Fuel-Air Ratio Determination From Cylinder Pressure Time Histories

1985 ◽  
Vol 107 (4) ◽  
pp. 252-257 ◽  
Author(s):  
J. C. Gilkey ◽  
J. D. Powell
Keyword(s):  
Time History ◽  
Operating Conditions ◽  
Cylinder Pressure ◽  
Pressure Time ◽  
Wide Range ◽  
Pressure Trace ◽  
Time Histories ◽  
High Bandwidth ◽  
Ratio Determination ◽  
Microprocessor Technology

Determining fuel-air ratio quickly over a wide range of engine operating conditions is desirable for better transient engine control. This paper describes a method based on cylinder pressure time history pattern recognition which has potential for providing such a high bandwidth measurement. The fact that fuel-air ratio has an effect on the shape of the cylinder pressure trace is well-known. It should therefore be possible to obtain the fuel-air ratio of an engine by examining the pressure trace if the engine speed, load, and EGR are known. The difficulty lies in separating the effects of unknown engine load, speed, and EGR from the fuel-air ratio effects. An algorithm was developed using a wide range of steady state experimental data from a single cylinder engine. Application of the algorithm requires the calculation of first, second and third moments of the cylinder pressure time history. Verification of the algorithm showed that the root mean square error in estimates were about 5 percent for fuel-air ratio and 3 percent for a combination of fuel-air and EGR. These results were obtained using a single pressure trace which yields a response time of 1.5 engine revolutions. The algorithm was also found to be relatively insensitive to the use of different fuels, errors in spark advance, and variations in relative humidity. Research is continuing to verify the accuracy under transient engine conditions. An operational count shows that this algorithm should be well within the limits of present microprocessor technology.

Cycle-Resolved Detection of Combustion Start in SI Engines by Means of Different In-Cylinder Pressure Data Reduction Techniques

2006 ◽  
Author(s):  
Mirko Baratta ◽  
Stefano d’Ambrosio ◽  
Ezio Spessa ◽  
Alberto Vassallo
Keyword(s):  
Direct Analysis ◽  
Chemical Energy ◽  
Pressure Curve ◽  
Cylinder Pressure ◽  
Compression Stroke ◽  
Cycle Simulation ◽  
Pressure Time ◽  
Wide Range ◽  
Time Histories ◽  
Si Engines

An original technique for the detection of combustion start in SI engines on a cycle-by-cycle basis was proposed and applied to the analysis of pressure time-histories taken on a bi-fuel engine fueled by either gasoline or CNG. Such a technique locates the onset of combustion on the basis of the earliest release of chemical energy. It stems from the fact that, during the compression stroke, changes in the charge sensible energy, and thus in the cylinder pressure, are ruled only by work and heat exchanges with the combustion chamber walls. Hence, an imbalance in these three energies indicates the correspondent release of chemical energy, identifying combustion onset. The results of this technique were compared to those obtained through a direct analysis of in-cylinder pressure time-histories on logarithmic-coordinates p-V diagrams. More specifically, compression stroke appears like a segment on such diagrams and thus combustion onset can be defined by the detachment of in-cylinder pressure curve from linearity. The results of the different approaches for combustion start detection were compared on a wide range of working conditions of the bi-fuel SI engine under both gasoline and CNG fueling. The experimental matrix covered different engine speeds (N = 2000–4600 rpm), loads (bmep = 200–790 kPa), relative air-fuel ratios (RAFR = 0.80–1.60) and spark advances (SA ranging from 8 deg retard to 2 deg advance from MBT timing). 100 consecutive in-cylinder pressure traces were analyzed for each point in the test matrix. Particular attention was also given to the techniques applied for in-cylinder pressure filtering, which proved to be fundamental for accurate cycle-by-cycle investigation. Finally, on the basis of the experimental results obtained through the chemical-energy approach, two correlations for flame-development angle prediction are proposed, one for gasoline and the other for CNG. These correlations are based on cylinder-average thermodynamic properties at SA and can be usefully applied for triggering the flame propagation routines in indicated-cycle simulation codes.

Determination of a most representative cycle from cylinder pressure ensembles via statistical method using distribution skewness

2021 ◽  
pp. 146808742110655
Author(s):  
Jorge Pulpeiro González ◽  
Carrie M Hall ◽  
Christopher P Kolodziej
Keyword(s):  
Statistical Method ◽  
Combustion Engine ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Cylinder Pressure ◽  
Pressure Trace ◽  
Combustion Knock ◽  
Engine Operating Condition ◽  
Combustion Processes

In internal combustion engine research, cylinder pressure measurements provide valuable information about the underlying thermodynamic and combustion processes, and are typically collected in ensembles of several 100 traces. Although in some particular fields of combustion research all traces are analyzed, in most cases only one trace is studied because analyzing all the traces is impractical due to the large number of collected samples. Instead, an ensemble-averaged pressure trace is commonly calculated and used for analysis. However, this pressure trace is highly smoothed and dynamic information is lost during the averaging process. With the average trace, pressure rise rates are lower and pressure oscillations such as the ones resulting from combustion knock are lost. In this work, a statistical method was developed to determine the “most representative cycle,” which is the cycle from the ensemble that has the pressure trace most representative of the engine operating condition. Eleven characteristic parameters are computed from each pressure trace and probabilistic distributions are obtained for each of the parameters using all the traces in the ensemble. Finally, the most representative cycle is selected by means of a cost function minimization. The benefits of this method are illustrated using experimental data from four very different engine platforms, under four different combustion modes and over a range of operating conditions.

Experimental Investigation of Invar Edge Effect in Membrane LNG Tanks

2010 ◽  
Author(s):  
Mateusz Graczyk ◽  
Kjetil Berget ◽  
Joachim Allers
Keyword(s):  
Fluid Motion ◽  
Structural Response ◽  
Time History ◽  
Pressure Profile ◽  
Pressure Effects ◽  
Local Pressure ◽  
Temporal And Spatial Distribution ◽  
Containment System ◽  
Pressure Time ◽  
Time Histories

Sloshing, a violent fluid motion in tanks is of current interest for many branches of the industry, among them gas shipping. Although different methods are commonly combined for analyzing sloshing in LNG carriers, time histories of the pressure in the tanks are most reliably obtained by experiments. Very localized pressures may be important for the structural response of the tank containment system. Moreover, the typical pressure time history duration is similar to the structural natural frequency. Therefore, pressure measurements need to be performed with due account for temporal and spatial distribution. This requires a high sampling resolution both in time and space. Fine spatial resolution becomes especially important when local pressure effects are of interest, such as pressure profile passing a membrane corrugation of Mark III containment or Invar edge of No.96 containment. In this paper experimental approach applied by MARIN-TEK for analyzing sloshing phenomenon is presented. The focus is put on investigating effects of Invar edges. A transverse 2D model of a typical LNG carrier is used. Local pressure effects are investigated based on low filling level tests with different wall surfaces: smooth and with horizontal protrusions representing the surface similar to the No.96 containment system.

Modeling heavy-duty diesel engines using tabulated kinetics in a wide range of operating conditions

2020 ◽  
pp. 146808741989616 ◽  
Author(s):  
Qiyan Zhou ◽  
Tommaso Lucchini ◽  
Gianluca D’Errico ◽  
Gilles Hardy ◽  
Xingcai Lu
Keyword(s):  
Diesel Engines ◽  
Operating Conditions ◽  
Scalar Dissipation ◽  
Cylinder Pressure ◽  
Heavy Duty ◽  
Variable Model ◽  
Progress Variable ◽  
Wide Range ◽  
Heavy Duty Diesel ◽  
Operating Points

Fast and high-fidelity combustion models including detailed kinetics and turbulence chemistry interaction are necessary to support design and development of heavy-duty diesel engines. In this work, the authors intend to present and validate tabulated flamelet progress variable model based on tabulation of laminar diffusion flamelets for different scalar dissipation rate, whose predictability highly depends on the description of fuel–air mixing process in which engine mesh layout plays an important role. To this end, two grids were compared and assessed: in both grids, cells were aligned on the spray direction with such region being enlarged in the second one, where the near-nozzle and near-wall mesh resolution were also improved, which is expected to better account for both spray dynamics and flame–wall interaction dominating the combustion process in diesel engines. Flame structure, in-cylinder pressure, apparent heat release rate, and emissions for different relevant operating points were compared and analyzed to identify the most suitable mesh. Afterwards, simulations were carried out in a heavy-duty engine considering 20 operating points, allowing to comprehensively verify the validity of tabulated flamelet progress variable model. The results demonstrated that the proposed approach was capable to accurately predict in-cylinder pressure evolution and NO x formation across a wide engine map.

The Use of Plastic Cold Flow in the Development of an Externally Connected Transducer for Recording Pressure-Time Histories of Diesel Fuel Injection Phenomena and Its Application in Fault Diagnosis

1977 ◽  
Vol 99 (2) ◽  
pp. 274-278
Author(s):  
W. S. Heggie
Keyword(s):  
Diesel Fuel ◽  
Fuel Injection ◽  
Dynamic Pressure ◽  
Time History ◽  
Diagnostic Techniques ◽  
Field Application ◽  
Cold Flow ◽  
Pressure Time ◽  
Time Histories ◽  
Diesel Fuel Injection

An investigation of possible methods for obtaining a pressure-time history of the diesel fuel injection cycle was conducted, with the object of producing a rugged externally connected pressure transducer. A resistance technique that discriminates against characteristics not directly associated with dynamic pressure was developed and the resulting principles incorporated into the design of a compact transducer [1]. In order to eliminate the necessity of cementing a resistance element directly to the high-pressure line, a technique using the cold flow of cured resin held captive in a steel enclosure was developed. This has resulted in an instrument of equal sensitivity and fidelity which may be installed in the field by personnel without specialized training. Diagnostic techniques applied to the analysis of diesel fuel injection health are described that are considered to have practical field application, using an externally connected transducer. No numerical measure is required, the method being based on comparison of fault signatures with a healthy master. The signature is considered to contain a definite quantity of criteria evaluated by a defined series of qualities resulting in a less nebulous approach than that of random comparison by superimposure. Nine of the most common diesel fuel injection faults are induced, checked for repeatability, and used as representative examples to illustrate the method.

Bayesian Methods for Updating Dynamic Models

2011 ◽  
Vol 64 (1) ◽  
Author(s):  
Ka-Veng Yuen ◽  
Sin-Chi Kuok
Keyword(s):  
Response Time ◽  
Bayesian Methods ◽  
Dynamic Models ◽  
Model Updating ◽  
Time History ◽  
Recent Decade ◽  
Model Complexity ◽  
Matching Process ◽  
Wide Range ◽  
Time Histories

Model updating of dynamical systems has been attracting much attention because it has a very wide range of applications in aerospace, civil, and mechanical engineering, etc. Many methods were developed and there has been substantial development in Bayesian methods for this purpose in the recent decade. This article introduces some state-of-the-art work. It consists of two main streams of model updating, namely model updating using response time history and model updating using modal measurements. The former one utilizes directly response time histories for the identification of uncertain parameters. In particular, the Bayesian time-domain approach, Bayesian spectral density approach and Bayesian fast Fourier transform approach will be introduced. The latter stream utilizes modal measurements of a dynamical system. The method introduced here does not require a mode matching process that is common in other existing methods. Afterwards, discussion will be given about the relationship among model complexity, data fitting capability and robustness. An application of a 22-story building will be presented. Its acceleration response time histories were recorded during a severe typhoon and they are utilized to identify the fundamental frequency of the building. Furthermore, three methods are used for analysis on this same set of measurements and comparison will be made.

Thermal Charge Conditioning for Optimal HCCI Engine Operation

2002 ◽  
Vol 124 (1) ◽  
pp. 67-75 ◽  
Author(s):  
Joel Martinez-Frias ◽  
Salvador M. Aceves ◽  
Daniel Flowers ◽  
J. Ray Smith ◽  
Robert Dibble
Keyword(s):  
High Efficiency ◽  
Thermal Control ◽  
Operating Conditions ◽  
Cylinder Pressure ◽  
Detailed Chemical Kinetics ◽  
Engine Operation ◽  
Hcci Engine ◽  
Peak Cylinder Pressure ◽  
Wide Range ◽  
Gas Recirculation

This work investigates a purely thermal control system for HCCI engines, where thermal energy from exhaust gas recirculation (EGR) and compression work in the supercharger are either recycled or rejected as needed. HCCI engine operation is analyzed with a detailed chemical kinetics code, HCT (Hydrodynamics, Chemistry and Transport), which has been extensively modified for application to engines. HCT is linked to an optimizer that determines the operating conditions that result in maximum brake thermal efficiency, while meeting the restrictions of low NOx and peak cylinder pressure. The results show the values of the operating conditions that yield optimum efficiency as a function of torque for a constant engine speed (1800 rpm). For zero torque (idle), the optimizer determines operating conditions that result in minimum fuel consumption. The optimizer is also used for determining the maximum torque that can be obtained within the operating restrictions of NOx and peak cylinder pressure. The results show that a thermally controlled HCCI engine can successfully operate over a wide range of conditions at high efficiency and low emissions.

Liquid Pipeline Location Specific Cyclic Pressure Determination

2018 ◽  
Author(s):  
Vlado Semiga ◽  
Aaron Dinovitzer ◽  
Sanjay Tiku ◽  
Geoff Vignal
Keyword(s):  
Pressure Range ◽  
Time History ◽  
Pressure Profile ◽  
Integrity Assessment ◽  
Cyclic Pressure ◽  
Pump Station ◽  
Pressure Time ◽  
Pipeline Segment ◽  
Time Histories ◽  
Discharge Pressure

In the majority of liquid pipelines, the pump station discharge pressure ranges are much greater than the pressure ranges experienced at the suction end of the downstream pump station. Consequently, the cyclic pressure induced fatigue damage accumulation rate is greater at the discharge end than at the suction end of a given pipeline segment. In completing an integrity assessment of a fatigue susceptible feature, assuming that the pump station discharge cyclic pressure profile applies to all features in the line segment is conservative. This conservative assumption can lead to un-necessary repairs, unintentional damage from over-prescribed maintenance, or inefficient decisions regarding maintenance action prioritization. The following paper presents the results of a Canadian Energy Pipeline Association (CEPA) initiative to develop a simple approach to define the cyclic pressure history at any point in a liquid pipeline segment based on the bounding discharge and suction pump station Supervisory Control and Data Acquisition (SCADA) pressure time history data. The approach was developed based on collected operating pipeline SCADA pressure time history data for line segments with intermediate measurement points which could be used to validate the developed model. The pressure time histories for all the locations were analyzed using a Rainflow cycle counting technique to develop pressure range spectra (i.e. histograms of pressure range events) and the cyclic pressure severity of each of the time histories was characterized by the Spectrum Severity Indicator (SSI). The SSI represents the number of annual 90MPa hoop stress cycles required to accumulate the same fatigue damage as the actual pressure spectrums. The technique presented in this paper illustrates how to infer the pressure range spectra or SSI at intermediate locations. The technique is shown to be a significant improvement (i.e. higher location specific accuracy) than either applying the discharge pressure spectrum or applying a linear interpolation between discharge and suction conditions in fatigue life assessments. The liquid pipeline cyclic pressure characterization technique presented in this paper will permit integrity assessment or severity ranking of features along a pipeline to be based on an accurate local pressure profile rather than an upper bound. This understanding will help to improve the accuracy of defect loading, one of the three main pillars in integrity assessment (i.e., loading, geometry, materials) for defects susceptible to cyclic loading (e.g., cracking, mechanical damage).

Exhaust Energy Recovery for Control of a Homogeneous Charge Compression Ignition Engine

2000 ◽  
Author(s):  
Joel Martinez-Frias ◽  
Salvador M. Aceves ◽  
Daniel Flowers ◽  
J. Ray Smith ◽  
Robert Dibble
Keyword(s):  
High Efficiency ◽  
Thermal Control ◽  
Operating Conditions ◽  
Cylinder Pressure ◽  
Detailed Chemical Kinetics ◽  
Compression Ignition Engine ◽  
Engine Operation ◽  
Hcci Engine ◽  
Peak Cylinder Pressure ◽  
Wide Range

Abstract This work investigates a purely thermal control system for HCCI engines, where thermal energy from exhaust gas recirculation (EGR) and compression work in the supercharger are either recycled or rejected as needed. HCCI engine operation is analyzed with a detailed chemical kinetics code, HCT (Hydrodynamics, Chemistry and Transport), which has been extensively modified for application to engines. HCT is linked to an optimizer that determines the operating conditions that result in maximum brake thermal efficiency, while meeting the restrictions of low NOx and peak cylinder pressure. The results show the values of the operating conditions that yield optimum efficiency as a function of torque for a constant engine speed (1800 rpm). For zero torque (idle), the optimizer determines operating conditions that result in minimum fuel consumption. The optimizer is also used for determining the maximum torque that can be obtained within the operating restrictions of NOx and peak cylinder pressure. The results show that a thermally controlled HCCI engine can successfully operate over a wide range of conditions at high efficiency and low emissions.

Determination of the transfer function between the injected flow-rate and high-pressure time histories for improved control of common rail diesel engines

2016 ◽  
Vol 18 (3) ◽  
pp. 212-225 ◽  
Author(s):  
Alessandro Ferrari ◽  
Emanuele Salvo
Keyword(s):  
Transfer Function ◽  
Working Conditions ◽  
Flow Rate ◽  
Diesel Engines ◽  
Time History ◽  
Common Rail ◽  
Rail Pressure ◽  
Experimental Estimation ◽  
Pressure Time ◽  
Time Histories

Theoretical and experimental methodologies have been proposed and illustrated to determine the transfer function between the injected flow-rate and the rail pressure for common rail injection systems. An analytical transfer function has been calculated in the frequency domain, utilizing a previously developed lumped parameter model of the overall hydraulic layout of a common rail system. The predicted transfer function has been compared, in a Bode diagram, with an experimental estimation of the transfer function, based on the measured rail pressure and injected flow-rate time histories that were acquired at the hydraulic rig for different working conditions. The experimental estimation of the transfer function has been worked out by applying a selective spectral technique in order to reduce the effects of measurement noise on the rail pressure and injected flow-rate time histories. The accuracy of the model-derived transfer function has been improved significantly by integrating a pressure control system sub-model, which includes the action of the electronic control unit on the rail pressure time history through the pressure regulator, in the hydraulic model of the common rail circuit. Finally, the time histories of the rail pressure, predicted by means of the complete injection apparatus model, have been compared with the corresponding experimental traces at different working conditions and a very satisfactory agreement has in general been found. The methodologies proposed for the accurate evaluation of the transfer function between the injected flow-rate and the rail pressure time histories can be applied to diesel engines in order to implement innovative closed-loop strategies for the injected mass control.

Sign in / Sign up

Export Citation Format

Share Document