Felület-morfológiai eljárás kifejlesztése szilárd peremek adaptív optimalizálására = Development of Surface Morphing Method for the Adaptive Optimisation of Solid Wall

A jelen kutatás célja egy olyan új felület-morfológiai elven működő numerikus áramlástani eljárás kidolgozása, amely képes az áramlást határoló szilárd falak adaptív optimalizálására. A Navier-Stokes és Euler megoldók FORTRAN és C++ környezetben való elkészítését és áramlástani validációját követően az a következtetés vonható le, hogy az összenyomható áramlás modellezése a súrlódás elhanyagolásával is kielégítő eredményt szolgáltat a mérési eredményekkel való összehasonlításakor a vizsgált esetekben. Ezért, az optimalizációs módszer a 2D-s Euler egyenletek strukturált, cellaközpontú véges térfogat elven működő numerikus megoldásán alapul. Az optimalizációs modul első részében állíthatók elő az optimális fali nyomás-eloszlás görbék a végpontokban jelentkező inkonzisztencia (pl. negatív lapátvastagság, nyitott kilépő él) miatt szükséges finomhangolásokkal. A második részben, egy inverz tervező-eszköz segítségével jön létre az a 3-10 iterációt magába foglaló folyamat, amelynek során kialakul az előírt nyomáseloszláshoz tartozó geometria. Az eljárás helyes működésének tesztelése, vagyis a szilárd falak alkalmazástól függő optimális előállítása belső-, külső-, és lapátrácsban kialakult áramlások segítségével történt meg. A módszer a gyakorlati életben jelentősen lerövidítheti az áramlás és teljesítmény szempontjából optimális geometria előállításának irányába tett erőfeszítéseket. Az eljárás pontossága 3D-s kiterjesztéssel és a súrlódás figyelembevételével tovább növelhető. | The goal of the present research is to develop a new CFD (Computational Fluid Dynamics) based surface-morphing method for an adaptive optimization of solid walls. After implementing the Navier-Stokes and Euler solvers in FORTRAN and C++ environment, several analyses have been completed for validation. Beside the viscous flow modeling, the result of the inviscid approach also shows acceptable agreement with the measurement in the investigated cases, hence Euler equations are used as governing equations hereafter. Cell centered finite volume method has been implemented with Roe’s approximated Riemann solver, higher order spatial discretization and MinMod limiter for the numerical solution of the non-linear system of the partial differential equations. The optimal pressure distributions are generated in the first part of the optimization module with fine-tuning process to avoid geometry problems such as negative thickness or opening trailing edge. The second part of the optimization procedure forms the desired geometry over an evolution strategy belongs to the optimal pressure distribution by means of an inversed design solver. Generally, the optimum geometry is appeared within 3-10 iteration cycles. The testing of the correct operation of the entire optimization process has been successfully completed for internal, external and cascade flows. The industrial application of the presented method can significantly reduce time, cost and capacity in the pre- and serial developments

Computational Investigation on Deswirl Vanes for Multistage Centrifugal Compressors

The goal of this project is to report on some computational investigations about the return flow passages. The return flow channel provides the connection and carries the flow between two stages of a multistage centrifugal compressor. Of course, deswirl vanes are indispensable between the inlet and outlet section, because usually the inlet flow angle, which comes from the impeller, is 70° -75° measured from radius and the downstream flow angle should be axial, for the next stage. Generally, the shape of this unconventional blade is unique; it is not possible to choose it from any catalogues. During the design procedures, a couple of new blade design techniques have been developed; among them one is based on a zero circulation over the control surface, between two blades with the meaning of CBL (constant blade loading) [14]. The purpose of this investigation is to construct a 3D blade for the return passage. In addition, a system of programs for UNIX was developed to help us to communicate between the different software. The next step is to use the inviscid inverse design program to make the most relevant blade; provided by the CBL design, as perfect as possible and introduce negative and positive lean to improve the design specifications. Finally, we should analyse the configuration with a 3D Navier-Stokes solver to have some conclusions about the new blade geometry. Of course, in the design process, the loss coefficient and pressure recovery factor are the two main parameters, which are always taken into consideration to check the correctness of the design

Novell Application of CFD for Rocket Engine Nozzle Optimization

Numerical analyses, validation and geometric optimization of a converging-diverging nozzle flows has been established in the present work. The optimal nozzle contour for a given nozzle pressure ratio and length yields the largest obtainable thrust for the conditions and thus minimises the losses. Application of such methods reduces the entry cost to the market, promote innovation and accelerate the development processes. A parametric geometry, numerical mesh and simulation model is constructed first to solve the problem. The simulation model is then validated by using experimental and computational data. The optimizations are completed for conical and bell shaped nozzles also to find the suitable nozzle geometries for the given conditions. Results are in good agreement with existing nozzle flow fields. The optimization loop described and implemented here can be used in the all similar situations and can be the basis of an improved nozzle geometry optimization procedure by means of using a multiphysics system to generate the final model with reduced number sampling phases

A 2D MATHEMATICAL MODEL ON TRANSONIC AXIAL COMPRESSOR ROTOR FLOW

The goal of this project is to develop a new simplified computational method by means of 2D approach to determine the 3D axial compressor rotor performance map. Hence, an inviscid flow solver is reconstructed for transonic flow regime to describe the internal phenomenon. The code is based on two dimensional cell centered shock capturing Euler finite volume scheme using an artificial viscosity and explicit MacCormack´s predictor-corrector method for time stepping. For validation, Laval´s convergent-divergent nozzle flow and Rizzi, A. W. test case [5] are implemented

Past and Future Practical Solutions for Torsional Vibration Damping in Vehicle Industry

In addition to material and production costs, consumption and emission limits, the requirements for performance, efficiency and space utilization must be met when it comes to the design of today's internal combustion engines for the automotive industry. As a result, three new design trends have been emerged (based on J. Pfleghaar and B. Lohmann's paper in 2013): 1. downsizing: reduction of engine size (number of pistons and stroke) for fuel and space-saving and CO2 emission reduction purposes, 2. downspeeding: reduction of engine speed to save fuel, which necessarily entails significantly higher torques being generated and transmitted in the engine, 3. turbo supercharging: increasing the pressure and compression ratio in the engine piston cylinder to cover the increased torque demand, which is accompanied by NOx gas emissions. Due to these new design trends, significant transverse, axial, and torsional oscillations can occur on the engine's crankshaft. To avoid power loss and fatigue due to the torsional oscillations, a torsional vibration damper is advised to be installed on the free end of the crankshaft or integrated into the flywheel. This review paper focuses on the possible reasons for torsional vibrations, the applied methods used to dampen them, and expected future trends

Compressible viscous flow solver

Nowadays, in spite of disadvantages of turbulence closure models for RANS (Reynolds Averaged Navier-Stokes equations), they are at present the only tools available for the computation of complex turbulent flows of practical relevance. Their popularity comes from high efficiency in terms of accuracy and computational cost, which makes them widely used in commercial codes and related multidisciplinary applications. Hence, for modelling compressible flow, as a framework of complex inverse design optimisation tool, Navier-Stokes solver is implemented by using k-ω turbulence model in C++ environment. The governing equations in conservative form are deduced by using Favre averaging to filter local fluctuations. The code is based on structured, density based cell centred finite volume method. The convective terms are discretized by Roe approximated Riemann method. Central discretization is applied for diffusive terms. MUSCL approach is implemented for higher order spatial reconstruction with Mulder limiter for monotonicity preserving. Wilcox k-ω two equations turbulence model is implemented for turbulence modelling. The explicit system of the equations is solved by the 4th order Runge-Kutta method. The numerical boundary conditions are based on the method of characteristics. The interest is mostly in high speed aeronautical applications with the possibility of extension for surface optimisation. Hence, the applied validational test cases are in transonic and supersonic flow regime: circular bump in the transonic channel and compression corner

Technology Roadmap for Aircraft Maintenance, Repair and Overhaul = Technológiai ütemterv a légi járművek karbantartásával, javításával és nagyjavításával foglalkozó vállalatok részére

Nowadays, the demand for aircraft Maintenance, Repair and Overhaul (MRO) is constantly growing. The market size of the European MRO segment is estimated to be USD 206.13 billion in 2022, growing at a Compound Annual Growth Rate (CAGR) of 2.8% between 2022 and 2030. This forecast is a good indication of the growth in the number of incoming assignments. As a result, airlines and aircraft operators will increasingly rely on companies with experience in the MRO field to perform maintenance and repair work. Furthermore, as many airlines now choose to outsource maintenance and repair, this will further increase the load on MRO companies. As the number of incoming jobs increases, the companies concerned are constantly looking for and implementing new and better methods and technologies, with another aim of gaining a larger market share. Moreover, as there is still scope for the development and introduction of new technologies and processes in this area, a significant number of research and development projects are underway or in the pipeline. Therefore, the main objective of this study is to use the available information to present a generalised technology roadmap for the companies involved in MRO activities and, on this basis, to collect, present and categorise the state-of-the-art developments in the MRO sector, highlighting what the future will hold for companies that incorporate these revolutionary innovations into their daily work processes. Napjainkban a légi járművek karbantartása, javítása és nagyjavítása (Maintenance, Repair and Overhaul [MRO]) iránti kereslet folyamatosan növekszik. Az európai MRO-szegmens piaci méretét 2022-ben 206,13 milliárd USD-ra becsülték, ami 2022 és 2030 között várhatóan 2,8%-os összetett éves növekedési rátával (Compound Annual Growth Rate [CAGR]) fog növekedni. Ez az előrejelzés az iparág fejlődése mellett a beérkező feladatok számának növekedését is jól mutatja. Ennek eredményeképpen a légitársaságok és a repülőgép-üzemeltetők egyre inkább az MRO-területen tapasztalattal rendelkező társaságokra támaszkodnak majd a karbantartási ésjavítási munkák elvégzésében. Továbbá, mivel ma már sok légitársaság a karbantartás és -javítás kiszervezése mellett dönt, ez tovább növeli az MRO-vállalatok terheléseit. A beérkező feladatok számának növekedése miatt az érintett vállalatok folyamatosan keresik az újabb és jobb módszereket és technológiákat, illetve azok bevezetését, aminek másik célja a nagyobb piaci részesedés elérése. Továbbá, mivel ezen a területen még van lehetőség új technológiák és folyamatok kifejlesztésére és bevezetésére, jelentős számú kutatási és fejlesztési projekt van folyamatban, illetve körvonalazódik. Ezért e tanulmány fő célja, hogy a rendelkezésre álló információk felhasználásával ismertesse az MRO-tevékenységben érintett vállalatok általánosított technológiai ütemtervét, valamint ebből kiindulva összegyűjtse, bemutassa és kategorizálja az MRO-ágazat legmodernebb fejlesztéseit rávilágítva arra, hogy milyen lesz a jövő azon vállalatok részére, amelyek ezeket a forradalmi újításokat a mindennapi munkafolyamataikba beépítik

A viszkózus torziós lengéscsillapítók termikus vizsgálata hőmérséklet csökkentés céljából = A heat transfer analysis of viscous torsional dampers for temperature reduction

A torziós lengéscsillapítók biztonságkritikus alkatrésznek minősülnek a gépjárműiparban. Szilikon olajjal működő viszkózus változatuk hatásosan csillapítja a motorok főtengelyén fellépő torziós lengéseket bármely frekvencia tartományon. A csillapítás során elnyelt energia hő formájában disszipálódik, ami károsan befolyásolja a szilikonolaj élettartamát. A jelen munka egy lengéscsillapító csatolt áramlástani és termikus szimulációját mutatja be az eredmények részletes magyarázatával különös tekintettel hűtés hatékonyságának javítására

Model Development with Verification for Thermal Analysis of Torsional Vibration Dampers

The crankshaft of aircraft's piston engine is exposed to harmful torsional vibration. If the oscillation reaches high value of amplitude fatigue damage of the propeller system occurs. To avoid this, torsional vibration damper can be mounted onto the free-end of the crankshaft. Visco-dampers are the simplest in structure but one of the most effective type of torsional vibration dampers, which have working fluid of silicone oil. Silicone oil is a non-Newtonian fluid and the highest effect on its lifetime is the temperature. Due to the thermal complexity of the structure and due to the lack of proper thermal measurement technology, it is a challenging task to perform thermal management of the damper especially based on purely analytical way. Numerical methods must be applied in design and development phase of the product to approximate the temperature field for lifetime calculation. A finite-difference-method based 2D thermal calculation procedure has been developed in MATLAB environment in order to reveal the hidden heat transfer processes among the damper components and to approximate the temperature distribution inside the structure with especial care for the silicone oil. The accuracy of the developed thermal model has been verified by a finite-volume-method based engineering software in ANSYS environment. The newly developed and verified thermal model has been used to update the Iwamoto-equation for providing more accurate outer surface temperature for the recently investigated damper housing in analytical way