| 1. |
- Ghosh, Debarshee, 1995, et al.
(författare)
-
Aerodynamic Analysis of Low-Pressure Axial Fans Installed in Parallel
- 2024
-
Ingår i: Journal of Fluids Engineering, Transactions of the ASME. - 1528-901X .- 0098-2202. ; 146:5
-
Tidskriftsartikel (refereegranskat)abstract
- Ducted rotor-only low-pressure axial fans play an integral role in automotive thermal management. The tightly packed under-hood region and down-stream heat-exchanger shape limit the fan diameter. In order to circumvent this limitation, multiple cooling fans of small diameters are tightly packaged and placed in parallel. Currently, there is limited scientific work, that study the aerodynamics of low-pressure axial fans when installed in parallel. This work aims to quantify the aerodynamic performance and the flow-field as a result of installing low-pressure axial fans in parallel through computational fluid dynamics (CFD). Publicly available experimental data from Friedrich-Alexander University is used for the validation of the numerical setup. Three-dimensional, full-annulus, unsteady Reynolds-averaged Navier‐Stokes (URANS) analysis has been performed for both a single-fan and two-fans installed in parallel and their respective aerodynamic performance has been compared for the operation condition identified as the best efficiency point in experiments. Only small differences are observed in the overall aerodynamic performance of the two-fans in parallel compared to a single-fan. A circumferential nonuniformity in the form of a local high-pressure zone at the inlet of the fan is observed when the two-fans are placed in parallel. The resulting circumferential nonuniformity is quantified, both in space and time. A strong correlation is found between the pressure fields of the two-fans installed in parallel.
|
|
| 2. |
- Ghosh, Debarshee, 1995
(författare)
-
Aerodynamic Design and Installation Effects of Automotive Electric Cooling Fans
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Electric cooling fans play a crucial role in automotive thermal management. They generate the airflow required for heat rejection from the expended coolant circulating within the heat exchanger. This thesis focuses on the aerodynamic design and installation effects of electric cooling fans or "E-fans". E-fans are low-pressure axial fans powered by individual electric motors due to the absence of an internal combustion engine in electric vehicles. These E-fans are often packaged very tightly due to the limited space in the underhood region. Additionally, they are often subjected to non-uniform inflow conditions as they are placed downstream of other components in the underhood region. This thesis details the design process of low-pressure axial fans with low-solidity blades using the Blade Element Momentum (BEM) method. The design process takes into consideration the cooling system requirements. Three-dimensional, steady-state, Reynolds-Averaged Navier Stokes (RANS) simulations are performed on a single blade passage for a low-pressure axial fan rotor blade with a dimensional resemblance to the fans used for automotive cooling. The effect of an upstream blockage on the aerodynamic performance of the fan is investigated. A strong influence of the flow blockage on the aerodynamic performance is observed. A decrease in efficiency, an earlier onset of stall, and peak efficiency at lower volume rates is observed for increasing blockage of the fan face. Furthermore, the effect of installing two low-pressure axial fans in parallel on the aerodynamic performance of the fans is investigated. A circumferential non-uniformity in the flow which varies in space and time is observed at the fan inlet. However, this non-uniformity does not propagate down to the rotor blade and affect its performance. Consequently, no significant differences are observed in the operating condition of each of the fans in the two-fan installation in comparison to a single fan. This is considered as a positive outcome for vehicle manufacturers using similar multi-fan setups, where cooling fans are placed in parallel and in close proximity to one another.
|
|
| 3. |
- Ghosh, Debarshee, 1995, et al.
(författare)
-
Computational Fluid Dynamics Simulations of Aerodynamic Performance of Low-Pressure Axial Fans with Upstream Blockage
- 2024
-
Ingår i: SAE Technical Papers. - 0148-7191 .- 2688-3627.
-
Konferensbidrag (refereegranskat)abstract
- Rotor-only ducted low-pressure axial fans play a crucial role in automotive thermal management of the tightly packed under-hood region. Most current scientific work concerning low-pressure axial fans investigate the aerodynamic performance of these fans while operating with uniform inlet flow conditions. This is rarely the case in real-world applications. This work aims to investigate the aerodynamic performance of low-pressure axial fans operating with upstream blockages. First, a validation study is performed in the absence of any upstream blockage. Numerical results are compared against publicly available experimental data. Steady-state, Reynolds-Averaged Navier Stokes (RANS) analysis is performed on a single-blade passage. The validation study also evaluates the choice of turbulence model and suggests the use of the k- ε turbulence model with wall functions for the best comparison against experimental data. To study the effect of upstream blockage, a generic blockage disc is positioned upstream of the fan inlet. Three different radial extents of the blockage disc is evaluated, such that different radial extents of the blade span is blocked. A strong influence of the upstream blockage is observed on the fan performance and flow distribution along the blade span. The total-to-static pressure coefficient and the total-to-static efficiency decrease proportionately to the extent of blockage in the radial direction. The peak total-to-static efficiency moves to a lower flow coefficient with increase in upstream flow blockage. This is deemed undesirable for automotive applications where it is desirable to have maximum aerodynamic efficiency at the highest possible flow coefficient.
|
|
| 4. |
- Jonsson, Isak, 1990, et al.
(författare)
-
Design of Chalmers new low-pressure compressor test facility for low-speed testing of cryo-engine applications
- 2021
-
Ingår i: 14th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2021. ; 14
-
Konferensbidrag (refereegranskat)abstract
- As a part of the ongoing Horizon 2020 ENABLEH2 project, a new low-speed compressor test facility is being constructed at the Chalmers University Laboratory of Fluids and Thermal Sciences. The ENABLEH2 project investigates critical technologies for cryogenic H2 applications in commercial aviation, including new combustion and heat management systems. This paper revolves around the design and construction of a core cooling flow facility which was commissioned to study and verify the potential benefits of incorporating a heat management system into the intermediate compressor duct (ICD). The test facility is designed to operate continuously at rotor midspan chord Reynolds number up to 600,000 to allow for detailed aerothermal studies at a technical readiness level four. The two-stage axial compressor is representative of the low-pressure compressor and ICD of a mid-size commercial jet engine. The compressor is powered by a 147kW electric motor at 1920 RPM. The mass-flow and pressure ratio are controlled by restricting valves located at the inlet of the facility. A compact volute settling chamber, with an integrated thermal control system is used to control the inlet temperature and remove flow non-uniformities downstream the restrictor valves before entering the compressor. At the compressor inlet, a turbulence mesh is mounted to increase the turbulence intensity levels to 3-4% at the leading edge of the variable inlet guide vanes. The compressor is mounted vertically to allow for easy access to the downstream ICD and mitigate non-axisymmetric mechanical loads. The compressor unit allows for optical and traverse access at two +- 9-degree sectors for all the rotor-stator interfaces. Upstream the OGV, there are four independent $\pm$ 180-degree access traverse systems. In the ICD, measurements are carried out by a single ABB robot with a U-shaped probe mount, providing full volume probing access of the ICD. At the first design iteration the ICD is designed to be instrumented with multi-hole probes, hot-wire anemometry and heat transfer measurement using IR-thermography. The paper describes the facility and the process of achieving a high case similarity (engine representative) while maximising the quality of the experimental data over a large test domain, targets that often produce conflicting design demands.
|
|
| 5. |
- Martensson, H., et al.
(författare)
-
Design of a sub-scale fan for a boundary layer ingestion test with by-pass flow
- 2022
-
Ingår i: Aeronautical Journal. - : Cambridge University Press (CUP). - 0001-9240 .- 2059-6464. ; 126:1302, s. 1288-1302
-
Tidskriftsartikel (refereegranskat)abstract
- A design of a sub-scale Boundary Layer Ingestion (BLI) fan for a transonic test rig is presented. The fan is intended to be used in flow conditions with varying distortion patterns representative of a BLI application on an aircraft. The sub-scale fan design is based on a design study of a full-scale fan for a BLI demonstration project for a Fokker 100 aircraft. CFD results from the full-scale fan design and the ingested distortion pattern from CFD analyses of the whole aircraft are used as inputs for this study. The sub-scale fan is designed to have similar performance characteristics to the full-scale fan within the capabilities of the test facility. The available geometric rig envelope in the test facility necessitates a reduction in geometric scale and consideration of the operating conditions. Fan blades and vanes are re-designed for these conditions in order to mitigate the effects of the scaling. The effects of reduced size, increased relative tip clearance and thicknesses of the blades and vanes are evaluated as part of the step-by-step adaption of the design to the sub-scale conditions. Finally, the installation effects in the rig are simulated including important effects of the by-pass flow on the running characteristics and the need to control the effective fan nozzle area in order to cover the available fan operating range. The predicted operating behaviour of the fan as installed in the coming transonic test rig gives strong indication that the sub-scale fan tests will be successful.
|
|
| 6. |
- Wikström, Andreas, et al.
(författare)
-
Wind tunnel & CFD investigations of ICE3 train
- 2019
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Cruise speeds of trains have steadily increased over the years. These high cruise speeds, in the order of 300 km/h, lead to high values of drag, a significant wake region behind the train and high noise levels (90 - 100dBA). While the high drag directly affects the performance of the train, the wake region and the noise levels can have a hazardous effect on the neighbouring areas through which the rail-line passes and on the ground workers. Therefore addressing these issues is of utmost importance. This is where aerodynamics and flow visualization plays a significant role. CFD simulation provides a powerful tool to achieve these things. However, the validity of CFD models first needs to be established against experimental values. In this project such a CFD model is created. A simplified scale model of an ICE3 train is also manufactured and is used to verify the CFD model. The pressure is obtained at different points using pressure taps on the experimental model during wind tunnel testing. Then, a comparison of the normalized pressure coefficients is made between the experimental and the numerical model to verify the validity of the latter. Once the numerical model is established, it is used to analyze the influence of the ground clearance on the train. It was found that the increase in the ground clearance resulted in higher drag and lift forces experienced by the train.
|
|
