Flowfield around the isolated main rotor of UH-60A helicopter was simulated to validate flow solv... more Flowfield around the isolated main rotor of UH-60A helicopter was simulated to validate flow solver FINFLO for rotary wing applications. The computational model treated the four blades as rigid but hinged at their roots, and their dynamic movements resulting from the blade angle controls were solved interactively with the time-accurate flow solution that applies Reynolds-averaged Navier-Stokes equations. A hover case and a fast flight forward were studied with an overset grid system having around 20 million cells. With approximate modeling of appreciable blade elastic torsion, quite good agreement with the experimental and computational data taken from the literature was achieved.
In this paper the Potsdam Propeller Test Case is numerically investigated in oblique inflow condi... more In this paper the Potsdam Propeller Test Case is numerically investigated in oblique inflow conditions. We consider three different topics: open water performance curves, cavitation observations, and pressure pulses induced by the propeller to the ceiling of the cavitation tunnel. In the oblique flow case, the inflow is not uniform from the perspective of the propeller, which results in the dependency of the propeller blade loading and cavitation on the blade rate frequency. The numerical simulations were compared to experimental results for each investigated case. Additionally, we analyzed the unsteady features of the cavitation on the blades as well as the pressure peaks in the propeller wake due to collapsing cavities. We found that the global performance and cavitation patterns close to the blades agree well with the tests in the numerical simulations. The agreement with the tests for the pressure pulses on the tunnel ceiling was better in the non-cavitating case. The unsteady cavitation shed behind the propeller and the subsequent collapse events induced a vast increase in recorded maximum pressure values. Root cavitation collapse produced pressure pulses an order of magnitude greater than the collapse of tip vortex cavitation. Also the collapse of cavities on the blades contributed to a significant increase in the pressure fluctuations on the blades.
The appearance of the propeller hull vortex (PHV) has been investigated using the FINFLO RANS sol... more The appearance of the propeller hull vortex (PHV) has been investigated using the FINFLO RANS solver. This specific phenomenon occurs when solid surfaces placed in the neighbourhood of the propeller prevent the natural flow contraction resulting from the local flow acceleration. As the propeller blades near the solid surfaces may not obtain enough mass flow from the inlet -i.e., the propeller is starved of water -the flow may reverse locally so that water is sucked from the outlet. The small tip clearance combined with the low advance number as well as the geometry of the solid surfaces may affect the inception of the PHV. Time-dependent computations were carried out at seven advance numbers. During the analysis of the results, several quantities were examined to detect the inception of the PHV. Streamlines were found to be the best technique to trace the vortices from an extremely complex flow field. The flow patterns on the flat plate were compared to published experimental observations using the limiting streamlines along the plate. Flow patterns similar to those discovered in the experiments were also obtained by RANS simulations, so the RANS method is able to predict the occurrence of the PHV at least on a qualitative level.
Since 1995 the Swiss and Finnish Airforces have been operating the F/A-18C/D Hornet as their lead... more Since 1995 the Swiss and Finnish Airforces have been operating the F/A-18C/D Hornet as their leading fighter aircraft. Both countries decided to invest in Computational Fluid Dynamics (CFD) simulation tools to study and analyze the flow over the F/A-18. The goal was to develop a modern simulation environment to support the engineering and maintenance of this aircraft, and in particular its structural integrity. In 2005 at the first meeting between RUAG/CFS from Switzerland and Finflo Ltd. from Finland it was decided to perform common research on CFD to improve the grids and solver technology used to simulate the flow over the F/A-18 aircraft. The main objective of these CFD simulations is to provide steady and unsteady loads for engineering investigation as a supplement to the very expensive flight test program. A first series of CFD calculations were carried out in Switzerland for Swiss design load conditions and aerodynamic forces and pressure distributions were compared to the da...
CFD-Simulation and Measurement of Indoor Environment in a Multipurpose Arena
Indoor environment is designed for people and the standards give the framework for the design obj... more Indoor environment is designed for people and the standards give the framework for the design objectives. A foreseeable analysis is often necessary in the design process, based on the requirements defined by the client and the intended usage. One of the main objectives is to find a design solution that is suited for all the design conditions and to predict the impact of the design solution on the indoor environment. Computational fluid dynamics has proved to be a suitable method to provide foreseeable data for the indoor environment analysis. This study presents CFD simulations and measurements in a large scale multipurpose arena. The aim of a multipurpose arena is to facilitate a variety of different activities from ice hockey to concerts. The measurements and CFD were done during an ice hockey game and a concert event. It was found that the indoor environment of the multipurpose arena can be predicted by using CFD in specific conditions. However, correctly defined CFD and boundary...
Raportissa tarkastellaan sähköteknisten tuotteiden virtauksen ja lämmönsiirron laskentaa. Virtaus... more Raportissa tarkastellaan sähköteknisten tuotteiden virtauksen ja lämmönsiirron laskentaa. Virtausyhtälöiden ratkaisussa oleviin perusongelmiin luodaan lyhyt katsaus. Tuloksia esitellään yhdelle esimerkkitapaukselle. Lopuksi esitetään suunnitelmia alan simulointijärjestelmän sekä tutkimuksen ja koulutuksen luomiseksi. Ehdotus sähköteknisten tuotteiden lämpö-ja virtaustekniseksi tutkimushankkeeksi
In this paper aeroelastic simulations are presented for the F/A-18 fighter. Two CFD solvers (NSMB... more In this paper aeroelastic simulations are presented for the F/A-18 fighter. Two CFD solvers (NSMB and FINFLO) developed in two countries, two computational grids and FEM models are utilized. In addition, different turbulence closures are applied. Results are given for a deformed and undeformed geometries by varying turbulence models, grid densities and the computational grids.
Tässä raportissa kuvataan TKK:ssa kehitetyn FINFLO-ratkaisijan ja kaupallisen Fluent-ohjelmiston ... more Tässä raportissa kuvataan TKK:ssa kehitetyn FINFLO-ratkaisijan ja kaupallisen Fluent-ohjelmiston vertailulaskentaa kaksidimensioisessa U-putkessa, jonka sisääntulohalkaisijaan referoitu Reynoldsin luku on 522 000 vastaten turbulenttia virtausta. Molempien ratkaisijoiden k -ω SST turbulenssimalleja vertailtiin keskenään identtisen laskentatapauksen avulla. Laskentatulokset eivät poikenneet merkittävästi toisistaan, eikä konvergenssinopeuksissa ollut suuria eroja. FINFLO-laskenta vaikutti aluksi keskeneräiseltä seinämän läheisten paineiden perusteella. Kävi kuitenkin ilmi, että Fluentin tulostama paine on efektiivinen sisältäen turbulentin paineen ja FINFLOn paine on staattinen. Kun tämä otetaan huomioon, tulokset ovat pääsuureiden osalta hyvin lähellä toisiaan. Turbulenssisuureet ovat kvalitatiivisesti samoja. Tulosten perusteella voidaan kuitenkin päätellä turbulenssimallien olevan toiminnaltaan samoja.
A new kind of planetary exploration mission for Mars is under development in collaboration betwee... more A new kind of planetary exploration mission for Mars is under development in collaboration between the Finnish Meteorological Institute (FMI), Lavochkin Association (LA), Space Research Institute (IKI) and Institutio Nacional de Tecnica Aerospacial (INTA). The Mars MetNet mission is based on a new semi-hard landing vehicle called MetNet Lander (MNL). The scientific payload of the Mars MetNet Precursor [1] mission is divided into three categories: Atmospheric instruments, Optical devices and Composition and structure devices. Each of the payload instruments will provide significant insights in to the Martian atmospheric behavior. The key technologies of the MetNet Lander have been qualified and the electrical qualification model (EQM) of the payload bay has been built and successfully tested. 1. MetNet Lander The MetNet landing vehicles are using an inflatable entry and descent system instead of rigid heat shields and parachutes as earlier semi-hard landing devices have used. This wa...
Geoscientific Instrumentation, Methods and Data Systems Discussions, 2016
Investigations of global and related local phenomenon on Mars such as atmospheric circulation pat... more Investigations of global and related local phenomenon on Mars such as atmospheric circulation patterns, boundary layer phenomena, water, dust and climatological cycles and investigations of the planetary interior would benefit from simultaneous in situ measurements with a good spatial coverage. Practically, such an observation network would require low mass landers, with a high packing density, so a large number of landers could be delivered to Mars with the minimum amount of launchers. The Mars Network Lander (MNL), a small semi-hard lander/penetrator design with a payload mass fraction of approximately 17 % has been developed, tested and prototyped. The MNL features an innovative Entry, Descent and Landing System (EDLS) that is based on inflatable structures. The EDLS is capable of decelerating the lander from interplanetary transfer trajectories down to a surface impact speed of 50-70 m s -1 with a deceleration of < 500 g for < 20 ms. The total mass of the prototype design is ≈ 24 kg, with ≈ 4 kg of mass available for the payload. The EDLS is designed to orientate the penetrator for a vertical impact. As the payload bay will be embedded in the surface materials, the bay's temperature excursions will be much less than if it was fully exposed on the Martian surface allowing some savings on mass. The MNL is well suited for delivering meteorological and atmospheric instruments to the Martian surface. The payload concept also enables the use of other environmental instruments. The small size and low mass of a MNL makes it ideally suited for piggy-backing on larger spacecraft. MNLs 1
The heat transfer and flow characteristics of air jet impingement on a curved surface are investi... more The heat transfer and flow characteristics of air jet impingement on a curved surface are investigated with computational fluid dynamics (CFD) approach. The first applied model is a one-equation SGS model for large eddy simulation (LES) and the second one is the SST-SAS hybrid RANS-LES. These models are utilized to study the flow physics in impinging process on a curved surface for different jet-to-surface (h/B) distances at two Reynolds numbers namely, 2960 and 4740 based on the jet exit velocity ( ) and the hydraulic diameter (2B). The predictions are compared with the experimental data in the literature and also the results from RANS k-ϵ model. Comparisons show that both models can produce relatively good results. However, one-equation model (OEM) produced more accurate results especially at impingement region at lower jet-to-surface distances. In terms of heat transfer, the OEM also predicted better at different jet-tosurface spacings. It is also observed that both models show similar performance at higher h/B ratios.
Wall-Distance-Free Version of Spalart–Allmaras Turbulence Model
AIAA Journal, 2015
A wall-distance-free modification to the Spalart–Allmaras one-equation turbulence model is propos... more A wall-distance-free modification to the Spalart–Allmaras one-equation turbulence model is proposed and evaluated. The k and ϵ that render the hybrid timescale are determined using the ν˜ transport equation together with the Bradshaw and other empirical relations. The model coefficients and other empirical functions are constructed to preserve some anisotropic characteristics of turbulence for application to nonequilibrium turbulent flows. The modified Spalart–Allmaras model is applied to calculate a few well-documented flows, yielding predictions in good agreement with the direct numerical simulation and experimental data. Comparisons demonstrate that the modified SA model offers some improvement over the original Spalart–Allmaras model and is competitive with the shear-stress transport k-ω model.
The propagation of a pressure vave in fluid filled tubes is signifi-• c&&tly affected cy the _ipa... more The propagation of a pressure vave in fluid filled tubes is signifi-• c&&tly affected cy the _ipa wall motion and vice versa. A computer code TMOC (Ti-fXisife.-.is by the Method of Characteristics) is being developed for the analysis .of Zue coupled fluid and pipe vail transients. Because of the structural feedback the pressure can be calculated more accurately than in the programs commonly used.
A parallel pressure-based Navier-Stokes solver. The spatial discretization is based on a colocate... more A parallel pressure-based Navier-Stokes solver. The spatial discretization is based on a colocated finite-volume tecnique and a body fitted co-ordinate system. The solution is based on the traditional SIMPLE method. Time-dependent problems are solved with an implicit three-level method. The parallelization is based on a division of a computational domain into separate blocks and assigning each block into a processor of its own. Several flow cases are studied to test the solver, a steady-state cavity flow, a partly turbulent cavity flow, a fully developed turbulent pipe flow and finally jet in cross flow that has been studied experimentally by Crabb et. al . The results are compared with the measurements and the efficiency of the parallelization is shown.
Flowfield around the isolated main rotor of UH-60A helicopter was simulated to validate flow solv... more Flowfield around the isolated main rotor of UH-60A helicopter was simulated to validate flow solver FINFLO for rotary wing applications. The computational model treated the four blades as rigid but hinged at their roots, and their dynamic movements resulting from the blade angle controls were solved interactively with the time-accurate flow solution that applies Reynolds-averaged Navier-Stokes equations. A hover case and a fast flight forward were studied with an overset grid system having around 20 million cells. With approximate modeling of appreciable blade elastic torsion, quite good agreement with the experimental and computational data taken from the literature was achieved.
A time-dependent flow in a radial compressor with a vaneless diffuser and a volute is simulated. ... more A time-dependent flow in a radial compressor with a vaneless diffuser and a volute is simulated. A quasi-steady approach, where the impeller is rotating and the rest is stationary, and a time-accurate simulation are performed. In the latter case a sliding-mesh technique is utilized and a second-order fully implicit time integration is applied. Dual time-stepping is performed inside a physical time step. In both cases the Baldwin-Lomax turbulence model is used. Results obtained from the simulations are compared with the available experimental data.
Flowfield around the isolated main rotor of UH-60A helicopter was simulated to validate flow solv... more Flowfield around the isolated main rotor of UH-60A helicopter was simulated to validate flow solver FINFLO for rotary wing applications. The computational model treated the four blades as rigid but hinged at their roots, and their dynamic movements resulting from the blade angle controls were solved interactively with the time-accurate flow solution that applies Reynolds-averaged Navier-Stokes equations. A hover case and a fast flight forward were studied with an overset grid system having around 20 million cells. With approximate modeling of appreciable blade elastic torsion, quite good agreement with the experimental and computational data taken from the literature was achieved.
In this paper the Potsdam Propeller Test Case is numerically investigated in oblique inflow condi... more In this paper the Potsdam Propeller Test Case is numerically investigated in oblique inflow conditions. We consider three different topics: open water performance curves, cavitation observations, and pressure pulses induced by the propeller to the ceiling of the cavitation tunnel. In the oblique flow case, the inflow is not uniform from the perspective of the propeller, which results in the dependency of the propeller blade loading and cavitation on the blade rate frequency. The numerical simulations were compared to experimental results for each investigated case. Additionally, we analyzed the unsteady features of the cavitation on the blades as well as the pressure peaks in the propeller wake due to collapsing cavities. We found that the global performance and cavitation patterns close to the blades agree well with the tests in the numerical simulations. The agreement with the tests for the pressure pulses on the tunnel ceiling was better in the non-cavitating case. The unsteady cavitation shed behind the propeller and the subsequent collapse events induced a vast increase in recorded maximum pressure values. Root cavitation collapse produced pressure pulses an order of magnitude greater than the collapse of tip vortex cavitation. Also the collapse of cavities on the blades contributed to a significant increase in the pressure fluctuations on the blades.
The appearance of the propeller hull vortex (PHV) has been investigated using the FINFLO RANS sol... more The appearance of the propeller hull vortex (PHV) has been investigated using the FINFLO RANS solver. This specific phenomenon occurs when solid surfaces placed in the neighbourhood of the propeller prevent the natural flow contraction resulting from the local flow acceleration. As the propeller blades near the solid surfaces may not obtain enough mass flow from the inlet -i.e., the propeller is starved of water -the flow may reverse locally so that water is sucked from the outlet. The small tip clearance combined with the low advance number as well as the geometry of the solid surfaces may affect the inception of the PHV. Time-dependent computations were carried out at seven advance numbers. During the analysis of the results, several quantities were examined to detect the inception of the PHV. Streamlines were found to be the best technique to trace the vortices from an extremely complex flow field. The flow patterns on the flat plate were compared to published experimental observations using the limiting streamlines along the plate. Flow patterns similar to those discovered in the experiments were also obtained by RANS simulations, so the RANS method is able to predict the occurrence of the PHV at least on a qualitative level.
Since 1995 the Swiss and Finnish Airforces have been operating the F/A-18C/D Hornet as their lead... more Since 1995 the Swiss and Finnish Airforces have been operating the F/A-18C/D Hornet as their leading fighter aircraft. Both countries decided to invest in Computational Fluid Dynamics (CFD) simulation tools to study and analyze the flow over the F/A-18. The goal was to develop a modern simulation environment to support the engineering and maintenance of this aircraft, and in particular its structural integrity. In 2005 at the first meeting between RUAG/CFS from Switzerland and Finflo Ltd. from Finland it was decided to perform common research on CFD to improve the grids and solver technology used to simulate the flow over the F/A-18 aircraft. The main objective of these CFD simulations is to provide steady and unsteady loads for engineering investigation as a supplement to the very expensive flight test program. A first series of CFD calculations were carried out in Switzerland for Swiss design load conditions and aerodynamic forces and pressure distributions were compared to the da...
CFD-Simulation and Measurement of Indoor Environment in a Multipurpose Arena
Indoor environment is designed for people and the standards give the framework for the design obj... more Indoor environment is designed for people and the standards give the framework for the design objectives. A foreseeable analysis is often necessary in the design process, based on the requirements defined by the client and the intended usage. One of the main objectives is to find a design solution that is suited for all the design conditions and to predict the impact of the design solution on the indoor environment. Computational fluid dynamics has proved to be a suitable method to provide foreseeable data for the indoor environment analysis. This study presents CFD simulations and measurements in a large scale multipurpose arena. The aim of a multipurpose arena is to facilitate a variety of different activities from ice hockey to concerts. The measurements and CFD were done during an ice hockey game and a concert event. It was found that the indoor environment of the multipurpose arena can be predicted by using CFD in specific conditions. However, correctly defined CFD and boundary...
Raportissa tarkastellaan sähköteknisten tuotteiden virtauksen ja lämmönsiirron laskentaa. Virtaus... more Raportissa tarkastellaan sähköteknisten tuotteiden virtauksen ja lämmönsiirron laskentaa. Virtausyhtälöiden ratkaisussa oleviin perusongelmiin luodaan lyhyt katsaus. Tuloksia esitellään yhdelle esimerkkitapaukselle. Lopuksi esitetään suunnitelmia alan simulointijärjestelmän sekä tutkimuksen ja koulutuksen luomiseksi. Ehdotus sähköteknisten tuotteiden lämpö-ja virtaustekniseksi tutkimushankkeeksi
In this paper aeroelastic simulations are presented for the F/A-18 fighter. Two CFD solvers (NSMB... more In this paper aeroelastic simulations are presented for the F/A-18 fighter. Two CFD solvers (NSMB and FINFLO) developed in two countries, two computational grids and FEM models are utilized. In addition, different turbulence closures are applied. Results are given for a deformed and undeformed geometries by varying turbulence models, grid densities and the computational grids.
Tässä raportissa kuvataan TKK:ssa kehitetyn FINFLO-ratkaisijan ja kaupallisen Fluent-ohjelmiston ... more Tässä raportissa kuvataan TKK:ssa kehitetyn FINFLO-ratkaisijan ja kaupallisen Fluent-ohjelmiston vertailulaskentaa kaksidimensioisessa U-putkessa, jonka sisääntulohalkaisijaan referoitu Reynoldsin luku on 522 000 vastaten turbulenttia virtausta. Molempien ratkaisijoiden k -ω SST turbulenssimalleja vertailtiin keskenään identtisen laskentatapauksen avulla. Laskentatulokset eivät poikenneet merkittävästi toisistaan, eikä konvergenssinopeuksissa ollut suuria eroja. FINFLO-laskenta vaikutti aluksi keskeneräiseltä seinämän läheisten paineiden perusteella. Kävi kuitenkin ilmi, että Fluentin tulostama paine on efektiivinen sisältäen turbulentin paineen ja FINFLOn paine on staattinen. Kun tämä otetaan huomioon, tulokset ovat pääsuureiden osalta hyvin lähellä toisiaan. Turbulenssisuureet ovat kvalitatiivisesti samoja. Tulosten perusteella voidaan kuitenkin päätellä turbulenssimallien olevan toiminnaltaan samoja.
A new kind of planetary exploration mission for Mars is under development in collaboration betwee... more A new kind of planetary exploration mission for Mars is under development in collaboration between the Finnish Meteorological Institute (FMI), Lavochkin Association (LA), Space Research Institute (IKI) and Institutio Nacional de Tecnica Aerospacial (INTA). The Mars MetNet mission is based on a new semi-hard landing vehicle called MetNet Lander (MNL). The scientific payload of the Mars MetNet Precursor [1] mission is divided into three categories: Atmospheric instruments, Optical devices and Composition and structure devices. Each of the payload instruments will provide significant insights in to the Martian atmospheric behavior. The key technologies of the MetNet Lander have been qualified and the electrical qualification model (EQM) of the payload bay has been built and successfully tested. 1. MetNet Lander The MetNet landing vehicles are using an inflatable entry and descent system instead of rigid heat shields and parachutes as earlier semi-hard landing devices have used. This wa...
Geoscientific Instrumentation, Methods and Data Systems Discussions, 2016
Investigations of global and related local phenomenon on Mars such as atmospheric circulation pat... more Investigations of global and related local phenomenon on Mars such as atmospheric circulation patterns, boundary layer phenomena, water, dust and climatological cycles and investigations of the planetary interior would benefit from simultaneous in situ measurements with a good spatial coverage. Practically, such an observation network would require low mass landers, with a high packing density, so a large number of landers could be delivered to Mars with the minimum amount of launchers. The Mars Network Lander (MNL), a small semi-hard lander/penetrator design with a payload mass fraction of approximately 17 % has been developed, tested and prototyped. The MNL features an innovative Entry, Descent and Landing System (EDLS) that is based on inflatable structures. The EDLS is capable of decelerating the lander from interplanetary transfer trajectories down to a surface impact speed of 50-70 m s -1 with a deceleration of < 500 g for < 20 ms. The total mass of the prototype design is ≈ 24 kg, with ≈ 4 kg of mass available for the payload. The EDLS is designed to orientate the penetrator for a vertical impact. As the payload bay will be embedded in the surface materials, the bay's temperature excursions will be much less than if it was fully exposed on the Martian surface allowing some savings on mass. The MNL is well suited for delivering meteorological and atmospheric instruments to the Martian surface. The payload concept also enables the use of other environmental instruments. The small size and low mass of a MNL makes it ideally suited for piggy-backing on larger spacecraft. MNLs 1
The heat transfer and flow characteristics of air jet impingement on a curved surface are investi... more The heat transfer and flow characteristics of air jet impingement on a curved surface are investigated with computational fluid dynamics (CFD) approach. The first applied model is a one-equation SGS model for large eddy simulation (LES) and the second one is the SST-SAS hybrid RANS-LES. These models are utilized to study the flow physics in impinging process on a curved surface for different jet-to-surface (h/B) distances at two Reynolds numbers namely, 2960 and 4740 based on the jet exit velocity ( ) and the hydraulic diameter (2B). The predictions are compared with the experimental data in the literature and also the results from RANS k-ϵ model. Comparisons show that both models can produce relatively good results. However, one-equation model (OEM) produced more accurate results especially at impingement region at lower jet-to-surface distances. In terms of heat transfer, the OEM also predicted better at different jet-tosurface spacings. It is also observed that both models show similar performance at higher h/B ratios.
Wall-Distance-Free Version of Spalart–Allmaras Turbulence Model
AIAA Journal, 2015
A wall-distance-free modification to the Spalart–Allmaras one-equation turbulence model is propos... more A wall-distance-free modification to the Spalart–Allmaras one-equation turbulence model is proposed and evaluated. The k and ϵ that render the hybrid timescale are determined using the ν˜ transport equation together with the Bradshaw and other empirical relations. The model coefficients and other empirical functions are constructed to preserve some anisotropic characteristics of turbulence for application to nonequilibrium turbulent flows. The modified Spalart–Allmaras model is applied to calculate a few well-documented flows, yielding predictions in good agreement with the direct numerical simulation and experimental data. Comparisons demonstrate that the modified SA model offers some improvement over the original Spalart–Allmaras model and is competitive with the shear-stress transport k-ω model.
The propagation of a pressure vave in fluid filled tubes is signifi-• c&&tly affected cy the _ipa... more The propagation of a pressure vave in fluid filled tubes is signifi-• c&&tly affected cy the _ipa wall motion and vice versa. A computer code TMOC (Ti-fXisife.-.is by the Method of Characteristics) is being developed for the analysis .of Zue coupled fluid and pipe vail transients. Because of the structural feedback the pressure can be calculated more accurately than in the programs commonly used.
A parallel pressure-based Navier-Stokes solver. The spatial discretization is based on a colocate... more A parallel pressure-based Navier-Stokes solver. The spatial discretization is based on a colocated finite-volume tecnique and a body fitted co-ordinate system. The solution is based on the traditional SIMPLE method. Time-dependent problems are solved with an implicit three-level method. The parallelization is based on a division of a computational domain into separate blocks and assigning each block into a processor of its own. Several flow cases are studied to test the solver, a steady-state cavity flow, a partly turbulent cavity flow, a fully developed turbulent pipe flow and finally jet in cross flow that has been studied experimentally by Crabb et. al . The results are compared with the measurements and the efficiency of the parallelization is shown.
Flowfield around the isolated main rotor of UH-60A helicopter was simulated to validate flow solv... more Flowfield around the isolated main rotor of UH-60A helicopter was simulated to validate flow solver FINFLO for rotary wing applications. The computational model treated the four blades as rigid but hinged at their roots, and their dynamic movements resulting from the blade angle controls were solved interactively with the time-accurate flow solution that applies Reynolds-averaged Navier-Stokes equations. A hover case and a fast flight forward were studied with an overset grid system having around 20 million cells. With approximate modeling of appreciable blade elastic torsion, quite good agreement with the experimental and computational data taken from the literature was achieved.
A time-dependent flow in a radial compressor with a vaneless diffuser and a volute is simulated. ... more A time-dependent flow in a radial compressor with a vaneless diffuser and a volute is simulated. A quasi-steady approach, where the impeller is rotating and the rest is stationary, and a time-accurate simulation are performed. In the latter case a sliding-mesh technique is utilized and a second-order fully implicit time integration is applied. Dual time-stepping is performed inside a physical time step. In both cases the Baldwin-Lomax turbulence model is used. Results obtained from the simulations are compared with the available experimental data.
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Papers by Timo Siikonen