Firdaus Mohamad

Static stability of Baseline-II blended wing- body aircraft at low subsonic speed: Investigation via computational fluid dynamics simulation

A study of the effect of canard to Baseline-II blended wing-body aircraft is presented here with emphasis on investigating contributions of canards various setting angle to aerodynamic parameters and longitudinal static stability. A computational fluid dynamic (CFD) simulation has been conducted at low subsonic speed to collect aerodynamic data and found that its aerodynamic trend is similar to many BWB aircraft and consistent to previous studies conducted in UiTM. Canard setting angle affects the value of lift-at-zero incidence of a BWB aircraft, although fairly small for current canard size that it is not adequate to produce positive pitching moment-at-zero lift. Baseline-II is partially, statically stable in longitudinal motion because of negative moment change w.r.t. lift change but it has equilibrium incidence angle that only produces negative lift. Larger canard and/or modification to Baseline-II wing-body are needed to overcome this flaw. The location of new reference point provides ‘comfortable’ static margin. Data and mathematical characteristic obtained from BL-IIA SP CFD simulation is comparable to those from wind tunnel experiment and both show satisfactory-to-good correlation to theoretical calculations.

A study about the split drag flaps deflections to directional motion of UiTM's blended wing body aircraft based on computational fluid dynamics simulation

This paper discusses on the split drag flaps to the yawing motion of BWB aircraft. This study used split drag flaps instead of vertical tail and rudder with the intention to generate yawing moment. These features are installed near the tips of the wing. Yawing moment is generated by the combination of side and drag forces which are produced upon the split drag flaps deflection. This study is carried out using Computational Fluid Dynamics (CFD) approach and applied to low subsonic speed (0.1 Mach number) with various sideslip angles (β) and total flaps deflections (δT). For this research, the split drag flaps deflections are varied up to ±30°. Data in terms of dimensionless coefficient such as drag coefficient (CD), side coefficient (CS) and yawing moment coefficient (Cn) were used to observe the effect of the split drag flaps. From the simulation results, these split drag flaps are proven to be effective from ±15° deflections or 30° total deflections.

Yaw Stability Analysis for UiTM's BWB Baseline-II UAV E-4

This paper presents a study about yaw stability analysis for UiTMs Blended-Wing-Body (BWB) Baseline-II E-4. This aircraft is equipped with split drag flaps in order to perform directional motion. One of the split drag flaps will be deflected to generate yawing moment. This yawing moment is generated through the drag that is produced upon deflection of flaps. The study was carried out using Computational Fluid Dynamics (CFD) for various sideslip angles (β) and various flaps deflection angle (δT). The simulation was conducted at 0.1 Mach number (35 m/s) and results in terms of coefficient such yawing and rolling moment are tabulated in order to determine the stability of the aircraft. The result reveals that the aircraft is directionally unstable. This is as expected because the aircraft does not have any vertical tail configuration to provide the yawing moment. However, high deflection of split flaps can still generate adequate restoring moment for the aircraft.

The aerodynamics performance of Blended Wing Body Baseline-II E2

This paper discusses the aerodynamics characteristics of Blended Wing Body — Baseline II E2, unmanned aerial vehicle aircraft. A computational method, Computational Fluid Dynamic (CFD) Star CCM+ software has been performed to obtain the aerodynamics characteristic of the BWB. The aerodynamic characteristics prediction of BWB-Baseline II E2 aircraft was obtained through CFD analysis using unstructured mesh and standard one — equation turbulence model, Spalart-Allmaras was selected in the investigations. Lift coefficient (CL), drag coefficient (CD) and moment coefficient (CM) were studied at flight condition of Mach 0.1 (∼34 m/s) at different angles of attack, α. The CFD results were compared with the experimental result. The results show the trend of lift curves are similar at the linear region (α = −10° to 7°) but at the higher angle of attack the trends become nonlinear. The drag coefficient for CFD simulations is greater than experimental result and there are differences in pitching moment curves between CFD simulation and experiment data which the experiment data shows a steep curve than simulation.

Aerodynamics characteristic of UiTM's BWB UAV Baseline-II at different canard deflection angles at low pitching angle

This paper discusses the influence of canard deflection angle on the aerodynamics characteristic of a Blended Wing Body (BWB) Baseline-II aircraft obtained from wind tunnel test. Canard is added as longitudinal control. All tests are carried out in UiTM Low Speed Wind Tunnel using 1/6 scaled model at around 0.1 Mach number at several canard angle. The result of the lift coefficient (CL), the drag coefficient (CD), and the pitching moment coefficient (CM), are plotted and analyze to show the characteristics of the BWB with different canard deflection angles.

Wind Tunnel experiments of UiTM's blended wing body (BWB) Baseline-II unmanned aerial vehicle (UAV) at low subsonic speed

An experimental investigation is conducted to obtain aerodynamic characteristics and performance of a blended wing-body aircraft (BWB) under study by UiTM. The BWB design for unmanned aerial vehicle (UAV) known as “Baseline-II” is actually a completely-revised, redesigned version of “Baseline-I” BWB. The Baseline-II features have introduced a canard, a simpler planform, and slimmer body compared to its predecessor while maintaining wingspan. All tests are carried out in UiTM Low Speed Wind Tunnel using 1/6 scaled model of BWB at around 0.1 Mach number. The lift coefficient (CL), the drag coefficient (CD), the pitching moment coefficient (CM), and the Lift-to-Drag (L/D) ratio curves are then plotted at various angles of attack, including CL versus CD polar to show the performance of the BWB. The results obtained will show the aerodynamic

Development of 1:1 and 2:1 Channel Ratio Bipolar Plates (BPPs) for PEMFC

Proton Exchange Membrane Fuel Cell (PEMFC) is a device that generates electricity through an electrochemical reaction of oxygen air and hydrogen fuel. Thetransportofoxidantand fuel through the bipolarplatesis a significant factor affecting the cell performance. Currently, present work concentrates highly on flow field layout and channels design configurations. In this paper, the development two flow field layouts are discussed with different inlet/outlet channel ratio. Serpentine-paralleldesignisusedasthe base layout. The flow fields have inlet/outlet channel ratio of 1:1 and multiple inlet 2:1 configurations. Graphite is used as theplate material.Theanodeflowchannelis 2 mmx 1.2 mmx 2 mm meanwhile the cathode channel is 2 mm x 0.5 mm x 2 mm fora xbxwrespectively.Theactiveareais 25 cm2 with 5 cmx 5 cm dimensions. The fields were fabricated by Roland EGX-360 Desktop Engraver machine that involved drilling and profiling process. The fuel cell assembly process is explained in detail. The gasketmaterialis made from two materials which are Polyimide and Silicon. A series of pre-conditioning experiments were carried out in both fuel cells for confident purposes.

Operating Condition Optimization of PEMFC via Visualization Technique

Fuel cell water management has two conflicting requirements; too less water causing membrane dehydration and too much water causing liquid water flooding. Both phenomena resulting in significantly instability voltage performance because of imbalance water presence. Therefore, it is vital to analyze and understand the root cause of the problem hence a 96cm2 transparent fuel cell was analyzed experimentally. The fuel cell allows clear visualization of flow channels, thus making it practical to analyze the transportation of reactants and products behavior. The experimental analyses were conducted under different reactant flow rate and inlet humidification variations. Highest cell performance was obtained under both reactant inlets humidification with largest air flow rates. On the other hand, when fuel and air in dry conditions, relatively lower cell voltage was obtained. Meanwhile, stable voltage was obtained under anode humidified and cathode non-humidified conditions with correct air to fuel ratio. Images of liquid water and voltage behavior are presented graphically corresponding to the changes in performance.

Performance Analysis of Ground-Based Static Test for Hydrogen Fuelcell Propulsion System

Combustion engines are increasingly being regarded as unsustainable in the long-term, because of their negative impact on the environment (e.g. pollution, green-house gas production, and global warming). This has generated worldwide interest in propulsion systems based on renewable alternative energy sources for the future. Fuel cell technology is a promising alternative power source because of their high specific energy, efficiency, and reliability. Hydrogen proton exchange membrane fuel cell (PEMFC) in particular produces zero carbon emissions by having only water vapor as the exhaust. Although there has been much research by automotive industries in developing fuel cell hybrid electric vehicles (FCHEV), fuel cell research for aircraft application is relatively new. Therefore, there is a pressing need for research related to development of aircraft fuel cell electric propulsion systems. Universiti Teknologi MARA (UiTM) is conducting static experiments on different configurations of fuel cell electric propulsion systems. The objective of this study is to understand the behavior of a PEMFC propulsion system under a ground-based static test. A 1 kW PEMFC was used as the main power source for a brushless DC motor electric propulsion system. The electrical characteristics, rotational speed, and thrust data were presented for two different electrical propellers. Analyses of the results were used to characterize the effectiveness of the fuel cell system and its balance of plant. The results were beneficial as a predictive method on defining the optimum electric propulsion system performance needed for future actual flight development.

The Effects of Split Drag Flaps on Directional Motion of UiTM’s BWB UAV Baseline-II E-4: Investigation Based on CFD Approach

This paper presents a study about split drag flaps as control surfaces to generate yawing motion of a blended wing body aircraft. These flaps are attached on UiTM’s Blended Wing Body (BWB) Unmanned Aerial Vehicle (UAV) Baseline-II E-4. Deflection of split drag flaps on one side of the wing will produce asymmetric drag force and, as consequences, yawing moment will be produced. The yawing moment produced will rotate the nose of the BWB toward the wing with deflected split drag flaps. The study has been carried out using Computational Fluid Dynamics to obtain aerodynamics data with respect to various sideslip angles (ß). The simulation is running at 0.1 Mach number or about 35 m/s. Results in terms of dimensionless coefficient such as drag coefficient (CD), side force coefficient (CS) and yawing moment coefficient (Cn) are used to observe the effects of split drag Subscript text flaps on the yawing moment. All the results obtained shows linear trends for all curves with respect to sideslip angles (ß).