Isolating Effects of Area Ratio From Lobe Number for Turbofan Engine Exhaust Systems

2014 ◽  
Author(s):  
Alex Wright ◽  
Ali Mahallati ◽  
Julio Militzer
Keyword(s):  
High Speed ◽  
Engine Performance ◽  
Area Ratio ◽  
Fluid Viscosity ◽  
Engine Exhaust ◽  
Engine Operation ◽  
Low Speed ◽  
High Speed Engine ◽  
Speed Performance ◽  
Performance Results

This paper presents a numerical investigation of lobed mixer performance at experimentally validated low speed conditions and conditions representative of high speed engine operation. The purpose of this study was to first assess and understand how variations in bypass-to-core area ratio (AR) can affect engine performance, then isolate those effects to determine the efficacy of increasing the number of mixer lobes. The area ratio was manipulated via adjustment of the lobe crest and valley radiuses. No other geometric features were altered in any of the 5 mixers studied (12-lobe AR of 3, 2.5 and 3.5, 16-lobe AR of 3 and 18-lobe AR of 3). Results indicate that performance can be affected by area ratio. Low-speed results showed that pressure loss and thrust output were improved at lower area ratios. High speed results showed the opposite. This behavior is believed to be the result of a bypass-to-core momentum ratio difference between the two test conditions. These effects were avoided when studying the number of lobes by maintaining a constant area ratio. Results indicate that adding lobes enhanced exhaust mixing but hampered performance at low speed conditions. No appreciable performance difference was observed at high speed conditions. Fluid viscosity and associated viscous mixing losses are believed to be the parameters at fault for the reduced low-speed performance results.

Optical Investigation of the Effects of Ethanol/Gasoline Blends on Spark-Assisted HCCI

2013 ◽  
Author(s):  
Mohammad Fatouraie ◽  
Margaret S. Wooldridge
Keyword(s):  
Heat Release ◽  
High Speed ◽  
Engine Performance ◽  
Optical Investigation ◽  
Release Rates ◽  
High Speed Imaging ◽  
Engine Operation ◽  
Spark Timing ◽  
Combustion Properties ◽  
Ethanol Blends

Spark assist (SA) has been demonstrated to extend the operating limits of homogeneous charge compression ignition (HCCI) modes of engine operation. This experimental investigation focuses on the effects of 100% indolene and 70% indolene/30% ethanol blends on the ignition and combustion properties during SA HCCI operation. The spark assist effects are compared to baseline HCCI operation for each blend by varying spark timing at different fuel/air equivalence ratios ranging from ϕ = 0.4–0.5. High speed imaging is used to understand connections between spark initiated flame propagation and heat release rates. Ethanol generally improves engine performance with higher IMEPn and higher stability compared to 100% indolene. SA advances phasing within a range of ∼5 CAD at lower engine speeds (700 RPM) and ∼11 CAD at higher engine speeds (1200 RPM). SA does not affect heat release rates until immediately (within ∼5 CAD) prior to autoignition. Unlike previous SA HCCI studies of indolene fuel in the same engine, flames were not observed for all SA conditions.

Homogeneous Charge Catalytic Ignition of Water-Ethanol Blends in a CFR Engine

2009 ◽  
Author(s):  
Edwin Anderson ◽  
Jason Cyr ◽  
Dan Cordon ◽  
Steve Beyerlein
Keyword(s):  
High Speed ◽  
Engine Performance ◽  
High Water ◽  
Operating Characteristics ◽  
Emission Data ◽  
Engine Operation ◽  
Preparation Methods ◽  
Ethanol Injection ◽  
Hc Emissions ◽  
Ethanol Blends

The burning of water ethanol blends has the potential to reduce NOx, CO, and HC emissions while reducing the ethanol fermentation production cost of distillation and dehydration by utilization of these blends. The torch style ignition produced by the catalytic igniter allows for the operation and cold start of an SI engine on ethanol/water fuels up to a 50/50 blend. This paper describes the operating characteristics of a catalytic igniter in a modified Co-operative Fuels Research (CFR) engine. Performance data was evaluated using a high speed in-cylinder combustion pressure analyzer. Emission data for premixed ethanol/water was also compared to separate water and ethanol injection for concentrations of 0–30% water in ethanol. Emissions and performance results for both fuel preparation methods were compared with engine operation on 100% ethanol. Premixed ethanol/water displayed significantly lower NOx and CO emissions and somewhat higher hydrocarbon emissions than separate water and ethanol injection. At a compression ratio of 10:1, the catalytic igniter configuration studied in this work was able to control cycle to cycle pressure variation even at high water fractions.

The Use of Sweep and Dihedral in Multistage Axial Flow Compressor Blading: Part I — University Research and Methods Development

2002 ◽  
Author(s):  
Simon J. Gallimore ◽  
John J. Bolger ◽  
Nicholas A. Cumpsty ◽  
Mark J. Taylor ◽  
Peter I. Wright ◽  
...  
Keyword(s):  
High Speed ◽  
Axial Flow ◽  
Essential Element ◽  
University Research ◽  
Low Speed ◽  
High Speed Engine ◽  
Methods Development ◽  
Basic Ideas ◽  
Flow Compressor ◽  
The University

This paper describes the introduction of 3D blade designs into the core compressors for the Rolls-Royce Trent engine with particular emphasis on the use of sweep and dihedral in the rotor designs. It follows the development of the basic ideas in a university research project, through multistage low-speed model testing, to the application to high pressure engine compressors. An essential element of the project was the use of multistage CFD and some of the development of the method to allow the designs to take place is also discussed. The first part of the paper concentrates on the university-based research and the methods development. The second part describes additional low-speed multistage design and testing and the high-speed engine compressor design and test.

Optical Investigation of the Effects of Ethanol/Gasoline Blends on Spark-Assisted HCCI

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Mohammad Fatouraie ◽  
Margaret Wooldridge
Keyword(s):  
Heat Release ◽  
High Speed ◽  
Engine Performance ◽  
Optical Investigation ◽  
Release Rates ◽  
High Speed Imaging ◽  
Engine Operation ◽  
Auto Ignition ◽  
Spark Timing ◽  
Combustion Properties

Spark assist (SA) has been demonstrated to extend the operating limits of homogeneous charge compression ignition (HCCI) modes of engine operation. This experimental investigation focuses on the effects of 100% indolene and 70% indolene/30% ethanol blends on the ignition and combustion properties during SA HCCI operation. The spark assist effects are compared to baseline HCCI operation for each blend by varying spark timing at different fuel/air equivalence ratios ranging from Φ = 0.4–0.5. High speed imaging is used to understand connections between spark initiated flame propagation and heat release rates. Ethanol generally improves engine performance with higher net indicated mean effective pressure (IMEPn) and higher stability compared to 100% indolene. SA advances phasing within a range of ∼5 crank angle degrees (CAD) at lower engine speeds (700 rpm) and ∼11 CAD at higher engine speeds (1200 rpm). SA does not affect heat release rates until immediately (within ∼5 CAD) prior to auto-ignition. Unlike previous SA HCCI studies of indolene fuel in the same engine, flames were not observed for all SA conditions.

Exhaust Emission Reduction from Compression Ignition Engine by Using Palm Biodiesel Blended with Nano Zinc Oxide Additive

2017 ◽  
Vol 909 ◽  
pp. 249-254
Author(s):  
Ponrawee Wanriko ◽  
Karoon Fangsuwannarak
Keyword(s):  
Palm Oil ◽  
Diesel Fuel ◽  
High Speed ◽  
Alternative Fuel ◽  
Exhaust Emission ◽  
Crude Palm Oil ◽  
Compression Ignition Engine ◽  
Engine Operation ◽  
High Speed Engine ◽  
Speed Engine

Biofuel modifications play a major role in a substitution for fossil fuel to be used in diesel engines and reducing exhaust emission. The most amounts of crude palm oil produced from Asian region can be an alternative fuel, sustainably. By the modifying crude palm oil into pure palm oil biodiesel (POB100), alkali trans-esterification procedure was operated. In the present, the high-quality POB products have been investigated considerably for alternative fuel in 4-cylinders high-speed diesel engine. The aim of this paper is to study in the improvement of POB quality by repeated-distillation and blending POB with nanoZnO additive. The high-speed engine combustion from consuming blended POB fuel were investigated the influences of exhaust emission under speed engine operation of 2,000 rpm and 3,000 rpm. The experimental results were shown that the POB fuel yielded at 84.54% from using 400 g. of raw materials. Both of redistilled POB and POB blended with nanoZnO additive showed the improvement of physical properties including viscosity, specific gravity and cetane number values being under ASTM standard values for high-speed engine. In addition, the results of exhaust emission from the engine showed the effective decrease of carbon monoxide (CO), carbon dioxide (CO2) around 13% due to using redistilled POB and POB blended nanoZnO additive compared with diesel fuel. Unburned hydrocarbon (HC) and nitric oxide (NOx) emissions of the diesel fuel condition. Therefore, this study suggests that nanoZnO blending POB in the small fraction about 0.005 wt% is able to provide the high potentiality for as a clean and alternative fuel.

Modeling Non-Newtonian Piston Skirts EHL in the Initial Engine Start Up

2010 ◽  
Author(s):  
Syed Adnan Qasim ◽  
Usman F. Chaudhri ◽  
M. Afzaal Malik ◽  
Riaz A. Mufti
Keyword(s):  
High Speed ◽  
Relaxation Times ◽  
Radial Clearance ◽  
Solution Technique ◽  
Engine Operation ◽  
Low Speed ◽  
Start Up ◽  
Piston Skirts ◽  
Engine Start ◽  
Speed Engine

In the normal high speed engine operation at small piston-to-bore radial clearance, elastohydrodynamic lubrication (EHL) of skirts and non-Newtonian lubricant behavior prevent adhesive wear, but in the initial engine start up, the large clearance, low speed and absence of EHL, cause start up wear. This study models 2-D upper convected Maxwell viscoelastic EHL of piston skirts at small radial clearance in a few initial low speed engine start up cycles by solving the Reynolds equation and using the inverse solution technique. The numerical analysis incorporate characteristic lubricant relaxation times and a perturbation method to predict and compare hydrodynamic and EHL pressures and film profiles. The effects of viscoelasticity on the lubricant characteristics, transverse eccentricities of piston, film thickness, and pressure fields in the hydrodynamic and EHL regimes are investigated. This study suggests that EHL film is formed at very small piston-to-bore radial clearance at low start up speed under assumed conditions to prevent start up wear as viscoelasticity produces a beneficial effect on piston skirts lubrication in the initial engine start up.

scholarly journals Photo detector IC for Blu-ray-Disc applications: a realization applying efficient design methodologies

2011 ◽  
Vol 9 ◽  
pp. 219-223
Author(s):  
S. Lange ◽  
T. Reich ◽  
J. Nowak ◽  
B. Dimov ◽  
M. Meister ◽  
...  
Keyword(s):  
High Speed ◽  
Low Noise ◽  
Noise Power ◽  
The Novel ◽  
Efficient Design ◽  
Design Methodologies ◽  
Low Power Dissipation ◽  
Speed Performance ◽  
Performance Results ◽  
Novel Design

Abstract. A high-speed photo detector IC for application in Blu-ray/DVD/CD drives is presented. Bandwidths for the highest gain of 254 MHz and 221 MHz for 405 nm (Blu-ray) and 635 nm (DVD) wavelengths, respectively, were achieved by applying novel design methodologies. The combination of this outstanding speed performance with its low power dissipation of 192 mW at 5V supply and the low noise power of −72 dBm at 300 MHz makes it the best in literature reported optical transceiver IC for Blu-ray and Blu-ray/DVD/CD multi drives. Beside the excellent performance results, the usage of the novel design methodologies gave us an increased design efficiency with 25% compared to earlier similar design processes.

Analysis of the Combustion Process in a EURO III Heavy-Duty Direct Injection Diesel Engine

2002 ◽  
Vol 124 (3) ◽  
pp. 636-644 ◽  
Author(s):  
J. M. Desantes ◽  
J. V. Pastor ◽  
J. Arre`gle ◽  
S. A. Molina
Keyword(s):  
High Speed ◽  
Direct Injection ◽  
Combustion Process ◽  
Engine Performance ◽  
Injection Pressure ◽  
Pollutant Emissions ◽  
Injection Timing ◽  
Engine Operation ◽  
Operation Conditions ◽  
Representative Points

To fulfill the commitments of future pollutant regulations, current development of direct injection (DI) Diesel engines requires to improve knowledge on the injection/combustion process and the effect of the injection parameters and engine operation conditions upon the spray and flame characteristics and how they affect engine performance and pollutant emissions. In order to improve comprehension of the phenomena inherent to Diesel combustion, a deep experimental study has been performed in a single-cylinder engine with the main characteristics of a six-cylinder engine passing the EURO III legislation. Some representative points of the 13-mode engine test cycle have been considered modifying the nominal values of injection pressure, injection load, intake pressure, engine speed, and injection timing. The study combines performance and emissions experimental measurements together with heat release law (HRL) analysis and high-speed visualization. Controlling parameters for BSFC, NOx, and soot emissions are identified in the last part of the paper.

The Use of Sweep and Dihedral in Multistage Axial Flow Compressor Blading: Part II — Low and High Speed Designs and Test Verification

2002 ◽  
Author(s):  
Simon J. Gallimore ◽  
John J. Bolger ◽  
Nicholas A. Cumpsty ◽  
Mark J. Taylor ◽  
Peter I. Wright ◽  
...  
Keyword(s):  
High Speed ◽  
Axial Flow ◽  
Essential Element ◽  
Low Speed ◽  
High Speed Engine ◽  
Methods Development ◽  
Engine Compressor ◽  
Basic Ideas ◽  
Flow Compressor ◽  
Test Verification

This paper describes the introduction of 3D blade designs into the core compressors of the Rolls-Royce Trent engine series with particular emphasis on the use of sweep and dihedral in the rotor designs. It follows the development of the basic ideas in a university research project, through multistage low-speed model testing, to their application to the high pressure engine compressor. An essential element of the project was the use of multistage CFD and some of the development of the method to allow the designs to take place is also discussed. Part I of the paper concentrated on the fundamental university-based research and the methods development. Part II describes additional low-speed multistage design and testing and the high-speed engine compressor designs and tests.

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