Pulsating flow studies in a planar wide-angled diffuser upstream of automotive catalyst monoliths

Automotive catalytic converters are used extensively in the automotive industry to reduce toxic pollutants from vehicle exhausts. The flow across automotive exhaust catalysts is distributed by a sudden expansion and has a significant effect on their conversion efficiency. The exhaust gas is pulsating and flow distribution is a function of engine operating condition, namely speed (frequency), load (flow rate) and pressure loss across the monolith. The aims of this study are to provide insight into the development of the pulsating flow field within the diffuser under isothermal conditions and to assess the steady-state computational fluid dynamics (CFD) predictions of flow maldistribution at high Reynolds numbers. Flow measurements were made across an automotive catalyst monolith situated downstream of a planar wide-angled diffuser in the presence of pulsating flow. Cycle-resolved Particle Image Velocimetry (PIV) measurements were made in the diffuser and hot wire anemometry (HWA) downstream of the monoliths. The ratio of pulse period to residence time within the diffuser (J factor) characterises the flow distribution. During acceleration the flow remained attached to the diffuser walls for some distance before separating near the diffuser inlet later in the cycle. Two cases with J ~ 3.5 resulted in very similar flow fields with the flow able to reattach downstream of the separation bubbles. With J = 6.8 separation occurred earlier with the flow field resembling, at the time of deceleration, the steady flow field. Increasing J from 3.5 to 6.8 resulted in greater flow maldistribution within the monoliths; steady flow producing the highest maldistribution in all cases for the same Re. The oblique entry pressure loss of monoliths were measured using a one-dimensional steady flow rig over a range of approach Reynolds number (200 < Rea < 4090) and angles of incidence (0o < α < 70o). Losses increased with α and Re at low mass flow rates but were independent of Re at high flow rates being 20% higher than the transverse dynamic pressure. The flow distribution across axisymmetric ceramic 400 cpsi and perforated 600 cpsi monoliths were modelled using CFD and the porous medium approach. This requires knowledge of the axial and transverse monolith resistances; the latter being only applicable to the radially open structure. The axial resistances were measured by presenting uniform flow to the front face of the monolith. The transverse resistances were deduced by best matching CFD predictions to measurements of the radial flow profiles obtained downstream of the monolith when presented with non-uniform flow at its front face. CFD predictions of the flow maldistibution were performed by adding the oblique entry pressure loss to the axial resistance to simulate the monolith losses. The critical angle approach was used to improve the predictions, i.e. the oblique entry loss was limited such that the losses were assumed constant above a fixed critical angle, αc. The result showed that the perforated 600 cpsi monolith requires the entrance effect to be restricted above αc = 81o, while the losses were assumed constant above αc = 85o for the ceramic 400 cpsi monolith. This might be due to the separation bubble at the monolith entrance being restricted by the smaller hydraulic diameter of the perforated monolith thus limiting the oblique entry loss at the lower incidence angle

Design and Development of Light Weight Engine Mounting for UTeM Formula Varsity Race Car

This manuscript provides the design of the engine mounting for Formula Varsity Race Car. Several concept designs were generated for the engine mounting and the final design was selected through in 3D modeling software namely CATIA V5 CAD software during the design phase in this project. The aluminum Alloy 6061 T6 was selected as the lightweight engine mounting material due to high strength, light weight and versatility with many manufacturing processes. The light weight engine mounting was analyzed using finite element analysis in bending and yield strength cases. The result of the engine mounting analysis showed that the engine mounting is able to perform safely as per design requirement

Design Optimization of Thermal Management System for Electric Vehicle Utilizing CFD Analysis, DFMEA and CES

Thermal management design for electric vehicles (EV) is very important in order to manage the thermal dissipated by operating components. This research aims at performing design optimization of a thermal management system for battery modules, controller and electric motor in EV. A combination of passive and active cooling systems is proposed where air cooled is used in battery modules, water cooling for controller and water jacket for electric motor. Design Failure Mode and Effect Analysis (DFMEA) method is deployed to identify the potential failure modes and causes so that improvements can be made for battery modules, controller and electric motor. The design for all of the components and the thermal management system were done with CATIA V5. The material selections process for the designs was based on the analysis using Cambridge Engineering Selector (CES EduPack). Final design was utilizing water cooled for electric motor and controller while using air cooled for battery modules. It was found that best material for electric motor and controller water jacket is with aluminum alloy 6060 while air cooled ducting using High Density Poly Ethylene (HDPE) and battery housing using Polycyclohexylenedimethylene Terephthalate (PCT). The thermal management system for battery modules is simulated using ANSYS CFD software. Results from simulation were validated with manual calculation and have shown good agreement based on the data collected at various vehicle speeds

Self Tuning PID Control Of Antilock Braking System Using Electronic Wedge Brake

This paper describes the design of an antilock braking system (ABS) control for a passenger vehicle that employs an electronic wedge brake (EWB). The system is based on a two-degree-of-freedom (2-DOF) vehicle dynamic traction model, with the EWB acting as the brake actuator. The developed control structure, known as the Self-Tuning PID controller, is made up of a proportional-integral-derivative (PID) controller that serves as the main feedback loop control and a fuzzy supervisory system that serves as a tuner for the PID controller gains. This control structure is generated through two structures, namely FPID and SFPID, where the difference between these two structures is based on the fuzzy input used. An ABS-based PI D controller and a fuzzy fractional PID controller developed in previous works were used as the benchmark, as well as the testing method, to evaluate the effectiveness of the controller structure. According to the results of the tests, the performance of the SFPID controller is better than that of other PID and FPID controllers, being 10% and 1% faster in terms of stopping time, 8% and 1% shorter in terms of stopping distance, 9% and 1% faster in terms of settling time, and 40% and 5% more efficient in reaching the target slip, respectively

Vibration Control of a Passenger Car Engine Compartment Model using Passive Mounts Systems

Engine mounting is one of the devices that provide vibration isolation for unwanted vibration from engine to the driver. There are 3 types of engine mounting system which are passive, semi-active and active engine system. This study emphasizes on the validation of mathematical equation derived from Newton Second Law of Motion with real time experiment. The study of the characteristic of mounts using simulation the 3-Degree Of Freedom (DOF) mathematical modeling in Matlab Simulink software. Then, the mathematical model is verified by using experimental approach. By comparing the results from the experimental and simulation it shows that the model enables to give same response as in the experimental result

Thermal performance of carbon-based microencapsulated phase change materials

The aim of this study is to investigate the effect of carbon-based materials for the thermal performance of microencapsulated phase change material (µPCM). The sample was prepared separately by mixing 5 wt.% of Multiwall Carbon Nanotube (MWCNT) and 5 wt.% Expanded Graphite (EG) with µPCM using a powder metallurgy technique. The mixed powder was then compacted into a disc with a diameter of 45 mm and thickness of 5 mm using a hot compaction technique. The thermal performance was tested according to the ASTM standard. It was found that the addition of MWCNT into µPCM can absorb heat effectively as compared to pure µPCM and µPCM/EG composite

The Assessment Of The Effect Of Surface Roughness On Drag Coefficient And Aerodynamics Features Of Loggerhead Sea Turtle Carapace

The present investigation primarily studies the effect of surface roughness on the drag coefficient, Cd of a Loggerhead sea turtle carapace using a subsonic wind tunnel. The pressure coefficient, Cp distribution across the Loggerhead carapace was also investigated and is compared to the Cp trend of an airfoil in order to deduce the aerodynamics features of the Loggerhead carapace. One-to-five-scaled models are created based on the dimensions of a real Loggerhead turtle with simplification. Four roughness scales were employed to capture the Cd trend at increasing Reynolds numbers, Re. As expected, the Cd levelled off with Re for all four models investigated. However, the Re where constant Cd began varies with relative roughness of the carapace models. The results also show good correlation between the Cd and relative roughness. In addition, the wind tunnel results are able to capture the Cp trend of the carapace models and compared to Cp values of an airfoil. Results reveal that the upper surface of the Loggerhead carapace is streamlined but with restrictions of angle of attack

Magnetorheological Fluid Engine Mounts: A Review on Structure Design of Semi Active Engine Mounting

The demand for low cost, quiet operation, and increased operator comfort in automobiles and other applications requires new techniques to be developed for noise and vibration isolation. One approach to reduce noise vibration and harshness (NVH) is to develop a small low cost vibration isolator that can be used to mount components that generate vibration. Passive, semi-active and active control methods as well as different types of smart materials were studied to develop this isolator. Based on this study, the most promising approach seems to be a semi-active magnetorheological isolator. In this paper, an overview of recent advances in semi active engine mounts are presented, in term of working operation of Magnetorheological (MR) Fluid namely flow mode, shear mode, squeeze mode and mix mode. The issues are discussed with regard to the design and performance as vibration isolator device. The finding of this paper proposed the new semi active engine mounts design

Performance Analysis Of Biodiesel Engine By Addition Of Hho Gas As A Secondary Fuel

Biodiesel, an alternative fuel similar to fossil-based diesel, has the advantages of carbon-neutral, high flash point and emit no carbon dioxide (CO2). HHO gas has been introduced to the automotive industry as a new energy source, a fuel supplement in an internal combustion engine (IC). This paper presents the performance and emissions of diesel engines powered by biodiesel with HHO gas as a fuel supplement. The biodiesel used is a mixture of biodiesel B20 and B30. The effect of adding HHO gas on biodiesel fuel is evaluated on engine performance and emissions before and after using HHO gas as a secondary fuel. The results show an increase in engine performance on the B20 is 14% and on the B30 is 14.63%. The observation on smoke produce of the tailpipe exhaust also drastically improved. Based on the results above, that the addition of HHO gas supplements to biodiesel fuel has a positive effect on improving engine performance and reducing emissions that are very significant so that it can improve environmental aspects when compared to the use of biodiesel without HHO ga

Engine performance testing using variable RON95 fuel brands available in Malaysia

There are various gasoline fuel producers available in Malaysia. The effects of fuel variations from different manufacturers on vehicle performance have always been a debate among users and currently the facts still remains inconclusive. Hence, this study focuses on analyzing various RON95 fuel brands available in the Malaysian market and finding the differences towards engine performance. In terms of engine output, the important data of power (hp) and torque (Nm) will be gathered by using an engine dynamometer. Another data that would also be taken into account is the knocking where the relative knock index can be measured in percentage using the knock sensor accelerometer. Results have shown that the performance of different fuel brands tested are indeed different albeit by only a small margin even though all fuels are categorized with the same octane rating. The power and torque results also imply that both are influenced by the amount of vibration generated due to engine knocking. Based from the overall outcome, consumers would not need to only focus on a certain type of gasoline brand as all differentiates the engine performance marginally