Pseudo Bond Graph Research Articles

A Validated Unsteady Turbofan Engine Performance Simulation Using Pseudo Bond Graph Approach

Abstract In this paper, the unsteady performance of a turbofan engine is illustrated and modeled using the pseudo-bond graph approach. The pseudo-bond graph method allows multiphysical and interdisciplinary systems to be described analytically and comprehensibly across disciplines. In this study, a high bypass ratio turbofan engine is modeled using a pseudo-bond graph model that can be adapted for hybrid electric propulsion systems. The development of the model is followed by a full-scale test run of the in-house V2500-A1 turbofan engine. The highly instrumented turbofan engine enables the time-resolved recording of performance-specific variables, thus facilitating the validation of the numerical model. Slam acceleration and deceleration are performed to analyze the unsteady performance. It is shown that the pseudo-bond graph model is able to predict the dynamics of the turbofan engine. High deviations are explained by the incomplete modeling of the control system.

An integrated Petri net-pseudo bond graph model for nuclear hazard assessment

A pseudo-bond graph is presented to model the heat transferred from the fuel rods to the coolant via its cladding in a generic nuclear reactor case study. Simulations performed using this model are used to explore the temperatures of the core components under ordinary and emergency scenarios, considering various conditions of coolant supply and reactor power output. The model is combined with a timed stochastic Petri net to produce a hybrid model, in which the reactor operation and fault status is determined by the Petri net and fed into the bond graph to examine the resulting impact on core temperatures, which in turn are fed back into the Petri net process. The results predict the distribution of the reactor operational durations before a disruption occurs. The model provides the temperature profiles attained by the cladding and fuel components, indicating a low probability of dangerous temperatures.

Transient Dynamic System Behavior of Pressure Actuated Cellular Structures in a Morphing Wing

High aspect ratio aircraft have a significantly reduced induced drag, but have only limited installation space for control surfaces near the wingtip. This paper describes a multidisciplinary design methodology for a morphing aileron that is based on pressure-actuated cellular structures (PACS). The focus of this work is on the transient dynamic system behavior of the multi-functional aileron. Decisive design aspects are the actuation speed, the resistance against external loads, and constraints preparing for a future wind tunnel test. The structural stiffness under varying aerodynamic loads is examined while using a reduced-order truss model and a high-fidelity finite element analysis. The simulations of the internal flow investigate the transient pressurization process that limits the dynamic actuator response. The authors present a reduced-order model based on the Pseudo Bond Graph methodology enabling time-efficient flow simulation and compare the results to computational fluid dynamic simulations. The findings of this work demonstrate high structural resistance against external forces and the feasibility of high actuation speeds over the entire operating envelope. Future research will incorporate the fluid–structure interaction and the assessment of load alleviation capability.

Influence of combined compressor and turbine deterioration on the overall performance of a jet engine using RANS simulation and Pseudo Bond Graph approach

In this study, numerical models are used to analyse the influence of isolated component deterioration as well as the combination of miscellaneous deteriorated components on the transient performance of a high-bypass jet engine. For this purpose, the aerodynamic impact of major degradation effects in a high-pressure compressor (HPC) and turbine (HPT) is modelled and simulated by using 3D CFD (Computational Fluid Dynamics). The impact on overall jet engine performance is then modelled using an 1D Reduced Order Model (ROM). Initially, the HPC performance is investigated with a typical level of roughness on vanes and blades and the HPT performance with an increasing tip clearance. Subsequently, the overall performance of the jet engines with the isolated and combined deteriorated domains is computed by the in-house 1D performance tool ASTOR (AircraftEngine Simulation for Transient Operation Research). Degradations have a significant influence on the system stability and transient effects. In ASTOR, a system of differential equations including the equations of motion and further ordinary differential equations is solved. Compared to common ROMs, this enables a higher degree of accuracy. The results of temperature downstream of the high-pressure compressor and low-pressure turbine as well as the specific fuel composition and the HP rotational speed are used to estimate the degree and type of engine deterioration. However, the consideration of the system stability is necessary to analyse the characterisation in more detail. Finally, a simplified model which merges two engines with individual deteriorated domains into one combined deteriorated engine, is proposed. The simplified model predicts the performance of an engine which has been simulated with combined deteriorated components.

Structured dynamic modeling and simulation of parabolic trough solar collector using bond graph approach

The present paper deals with the modeling of a solar parabolic trough collector (PTC).The system is described by a lumped parameter model; its dynamic modeling is performed using the bond graph methodology which allows having a graphical structure of the modeled phenomena where the multi-domain coupling relationships are explicitly represented. The thermal domain of the pseudo bond graph (PBG) supports all heat transfer modes established between the environment, the glass cover, the absorber tube and the fluid. The mass accumulation in the control volume is not taken into account since its dynamic effect remains largely negligible as demonstrated in this contribution. The state equation of the system is developed from the laws of the junctions, the resistance elements and capacitance elements. Numerical simulation is carried out via the Matlab software environment and the predicted results are compared with the experimental tests of the Sandia National Laboratory. For on-sun tests, the average relative errors obtained are about 0.17% for the heat transfer fluid (HTF) output temperature and about 0.96% for the energy efficiency. In the case of off-sun tests, the average relative error calculated for the predicted HTF output temperature is estimated at 0.08% and the heat losses absolute error is equal to 4.9 (W/m2). According to the previous comparisons, there is reason to affirm that the proposed model can accurately predict the thermal behavior of the collector. Finally, this work includes a case study that consists of PTC exergy performance assessment under climate conditions of three different North Africa sites.

Pseudo bond graph tunnel greenhouse model with accurate longwave/shortwave radiations model

ABSTRACT This research work is focused on the construction of an accurate longwave/shortwave radiation model on a tunnel greenhouse pseudo-bond graph model, widely used in Tunisia. This model includes sun position, useful incoming solar radiation model, sky longwave radiation model, inside longwave and shortwave radiation model. The key idea is to use bond graphs allowing a lumped modelling approach which is suitable for control applications. Furthermore, an evaluation of some longwave radiative model components was made, noting that these components are particularly sensitive regarding to the thermal behaviour of the model. Experimental tunnel greenhouse data are used as validation elements for the present model with globally good results. A comparative study was also performed between the present model and a previous bond graph model containing a simplistic radiative model. Practical simulation results show a clear improvement compared with the previous model.

Modeling dynamic systems: contribution to the unsteady behavior of a condenser based on the pseudo-bond graph approach

ABSTRACTThis article is devoted to the dynamic study of the brazed plate condenser (BPC). The proposed model is based on the bond graph theory. The proposed model is based on the bond graph theory because of its energetic approach and multi-physics character of the studied system. The model is discretized into five control volumes. The resolution of mass and energy equations is done by Runge-Kutta method embedded in 20sim software. Analyses of simulation results show that the model has a good ability to transcribe the time evolution of the temperature and pressure in both regimes, transitional and permanent. Also, the model is experimentally validated without any fitting of the set of thermal exchange coefficients.

Development of a bond graph based model library for turbocharged diesel engines

A model library for the turbocharged diesel engines using the pseudo-bond graph based on the three-level structure, technical component level, physical concept level and mathematical level, is presented. For each level, a general framework is explained. The detailed pseudo-bond graph models of each part of the engine as well as the mathematical models are presented. After that, a specific model for the 16PA6V-280STC turbocharged diesel engine is presented. Steady-state conditions of the model are validated with the experiment data. Dynamic conditions, such as the instantaneous load increase, rotational speed transient from 730 rpm to 1000 rpm, are simulated and validated. The evolutions of engine speed, load, rack position, of the dynamic processes are presented. Finally, the influence of the compression ratio and fuel supply advance angle on the specific fuel consumption of the diesel engine is studied on the 20-sim-Matlab co-simulation platform.

Pseudo Bond Graph Model of Thermal Transfers Supported by an Outside Cold Airflow of a Refrigerator to Improve Its Performance

This paper aims to prove the efficiency of using the naturally free and abundant cold airflow to improve the cooling inside a household refrigerator and to reduce the energy consumption in Nordic and high altitude countries. The cold airflow is spread out in a cavity covering the side wall of the appliance. This cavity is also connected to the cold outdoor environment through inlet and outlet ducts. For that purpose, a pseudo bond graph (BG) model is proposed to model this installation. It represents the thermal transfers by forced convection in the cavity and the ducts with the ambient and outdoor surroundings. The internal air temperature is computed according to the evaporator temperature and the outside cold airflow that is also computed according to the outside temperature. The simulation results show that the cooling process was speeded up by about 39% and the duration of the compressor functioning was reduced by about 10[Formula: see text]h and 8[Formula: see text]min, which allows reducing the total energy use by 0.88[Formula: see text]kWh, and thus achieving an energy saving of about 34.61%. Experimental data of the outside airflow temperature in Canada during 28 hours in January 2017 are used in the model and allow an energy saving of about 40%.

Application of Bond Graph approach in dynamic modelling of industrial gas turbine

Nowadays, gas turbines play a significant role in industry and power generation units. Therefore, any increase in their performance efficiency, is designers’ major concern. Power generation system’s principal considerations are performance, weight and reliability. Gas turbine engine is considered as a probable choice for such applications. This research develops and validates a Bond Graph model based on flow of energy and information of a gas turbine engine. Here, modelling of the gas turbine engine is achieved based on the pseudo Bond Graph approach. Subsequently, by coupling the Bond-Graph component models, a unified framework for model representation is presented. Also, to study the effect of changing external load on turbine’s performance, an industrial two-shaft gas turbine is simulated under large transient loads based on the previously developed component models. Finally, the commercial gas turbine simulation program (GSP) is used to validate the simulation results. Transient response simulations indicate an acceptable error between the GSP and Bond Graph model outputs.

Pseudo Bond Graph Modeling and Experimental Investigation of Thermal Transfers Inside a Household Refrigerator

This paper proposes a pseudo bond graph model of thermal transfers by natural convection inside a household refrigerator. It has two inputs: the ambient temperature and the temperature at the level of the evaporator wall. The latter assesses the functioning of the compressor cycles. A performance comparison, with the experimental data, was carried out in order to verify the model, in which, real measurements are used to modulate the evaporator temperature source. The simulation results show the effectiveness of the proposed approach.

Thermal-hydraulic modeling and analysis of hydraulic system by pseudo-bond graph

To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.

Thermal-hydraulic Analysis of Buffer System for Hydraulic Pile Hammers by Pseudo-bond Graph

The damage of cylinder and equipment due to the pile detaching can be avoided by using the buffer device with large flow, which adopts throttle buffer inside the cylinder combining with the control of the relief valve outside the cylinder. To investigate the thermodynamic characteristics of the cylinder chambers and the law of movement of piston, the accurate mathematic model need to be established so the method based on pseudo-bond graph is introduced. According to the conservation equations for mass and energy, the thermalhydraulic pseudo bond graph C and R elements are developed, and the connection rule for the two elements are determined based on their input and output variables. The bond graph model of the buffer system containing the coupled of multiple energy domains is obtained in a unified way based on the structure and working principle of buffer device, then the system state equations have been derived from the model. The model can be used in variable parameters’ simulation with the parameters in the experiment, the pressure simulation data of two chambers of impact cylinder agree well with the experimental results, which indicate that the model can be used for the design and optimization of buffer device of hydraulic pile hammer.

Pseudo bond graph model of thermal transfers sustained by ice quantity of a domestic refrigerator for energy saving application

This paper presents a study on the use of ice to improve the energy efficiency of a domestic refrigerator by applying a pseudo bond graph model that describes the thermal transfers sustained by a quantity of ice introduced inside the cavity of refrigeration. The use of ice resulted in a global energy saving of 4.68%. The effect of ice was found to be more significant during the transitional regime. It reduced the response time to reach the stable average temperature from 15 h to only 3.5 h compared to when not using ice. This achievement did not cost additional electrical power, but rather allowed a saving of electrical energy of 76.73%. However, during the steady state, a reduction in the energy efficiency was noted. An improvement in the cooling by keeping the temperature inside the refrigerator more homogeneous is also proved. The model has two inputs: the outside temperature, and the modulated temperature of the evaporator. This latter determines the functioning of the compressor cycle. The model describes the thermal transfers by natural convection inside the refrigerator. Two experiments were carried out to make a performance comparison and to prove the influence of ice in cooling and energy saving. We used real measurements to modulate the evaporator temperature source in the pseudo bond graph model. The simulation results show the effectiveness of the proposed approach. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

B213 空気圧システムモデル化のためのボンドグラフ法に関する一提案(OS3 フルードパワーの基礎と応用2)

Since a pneumatic system has fluid-flow and thermal fields. Therefore, in modeling a pneumatic system by bond-graph, two kinds of bonds, multi-port C element and multi-port R one have been used, which are not necessary in modeling of a hydraulic system in general. And, the resulting bond-graph model becomes complicated. In this study, a bond-graph method for modelling a pneumatic system is proposed. In modeling of fluid flow and thermal field in a pneumatic system, pseudo bond-graph is employed. And, only 1-port C and 1-port R elements are used for modeling of this system. To confirm the usefulness of the proposed method, simulations and experiments for a pneumatic system used an air gripper as an actuator.

Mathematical modelling of combined process drying by using bond graph approach

The main objective of this work is to quantify the energetic interest of combined drying process of natural products. This method of drying is realised in a climatic wind tunnel, seat of a flow of hot air and in the presence of a radiation source. A mathematical model that describes the phenomena of heat and mass transfers during the drying of a wet agricultural product has been determined by the use of the pseudo-bond graph methodology. Such methodology was very appropriate for this industrial process since it allows good management of the non-linearity present in the system. Some drying tests were realised on tomatoes and experimental results are compared with theoretical results for validation of the developed model.

Bond graph modeling for fault diagnosis: the continuous stirred tank reactor case study

Supervision of chemical and biochemical processes is difficult due to various factors, for example the evolution of nonlinear state variables, uncertainties in parameters and disturbances, and system operating conditions. The complexities arise out of the energetic couplings in the model. In this work, the bond graph representation, as a unified and multidisciplinary tool, is used for dynamic modeling and diagnosis for process engineering, incorporating the chemical kinetics of an equilibrated reaction, heat and mass transport phenomena. A pseudo bond graph model technique is applied to a pilot reactor fitted with a mono-fluid heating/cooling system. A modeling structure has been implemented through process sub-units and validated through experimental observations. This technique is proposed to indicate physico-chemical failures, for example matter leakage, caloric isolation, or the occurrence of a secondary reaction or temperature runaway when a very exothermic reaction occurs. It provides the computational algorithms to eliminate unknown variables from coupled thermochemical models and thus generate analytical redundancy relations (ARRs) in terms of measurements and parameters for online diagnosis.

Addition of momentum and kinetic energy effects in supersonic compressible flow using pseudo bond graph approach

In most of the papers published on compressible fluid using pseudo the bond graph approach, momentum and kinetic energy effects have been neglected due to low speed. However, in convergent–divergent nozzles that the flow is supersonic, these models will lose their validation. For the purpose of considering kinetic energy in compressible fluid flow, this paper introduces a new field (KE-field) to pseudo bond graph. This field can also be used to extract the momentum equation on the gaseous models. Furthermore, Karnopp’s suggested relation for an isentropic nozzle is developed to a convergent–divergent nozzle. The simulation results show that the thrust force obtained from the simulations has a very good agreement to analytical relationships. Therefore, it suggests that the KE-field can be used for modelling the thrust force. As bond graph method has been implemented in many software applications such as MS1, SYMBOLS2000 and 20SIM®, the new field can also be used in these software.

Dynamic modelling and performance study of solar gas tunnel dryer

The work presented in this article focuses on the analysis and modelling of heat and mass transfers in the tunnel dryer during the drying of agricultural products. The main objective of this work is to establish a global modelling of the studied system based on the bond graph methodology. The pseudo-bond graph methodology was used in modelling the system. Such methodology was very suitable for this thermal process since it allows good management of the nonlinearity present in the system.The thermal performance of the proposed dryer is analysed by solving the various energy balance equations. An application of drying tomatoes was achieved and a fair agreement was observed between predicted and experimental results.

Dynamic Analysis of a Complex Pneumatic Valve Using Pseudobond Graph Modeling Technique

In this work, the dynamic behaviors of a complex pneumatic reducer valve have been studied through the pseudobond graph modeling technique. This modeling approach graphically describes the energy and mass flows among pneumatic valve components during real operational conditions. State equations have been derived from the pseudobond graph model and have been numerically solved by matlab-Simulink. To validate the accuracy of the model, simulation results are compared with the real data of an experimental setup and good agreements between them are reported. The main advantage of the proposed model over other conventional approaches such as fluid dynamics theories is that it provides a physical model which accurately predicts the system's dynamic responses without any need to run huge computer programs or establish expensive experimental setups.