Transonic Combustion - Supercritical Gasoline Combustion Operating Range Extension for Low Emissions and High Thermal Efficiency

2012 ◽  
Author(s):  
Philip Zoldak ◽  
Chris de Boer ◽  
Shreeram Shetty
Keyword(s):  
Thermal Efficiency ◽  
Range Extension ◽  
Operating Range ◽  
Supercritical Gasoline

Control of combustion phasing and operating range extension of natural gas PCCI engines using ozone species

2019 ◽  
Vol 199 ◽  
pp. 112000 ◽  
Author(s):  
Mohammad Mahdi Salahi ◽  
Ayat Gharehghani
Keyword(s):  
Natural Gas ◽  
Range Extension ◽  
Operating Range

Experimental and Numerical Study of an Open Impeller Centrifugal Compressor Stage Utilising 3D Diffuser End Wall Contouring for Operating Range Extension

2020 ◽  
Author(s):  
Daniel Hermann ◽  
Manfred Wirsum ◽  
Douglas Robinson ◽  
Philipp Jenny
Keyword(s):  
Experimental Data ◽  
Mach Number ◽  
Centrifugal Compressor ◽  
Side Wall ◽  
Range Extension ◽  
Scale Model ◽  
Design Stage ◽  
Operating Range ◽  
Stabilizing Effect ◽  
End Wall

Abstract Highly efficient and concurrent flexible operation are heavy demands on today’s centrifugal compressor units. Diffuser end wall contouring is a measure to delay the incipience of instability and therefore to extend the compressor’s operating range while maintaining efficient performance. In the presented paper, a hubside wall contouring, applied in the vaneless space upstream the diffuser’s leading edge and within the diffuser passage of a state-of-the-art centrifugal compressor with an open impeller is examined. CFD computations are performed for both a baseline diffuser design with parallel channel walls and the hub-side wall contoured diffuser design. Comparisons of characteristic and diffuser stability decisive flow variables are made in perpendicular sections along an extrapolated camber line of the diffuser vane for full span, near shroud and near hub wall. In operating points near the stability limit at two different stage Mach numbers, the stabilizing effect of the hub-side wall contouring on the diffuser flow is clearly shown. In a scale-model test rig, experimental data including pneumatic 5-hole probe data for a full diffuser blade-to-blade passage, static wall pressures at various planes as well as total temperature was measured. The experimental data is utilized for validation of the presented numerical calculations. The flow stabilizing effect of the hub-wall contouring is clearly visible in the measurements, which showed 8% range extension at highest stage Mach number Mu2 = 1.16 and a range extension of 2% at design stage Mach number Mu2 = 1.0.

scholarly journals Life and Operating Range Extension of the BPT-4000 Qualification Model Hall Thruster

2006 ◽  
Author(s):  
Ben Welander ◽  
Christian Carpenter ◽  
Kristi de Grys ◽  
Richard Hofer ◽  
Thomas Randolph ◽  
...  
Keyword(s):  
Range Extension ◽  
Hall Thruster ◽  
Operating Range

Experimental Operating Range Extension of a Twin-Spool Turbofan Engine by Active Stability Control Measures

2004 ◽  
Vol 128 (1) ◽  
pp. 20-28 ◽  
Author(s):  
Stephan G. Scheidler ◽  
Leonhard Fottner
Keyword(s):  
Control System ◽  
Stability Control ◽  
Rotating Stall ◽  
Control Measures ◽  
Air Injection ◽  
Range Extension ◽  
Engine Operation ◽  
Turbofan Engine ◽  
Operating Range ◽  
The Stability

Modern engine operation is guided by the aim to broaden the operating range and to increase the stage loading allowing the stage count to be reduced. This is possible by active stability control measures to extend the available stable operating range. Different strategies of an active control system, such as air injection and air recirculation have been applied. While in the past results have been published mainly regarding the stability enhancement of compressor rigs or single-spool engines, this experimental study focuses on both the stability as well as the operating range extension of a twin-spool turbofan engine as an example of a real engine application on an aircraft. The objective of this investigation is the analysis of the engine behavior with active stabilization compared to unsupported operation. For this purpose, high-frequency pressure signals are used and analyzed to investigate the effects of air injection with respect to the instability onset progress and the development of any instabilities, such as rotating stall and surge in the low-pressure compression (LPC) system. These Kulite signals are fed to a control system. Its amplified output signals control fast acting direct-drive valves circumferentially distributed ahead of the LPC. For the application of air injection described in the paper, the air is delivered by an external source. The control system responsible for air injection is a real-time system which directly reacts on marked instabilities and their precursors. It allows the LPC System to recover from fully developed rotating stall by asymmetric air injection based on the pressure signals. Additionally, a delayed appearance of instabilities can be provoked by the system. Air injection guided by this control system resulted in a reduction of the required amount of air compared to constant air injection. Also, disturbances travelling at rotor speed can be detected, damped, and eliminated by this control system with a modulation of the injected air in such a way that the injection maximum travels around the ten injection positions.

Assessing the Influence of Compression Ratio on Engine Characteristics Including Operational Limits of a Biogas-Fueled Spark-Ignition Engine

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Sachin Kumar Gupta ◽  
Mayank Mittal
Keyword(s):  
Compression Ratio ◽  
Thermal Efficiency ◽  
Internal Combustion Engines ◽  
Fossil Fuels ◽  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Operating Range ◽  
Indicated Mean Effective Pressure ◽  
Wide Range

Abstract Biogas, which is a renewable alternative fuel, has high antiknocking properties with the potential to substitute fossil fuels in internal combustion engines. In this study, performance characteristics of a spark-ignition (SI) engine operated under methane (baseline case) and biogas are compared at the compression ratio (CR) of 8.5:1. Subsequently, the effect of CR on operational limits, performance, combustion, and emission characteristics of the engine fueled with biogas is evaluated. A variable compression ratio, spark-ignition engine was operated at various CRs of 8.5:1, 10:1, 11:1, 13:1, and 15:1 over a wide range of operating loads at 1500 rpm. Results showed that the operating range of the engine at 8.5:1 CR reduced when biogas was utilized in the engine instead of methane. However, the operating range of the engine for biogas extended with an increase in CR—an increase from 9.6 N-m-16.5 N-m to 2.8 N-m-15.1 N-m was observed when CR was increased from 8.5:1 to 15:1. The brake thermal efficiency improved from 13.7% to 16.3%, and the coefficient of variation (COV) of indicated mean effective pressure (IMEP) reduced from 12.7% to 1.52% when CR was increased from 8.5:1 to 15:1 at 8 N-m load. The emission level of carbon dioxide was decreased with an increase in CR due to an improvement in the thermal efficiency and the combustion process.

A computational study of operating range extension in a natural gas SI engine with the use of hydrogen

2015 ◽  
Vol 40 (17) ◽  
pp. 5966-5975 ◽  
Author(s):  
A. Gharehghani ◽  
R. Hosseini ◽  
M. Mirsalim ◽  
Talal F. Yusaf
Keyword(s):  
Natural Gas ◽  
Computational Study ◽  
Range Extension ◽  
Si Engine ◽  
Operating Range

Effect of Gas-Jet Ignition Technique on the Extension of CNG Lean Combustion Limit

2013 ◽  
Vol 315 ◽  
pp. 288-292 ◽  
Author(s):  
Mas Fawzi ◽  
Yoshiyuki Kidoguchi ◽  
Yuzuru Nada
Keyword(s):  
Thermal Efficiency ◽  
Equivalence Ratio ◽  
Fossil Fuels ◽  
Engine Performance ◽  
High Load ◽  
Gas Jet ◽  
Cyclic Variation ◽  
Operating Range ◽  
Lean Combustion ◽  
Cng Engine

Lean combustion of CNG has the advantage of high thermal efficiency and fewer pollutants than other fossil fuels. However, problems such as ignitability, cyclic variation and high THC emission were common at combustion leaner than equivalence ratio φ=0.7. The application of gas-jet ignition method to lean combustion was able to address such problems. This paper introduces the concept of gas-jet ignition method, which ensures ignitability at lean bulk equivalence ratio. Moreover, this method is applied to a real CNG engine. Results of engine performance experiment shows that two-stage injection method combined with gas-jet ignition has successfully widen the operating range of a CNG engine from low to high load at corresponding φ=0.17 to 1.1.

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