Volume 1 – Symposium

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group A: Materials Group B: System design & integration Group C: Novel system solutions Group D: Additive manufacturing Group E: Components Group F: Intelligent control Group G: Fluids Group H | K: Pumps Group I | L: Mobile applications Group J: Fundamental

Statistical analysis of silicone oil flow through drilled plates used in RC cars

the present work studies how to determine the best combined dimensions of control variables to achieve an optimal mass flowrate in order the better damping performance on radio-controlled vehicles. According to this, we are going to design a DOE based on Taguchi´s (10) to measure the influence of fluid viscosity (μ), perimeter holes diameter (PHD), centre hole diameter (CHD) and hole length (HL) of different drilled plates used as a critical part of a RC vehicle damper. This DOE design will be L16 with three control variables already described and a fixed value (μ, WAGNERSIL S200). On the other hand, drilled plates will be 3d printed and self-designed by CAD, using ARTILLERY SIDEWINDER X1 “fdm” printing system

Measured and Modeled Performance of a Spring Dominant Free Piston Engine Generator

Free Piston Engine Generators (FPEG) directly convert the reciprocating piston motion into electricity by using a linear alternator. Unlike conventional engines with piston motion restricted by a crankshaft mechanism, the FPEG piston motion is constrained by the energy available in the system. When stiff springs are considered in the design, the FPEG system attains high frequency with high power and efficiency. The main objective of this research was to model stiff spring-assisted FPEG system dynamics and performance accurately, and to apply the modeling results to the development of a 1kW, spark ignited, natural gas fueled, FPEG experimental prototype. The experimental data was further utilized to refine and improve the existing model. First, a MATLAB®/Simulink based multi-cycle numerical model was developed for single and dual cylinder FPEG systems to study the effects of major design parameters on FPEG dynamics and performance. When stiff springs were added, the dynamics became more sinusoidal and symmetric with respect to the initial starting position. For a total displacement of 34 cc, trapped compression ratio of 8.25, and assumed combustion efficiency of 95%, the modeled frequency and electric power varied from 72.3 Hz to 80.8 Hz and 0.81 kW to 0.88 kW for a single cylinder FPEG as the spring stiffness changed from 372 kN/m to 744 kN/m. For a dual cylinder FPEG with the same conditions, these modeled values changed from 76.8 Hz to 84.1 Hz and 1.7 kW to 1.8 kW with increasing spring stiffness. The numerical model was then expanded for sensitivity studies of major design parameters. When FPEG operating conditions were considered, the effective stroke length was found to have a dominant effect on efficiency followed by compression ratio, cylinder bore, and spring stiffness respectively. The experimental FPEG prototype generating 550 W of electricity with indicated efficiencies exceeding 13.8% was used for model validation. Finally, the stable FPEG system requires a control strategy to match the power generated by the engine to the power demanded by the alternator. A model-based control strategy was developed in Stateflow® for alternator mode switching, calibration maps, energy management, ignition and fuel injection timings. With the proposed control strategy and stiff spring dominance, the modeled and experimental FPEG system maintained stable operation with cycle-to-cycle variations less than 5%

Volume 2 – Conference: Wednesday, March 9

10. Internationales Fluidtechnisches Kolloquium:Group 1 | 2: Novel System Structures Group 3 | 5: Pumps Group 4: Thermal Behaviour Group 6: Industrial Hydraulic

Volume 1 – Symposium: Tuesday, March 8

Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Components:Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Component

Development of a Rapid Compression Controlled-Expansion Machine for Chemical Ignition Studies

The ability to accurately model fuel combustion processes is essential to the development of transportation, power generation, and manufacturing technology. Models describing the kinetics of chemical oxidation are readily available and highly refined for a wide range of test fuels. However, these models still suffer from high levels of uncertainty under engine-relevant conditions, largely due to a lack of consistency between published validation data. An experimental testing apparatus, known as the Rapid Compression Controlled-Expansion Machine (RCCEM) has been designed and fabricated to conduct chemical kinetic studies. The RCCEM features a pneumatically-driven, custom-designed cam, which governs the volumetric compression and expansion of the combustion chamber. This machine has been designed to test various compression ratios, compressed pressures, and compressed temperatures. Central to the operation of the RCCEM, the cam assembly is modular with the ability to incorporate different cams with unique compression and expansion profiles. This capability is intended to control heat loss rates in experiments via volumetric expansion, and as a result, increase understanding of its influence on the interpretation of validation data. Performance characterization of the RCCEM, using iso-octane and hexane, has shown that the machine is capable of testing a wide range of conditions with exceptional repeatability. Ignition delay times for iso-octane are reported for compressed temperatures of 630-700 K. Additionally, two computational fluid dynamics (CFD) studies have been conducted to investigate the role of non-uniform boundary temperatures as a potential cause of discrepancies among data in the literature. The effect of these boundary conditions on ignition delay time predictions and compressed-gas temperature field development has been investigated for heated RCM experiments that use either creviced or flat pistons. Three unique boundary temperature cases for non-reactive simulations showed that a large temperature gradient forms over the crown of the piston due to heterogeneities present in the initial temperature fields. Subsequently, five boundary temperature cases were investigated for reactive simulations and demonstrated the effect of these non-uniformities on ignition delay time predictions. Through this work, it was determined that the flat piston is susceptible to these non-uniform conditions causing discrepancies in ignition delay times, whereas the creviced piston data was only minimally influenced

Waste-heat recovery and power generation with reciprocating motion

The utilization of renewable and waste heat from industrial processes is an important step towards the reduction of emissions and the increase in the efficiency of energy systems. This heat is available at different and mostly low grade temperatures (ca 100 °C to 550 °C) and various mass flow rates. The current work focuses on the understanding of the most important parameters that determine the potential efficiency of generalised heat engines from a technology agnostic perspective, followed by the development of modelling frameworks that correspond to two specific engines that can make use of heat sources at low temperature levels. The efficiency and power output of generalised heat engines when optimising different objective functions have been examined. These are the power output and the ecological- criterion value. The efficiency remains within upper and lower bounds, when varying the heat capacity of the heat source and heat sink, as well as the contact time between the external heat reservoirs and the working fluid. The corresponding power output variations are considerably higher than those observed for the efficiency. The power output reaches a maximum for values of the heat capacity of the heat source or sink larger than those of the working fluid or for contact times of the heat-exchange processes that are short or of approximately equal length. From these technology-agnostic considerations and the resulting limits that are imposed on the expected performance of real engines, we proceed to consider two specific technologies in the context of waste-heat recovery and power generation. The common feature of these technologies is that they involve reciprocating motion, either as part of a dedicated component (i.e., expander) or inherently as part of the overall operation of the entire device. The first engine, called Up-THERM, is a two-phase thermofluidic oscillator with low investment costs. A dynamic non-linear model framework of the Up-THERM has been developed. The dominant fluid or thermal effect in each engine component is described by a first-order differential equation. The temperature profile along the heat-exchanger walls has been validated experimentally. After the validation a parametric study has been performed examining the effects of five geometric parameters and the heat-source temperature on the engine’s performance. It is found that the heat-source temperature should be high for high power outputs, the volume of the gas spring small and the diameterof the displacer cylinder should be at its nominal value or somewhat larger. The Up- THERM engine has been compared with organic Rankine cycle (ORC) engines in terms of technical and economical performance. While for low temperature heat-sources the ORC engines have a higher power output, for higher heat-source temperatures this becomes comparable between the two engines. Due to the lower investment costs, the costs per unit power become lower for the Up-THERM engine at high heat-source temperatures. The second engine is an open cycle hot air Ericsson engine. It uses two reciprocating- piston cylinders as compressor and expander, inter-linked by a heat exchanger. It is particularly suitable for heat-sources at higher temperatures with small mass flow rates. The engine is described by a system of 12 equations. Pressure losses across valves, heat losses in the cylinders, friction and mass leakage are considered as loss mechanisms. Pres- sure losses and heat losses together account for 99% of the total losses. An optimisation using neural networks has been performed at five different heat-source conditions. Three operational and four geometric parameters are varied to maximise the power output of the engine. The net power output scales nearly linearly with the mass flow rate of the heat source. The thermal efficiency is constant at around 15% for a heat-source tem- perature of 350 °C and mass flow rates between 0.025 kg/s and 0.1 kg/s. The exergy efficiency increases with decreasing mass flow rate from 3.1% to 6.4%. For a heat-source mass flow rate of 0.1 kg/s the net power output increases from 1.9 kW at 250 °C to 7.2 kW at 350 °C and 48 kW at 450 °C. Higher heat-source temperatures also result in higher thermal efficiencies, but lower exergy efficiencies. Comparing the Ericsson to an equivalent ORC engine, which is a mature waste-heat recovery technology, reveals that the former can operate at lower thermal heat inputs, which allows operation over a wider range of applications with different heat-source mass flow rates. For comparable heat inputs and heat-source temperatures the power output and thermal efficiency of the Ericsson engine are higher than those of the ORC engine. Therefore, the Ericsson engine is an attractive alternative to existing waste-heat recovery technologies.Open Acces

A contribution to the global modeling of heat transfer processes in Diesel engines

[EN] Current challenges in research and development of powertrains demand new computational tools capable of simulating vehicle operation under very diverse conditions. This is due, among other reasons, to new homologation standards in the automotive sector requiring compliance of exhaust emissions regulations under any possible driving condition on the road. Global engine or vehicle models provide many advantages to engineers because they allow to reproduce the entire system under study, considering the physical processes that take place in different components and the interactions among them. This thesis aims to enable the modeling of heat transfer processes in a complete engine simulation tool developed at CMT-Motores Térmicos research institute. This 0D/1D simulation tool is called Virtual Engine Model (VEMOD). The development of heat transfer models comprises the engine block and the ancillary systems. The model of heat transfer in the engine block deals with the central problem of in-cylinder convection by means of a combination of experimental research, CFD simulation and multizone 0D modeling. The other thermal processes present in the engine block are examined in order to implement suitable submodels. Once the model is complete, it undergoes a validation with experimental transient tests. Afterwards, the ancillary systems for engine thermal management are brought into focus. These systems are considered by means of two new models: a model of heat exchangers and a model of thermo-hydraulic circuits. The development of those models is reported in detail. Lastly, with the referred thermal models integrated in the global simulation tool, a validation study is undertaken. The goal is to validate the ability of the Virtual Engine Model to capture the thermal response of a real engine under various operating conditions. To achieve that, an experimental campaign combining tests under steady-state operation, under transient operation and at different temperatures is conducted in parallel to the corresponding simulation campaign. The capacity of the global engine simulations to replicate the measured thermal evolution is finally demonstrated.[ES] Los retos actuales en la investigación y desarrollo de trenes de potencia demandan nuevas herramientas computacionales capaces de simular el funcionamento de un vehículo en condiciones muy diversas. Esto se debe, entre otras razones, a que los nuevos estándares de homologación en el sector de la automoción obligan al cumplimiento de las regulaciones de emisiones en cualquier condición posible de conducción en carretera. Los modelos globales de motor o de vehículo proporcionan muchas ventajas a los ingenieros porque permiten reproducir el sistema entero a estudiar, considerando los procesos físicos que tienen lugar en los distintos componentes y las interacciones entre ellos. Esta tesis pretende hacer posible el modelado de los procesos de transmisión de calor en una completa herramienta de simulación de motor desarrollada en el instituto de investigación CMT-Motores Térmicos. Esta herramienta de simulación 0D/1D se denomina Motor Virtual o Virtual Engine Model (VEMOD). El desarrollo de modelos de transmisión de calor comprende el bloque motor y los sistemas auxiliares. El modelo de transmisión de calor en el bloque motor aborda el problema central de la convección en el interior del cilindro mediante una combinación de investigación experimental, simulación CFD y modelado 0D multizona. El resto de procesos térmicos presentes en el bloque motor son examinados para poder implementar submodelos adecuados. Una vez el modelo está terminado, se realiza una validación con ensayos experimentales en régimen transitorio. A continuación, el foco de atención pasa a los sistemas auxiliares de gestión térmica. Estos sistemas se toman en consideración por medio de dos nuevos modelos: un modelo de intercambiadores de calor y un modelo de circuitos termohidráulicos. El desarrollo de los modelos se explica en detalle en esta tesis. Por último, con los citados modelos integrados en el Motor Virtual, se lleva a cabo un estudio de validación. El objectivo es validar la capacidad del Motor Virtual para reproducir la respuesta térmica de un motor real en varias condiciones de funcionamento. Para conseguirlo, se realiza una campaña experimental que combina ensayos en régimen estacionario, en régimen transitorio y a diferentes temperaturas, en paralelo a la campaña de simulación correspondiente. La capacidad de las simulaciones globales de motor para replicar la evolución térmica medida experimentalmente queda finalmente demostrada.[CA] Els reptes actuals en la recerca i el desenvolupament de trens de potència demanden noves eines computacionals capaces de simular el funcionament d'un vehicle en condicions molt diverses. Açò es deu, entre altres raons, a que els nous estàndards d'homologació al sector de l'automoció obliguen al compliment de les regulacions d'emissions en qualsevol condició possible de conducció en carretera. Els models globals de motor o de vehicle proporcionen molts avantatges als enginyers perquè permeten reproduir el sistema sencer a estudiar, considerant els processos físics que tenen lloc als distints components i les interaccions entre ells. Aquesta tesi pretén fer possible el modelat dels processos de transmissió de calor en una completa eina de simulació de motor desenvolupada a l'institut de recerca CMT-Motores Térmicos. Aquesta eina de simulació 0D/1D s'anomena Motor Virtual o Virtual Engine Model (VEMOD). El desenvolupament de models de transmissió de calor comprén el bloc motor i els sistemes auxiliars. El model de transmissió de calor al bloc motor aborda el problema central de la convecció a l'interior del cilindre mitjançant una combinació de recerca experimental, simulació CFD i modelat 0D multizona. La resta de processos tèrmics presents al bloc motor són examinats per a poder implementar submodels adequats. Una vegada el model està acabat, es fa una validació amb assajos experimentals en règim transitori. A continuació, el focus d'atenció passa als sistemes auxiliars de gestió tèrmica. Aquests sistemes es prenen en consideració per mitjà de dos nous models: un model d'intercanviadors de calor i un model de circuits termohidràulics. El desenvolupament dels models s'explica en detall en aquesta tesi. Per últim, amb els referits models integrats al Motor Virtual, es porta a terme un estudi de validació. L'objectiu és validar la capacitat del Motor Virtual per a reproduir la resposta tèrmica d'un motor real en diverses condicions de funcionament. Per a assolir-ho, es realitza una campanya experimental que combina assajos en règim estacionari, en règim transitori i a diferents temperatures, en paral·lel a la campanya de simulació corresponent. La capacitat de les simulacions globals de motor per a replicar l'evolució tèrmica observada experimentalment queda finalment demostrada.European funds received in the framework of Horizon 2020’s DiePeR project have contributed to the validation and improvement of the Virtual Engine Model. My own dedication has been funded by Universitat Politècnica de València through the predoctoral contract FPI-S2-2016-1357 of “Programa de Apoyo para la Investigaci´on y Desarrollo (PAID-01-16)”.Salvador Iborra, J. (2020). A contribution to the global modeling of heat transfer processes in Diesel engines [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149575TESI

Engineering Fluid Dynamics 2019-2020

This book contains the successful submissions to a Special Issue of Energies entitled “Engineering Fluid Dynamics 2019–2020”. The topic of engineering fluid dynamics includes both experimental and computational studies. Of special interest were submissions from the fields of mechanical, chemical, marine, safety, and energy engineering. We welcomed original research articles and review articles. After one-and-a-half years, 59 papers were submitted and 31 were accepted for publication. The average processing time was about 41 days. The authors had the following geographical distribution: China (15); Korea (7); Japan (3); Norway (2); Sweden (2); Vietnam (2); Australia (1); Denmark (1); Germany (1); Mexico (1); Poland (1); Saudi Arabia (1); USA (1); Serbia (1). Papers covered a wide range of topics including analysis of free-surface waves, bridge girders, gear boxes, hills, radiation heat transfer, spillways, turbulent flames, pipe flow, open channels, jets, combustion chambers, welding, sprinkler, slug flow, turbines, thermoelectric power generation, airfoils, bed formation, fires in tunnels, shell-and-tube heat exchangers, and pumps