Nik Ahmad Ridhwan Nik MohdUniversiti Teknologi Malaysia | UTM · Department of Aeronautics Engineering [ AERO ]
Nik Ahmad Ridhwan Nik Mohd
Dip. Eng B.Eng M.Eng Ph.D
About
39
Publications
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Introduction
Interested in CFD modelling to predict steady and unsteady aerodynamic or fluid dynamics problems and vibration associate to it. For now, I am using OpenFOAM as tool for CFD modelling.
Education
October 2007 - October 2011
January 2003 - January 2005
January 2000 - January 2003
Publications
Publications (39)
Flow field around rotors in axial flight is known to be complex especially in steep descent where the rotor is operating inside its own wake. It is often reported that, in this flight condition, the rotor is susceptible to severe wake interactions causing unsteady blade load, severe vibration, loss of performance, as well as poor control and handli...
Two-dimensional flows over harmonically oscillating symmetrical aerofoil at reduced frequency of 0.1 were investigated for a Reynolds number of 135,000, with focus on the unsteady aerodynamic forces, pressure and vortex dynamics at post-stall angles of attack. Numerical simulations using
ANSYS® FLUENT CFD solver, validated by wind tunnel experimen...
![Figure 1 : Schematic of the source-sink (Adapted from Srinivasan[8] and...](profile/Nik-Ahmad-Ridhwan-Nik-Mohd/publication/259803052/figure/fig8/AS:668693902131203@1536440458051/Schematic-of-the-source-sink-Adapted-from-Srinivasan8-and-the-vortex-tube-models_Q320.jpg)
The computation of rotor flowfields is a challenging problem in theoretical aerodynamics and essential for rotor design. In this paper we discuss the prediction of rotor hover performance, wake geometry and its strength using CFD methods. The benefits and differences between simple, momentum-based source-sink models and truncated vortex-tube far-fi...
Accurate prediction of rotor loads and wake geometry is a challenging problem in theoretical aerodynamics and essential for the design of rotors with good performance.
The capability of CFD solver to accurately capture the wake trails behind the rotor usually associated with mesh resolution used to reduce artificial dissipation raised due to numeri...
![Figure 4: Experimental setup of Caradonna and Tung rotor testing [6,8].](profile/Nik-Ahmad-Ridhwan-Nik-Mohd/publication/260250185/figure/fig3/AS:392446262431750@1470577888468/Experimental-setup-of-Caradonna-and-Tung-rotor-testing-6-8_Q320.jpg)
The computation of the helicopter rotor flow field is one of the challenging problems in theoretical aerodynamics and its accurate prediction is essential for the design of rotors with good performance. In this paper, simple, momentum- based source-sink and vortex-tube models for hovering rotor flow computations are presented. The studies were perf...
The development of a supersonic flow in the air intake is critical to the operation of a scramjet engine since it determines how well the engine performs. The configuration of the air intake plays a key role in determining whether or not the required pressure recovery of the intake is attained, which in turn affects the efficiency of the combustion...
Flow-induced vibration is a low-frequency failure phenomenon caused by the interaction between fluid flow and physical structure. This work aims to investigate the potential of flow-induced instability within a cage-type steam turbine control valve in which the throttle valve stem failed due to flow-induced vibration. In this work, a computational...
Ocean Thermal Energy Conversion (OTEC) is a system that produce energy of electricity by exploiting the temperature difference between surface part of seawater and deep region of seawater. The thermal energy at the surface seawater is used to convert working fluid into vapor which expands in the turbine to generate electricity and revert into liqui...
Organic Rankine Cycle (ORC) applications include ocean thermal energy conversion (OTEC), in which mechanical work is generated from heat energy to rotate generators and generate electricity. The OTEC system heated and cooled its refrigerant by taking advantage of the relatively small temperature difference between the warmer surface seawater and th...
Thruster performances can be optimized by adjusting the geometrical configurations and its operating conditions. Attributes such as pressure loss across catalyst bed, mass flowrate, and velocity are essential parameter to its performance. The presence of silver catalyst as porous medium affecting the flow and reaction inside the chamber due to its...
In monopropellant system, hydrogen peroxide is used with catalyst to create an exothermic reaction. Catalyst made of silver among the popular choice for this application. Since the catalyst used is in porous state, the effect of its porosity in the hydrogen peroxide monopropellant thruster performances is yet unknown. The porosity changes depending...
Scramjet intakes function as a no-moving-parts compressor, compressing air either externally, internally, or mixed with the use of shock waves. The cowl shape is critical in this procedure because it directs the maximum flow rate of air into the engine's isolator and then into the combustion chamber. Sharp cowl was determined to be the optimal desi...
The vortex-induced vibration of an isolated circular cylinder has a wide range of engineering applications and for decades has been a subject of interest among researchers. Excessive vibration caused by vortex flows can decrease the life span of the structure elements if the excitation frequency generated by the aerodynamic effect is closed or coin...
In this research work, a new design concept for shrouded turbines is introduced using a circular flange ring instead of a diffuser. The performance of a wind turbine shrouded with the conventional configuration of flanged diffusers is firstly investigated. This allows comparison to be made with the performance of the new design proposed in this pro...
This paper reports on flow visualisation and surface pressure measurements over the upper surface of a blunt-edged delta wing model at high angles of attack. The flow structure above the upper surface of the blunt-edged delta wing was found to be different compared to delta wing with sharp leading edge. The flow becomes more complicated especially...
From the world's tiny flying bugs to gigantic dobsonflies, inflight locomotion of a flying creature requires complex biomechanical strategies to cope with air turbulence. These unpredictable changes in ambient airflow strength and direction may destabilize body posture and orientation. To record this behaviour in further detail, we scientifically e...
Induction system or also known as the breathing system is a sub-component of the internal combustion system that supplies clean air for the combustion process. A good design of the induction system would be able to supply the air with adequate pressure, temperature and density for the combustion process to optimizing the engine performance. The ind...
The critical area on the main rotor blade when a helicopter is in forward flight conditions was assessed in this research using Blade Element Theory program. Two cases have been analyzed in this studied which are the effects of increasing forward speed and blade collective pitch angle. The Blade Element Theory was used throughout in the research. T...
From the world's tiny flying bugs to gigantic dobsonflies, inflight locomotion of a flying creature requires complex biomechanical strategies to cope with air turbulence. These unpredictable changes in ambient airflow strength and direction may destabilize body posture and orientation. To record this behaviour in further detail, we scientifically e...
Delta wing is a triangular-shaped platform that can be applied into the unmanned aerial vehicle (UAV) or drone applications. However, the flow above the delta wing is governed by complex leading-edge vortex structures which result in complicated aerodynamics behaviour. At higher angles of attack, the vortex burst can take place when the swirling fl...
This paper is focusing on analysis of angle of attack and lift distribution along the helicopter blade in forward flight conditions and the effects of increasing helicopter's speed. The Blade Element Theory (BET) is used throughout this study. The result was in good agreement with the existing data. From the analysis, the angle of attack and lift a...
Diffusing S-shaped ducts are critical components in modern vehicle, primarily employed in directing the airflow to the engine. It links the air box and the engine in a very restricted place. The air flow through an S-duct is complex in nature, which perhaps includes boundary layer separation, secondary flow, and total pressure loss effects that inf...
This paper presents the aerodynamic loads' prediction of a generic helicopter fuselage in forward flight using computational fluid dynamics. The multipurpose ANSYS Fluent CFD solver that is based on the cell-centered finite volume method for solving Reynolds-averaged Navier-Stokes equations has been used and calculated for Reynolds numbers of 4.46...
This paper summarizes a study of the aerodynamic characteristics of a curved fin rocket. The study was conducted with the use of semi-empirical method and numerical simulation. The semi-empirical method was implemented with USAF DATCOM as a reference. The ANSYS Fluent was used for the numerical simulation. The curved fin rocket configuration includ...
This paper summarizes a study of the aerodynamic characteristics of a curved fin rocket. The study was conducted with the use of semi-empirical method and numerical simulation. The semi-empirical method was implemented with USAF DATCOM as a reference. The ANSYS Fluent was used for the numerical simulation. The curved fin rocket configuration includ...
In this study, the helicopter blade in forward-flight condition was investigated. The blade element theory (BET) was used throughout this analysis to investigate the angle of attack variations at the blade cross sections, lift distribution along the blade and effects of increasing helicopter speed. Prouty's helicopter data was used to validate the...
The need for high performance and green aircraft has brought the blended wing (BWB) aircraft concept to the centre of interest for many researchers. BWB is a type of aircraft characterized by a complex blending geometry between fuselage and wing. Recently, many researches had been performed to unlock its aerodynamic complexity that is still not wel...
In the early design phase of automotive sector, the flow field around the vehicle is important in decision making on design changes. It would consume a lot of money and time for multiple prototypes development if adopt traditional testing method which is wind tunnel test. Thus, numerical method such as Computational Fluid Dynamics (CFD) simulation...
In the early design phase of automotive sector, the flow field around the vehicle is important in decision making on design changes. It would consume a lot of money and time for multiple prototypes development if adopt traditional testing method which is wind tunnel test. Thus, CFD simulation plays an important role here. In this paper, a CFD simul...
In this study, two 5-seater helicopters that are in the same FAR 27 category were chosen for the forward flight speed comparison. In order to improve the helicopter cruising speed, the main rotor blade of a helicopter that posses a lesser flight speed was modified through the usage of different number of main rotor blade (from 3 to 4 blades), diffe...
Aerodynamic characteristics of a 5-seater helicopter with different rotor configuration (i.e.; blade number and size) operating in forward flight mode were simulated by using commercial computational fluid dynamic (CFD) software called FLUENT. The main objective of this simulation is to calculate the aerodynamic load generated by rotor during hover...
The purpose of this paper is to study the feasibility on improving a 5-seaterr helicopter forward flight speed via applying the different combination between rotor and engine. The emphasis of this study is given to the increment in the main rotor number of blade from 3 to 4 blades and blade sizing at which to meet the better forward flight speed th...
Aerodynamic characteristics of a 5-seater helicopter with different rotor configuration (i.e.; blade number and size) operating in forward flight mode were simulated by using commercial computational fluid dynamic (CFD) software called FLUENT. The main objective of this simulation is to calculate the aerodynamic load generated by rotor during hover...
Questions
Question (1)
I am interested in exploring the aerodynamics of tip vortex. However, I do not really know what really create tip vortex. Is it pressure difference? is it the model geometry ? is it boundary layer? or what. Let say I have a flat plate with one end attach to the wall, at zero angle of attack. Will we see the tip vortex? So, anyone in this topic could help me on understanding this matter.
