Dissertations / Theses on the topic 'Turbocharger Turbine'

One of the common failure modes of the diesel engine turbochargers is high-cycle fatigue of the turbine-wheel blades. Mistuning of the blades due to the casting process is believed to contribute to this failure mode. A laser vibrometer is used to characterize mistuning for a population of turbine wheels through the analysis of the blade-response to piezo-speaker induced noise. The turbine-wheel design under investigation is radial and is typically used in 6-12L diesel engine applications. FRFs and resonance frequencies are reviewed and summarized. The study includes test results for a paddle wheel that represents a perfectly tuned system and acts as a reference. A discrete mass-spring model is developed for the paddle wheel and the model suitability is tested against measured data. Density randomization is applied to model mistuning in the turbine wheels. Frequency mistuning and relative amplitude modelling for blade modes is found in good agreement with the data, however the mass-spring model over-predicts amplitude-amplification factors for a population of radial-turbine wheels, especially with regard to hub-dominant modes. A continuous twisted-blade model is developed in Matlab using finite-element techniques. Experimental data is shown to have good agreement with the twisted-blade model. Whitehead’s maximum amplitude-amplification prediction using RMS value for a tuned amplitude value is calculated, and the turbine-wheel response is found to fit within the theoretical limit. Different mistuning patterns are studied using the twisted-blade model. Maximum and minimum response patterns are identified and recommended.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.
Includes bibliographical references (leaf 24).
The turbocharger gas turbine engine was designed with the intent of being built as a demonstration for the Massachusetts Institute of Technology Department of Mechanical Engineering courses 2.005 and 2.006 to supplement material covered. A gas turbine operates on an open version of the Brayton cycle and consists of a compressor, a combustion chamber and a turbine. An automobile turbocharger was chosen because it contains a compressor and turbine on a common shaft. Designs for the combustion chamber, oil system, fuel system, and ignition system were created based on research of similar projects. Many of the necessary parts were also specified.
by Keane T. Nishimoto.
S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004.
Includes bibliographical references.
As portable electronic devices proliferate (laptops, GPS, radios etc.), the demand for compact energy sources to power them increases. Primary (non-rechargeable) batteries now provide energy densities upwards of 180 W-hr/kg, secondary (rechargeable) batteries offer about 1/2 that level. Hydrocarbon fuels have a chemical energy density of 13,000-14,000 W-hr/kg. A power source using hydrocarbon fuels with an electric power conversion efficiency of order 10% would be revolutionary. This promise has driven the development of the MIT micro gas turbine generator concept. The first engine design measures 23 x 23 x 0.3 mm and is fabricated from single crystal silicon using MEMS micro-fabrication techniques so as to offer the promise of low cost in large production. This thesis describes the development and testing of a MEMS turbocharger. This is a version of a simple cycle, single spool gas turbine engine with compressor and turbine flow paths separated for diagnostic purposes, intended for turbomachinery and rotordynamic development. The turbocharger design described herein was evolved from an earlier, unsuccessful design (Protz 2000) to satisfy rotordynamic and fabrication constraints. The turbochargers consist of a back-to-back centrifugal compressor and radial inflow turbine supported on gas bearings with a design rotating speed of 1.2 Mrpm. This design speed is many times the natural frequency of the radial bearing system. Primarily due to the exacting requirements of the micron scale bearings, these devices have proven very difficult to manufacture to design, with only six near specification units produced over the course of three years. Six proved to be a small number for this development program since these silicon devices are brittle
(cont.) and do not survive bearing crashes at speeds much above a few tens of thousands of rpm. The primary focus of this thesis has been the theoretical and empirical determination of strategies for the starting and acceleration of the turbocharger and engine and evolution of the design to that end. Experiments identified phenomena governing rotordynamics, which were compared to model predictions. During these tests, the turbocharger reached 40% design speed (480,000 rpm). Rotordynamics were the limiting factor. The turbomachinery performance was characterized during these experiments. At 40% design speed, the compressor developed a pressure ratio of 1.21 at a flow rate of 0.13 g/s, values in agreement with CFD predictions. At this operating point the turbine pressure ratio was 1.7 with a flow rate of 0.26 g/s resulting in an overall spool efficiency of 19%. To assess ignition strategies for the gas turbine, a lumped parameter model was developed to examine the transient behavior of the engine as dictated by the turbomachinery fluid mechanics, heat transfer, structural deformations from centrifugal and thermal loading and rotordynamics. The model shows that transients are dominated by three time constants - rotor inertial (10⁻¹ sec), rotor thermal (lsec), and static structure thermal (10sec). The model suggests that the engine requires modified bearing dimensions relative to the turbocharger and that it might be necessary to pre-heat the structure prior to ignition ...
by Nicholas Savoulides.
Ph.D.

The vibration of a turbocharger blade and dynamic characteristics of bladed packets connected by a lacing wire have been studied. The study was carried out using three analytical and experimental methods. They are: Modal Testing, Electronic Speckle Pattern Interferometry (ESPD and Finite Element Analysis (FEA)). Vibration modes of a turbocharger blade with aerodynamic profile, with and without a lacing wire, were identified using model blades with simplified geometry. The separation of coupled modes was achieved using ESPI tests. The modes of vibrations of bladed packets were identified. The effect of inter-blade coupling through a lacing wire is that a cluster of sub-modes are generated in bladed packets corresponding to each fundamental mode of the freestanding blade, the number of the sub-modes being equal to the number of blades in the packet. Apart from the fundamental sub-mode, the vibration of all other submodes are out of phase with different phase relations. The stiffness of the lacing wire and its location with respect to the blade make great contributions towards certain mode clusters in terms of mode shapes and natural frequencies. The nonlinearity of the stiffness of the deformed lacing wire caused by centrifugal force was established. The coupling of this non linearity with different vibration amplitudes, due to different phase relation, results in the dynamic mistuning in lacing wire stiffness. This mistuning is considered to be a major attribute in reducing the responses at resonance.

Turbochargers are becoming an essential device in internal combustion engines as they boost the intake air with more pressure in order to increase the power output. These devices are normally designed for a single steady design point but the pulsating flow delivered from the internal combustion engine is everything but steady. The efficiency drop experienced in the off-design points by the fixed geometry turbochargers have made some research groups to look into new variable geometry solutions for turbocharging. A nozzle ring is a device which normally achieves a higher performance under design conditions, but the efficiency rapidly drops at off-design conditions. In this paper, a variable angle nozzle ring is designed and implemented in the model of a radial turbine of a turbocharger in order to study its potential when working under real internal combustion engine cycles. To understand the profit margin the turbine performance is compared with two turbines with the same impeller geometry: one without nozzle ring and one with a nozzle ring with a fixed angle. The results show that the maximum efficiency angle function calculated for the variable angle nozzle ring achieves an improvement in the total efficiency of 5 % when comparing with a turbine with a fixed angle and 18 % when comparing with a vaneless turbine. The improved guidance achieved due to the variable blade angle leads to less turbine losses and therefore more mechanical energy can be extracted from the exhaust mass flow throughout all the combustion cycle but a further study should be made in order to match all the engine operations points. Notably, taking the pulsating boundary conditions into consideration, a remarkable improvement is achieved already for the fixed angle nozzle ring.

This thesis investigates the impact of volute design on the performance of a mixed flow turbine. Both computational and experimental methods were used to assess performance. All computational work as conducted in CFX under both steady state and unsteady pulsating conditions with the models including inlet, volute, rotor and outlet volumes. Both the mixing plane and sliding mesh approaches were implemented and the results compared. The k-w SST turbulence model was implemented throughout this thesis with the exceptions of chapters 8 and 9 where the SAS SST model was used in an attempt to accurately capture secondary flows. Further SBES simulations were included for flow validation. It was found that pulse shape had a significant impact on the instantaneous performance while the cycle averaged performance remained largely insensitive to the changes. Further thorough analysis showed, under a range of pulse frequencies, loads and amplitudes, significant variations in LE incidence over the pulse cycle. Furthermore, the spanwise distribution of the incidence also changed considerably over the pulse due to volute secondary flow development. As result of the initial analysis both volute tilt and aspect ratio (and a combination of the two) were assessed. A new tilted volute was introduced which resulted in a performance improvement of up to 2.356% in cycle averaged rotor efficiency and 2.171% improvement in cycle average stage efficiency. This improvement reduced when volute A/r was reduced. The impact of volute aspect ratio showed that the MFP varied by up to 4.3%. Furthermore, volute secondary flows were significantly impacted by aspect ratio with smaller aspect ratios resulting in strong vortices that persisted around the volute. Increasing the aspect ratio removed these vortices. However, the span-wise distribution of LE incidence was only slightly improved with increasing aspect ratio. The maximum efficiency improvement measured over the aspect ratio range was 1.47% for the turbine stage. Combining both tilt and aspect ratio showed a maximum performance variation between the worst performing design, radial AR=0.5 and the best performing design tilted AR=2 of 3.00% in the rotor region and 2.87% over the entire stage. Extensive experimental testing under steady state and pulsating flows was conducted at Imperial College, London to validate the computational work. It was observed that the tilted volute resulted in pulsating efficiency improvements at 48krpm and 56krpm. This trend was found to increase as pulse frequency increased. However, steady state testing only showed efficiency improvements at 30krpm for the tilted volute.

Variable Geometry Turbochargers (VGT) are widely used to improve engine-turbocharger matching and currently common in diesel engines. VGT has proven to provide air boost for wide engine speed range as well as reduce turbo-lag. This thesis presents the design and experimental evaluation of a variable geometry mixed flow turbocharger turbine. The mixed flow rotor used in this study consists of 12 blades with a constant inlet blade angle of +20°, a cone angle of 50° and a tip diameter of 95.2mm. A variable geometry stator has been designed within this work, consists of 15 vanes fitted into a ring mechanism with a pivoting range between 40° and 80°. A novel nozzle vane was designed to have 40° lean stacking (from the axial direction). This geometrically achieves 3-dimensional match with the mixed flow rotor and aims to improve the turbine stage performance. A conventional straight nozzle vane was also constructed in order to have a comparative design to assess the benefits of the new lean vane. The steady flow performance results are presented for vane angle settings of 40°, 50°, 60°, 65° and 70° over a non-dimensional speed range of 0.833-1.667. The tests have been carried out with a permanent magnet eddy current dynamometer within a velocity ratio range of 0.47 to 1.09. The optimum efficiency of the variable geometry turbine was found to be approximately 5 percentage points higher than the baseline nozzleless unit. The peak efficiency of the variable geometry turbine corresponds to vane angle settings between 60° and 65°, for both the lean and straight vanes. The maximum total-to-static efficiency of the turbine with lean vanes configuration was measured to be 79.8% at a velocity ratio of 0.675. The equivalent value with straight vanes configuration is 80.4% at a velocity ratio of 0.673. The swallowing capacity of the turbine was shown to increase with the lean vanes, as much as 17% at 70° vane angle and pressure ratio of 1.7. The turbine pulsating flow performance is presented for 50% and 80% equivalent speed conditions and a pulse frequency range of 20-80 Hz, these frequencies correspond to an engine speed range of 800-3200 RPM respectively. The turbine was observed to go through a period of choking within a pulse for vane angle settings between 60°-70°. The unsteady efficiency of a nozzled turbine was found to exhibit larger deviation from the quasi-steady curve compared to a nozzlesless turbine, by as much as -19.4 percentage points. This behaviour was found to be more pronounced towards the close nozzle settings, where the blockage effect is dominant. The nozzle ring was also shown to act as a 'restrictor' which shields the turbine rotor from being completely exposed to the unsteadiness of the flow. This coupled with the phase shifting ambiguity was shown to result in the inaccuracy of the point-by-point instantaneous efficiency; where as much as 25% of a cycle exhibits instantaneous efficiency above unity. Finally the turbine was tested by adapting to the pulsating flow (20-60 Hz) by cyclic variation in the opening and closing of the nozzle vanes, called Active Control Turbocharger (A.C.T.). The nozzle vane operating schedules for each pulse period were evaluated experimentally in two general modes; natural oscillating opening/closing of the nozzle vanes due to the pulsating flow and the forced sinusoidal oscillation of the vanes to match the incoming pulsating flow. The spring stiffness was found to be a dominant factor in the effectiveness of the natural oscillation mode. In the best setting, the turbine energy extraction was shown to improve by 6.1% over a cycle for the 20 Hz flow condition. In overall it was demonstrated an optimum A.C.T. operating condition could be achieved by allowing the nozzle ring to oscillate naturally in pulsating flow, against an external spring pre-load, which eliminates the use of complex mechanism and external drive. However, the current result suggest the benefits of A.C.T. are best realised in large low speed engines.

This work investigated the wear mechanisms of turbocharger components in heavy duty diesel engines. By understanding the wear mechanisms that are occurring in turbochargers the life time of the turbocharger components can be improved. For better understanding, as to why the components are worn out, an analysis of several turbocharger components and tribological tests were carried out.   The contact surfaces between turbocharger and sealing rings were analysed. Surfaces are analysed by several methods, including chemical composition of the surface. Influence of different parameters such as contact pressure, sliding velocity, temperature, and distance on friction and wear behaviour are established by performing tribological tests. Pin on disc sliding wear tests were carried out at both room temperature and at high temperature of 300˚C. The pin and the disc, that were used during the tribological tests, were made of the same materials that are used in turbocharger components.   Analysis of pins and discs from tribo-tests and turbocharger components (turbine sealing rings and shafts) show abrasive and adhesive wear on the worn surfaces of the components, from both the tribological tests and the turbochargers respectively. An increase of the temperature resulted in a reduced friction due to the formation of oxide layers on the sliding surfaces of pins and discs. In the turbocharger, traces of lubricant between the sliding surfaces was found, in addition to plastic deformations on the worn surfaces of the shafts and adhesive and abrasive wear on both worn surfaces that were in contact with each other. On the other hand, on the worn surfaces of the turbine sealing rings some cracks were observed that were perpendicular to the sliding direction, which indicates presence of a fatigue process. The presence of fatigue cracks is probably due to the way the trucks were operated, the increase and decrease of temperature and pressure in the turbocharger is probably the cause of these cracks.   To minimize the wear mechanisms that occurs in turbocharger components such as sealing rings and shafts, there are some parameters such as contact pressure between the sliding surfaces of the components that can be minimized. By minimizing the contact pressure between the sliding surfaces, the lifetime of turbocharger can be improved. A better surface finishing and geometry of the contacting surfaces can also improve the sealing rings and shafts lifetime. To minimize the relaxation of turbine sealing rings, materials that can better keep the mechanical properties of the sealing rings at high temperatures must be used.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
Includes bibliographical references (leaves 31-32).
The Massachusetts Institute of Technology Department of Mechanical Engineering teaches thermodynamics and fluid mechanics through a pair of classes, Thermal Fluids Engineering I & II. The purpose of this project was to design and fabricate a gas-turbine engine for demonstration use in these two classes. The engine was built from an automobile turbocharger with a combustion chamber connected between its compressor and turbine. Pressure and temperature sensors at different points of the engine cycle allow students to monitor the performance of the individual engine components and the complete engine cycle.
by Lauren Tsai.
S.B.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.
Includes bibliographical references (leaf 50).
Thermal-Fluids Engineering is taught in two semesters in the Department of Mechanical Engineering at the Massachusetts Institute of Technology. To emphasize the course material, running experiments of thermodynamic plants are integrated into the course as demonstrations. The aim of this thesis is to supplement the course demonstrations of thermodynamic plants through the design and fabrication of a gas-turbine engine. The engine operates on an open version of the Brayton cycle. Students will be able to evaluate the energy conversion efficiency and net work ratio from air temperature measurements in three stages of the cycle. The gas-turbine engine is made from an automobile turbocharger for its common shaft turbine and compressor. A combustion chamber was placed between the outlet of the compressor and the inlet of the turbine. The temperature measurement system was designed from the placement of thermocouples on the outside wall of a pipe leading from the compressor to the combustor, on the outside wall of a pipe leading from the combustor to the turbine, and on the outside wall of the turbine exhaust pipe. As the temperature measured by the thermocouple will be that of the outside walls of the engine, the model will depict the cross-sectional temperature profile so the students will know the actual bulk temperature of the working fluid, air.
by Jorge Padilla, Jr.
S.B.

The turbocharger remains one of the best means available to the engine developer to satisfy the power density demands on a modern internal combustion engine. This simple device uses the otherwise waste exhaust gas energy to provide significant improvements in the volumetric efficiency or ‘breathing capacity’ of an engine. In order to maximize the energy of the exhaust driving the turbine, most applications utilize pulse turbocharging where a compact exhaust manifold feeds the highly pulsating exhaust flow directly into the turbine wheel. This thesis considers the influence that this pulse-charging has on a double-entry turbocharger turbine. The design of this turbine plays an important role in much of the research presented in this thesis. The turbine is equipped with a mixed-flow rotor with 12 blades that are fed by a 24 blade nozzle ring. The circumferentially divided volute is designed with two gas inlet passages that each feed a separate 180° section of the nozzle ring. Thus, there is no communication between the entries from the volute inlet to the exit of the nozzles. At the exit to the nozzle, the fluid from both inlets expands into an interspace that spans the circumference of the rotor inlet. This small volume that is formed between the nozzle and the mixed flow rotor is the first area where interaction between the flows can occur. The core of this report contains three main divisions: Steady flow experimental results, CFD modelling, and unsteady flow experimental results. These sections are preceded by an introduction explaining the background of the research study, and an essential outline of the equipment and the method of experimentation. The aim of this work is to use a combination of experiments and computational modelling to build up a picture of the performance of the turbine under a wide variety of flow conditions that will eventually lead to further insight into its unsteady performance. First, a comprehensive steady-state experimental data set was obtained to establish the base-line turbine performance. Steady, equal admission tests yielded excellent performance, peaking at 80% efficiency. Owing to the double-entry arrangement, steady flow could also be introduced in the two inlets unequally. During unequal, steady-state operation a notable decrease in performance was observed. The correlation between the ratios of entry pressures and the efficiency of operation was apparent but essentially independent of which flow was varied. In the extreme, when the turbine was only partially supplied with air, the consequence was a 28 point decrease in performance at the optimal velocity ratio. Despite the division between the two entries, the experiments showed that the flows through each inlet were interdependent. Compared to full flow,of the performance of the turbine under a wide variety of flow conditions that will eventually lead to further insight into its unsteady performance. First, a comprehensive steady-state experimental data set was obtained to establish the base-line turbine performance. Steady, equal admission tests yielded excellent performance, peaking at 80% efficiency. Owing to the double-entry arrangement, steady flow could also be introduced in the two inlets unequally. During unequal, steady-state operation a notable decrease in performance was observed. The correlation between the ratios of entry pressures and the efficiency of operation was apparent but essentially independent of which flow was varied. In the extreme, when the turbine was only partially supplied with air, the consequence was a 28 point decrease in performance at the optimal velocity ratio. Despite the division between the two entries, the experiments showed that the flows through each inlet were interdependent. Compared to full flow, 4 when the pressure in one entry was low, the second entry could swallow more mass, and when it was high, the second entry swallowed less. A three-dimensional CFD model was constructed in order to permit a detailed study of the flow in the double-entry design and answer specific questions regarding the observed steady-state performance. For both equal and unequal admission simulations, the model showed close agreement with the experimental mass flow behaviour and reproduced the measured efficiency trends quite well. The interdependence of the swallowing capacity of the two inlets was also predicted by the model, thereby allowing the analysis of the physical flow effects that drive this trend. It was found that the interspace region near the tongues was the site of much of the interaction between inlets. A major emphasis of this modelling work was also to discover areas of loss generation that could lead to the decrease in performance. By focussing on partial admission, this study found that the windage loss in the interspace region of the non-flowing entry proved to be one of the more significant areas of loss generation. Pulsating air flow was then introduced using the range of frequencies typically produced by an internal combustion engine. The operating point of the turbine, traced an orbit within a 3-D space defined by three non-dimensional parameters: velocity ratio, pressure ratio across inlet one, and pressure ratio across inlet two. Direct comparison between steady and unsteady values at the same pressure ratios and velocity ratio was possible due to the large amount of steady data measured. Thus, a quasi-steady versus unsteady comparison was made on the basis of efficiency, mass flow and output power. In general, under pulsating flow conditions, the turbine behaved quite differently than that predicted by the quasi-steady assumption. Lower frequency, higher amplitude pulsations produced the lowest unsteady cycle-averaged efficiency and also produced the most significant departure from quasi-steady behaviour.

Tato práce se zabývá problematikou aerodynamického zatížení statorových lopatek turbodmychadla s variabilní geometrií turbíny a jeho následnou optimalizací. Metody výpočtového modelování tekutin jsou aplikovány s využitím komerčního softwaru ANSYS CFX. Výpočtový model celého turbínového stupně je použit pro analýzu aerodynamického zatížení statorových lopatek v několika polohách a pro různé operační podmínky. Provedená byla detailní analýza vlivu rozložení tlaku v turbínové skříni, úhlu natočení lopatky, jakož i vlivu distančních pinů na aerodynamické zatížení. Následně bylo vyvinuto experimentální zařízení pro přímé měření aerodynamického momentu statorových lopatek s využitím testovacího zařízení s názvem Gas Stand. Toto zařízení spaluje zemní plyn a dokáže vytvořit velmi stabilní podmínky proudění při vysokých teplotách, což umožňuje vyloučit vliv pulzací plynu, vibrací motoru, jakož i vlivu řídící strategie motoru na měřenou veličinu. Výsledky experimentu jsou následně porovnány s vypočtenou hodnotou pomocí CFD modelu a je dosažená velmi dobrá shoda. Validovaný CFD model je následně zredukován s využitím podmínek cyklické symetrie na model jen jednoho segmentu statoru a rotoru. Umožňuje to výrazně zvýšit produktivitu simulací a prozkoumat několik návrhových parametrů statoru v celém rozsahu pohybu statorových lopatek. Provedená analýza citlivosti těchto parametrů položila výborný základ pro jejich následnou optimalizaci a ukázala významný potenciál několika z nich. Na základě analýzy požadavků na aerodynamické zatížení statorových lopatek byla následně vytvořena definice ideálního zatížení, která byla ustavena jako cíl pro jeho optimalizaci. Použitých bylo několik optimalizačních strategií s využitím metody analýzy působících silových vektorů a jejich výsledky byly následně zhodnoceny a porovnány z více aspektů. Výsledné optimalizované řešení bylo následně přepočteno pomocí modelu celého turbínového stupně, čímž se prokázali jeho výborné vlastnosti z hlediska aerodynamického zatížení a zvýšení účinnosti ve spodní části charakteristiky.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 65-66).
A novel humidification dehumidification desalination system was developed at the Rohseneow Kendall Heat Transfer Laboratory. The HDH system runs by having different pressures in the humidifier and dehumidifier. One of the components that will keep the different pressures is an expander. The expander specification is to work with a pressure ratio of 1.2 while having a high efficiency. Two approaches were developed to achieve this result, one was through the design of a turbine and the second was through the selection and testing of a car turbocharger. The design of a turbine is given in detail and follows the process given in "Design of High- Efficiency Turbomachinery and Gas Turbines" by David Wilson. The final design of the turbine blades was sand cast. Due to the sand casting process, cavitation on the blade material was shown and testing of the blades was not pursued for fear of fast fracturing. The second option of selecting a turbocharger is shown and the process which led to its selection is explained. Through such process a K03 turbocharger was selected to be suitable to run at the low pressure ratios with a moderate efficiency. Testing of the K03 was conducted. The static-to-static isentropic efficiency calculated was 53% ± 11% for a pressure ratio of 1.2 while the total-to-total isentropic efficiency 60% ± 14% at a pressure ratio of 1.2. The high error associated with the efficiencies are due to the turbine experiencing small temperature drops in the order of 10°C or less. The K03 turbocharger is meant to run at higher pressure ratios, in the order of 2 with a manufacturer specified efficiency of 70%. Running the K03 at a pressure ratio of 1.2 decreases the efficiency since its not specified to run at those low pressure ratios. If a turbine or a turbocharger is designed for the exact specifications of the desalination system, it can work with low pressure ratios and be highly efficient.
by Yoshio Samaizu Perez Zuniga.
S.B.

A new turbocharger turbine concept that enhances exhaust energy recovery has been developed; it is known as the ‘rotating vane turbine’ (RVT). It aims to address the negative impact of the pulsating exhaust flow on the turbocharger turbine, so that the exhaust energy can be recovered more efficiently compared to the state of art turbocharging technologies. Different from traditional turbine configurations, in which the nozzle is stationary, the RVT incorporates a rotating nozzle ring at a relatively low speed. It thus minimises the deviation of the turbine incidence angle from the optimal design angle on average through a pulse cycle, it as such leads to an improvement of turbine performance. Two control methods are investigated for the rotating nozzle: a passive self-rotation and one that is controlled from the outside with the use of an external driving turbine. The geometry of the rotating nozzle ring is also optimized to reduce the incidence loss on the nozzle blade under unsteady flow. The new RVT is studied through numerical calculation in order to demonstrate that the rotating nozzle ring can adaptively change the flow angle at the turbine inlet through a pulse cycle. As a result, the turbine operating point is pushed to better performance region with higher turbine efficiency and lower pressure ratio, compared to a traditional stationary nozzle ring. The flow analysis shows that the turbine performance improvement is due to the reduction of the flow separation on the turbine blade under sub-optimal operating conditions. Detailed experimental testing is also carried out to further validate the new concept. Two rotating nozzles with different angles are tested under different flow frequencies, turbine speeds, turbine loads and mass flow rates. As comparisons, stationary vane turbine (SVT) and nozzleless turbine are also tested under the same operating conditions as for RVT. The testing results demonstrate that, the rotating nozzle ring can reduce the amplitude of the flow pulses, thereby reducing the unsteadiness level of the turbine operation. Similar to the simulation results, a significant increase in average turbine efficiency as well as a reduction of turbine pressure ratio are observed for RVT, compared to for SVT or nozzleless turbine. A preliminary study of 1D engine simulation is also carried out to investigate the impact of the new RVT on the engine performance. The simulation results show that, the back pressure of the engine with RVT is reduced based on the same engine power output. This indicates the new RVT can effectively reduce the BSFC of an engine, compared to a traditional SVT.

Methods of determining natural frequencies of the D76D88, B76D88, A86E93, C86G90, C86L90 and C125L89 turbine wheel designs for various environmental conditions were investigated by application of Finite Element Analysis and beam theory. Modelling and simulation methods were developed ; the first method composed of 15 finite element simulations ; the second composed of 15 finite element simulations and a set of experimental frequency survey results; the third composed of 5 simulations , an incorporated mathematical model and a set of experimental frequency survey results. Each of these methods was designed to allow prediction of resonant frequency changes across a range of exhaust gas temperature and shaft rotational speed. For the new modelling and simulation methods, an analysis template and a plotting tool were developed using Microsoft Excel and MATLAB software. A graph showing a frequency-temperature-speed variations and a Campbell Diagram that incorporates material stiffening and softening effects across a range of rotational speeds was designed, and applied to the D76D88, B76D88, A86E93, C86G90, C86L90 and C125L89 turbine wheel designs. New design methodologies for turbine wheels were formulated and validated, showing a good agreement with a range of data points from frequency survey, strain-gauge telemetry and laser tip-timing test results. The results from the new design method were compared with existing single compensation factor methodology, and showed a great improvement in accuracy of prediction of modal vibration. A new nomenclature for the mode shapes of a turbocharger’s blade was proposed, designed and demonstrated to allow direct identification of associated mode shape. It is concluded that Finite Element Analysis combined with the frequency survey is capable of predicting changes in turbine natural frequencies and, when incorporated into the existing turbine design methodology, resulted in a major improvement in the accuracy of the predictions of vibration frequency.

This dissertation aims to improve the aerodynamic performance of a turbocharger turbine using the design of experiments method (DoE) and optimisation algorithms; the design of experiments aims at predicting the outcome by introducing a change of the preconditions, which are represented by one or more independent variables, also referred to as "input variables" or "predictor variables"; the change in one or more independent variables is generally hypothesized to result in a change in one or more dependent variables, also referred to as "output variables" or "response variables". The dissertation is structured in the following main points: a first chapter resuming a literature background on turbomachinery, a second chapter containing the design of experiments and the optimisation methods, then the DoE, which is performed by first setting properly the upper and lower bounds for each turbine geometrical parameter, followed by a Latin hypercube sampling (LHS) of the design space; a third chapter which presents the turbine geometries building process using Daimler in-house tools; this step is then followed by the CFD simulations and a final chapter where the metamodels for the turbine performance prediction are build through the software OptiSlang and finally the optimisation process using an adaptative response to surface (ARSM) algorithm, an evolutionary algorithm (EA) and the non-linear programming by quadratic lagrangian (NLPQL) algorithm. This paper present the results obtained from three different optimization algorithms, namely the improved designs predicted by the metamodels and the validation results from the CFD simulations; it is found that in case of a single objective optimization with few constraints which is our specific case, the NLPQL algorithm finds the best improved design with an increment in efficiency of 1:3% with respect to the base turbine, this result is further validated with CFD simulations.

The transient nature of automotive exhaust gas flow is a significant obstacle to turbocharger turbine optimisation, with the need to optimise performance for pulsating flow and maintain acceptable performance across a wide range of engine operating conditions. Standard industrial testing methods are incapable of applying the desired power absorption, due to the inherent limitations of radial compressors, and therefore are limited in their ability to map turbine characteristics. Firstly, this project investigated existing technologies and identified a design approach which allowed development of a novel turbine dynamometer for small automotive turbine applications. The design approach was documented with consideration of component sizing, stress, rotordynamics, component assembly and instrumentation requirements. A novel model for determining viscous torque within a high speed oil film operating under shear stress was developed. A prototype test rig was designed and commissioned based on an existing turbocharger unit which was modified to accept a novel loading device. This prototype device was used to test the turbine over a wide range of conditions, and was used to validate the new viscous model. A second test rig was developed with an expanded feature set, based on the findings of the prototype. Velocity ratio values from 0.075 to 0.596 were achieved and a new loading device configuration was implemented to allow for continuous loading variation during tests. Measured efficiency values were shown to match well with CFD simulations. Instability within the oil film of the device was identified and studied, indicating areas where this was likely to occur and suggesting that shaft vibration interacting with cavitation regions was causing fracture of the oil film. A CFD analysis of the oil film was used in conjunction with experimental data to identify flow phenomena which caused the initiation of this film fracture.

It is commonly known that the turbocharger turbine is still designed using the quasi-steady assumption despite its highly pulsating unsteady working conditions. The positioning of a turbocharger in close proximity to the exhaust valve in order to extract substantial energy ultimately necessitates a thorough investigation regarding its performance under pulsating flow conditions. This thesis presents experimental and numerical work, as well as the design of new advanced stator concept to improve turbine performance under pulsating flow conditions. A cold flow test facility is setup mainly to isolate the effect of pulsating flow conditions and therefore allowing the performance deviation from the quasi-steady approach to be properly recorded and documented. Since experimental data alone is not sufficient for understanding the detailed flow field within the turbocharger turbine stage, a complete 3-D Computational Fluid Dynamics model is developed using commercial software Ansys CFX. The model is validated against experimental data for all steady and pulsating conditions. During pulsating conditions, the incidence angle close to the rotor inlet changed significantly which directly affected the turbine performance. A study on the turbine performance improvement by aggressive reduction of nozzle vanes are conducted and experimentally tested. Results of steady and pulsating conditions suggested that the new vanes arrangement delivered significantly improved performance under both operating conditions especially at 50% speed (equivalent to 30000 rpm). At 80% speed (48000 rpm), the turbine efficiency is either similar or better (up to 8 efficiency point improvement) than the baseline arrangements.

Diploma thesis focus on the design of turbocharger in SW MS Excel. For required flow and pressure ratio, the thermodynamics parameters were calculated for the turbocharger. From these, geometry was designed and the condition of mediums was calculated for each part of the turbine and compressor. At last basic characteristics of the turbine and compressor on varying the regime of engine operation the rotation was made and offered an idea about the working point position.

[ES] Está fuera de toda duda que la industria del automóvil está viviendo una profunda transformación que, durante los últimos años, ha progresado a un ritmo acelerado. Debido a la crecientemente estricta regulación sobre emisiones contaminantes y la necesidad de satisfacer la siempre creciente demanda de movilidad sostenible, es necesario que los motores de combustión modernos reduzcan su consumo y emisiones manteniendo el rendimiento del motor. Para enfrentarse a este desafío, los ingenieros de investigación y desarrollo han redoblado sus esfuerzos a la hora de diseñar y mejorar los modelos unidimensionales, hasta el punto en el que el desarrollo de modelos 1D así como la simulación juegan un papel fundamental en los primeras etapas de diseño de nuevos motores y tecnologías. Al mismo tiempo, la tecnología de turbosobrealimentación se ha consolidado como una de las más efectivas a la hora de construir motores de alta eficiencia, lo que ha hecho evidente la importancia de comprender y modelar correctamente los efectos asociados a los turbogrupos. Particularmente, los fenómenos que ocurren en la turbina en condiciones de flujo fuertemente pulsante han demostrado ser complicadas de modelar y sin embargo decisivas, ya que los códigos de simulación son especialmente útiles cuando son diseñados para trabajar en condiciones realistas. Este trabajo se centra en mejorar los modelos unidimensionales actuales así como en desarrollar nuevas soluciones con el objetivo de contribuir a una mejor predicción del comportamiento de la turbina sometida a condiciones de flujo pulsante. Tanto los esfuerzos realizados en los trabajos experimentales como en los de modelado se han producido para poder proporcionar métodos que sean fáciles de adaptar a las diferentes configuraciones de turbogrupo usadas en la industria, por ello, pueden ser aplicados por ejemplo en turbinas de entrada simple y también en las cada vez más usadas turbinas de entrada doble. En cuanto al trabajo de modelado en la parte de turbina de entrada simple, el foco se ha puesto en presentar una versión mejorada de un código quasi-2D. La validación del modelo se basa en los datos experimentales que están disponibles de trabajos enteriores de la literatura, proporcionando una comparación completa entre los modelos quasi-2D y el clásico modelo 1D. La presión a la entrada y salida de la turbina se ha descompuesto en ondas que viajan hacia delante y hacia atrás por medio de la descomposición de presiones, empleando la componente reflejada y transmitida para verificar la bondad del modelo. El trabajo experimental de esta tesis se centra en desarrollar un nuevo método para ensayar cualquier turbina de doble entrada sometida a condiciones de flujo fuertemente pulsante. La configuración del banco de gas se ha diseñado para ser suficientemente flexible como para realizar pulsos en las dos ramas de entrada por separado, así como para usar condiciones de flujo caliente o condiciones ambiente con mínimos cambios en la instalación. La campaña experimental se usa para validar un modelo integrado unidimensional de turbina tipo twin scroll con especial foco en las componentes reflejada y transmitida para analizar el desempeño del modelo su capacidad de predicción de la acústica no lineal. Finalmente, después de desarrollar el trabajo experimental y de modelado, se presenta un procedimiento para caracterizar el sonido y ruido de la turbina por medio de matrices de transferencia acústica que es comparado con el código unidimensional completo. En este sentido, el método proporciona una herramienta útil y fácil de implementar para simulaciones en tiempo real que aplica de una manera práctica el trabajo de modelado expuesto a lo largo de esta tesis.
[CAT] Està fora de tot dubte que la indústria de l'automòbil està vivint una profunda transformació que, durant els últims anys, ha progressat a un ritme accelerat. A causa de la creixentment estricta regulació sobre emissions contaminants i la necessitat de satisfer la sempre creixent demanda de mobilitat sostenible, és necessari que els motors de combustió moderns reduïsquen el seu consum i emissions mantenint el rendiment del motor. Per a enfrontar-se a aquest desafiament, els enginyers de recerca i desenvolupament han redoblat els seus esforços a l'hora de dissenyar i millorar els models unidimensionals, fins al punt en el qual el desenvolupament de models 1D així com la simulació juguen un paper fonamental en les primeres etapes de disseny de nous motors i tecnologies. Al mateix temps, la tecnologia de turbosobrealimentación s'ha consolidat com una de les més efectives a l'hora de construir motors d'alta eficiència, la qual cosa ha fet evident la importància de comprendre i modelar correctament els efectes associats als turbogrupos. Particularment, els fenòmens que ocorren en la turbina en condicions de flux fortament polsant han demostrat ser complicades de modelar i no obstant això decisives, ja que els codis de simulació són especialment útils quan són dissenyats per a treballar en condicions realistes. Aquest treball se centra en millorar els models unidimensionals actuals així com a desenvolupar noves solucions amb l'objectiu de contribuir a una millor predicció del comportament de la turbina sotmesa a condicions de flux polsant. Tant els esforços realitzats en els treballs experimentals com en els de modelatge s'han produït per a poder proporcionar mètodes que siguen fàcils d'adaptar a les diferents configuracions de turbogrupo usades en l'indústria, per això, poden ser aplicats per exemple en turbines d'entrada simple i també en les cada vegada més usades turbines d'entrada doble. Pel que fa al treball de modelatge en la part de turbina d'entrada simple, el focus s'ha posat a presentar una versió millorada d'un codi quasi-2D. La validació del model es basa en les dades experimentals que estan disponibles de treballs anteriors de la literatura, proporcionant una comparació completa entre els models quasi-2D i el clàssic model 1D. La pressió a l'entrada i eixida de la turbina s'ha descompost en ones que viatgen cap avant i cap enrere per mitjà de la descomposició de pressions, emprant la component reflectida i transmesa per a verificar la bondat del model. El treball experimental d'aquesta tesi se centra en desenvolupar un nou mètode per a assajar qualsevol turbina de doble entrada sotmesa a condicions de flux fortament pulsante. La configuració del banc de gas s'ha dissenyat per a ser prou flexible com per a realitzar polsos en les dues branques d'entrada per separat, així com per a usar condicions de flux calent o condicions ambient amb mínims canvis en la instal·lació. La campanya experimental s'usa per a validar un model integrat unidimensional de turbina tipus twin-scroll amb especial focus en les components reflectida i transmesa per a analitzar l'acompliment del model la seua capacitat de predicció de l'acústica no lineal. Finalment, després de desenvolupar el treball experimental i de modelatge, es presenta un procediment per a caracteritzar el so i soroll de la turbina per mitjà de matrius de transferència acústica que és comparat amb el codi unidimensional complet. En aquest sentit, el mètode proporciona una eina útil i fàcil d'implementar per a simulacions en temps real que aplica d'una manera pràctica el treball de modelatge exposat al llarg d'aquesta tesi.
[EN] It is beyond all doubt that the automotive industry is living a deep transformation that, during the last years, has progressed at an ever accelerating rate. Due to the increasingly stringent pollutant emission regulations and the necessity to fulfil an ever growing demand for sustainable mobility, the modern internal combustion engines are required to strongly reduce the fuel consumption and emissions, while keeping the engine performance. In order to confront this challenge, engine research and development engineers have redoubled their efforts in designing and improving one-dimensional codes, to the point that the development of 1D models and simulation campaigns play a major role in the early steps of designing new engines or technologies. At the same time as the turbocharging technology has arisen as one of the most effective and extended solutions for building high efficient engines, the importance of understanding and modelling correctly the turbocharger effects has become evident. In particular, the phenomena that occurs in the turbine under highly pulsating conditions have proven to be challenging to model and yet decisive, as simulation codes are especially useful when they are designed to work under realistic conditions. This work focusses on the improvement of current one-dimensional models as well as in the development of new solutions with the aim of contributing to a better prediction of the turbine performance under pulsating conditions. Both experimental and modelling efforts have been made in order to provide methods that are easily adaptable to different turbocharger configurations used in the industry, so they can be applied for example in single turbines and also in the increasingly used two-scroll turbine technology. Regarding the modelling work of the single entry turbine part, the work has been focused in presenting an improved version of a quasi-2D code. The validation of the model is based on the experimental data available from previous works of the literature, providing a complete comparison between the quasi-2D and a classic 1D model. By means of a pressure decomposition, the pressure at the turbine inlet and outlet has been split into forward and backward travelling waves, employing the reflected and transmitted components to verify the goodness of the model. The experimental work of the thesis is centred in developing a new method in order to test any two-scroll turbine under highly pulsating flow conditions. The gas stand setup has been designed to be flexible enough to perform pulses in both inlet branches separately as well as to use hot or ambient conditions with minimal changes in the installation. The experimental campaign is used to fully validate an integrated 1D twin-scroll turbine model with special focus in the reflected and transmitted components for analysing the performance of the model and its non-linear acoustics prediction capabilities. Finally, after the experiment and modelling work is developed, a procedure to characterise the turbine sound and noise by means of acoustic transfer matrices is presented and tested against the fully one-dimensional code. In this sense, this method provides a useful and easily-implementable tool for fast and real time simulations that applies in a practical way the modelling work exposed along this thesis.
Soler Blanco, P. (2020). Simulation and modelling of the performance of radial turbochargers under unsteady flow [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/141609
TESIS

The demand for drastic reduction in CO2 emission among road vehicles has seen downsizing becoming a megatrend in modern engine developments due to its benefits in reducing throttling loss and improvement in engine efficiency. In light of this, turbocharging is seen as one of the key enabling technologies and therefore carries along with it an ever-increasing challenge in terms of system-matching as the device is required to operate in ranges never encountered before. The increasing reliance on 1-D engine performance simulation tools calls for more accurate representation of the turbocharger model. The present study assessed the turbocharger turbine maps for use in commercial 1-D gas dynamics engine code from several aspects, namely the width of the map and the representation of turbine unsteady performance in the virtual environment. Furthermore, the present work assessed the performance of turbine under waste-gated operations. For this, an experimental work has been carried out on a bespoke waste-gated turbine layout over a wide range of operating conditions. The performance of the radial turbine under steady inlet conditions was evaluated for different waste-gate openings, at various points along several speed-lines. Then the unsteady tests saw the turbine performance evaluated at various sets of pulse frequencies, turbine loadings and waste-gate openings. Analysis of this study include the impact of turbine map width on the turbine performance modelling in a commercial 1-D gas dynamics engine simulation software and subsequently the prediction of the engine’s performance. This simulation work is carried out based on an actual heavily downsized gasoline engine with a series super-turbocharging system. The study also examined the method of incorporating the effects of turbine unsteady performance under waste-gated and non-waste-gated conditions in the performance maps used in 1-D code and evaluate its impact on the engine performance prediction. The outcome of the study aims at providing a deeper understanding on the unsteady performance of a turbocharger turbine which will lead to improved turbocharger-engine matching methods in the future.

The purpose of this analysis is used PBS Turbo turbochargers like a steam-air turbine in the Flexible Energy System. The System is analogy of Brayton cycle with high efficiency, but heat is transferred to the cycle through a heat exchanger. Main parts of this work are the literature search, the thermodynamic model of the steam-air cycle, and solution for other possibilities. The goal is to find maximum available electrical output and efficiency. The thermodynamic model is used to: - check computation of the standard turbocharger - computation of the steam-air turbine contain one turbocharger - computation of the steam-air turbine contain two turbochargers. The steam-air turbine is different from the turbocharger. They are compared and than there is found some new design of the new steam-air turbine. The one-turbocharger steam-air turbine is used to test steam-air cycle. The double-turbocharger steam-air turbine is suitable for Flexible Energy System. This solution has a lot of advantages.

Moisture recovery is important in the operation of many fuel cell systems, especially proton exchange membrane (PEM) fuel cells. The exhaust of a PEM fuel cell is a moderate temperature, pressurized humid air stream. A system that recovers liquid water condensate from the pressurized humid exhaust stream of a PEM fuel cell would markedly increase the effectiveness of such a system. The recovered water could be used to hydrate the fuel cell membrane, and it could supply a hydrocarbon reformer used for generating hydrogen. This project investigated and documented moisture recovery from the simulated humid exhaust stream of a 25 kW fuel cell with an improved axial flow separator. An axial flow centrifugal separator design was chosen as the best candidate due to its high efficiency and low pressure drop and a prototype was designed and constructed. The separator was then integrated into an experimental test system. First, the stream was simulated by heating compressed air and then humidifying it with superheated steam. Then, after expanding through the turbine section of an automotive turbocharger, the humid stream was passed through the moisture separator where liquid water condensate was removed from the flow. Results are presented for varying turbine inlet conditions at three separate separation lengths. It is shown that the separation efficiency for the improved design was 40% higher and the pressure drop was only 1/3 that of the conventional separator.

Variable Geometry Turbines are widely used in High Pressure Loop Exhaust Gas Recirculation to enhance positive pressure gradient between turbine inlet and compressor outlet. Multiple-entry turbines (twin or double) can achieve an enhanced pulse energy extraction when compared with single entry devices. However, when EGR takes place, an imbalance of mass flow can lead to significant energy loss. This thesis presents the design and experimental assessment of a novel asymmetric double entry turbine that aims to achieve pulse energy recovery even in the face of high EGR. The asymmetric double entry volute was developed with two different scroll lengths: a small scroll that feeds the rotor between azimuth angle of 0° and 160°, beyond which rotor is fed by the large scroll. A pivoting action is designed to enable an optimisation of the optimum angle in each scroll sector. Extensive testing was carried out to characterise the novel turbine under various steady and unsteady flow conditions (full, partial, unequal, in phase and out of phase). The peak recorded efficiency for the full admission nozzleless condition was found to be 78%. When nozzle was present in the small scroll, the efficiency had a similar magnitude (77.6%); while when nozzles were present in both scrolls a lower efficiency was found (74.4%). Considering nozzles only on the small sector: as the vane angle opening changes from most open position (51°) to mid open position (71°) an increase in stage efficiency was observed. Under partial admission, the nozzleless unit showed a very significant the deficit in peak efficiency: 17 points with large scroll flowing and 25 points with small scroll flowing. When nozzle vanes are introduced in the small scroll sector a similar drop was found; but when vanes were present in both scrolls the deficit during partial reduced (13.9% for the best performing configuration). During unequal admission the nozzleless and small nozzle setting displayed a symmetrical efficiency characteristic. During unsteady flow admission at 30k RPM for all frequencies showed that the nozzle configurations recorded higher cycle average efficiency than the base line nozzleless unit. Test results at 20 Hz and 40 Hz have shown higher cycle average efficiency than 60 Hz. Interestingly when nozzles were present on both scrolls the cycle average efficiency increased by almost 13 percentage point higher than nozzleless indicating the value of introducing nozzles.

The demands on heavy duty vehicles is constantly raising with government legislations on CO2 emissions becoming stricter and increasing customer demands. A continuous search for new methods and tools is a crucial element in finding more performance and lower emissions, which are prerequisites for heavy duty vehicles of the future. This thesis is conducted at Scania CV AB and aims at proposing a co-simulation setup which implements the engine management system, EMS, for turbocharger control, into engine simulation models that the company uses to simulate the behaviour of their combustion engines. The EMS software for turbocharger control is modelled in a MATLAB Simulink model and the engine simulation model is modelled in GT-SUITE. The thesis is also suggesting improvements to a turbine model that is modelled within the given EMS software. The results suggest a co-simulation setup that enables the engine simulation models to utilize the EMS software for turbocharger control which thereby enhances their ability to predict engine behaviour. The setup can also be used as a tool during the development process for other part of the EMS and could ease the need for physical engine tests in test cell. The suggested improvements to the turbine model revolves around building a model capturing the aspects of a so called twin scroll turbine and also to implement a better estimation of the turbine efficiency. The improvements to the turbine model ultimately leads to improving the response behaviour of the EMS turbocharger control system.

The aim of this thesis is to provide research into turbocharger regulation, and analyze the force load of vanes in the VNT mechanism of Garrett turbocharger by CFD simulation. In the thesis there is one model with two different mesh densities. It describes the relevance of supercharging vehicle engines and the kinds of supercharging aggregates in the introduction. Then, the thesis is divided into two chapters. The first chapter provides research, describing primary principle of supercharging, turbocharger construction and kinds of air regulation. The practical part of the thesis solves the force load of VNT mechanisms. It was necessary to optimalize the 3D Garrett turbocharger model, create two meshes with different element densities, specify boundary conditions and analyse the results of both cases. A general description of solved problems, comparison of results of force load vanes and propose simplifying and verifying the CFD calculation are included in the conclusion.

This diploma thesis is focused on the concept of threaded connection of the turbine wheel and shaft. At the beginning are described current welding methods of the turbine wheel and shaft connections as well as methods of the compressor wheel and shaft connections. Four possible concepts were designed and evaluated, and the best concept was chosen. For this concept was calculated tightening torque and concept was evaluated in terms of turbocharger operating conditions.

The goal of this thesis project is the creation and the validation of an estimation model developed for the prediction of the Wastegate valve behaviour, to define the splitting of mass flow rate between the turbine and the bypass valve in all the operative conditions of the turbocharger system, by an analysis of the experimental data obtained from tests performed in the engine test bench of the University.

This master’s thesis deals with kinematics model of blade rotating mechanism of turbocharger, which is called as VNT (“Variable nozzle turbine”). The first section treat of turbochargers generally, why we use them, summary description of construction and parts. In the next section deals with supercharge control, about types of controlling and theirs principles, of their vantages or disadvantages and comparison. Following section is about building kinematics model in software ADAMS. First step is analytics solving of mechanism, because it was necessary for parametric model. After this is described main model building. In the last section is kinematics model used on real turbocharger for checking results.

The diploma thesis consists of a theoretical part, which deals with the description of reversing turbocharger and its components. The following part is devoted to calculating the radial-axial compressor and turbine. It also performs a calculation of gear box and characteristics of the turbine.

The Diploma thesis deals with the testing of turbochargers. Aim of this work is to perform a search on a teststands. Further suggest the teststand's construction. Part of the work is the creation of software for utility measurements available. The program will serve as a basis for checking the measurement data of the turbocharger.

In search for quieter engines there is a need for a better understanding of the acoustic properties of engine intake and exhaust system components. Besides mufflers which have the purpose of reducing pressure pulses originating from the internal combustion (IC) engine, there are many components in a modern car exhaust and intake system, e.g., air-filters, coolers, catalytic converters, particulate filters - all having an effect on the pressure pulses or sound field in the system. In this work the focus is on the turbocharged IC-engine where both, sound scattering (reflection and transmission) and sound generation from automotive turbochargers are studied. In addition, sound reflection from an open ended pipe, such as the tailpipe of an IC-engine exhaust is investigated.             Accurate and efficient methods to fully characterize turbochargers by measuring the acoustic two-port have been developed.  Compared to earlier work, a number of modifications are suggested for improving the quality of the results. A study on three different automotive turbochargers is also presented, including data for sound scattering for both the compressor and turbine. The results for the transmission of sound, which is of interest for the ability of a turbocharger to reduce noise coming from the engine, is plotted for all tested cases against a dimensionless frequency scale (Helmholtz-number). This makes it possible to generalize the result in order to draw conclusions about the behavior for any turbocharger.              The sound generation was also studied and three different methods to estimate the sound power are suggested. The methods were used to investigate sound generation at different operating points and identify source mechanisms for a turbocharger compressor.             An accurate method for measuring the reflection of plane acoustic waves from a pipe termination in a duct with hot gas flow has been developed and tested. Representing the acoustical conditions at an exhaust tail-pipe, the data obtained is important for effective modeling of exhaust systems. The experimental results of the reflection coefficient were compared with Munt`s theory on flow duct openings. The measurements were carried out for air jet velocities up to Mach 0.4 and for flow temperatures up to 100°C in order to study temperature effects on the reflection properties. It was concluded, that the experimental results agree well with the Munt theory.

Економія традиційних видів палива є актуальною у наш час. Завдяки використанню біогазових установок отриманий біогаз ми можемо витратити на виробництво теплової і електричної енергії. Забруднення атмосфери – проблема, яка стосується кожного з нас, а при використанні даних установок ми можемо знизити викиди парникових газів в атмосферу, припинити вивіз органічних відходів на полігони їхнього поховання. В даний час спостерігається збільшення застосування ДВЗ для отримання теплової та електричної енергії. Ці автономні теплоелектростанції (когенераційні установки) відповідають найсучаснішим вимогам і мають високий ККД. Спільне виробництво тепла і електроенергії можливо, як при використанні газопоршневих двигунів, так і газових турбін. Але, за оцінками багатьох експертів, застосування турбін більш доцільно при експлуатації установок великої потужності (10 - 20 МВт), а також в тих випадках, коли цілий рік існує потреба в постійному великому споживанні теплової енергії. Така точка зору заснована на високу вартість розробки і монтажу існуючих установок іноземного виробництва. Сучасні мікро- газотурбінні установки (МГТУ) мають високу вартість, складні в обслуговуванні, експлуатації, а ремонт вимагає спеціально підготовленого персоналу. Використання в мікро- газотурбінних установках заводських вузлів, що серійно випускаються, дозволяє знизити їх вартість і переглянути існуючу думку про недоцільність їх використання.
Економія традиційних видів палива є актуальною у наш час. Завдяки використанню біогазових установок отриманий біогаз ми можемо витратити на виробництво теплової і електричної енергії. Виходячи зі зробленого аналізу існуючих конструкторських рішень газотурбінних установок і мікро газотурбінних установок найбільш придатною є радіальна доцентрова турбіна. У роботі проведено огляд і аналіз існуючих систем енергопостачання на основі газотурбінних технологій. Проаналізовано та вибрано методики розрахунку для створення мікро- газотурбінної електростанції, що використовує турбокомпресор двигуна внутрішнього згорання з можливістю роботи на різних видах газоподібного палива. Запропоновано систему автоматичного управління, що дозволяє здійснювати регулювання всіх необхідних параметрів в потрібній заданій послідовності з дотриманням заданого режиму горіння.
Saving traditional fuels is relevant today. Due to the use of biogas plants, the obtained biogas can be spent on the production of heat and electricity. Based on the analysis of existing design solutions of gas turbines and micro gas turbines, the most suitable is a radial centrifugal turbine. The paper reviews and analyzes the existing power supply systems based on gas turbine technologies. The calculation methods for the creation of a micro-gas turbine power plant using a turbocharger of an internal combustion engine with the ability to work on different types of gaseous fuel are analyzed and selected. An automatic control system is proposed, which allows to adjust all the necessary parameters in the desired set sequence in compliance with the set combustion mode
ВСТУП 1 АНАЛІТИЧНИЙ РОЗДІЛ 8 1.1 Області застосування й існуючі системи автономного енергопостачання 8 1.2 Переваги та недоліки газотурбінних генераторів 10 1.3 Висновки до розділу 15 2 ПРОЕКТНО-КОНСТРУКТОРСЬКИЙ РОЗДІЛ 16 2.1 Принцип роботи газотурбінних установок 16 2.2 Методика підбору турбокомпресора ДВЗ, для використання в МГТУ в якості головного робочого органу двигуна 20 2.3 Методика розрахунку термодинамічних параметрів газового потоку в жарову трубу МГТУ 30 2.4 Висновки до розділу 42 3 РОЗРАХУНКОВИЙ РОЗДІЛ 43 3.1 Розрахунок параметрів камери згоряння при використанні різних видів палива на газотурбінній установці 43 3.2 Методика розрахунку камери згоряння для багатопаливної МГТУ 46 3.2.1 Розрахунок паливної форсунки і тиску подачі пропан-бутану або біогазу в камеру згоряння 46 3.2.2 Розрахунок геометричних параметрів жарової труби камери згоряння 58 3.2.3 Розрахунок геометричних параметрів камери згоряння 64 3.3 Розрахунок параметрів силової турбіни 69 3.4 Розробка системи управління 70 3.5 Розрахунок ККД газотурбінної установки 74 3.6 Висновки до розділу 75 4 БЕЗПЕКА ЖИТТЄДІЯЛЬНОСТІ ТА ОСНОВИ ОХОРОНИ ПРАЦІ 76 4.1 Основні вимоги безпеки до улаштування та експлуатації технологічного обладнання 76 4.2 Особливості електротравматизму, електричний струм як чинник небезпек 80 ЗАГАЛЬНІ ВИСНОВКИ 81 ПЕРЕЛІК ПОСИЛАНЬ 82

The thesis deals with the flow in pipe bends and radial turbines geometries that are commonly found in an Internal Combustion Engine (ICE). The development phase of internal combustion engines relies more and more on simulations as an important complement to experiments. This is partly because of the reduction in development cost and the shortening of the development time. This is one of the reasons for the need of more accurate and predictive simulations. By using more complex computational methods the accuracy and predictive capabilities are increased. The disadvantage of using more sophisticated tools is that the computational time is increasing, making such tools less attractive for standard design purposes. Hence, one of the goals of the work has been to contribute to assess and improve the predictive capability of the simpler methods used by the industry. By comparing results from experiments, Reynolds Averaged Navier-Stokes (RANS) computations, and Large Eddy Simulations (LES) the accuracy of the different computational methods can be established. The advantages of using LES over RANS for the flows under consideration stems from the unsteadiness of the flow in the engine manifold. When such unsteadiness overlaps the natural turbulence the model lacks a rational foundation. The thesis considers the effect of the cyclic flow on the chosen numerical models. The LES calculations have proven to be able to predict the mean field and the fluctuations very well when compared to the experimental data. Also the effects of pulsatile exhaust flow on the performance of the turbine of a turbocharging system is assessed. Both steady and pulsating inlet conditions are considered for the turbine case, where the latter is a more realistic representation of the real flow situation inside the exhaust manifold and turbine. The results have been analysed using different methods: single point Fast Fourier Transforms (FFT), probe line means and statistics, area and volume based Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD).
Denna avhandling behandlar flödet i rörkrökar och radiella turbiner som vanligtvis återfinns i en förbränningsmotor. Utvecklingsfasen av förbränningsmotorer bygger mer och mer på att simuleringar är ett viktigt komplement till experiment. Detta beror delvis på minskade utvecklingskostnader men även på kortare utevklningstider. Detta är en av anledningarna till att man behöver mer exakta och prediktiva simuleringsmetoder. Genom att använda mer komplexa beräkningsmetoder så kan både nogrannheten och prediktiviteten öka. Nackdelen med att använda mer sofistikerade metoder är att beräkningstiden ökar, vilket medför att sådana verktyg är mindre attraktiva för standardiserade design ändamål. Härav, ett av målen med projektet har varit att bidra med att bedöma och förbättra de enklare metodernas prediktionsförmåga som används utav industrin. Genom att jämföra resultat från experiment, Reynolds Averaged Navier-Stokes (RANS) och Large Eddy Simulations (LES) så kan nogrannheten hos de olika simuleringsmetoderna fastställas. Fördelarna med att använda LES istället för RANS när det gäller de undersökta flödena kommer ifrån det instationära flödet i grenröret. När denna instationäritet överlappar den naturligt förekommande turbulensen så saknar modellen en rationell grund. Denna avhandling behandlar effekten av de cykliska flöderna på de valda numeriska modellerna. LES beräkningarna har bevisats kunna förutsäga medelfältet och fluktuationerna väldigt väl när man jämför med experimentell data. Effekterna som den pulserande avgasströmning har på turboladdarens turbin prestanda har också kunnat fastställas. Både konstant och pulserande inlopps randvillkor har används för turbinfallet, där det senare är ett mer realistiskt representation av den riktiga strömningsbilden innuti avgasgrenröret och turbinen. Resultaten har analyserats på flera olika sätt: snabba Fourier transformer (FFT) i enskilda punkter, medelvärden och statistik på problinjer, area och volumsbaserade metoder så som Proper Orthogonal Decomposition (POD) samt Dynamic Mode Decomposition (DMD).

QC 20140919

This master’s thesis deals with topological optimization of the impeller of a radial turbocharger turbine. It focuses on reducing the moment of inertia with unchanged aerodynamic properties. The optimization was carried out using CFD, thermal and structural analysis. The computational modeling was performed using the finite element analysis in ANSYS. The work proposes models of the impeller with the topological modification of the internal structure. Based on the values of moment of inertia, the stress and the strain the most suitable model was selected.

La diminution de la cylindrée ou le downsizing du moteur est potentiellement l'une des stratégies les plus efficaces pour améliorer la consommation de carburant et diminuer les émissions polluantes. Dans le domaine de la suralimentation, la simulation est limitée par les caractéristiques de fonctionnement des turbines fournies par les constructeurs. Une extrapolation précise et fiable des cartographies turbine est donc l’objectif de cette thèse. Une étude expérimentale sur une turbine radiale d’un turbocompresseur est effectuée avec différentes techniques pour mesurer la cartographie turbine la plus large possible. Les mesures sont effectuées sur un banc turbocompresseur classique avec différentes températures d'entrée turbine. Puis une technique de gavage en entrée et en sortie compresseur est testée. Le compresseur est ensuite remplacé par un autre compresseur à roue inversée qui peut aider la turbine à tourner et même l’entrainer. Les débits les plus faibles et même les débits négatifs sont mesurés. Un banc turbine électromécanique a également été développé, mais n’a pas pu donner de résultats satisfaisants à cause de problèmes techniques mais des évolutions à venir restent prometteuses. Les diverses techniques expérimentales testées ont aussi permis de mesurer le rendement isentropique de la turbine et le rendement mécanique du turbocompresseur. Finalement, plusieurs modèles d’extrapolation des courbes caractéristiques turbine ont été testés et confrontés aux résultats expérimentaux
Engine downsizing is potentially one of the most effective strategies being explored to improve fuel economy and reduce emissions. In the field of turbocharging,simulation is limited by the operating characteristics of turbines supplied by the manufacturers. An accurate and precise extrapolation of the turbine performance maps is the main aim of this study. An experimental study was done on a radial turbine of a turbocharger with different techniques to measure the wider turbine performance map possible. Measurements were done on a classic turbocharger test bench with different turbine inlet temperatures. Then air was blown to the compressor inlet and exit: it is the compressor “gavage”. The compressor is then replaced with another one with are versed rotor: this compressor can help the turbine turn and even drive it itself. The lowest mass flow rates are measured even the negative ones. An electromechanical turbine test bench was developed but did not work correctly because of technical problems but future developments are promising. The various experimental techniques used allowed also the measurement of the turbine isentropic efficiency and the turbocharger mechanical efficiency. Finally, many extrapolation models of the turbine performance maps were tested and compared to the experimental results

Résumé en français : Dans les turbomachines conventionnelles, l'estimation des performances (rendement, puissance et rapport de pression) se fait en général en admettant l'adiabaticité de l'écoulement. Mais, de nombreuses études ayant montré l'influence négative des échanges thermiques internes et externes sur les performances des petites turbomachines dans les faibles charges et aux bas régimes, cette hypothèse ne peut plus être recevable. L'objectif principal de cette thèse est de contribuer à lever l'hypothèse d'adiabaticité.Une étude préalable de l'état de l'art a permis de relever les différents types de transferts thermiques dans les turbomachines et de circonscrire notre étude.Puis, une analyse exergétique généralisée, ayant pour but la prise en compte des deux principes de la thermodynamique, a été effectuée et l'évolution de l'indice de performance caractérisant le niveau d'énergie récupérable en fonction des échanges thermiques est étudiée.Les performances des turbomachines à fluide compressible sont généralement représentées sous forme graphique dans des systèmes de coordonnées adimensionnelles établies avec l'hypothèse d'adiabaticité. Ces cartographies couramment utilisées par les exploitants et constructeurs ne conviennent pas aux machines fonctionnant avec transferts thermiques. L'étude de la similitude des turbomachines thermiques à fluide compressible présentée dans ce travail, propose de nouvelles coordonnées adimensionnelles pouvant être utilisées aussi bien en adiabatique que dans les écoulements avec transferts thermiques.Enfin, nous proposons un protocole de mesures et un modèle numérique pour l'évaluation des transferts thermiques dans un turbocompresseur.Certains résultats obtenus montrent que les performances calculées avec l'hypothèse d'adiabaticité de l'écoulement du fluide sont surestimées. Les nouvelles lois de la similitude proposées généralisent le théorème de Rateau au fluide compressible fonctionnant dans n'importe quelle condition et permettent de calculer les échanges thermiques à chaud à partir des résultats d'essai à froid. Une donnée supplémentaire (température de refoulement) est néanmoins nécessaire pour la prédiction complète des performances et des échanges thermiques.Le modèle numérique de calcul des échanges thermiques proposé donne des résultats en accord avec ceux attendus, mais nécessite des données réelles issues de mesure sur banc pour une validation complète.

The diploma thesis deals with the calculation of thermodynamic parameters of a turbocharged petrol engine with Miller cycle. A drive unit from Volkswagen, the EA211EVO model line, was chosen as the engine. The engine has a displacement of 1498 cm3 and engine power reaches 110kW at 5000 to 6000 RPM. In this work, a basic description of the thermodynamics of cycles of spark ignition engines is performed, then the problem of turbocharging and methods of its control are presented. The following are the created engine models in GTSuite environment in variants with WasteGate and Variable Turbine Geometry. Finally, operation optimizations with various valve timing changes are presented. The individual variants are the compared.