Engine (E₃) using the LEWICE3D Version 3 software. The particle trajectory and icing computations were performed using the new "block-to-block" collection efficiency method which has been incorporated into the LEWICE3D Version 3 software. The E₃ was developed by NASA and GE in the early 1980s as a technology demonstrator and is representative of a modern high bypass turbofan engine. The E₃ flow field was calculated using the NASA Glenn ADPAC turbomachinery flow solver. Computations were performed for the low pressure compressor of the E₃ for a Mach .8 cruise condition at 11,887 meters assuming a standard warm day for three drop sizes and two drop distributions typically used in aircraft design and certification. Particle trajectory computations were made for water drop sizes of 5, 20 and 100 microns.
Technical Paper

Flight Tests in Natural Icing of the PZL Mielec M28 Commuter Turboprop Airplane

2011-06-13
2011-38-0104
PZL Mielec is in the process of certificating the ice protection systems installed on the M28 turboprop aircraft so that customers of that aircraft may operate in icing conditions. The M28 airplane is derived from the Antonov An-28, which was certificated in Russia to their icing certification requirements many decades ago. The M28 is equipped with a lot of western equipment, including Pratt and Whitney Canada engines and Hartzell propellers, and now has a no-hazard certification for the use of the installed ice protection system. The M28 ice protection equipment includes wing and tail anti-icing, engine inlet anti-icing, propeller deicing, and wing strut deicing. These systems have undergone a series of development flight tests and icing wind tunnel tests. This paper presents an overview of the flight tests and wind tunnel tests conducted to date.
Technical Paper

The Challenges Identifying Weather Associated With Jet Engine Ice Crystal Icing

2011-06-13
2011-38-0094
This paper presents the latest findings resulting from ongoing research on jet engine ice crystal icing. It specifically focuses on the challenges for pilots to identify and potentially avoid weather associated with this type of engine icing. The case will be made that jet engine power loss and damage events are not only still occurring, but the overall number of events per year is increasing. Several case studies will be presented to illustrate that each event can vary significantly when viewed from the flight deck even though weather conditions are similar for each. Findings will be presented related to new events that are occurring on engines that were not previously affected along with new engine symptoms. Ongoing meteorological research has shed new light on how to identify weather associated with engine events utilizing infrared satellite imagery combined with atmospheric temperature profiles.
Technical Paper

Calculation of Control Laws for the Digital Fuel Control Unit of a Small Thrust Turbojet

1993-04-01
931411
The methods and the techniques set-up for evaluating the control laws for the digital Main Fuel Control Unit (MFCU) of a small thrust turbojet engine are shown. A suitable parameter defining the surge margin is considered. The paper deals with the results of a study carried out in order to evaluate the influence of engine operating parameters on the surge margin. For this aim the steady state engine simulation programs, based on the state vector technique, have proved to be very effective. Finally the codes and the obtained results have been used for calculating some suitable control laws for a digital MFCU.
Technical Paper

Some Case Studies of Unusual Icing Conditions Encountered by Turbine Engine Powered Airplanes

1996-10-01
965571
Two cases of unusual inflight icing encountered by turbine engine-powered airplanes are discussed. The atmospheric conditions in which the apparent icing occurred are unusual in that in both cases the temperature was colder than that typically associated with icing (at the altitudes at which the events occurred). The pilots' accounts of the events suggest that large supercooled droplets were encountered. These conditions are rare at any temperature, but especially at the temperatures at which these events occurred.
Technical Paper

Investigating Turbofan Engine Internal Aerodynamics

1996-10-01
965630
Abstract The intent of a balanced engine design process is to satisfy all systems requirements including operability, performance and durability. Due to the complexity of the trade-off process of the various metrics it is possible that system improvements may be required after a turbofan engine enters production. Also, in the case of derivative engines, configured for increased performance, the flowpath aerodynamics may be challenged and may have to be examined to ensure there is no flow field anomaly. By incorporating special diagnostic aero instrumentation at the earliest opportunity any required operability improvement can be identified and corrective action taken. The paper first delineates the component matching challenges of twin spool mixed flow turbofan engines. Then it discusses investigation of various potential destabilizing influences.
Technical Paper

Recommended Values of Rain and Hail Concentrations to be Considered in the Design of Turbine Engines

1996-10-01
965596
Extreme rain and hail conditions have caused engine rundowns during commercial airplane flights. In some cases, rain and hail conditions have caused all of the engines on the airplane to rundown simultaneously. This paper presents an analysis that quantifies the rain and hail threat in terms of the probability of encountering a storm of a given intensity for a given period of time. This analysis was used to establish recommended rain and hail concentration levels for design and certification of turbine engines.
Technical Paper

AC Starting Demonstration with Allison AE2100 Turboprop Engine

1997-06-18
971224
During the month of October 1995, Auxilec successfully demonstrated its newly developped AC engine start concept on the Allison AE2100 turboprop engine. This demonstration took place at the AE2100 engine development test cell, which is located in Indianapolis, Indiana. The Auxilec AC engine start system included an off-the-shelf 3OkVA brushless generator, which was derived from an existing helicopter application, together with a vector-controlled power inverter, which was derived from an existing automotive application. The engine start system was powered either by an 80 VDC conventional power supply, or by four NiCad 24VDC/42Ah batteries connected in series and kept at ambient temperature conditions. During this engine start demonstration, which lasted two days, Auxilec managed to perform forty-four (44) successive starts. Of these forty-four (44) engine starts, seven (7) were powered by batteries, while the rest were powered by the 80 VDC power source.
Technical Paper

Thermal Analysis of a Shower-Head Burner

1992-07-01
921226
The NASA Langley Research Center plans to cany out realistic full-scale tests of supersonic combustion ramjet engines at its 8-Foot High Temperature Tunnel (HTT). Consisting mainly of a shower-head type fuel injector (spray bar), the burner and combustion chamber of the tunnel provides the energy needed to attain high-temperature air flows ranging from 1300 to 3000 K and Mach numbers of 4 to 7 at the test section. Required high-temperature fields are generated during the combustion process in a Liquid Oxygen (Lox) Mode environment where air is enriched to about 47 percent by mass in oxygen concentration. The main objectives of this paper are to determine the most important parameters to enable computation of thermal stresses, heat-transfer coefficients, and convective temperatures on the spray bar. In order to compute heattransfer coefficients, NASA will utilize the FLUENT computer code along with well-known empirical methods such as Churchill, Bernstein and Petukhov.
Technical Paper

Hot End Cleaning - Corrosion Pitting of Turbine Discs

1992-04-01
920930
Over a period of years Rolls-Royce plc have experienced intermittent corrosion pitting of turbine discs manufactured from FV535. It was originally thought that this may have been caused by the acidic descaler. Recent work has shown that this corrosion pitting phenomenon is caused by low levels of alkaline permanganate, above 0.01% together with levels of chloride above 30 ppm on discs where there are areas of high chromium commensurate with low iron within the steel. The paper will describe the experimental work to substantiate these conclusions.
X