Estimation of Intake Oxygen Concentration Using a Dynamic Correction State With Extended Kalman Filter for Light-Duty Diesel Engines

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Kyunghan Min ◽  
Jaewook Shin ◽  
Donghyuk Jung ◽  
Manbae Han ◽  
Myoungho Sunwoo
Keyword(s):  
Kalman Filter ◽  
Mass Flow Rate ◽  
Extended Kalman Filter ◽  
Flow Rate ◽  
Conservation Law ◽  
Intake Manifold ◽  
Correction Algorithm ◽  
Dynamic Correction ◽  
Valve Model ◽  
Orifice Valve

An accurate estimation of the intake oxygen concentration (IOC) is a prerequisite to develop the optimal control strategy because it directly affects the combustion and emissions. Since the IOC is determined based on the mass conservation law in the intake manifold, estimating the mass flow rate of the exhaust gas recirculation (EGR) is most critical. However, to estimate the EGR mass flow rate, the conventional orifice valve model causes extrapolation error or inaccurate estimation results under transient operating conditions. In order to improve the estimation performance, this study proposes a correction algorithm for estimating IOC. A dynamic correction state is determined for the orifice valve model. In addition, the intake pressure dynamics is also derived based on the energy conservation law in the intake manifold. Using these dynamic models, a nonlinear parameter varying model is determined, and an extended Kalman filter (EKF) is applied to derive the value of correction state. Furthermore, unmeasurable physical states of the nonlinear parameter varying model are estimated from an air system model that only requires the engine-equipped sensors of mass production engines. The correction algorithm is validated through the engine experiments that clearly demonstrate high accuracy of the IOC estimation during transient conditions, which may apply for the vehicle application.

Unsteady Responses of the Impeller of a Centrifugal Compressor Exposed to Pulsating Backpressure

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Mengying Shu ◽  
Mingyang Yang ◽  
Ricardo F. Martinez-Botas ◽  
Kangyao Deng ◽  
Lei Shi
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Combustion Engine ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Intake Manifold ◽  
Unsteady Simulation

The flow in intake manifold of a heavily downsized internal combustion engine has increased levels of unsteadiness due to the reduction of cylinder number and manifold arrangement. The turbocharger compressor is thus exposed to significant pulsating backpressure. This paper studies the response of a centrifugal compressor to this unsteadiness using an experimentally validated numerical method. A computational fluid dynamic (CFD) model with the volute and impeller is established and validated by experimental measurements. Following this, an unsteady three-dimensional (3D) simulation is conducted on a single passage imposed by the pulsating backpressure conditions, which are obtained by one-dimensional (1D) unsteady simulation. The performance of the rotor passage deviates from the steady performance and a hysteresis loop, which encapsulates the steady condition, is formed. Moreover, the unsteadiness of the impeller performance is enhanced as the mass flow rate reduces. The pulsating performance and flow structures near stall are more favorable than those seen at constant backpressure. The flow behavior at points with the same instantaneous mass flow rate is substantially different at different time locations on the pulse. The flow in the impeller is determined by not only the instantaneous boundary condition but also by the evolution history of flow field. This study provides insights in the influence of pulsating backpressure on compressor performance in actual engine situations, from which better turbo-engine matching might be benefited.

Design and Optimization of the Restrictor of a Race Car

2015 ◽  
Author(s):  
Prithvi Raj Kokkula ◽  
Shashank Bhojappa ◽  
Selin Arslan ◽  
Badih A. Jawad
Keyword(s):  
Fluid Dynamics ◽  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Air Flow ◽  
Intake Manifold ◽  
Maximum Pressure ◽  
Cross Sectional ◽  
Formula Sae

Formula SAE is a student competition organized by SAE International. The team of students design, manufacture and race a car. Restrictions are imposed by the Formula SAE rules committee to restrict the air flow into the intake manifold by putting a single restrictor of 20 mm. This rule limits the maximum engine power by reducing the mass flow rate flowing to the engine. The pull is greater at higher rpms and the pressure created inside the cylinder is low. As the diameter of the flow path is reduced, the cross sectional area for flow reduces. For cars running at low rpm when the engine requires less air, the reduction in area is compensated by accelerated flow of air through the restrictor. Since this is for racing purpose cars here are designed to run at very high rpms where the flow at the throat section reach sonic velocities. Due to these restrictions the teams are challenged to come up with improved restrictor designs that allow maximum pressure drop across the restrictor’s inlet and outlet. The design considered for optimizing a flow restrictor is a venturi type having 20 mm restriction between the inlet and the outlet complying with the rules set by Formula SAE committee. The primary objective of this work is to optimize the flow restriction device that achieves maximum mass flow and minimum pull from the engine. This implies the pressure difference created due to the cylinder pressure and the atmospheric pressure at the inlet should be minimum. An optimum flow restrictor is designed by conducting analysis on various converging and diverging angles and coming up with an optimum value. Venturi type is a tubular pipe with varying diameter along its length, through which the fluid flows. Law of governing fluid dynamics states that the “Velocity of the fluid increases as it passes through the constriction to satisfy the principle of continuity”. An equation can be derived from the combination of Bernoulli’s equation and Continuity equation for the pressure drop due to venturi effect. [1]. A Computational Fluid Dynamics (CFD) tool is used to calculate the minimum pressure drop across the restrictor by running a series of analysis on various converging and diverging angles and calculating the pressure drop. As a result, an optimum air flow restrictor is achieved that maximizes the mass flow rate and minimizes the engine pull.

scholarly journals Validated Analytical Modeling of Diesel Engines Intake Manifold with a Flexible Crankshaft

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1287
Author(s):  
Salah A.M. Elmoselhy ◽  
Waleed F. Faris ◽  
Hesham A. Rakha
Keyword(s):  
Mass Flow Rate ◽  
Relative Error ◽  
Mass Flow ◽  
Flow Rate ◽  
Diesel Engines ◽  
Analytical Modeling ◽  
Vacuum Pressure ◽  
Analytical Models ◽  
Intake Manifold ◽  
Flow Losses

The flexibility of a crankshaft exhibits significant nonlinearities in the analysis of diesel engines performance, particularly at rotational speeds of around 2000 rpm. Given the explainable mathematical trends of the analytical model and the lack of available analytical modeling of the diesel engines intake manifold with a flexible crankshaft, the present study develops and validates such a model. In the present paper, the mass flow rate of air that goes from intake manifold into all the cylinders of the engine with a flexible crankshaft has been analytically modeled. The analytical models of the mass flow rate of air and gas speed dynamics have been validated using case studies and the ORNL and EPA Freeway standard drive cycles showing a relative error of 7.5% and 11%, respectively. Such values of relative error are on average less than those of widely recognized models in this field, such as the GT-Power and the CMEM, respectively. A simplified version for control applications of the developed models has been developed based on a sensitivity analysis. It has been found that the flexibility of a crankshaft decreases the mass flow rate of air that goes into cylinders, resulting in an unfavorable higher rate of exhaust emissions like CO. It has also been found that the pressure of the gas inside the cylinder during the intake stroke has four elements: a driving element (intake manifold pressure) and draining elements (vacuum pressure and flow losses and inertial effect of rotating mass). The element of the least effect amongst these four elements is the vacuum pressure that results from the piston's inertia and acceleration. The element of the largest effect is the pressure drop that takes place in the cylinder because of the air/gas flow losses. These developed models are explainable and widely valid so that they can help in better analyzing the performance of diesel engines.

Distributed Cooperative Localization

2013 ◽  
Vol 6 (3) ◽  
pp. 49-67 ◽  
Author(s):  
Stefano Panzieri ◽  
Federica Pascucci ◽  
Lorenzo Sciavicco ◽  
Roberto Setola
Keyword(s):  
Kalman Filter ◽  
Extended Kalman Filter ◽  
System Model ◽  
Cooperative Localization ◽  
Mobile Platforms ◽  
Dynamic Correction ◽  
Communication Signals ◽  
Field Robots ◽  
Indoor Scenarios ◽  
Position Estimate

Localization for mobile platforms, in indoor scenarios, represents a cornerstone achievement to effective develop service and field robots able to safely cooperate. This paper proposes a methodology to achieve such a result by applying a completely decentralized and distributed algorithm. The key idea of the solution developed is to enable a dynamic correction of the position estimate, computed by robots, through information, shared during random rendezvous. This objective is reached using a specific extension of the Extended Kalman Filter, called Interlaced Extended Kalman Filter, which allows exchanging the estimation performed by any single robot together with the corresponding uncertainties. The proposed unsupervised method provides a large flexibility: it facilitates the handling of heterogeneous proprioceptive and exteroceptive sensors, that can be merged taking into account both their accuracy and the system model one. The solution is particularly interesting for rescue scenario, since it is able to cope with irregular communication signals and loss of connectivity among robots team without requiring any synchronization.

Distributed Cooperative Localization

2019 ◽  
pp. 469-490
Author(s):  
Stefano Panzieri ◽  
Federica Pascucci ◽  
Lorenzo Sciavicco ◽  
Roberto Setola
Keyword(s):  
Kalman Filter ◽  
Extended Kalman Filter ◽  
Distributed Algorithm ◽  
Cooperative Localization ◽  
Mobile Platforms ◽  
Dynamic Correction ◽  
Communication Signals ◽  
Field Robots ◽  
Indoor Scenarios ◽  
Position Estimate

Localization for mobile platforms, in indoor scenarios, represents a cornerstone achievement to effective develop service and field robots able to safely cooperate. This paper proposes a methodology to achieve such a result by applying a completely decentralized and distributed algorithm. The key idea of the solution developed is to enable a dynamic correction of the position estimate, computed by robots, through information, shared during random rendezvous. This objective is reached using a specific extension of the Extended Kalman Filter, called Interlaced Extended Kalman Filter, which allows exchanging the estimation performed by any single robot together with the corresponding uncertainties. The proposed unsupervised method provides a large flexibility: it facilitates the handling of heterogeneous proprioceptive and exteroceptive sensors, that can be merged taking into account both their accuracy and the system model one. The solution is particularly interesting for rescue scenario, since it is able to cope with irregular communication signals and loss of connectivity among robots team without requiring any synchronization.

Experimental and Numerical Study of Supercritical Carbon Dioxide Flow Through Valves

2016 ◽  
Vol 2 (3) ◽  
Author(s):  
Haomin Yuan ◽  
Mark Anderson
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Validation Data ◽  
Choked Flow ◽  
Numerical Predictions ◽  
Valve Model ◽  
Supercritical Carbon

The supercritical carbon dioxide (sCO2) Brayton cycle shows advantages such as high efficiency, compactness, and low capital cost. These benefits make it a competitive candidate for future-generation power-conversion cycles. In order to study this cycle, valve characteristics under sCO2 flow conditions must be studied. However, the traditional models for valves may not be accurate due to the real gas property of sCO2. In this study, this problem was studied both experimentally and numerically. A small valve was tested in the authors’ experiment facility first to provide validation data. For this valve, numerical predictions of mass flow rate agree with experimental data. Then, simulations were scaled up to valves in a real power-cycle design. The traditional gas-service valve model fails to predict mass flow rate at low-pressure ratios. A modification was proposed to improve the current gas-service valve model by changing the choked-flow check.

Experimental Study on Centrifugal Compressor Performance at Pulsating Backpressure Conditions

2019 ◽  
Author(s):  
Mengying Shu ◽  
Mingyang Yang ◽  
Kaiyue Zhang ◽  
Ricardo F. Martinez-Botas ◽  
Kangyao Deng
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Rotational Speed ◽  
Hysteresis Loops ◽  
Intake Manifold ◽  
Stable Operation ◽  
Compressor Performance ◽  
Turbo Engine

Abstract The flow in the intake manifold of a downsized internal combustion engine has become more unsteady due to the reduction of cylinder number and increasing boosting level. The turbocharger compressor is thus imposed by an unsteady backpressure when matched with an engine. It has been experimentally confirmed that the compressor performance is affected when exposed to pulsating backpressure. In order to enhance compressor stability and achieve better turbo-engine matching, it is necessary to understand behaviors of compressor at pulsating backpressure conditions. In this study, the performance of compressor exposed to pulsating backpressure is experimentally studied on the compressor test rig located in Shanghai Jiao Tong University. The results show that compressor performance with pulsating backpressure is notably different from the one with constant backpressure. Hysteresis loops which encapsulate the steady performance are generated at pulsating backpressure conditions due to filling-emptying effect. The mass flow rate, pulse frequency and compressor rotational speed all have evident influence on dynamic behaviors of the compressor. As the mass flow rate and rotational speed increase, hysteresis loops are enlarged and the unsteady behaviors are enhanced. The influence of pulsating backpressure on the compressor surge margin is analyzed in detail. Results demonstrate that the stable operation range is evidently influenced by the pulsating backpressure. Particularly, the mass flow rate of surge is postponed by 15.1% compared with the corresponding constant backpressure condition. Fast Fourier Transform method (FFT) is applied to identify the initiation of surge. The frequency domain analysis proves that the pulsating backpressure has little influence on the frequency of surge, but the strength of surge is alleviated indicated by the magnitude of fluctuations. The study provides an insight on the influence of pulsating backpressure on the centrifugal compressor, which can benefit the design methodology of compressor as well as turbo-engine matching.

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