CFD Analysis Of Delta Wing Body Configurations At Lower Angle Of Attack
Satish Hiremath1*, Anand M Raikar2
1 Assistent Professor, Department of Aeronautical Engineering, ACSCE Bangalore, India.
2 Student, Department Of Aerospace VTU, CPGS Muddenahalli, Chikkaballapur, India.
*Corresponding Author
Satish Hiremath,
Assistent Professor, Department of Aeronautical Engineering, ACSCE Bangalore, India.
Email: satishaerospace@yahoo.com
Received: June 14, 2021; Accepted: August 09, 2021; Published: September 28, 2021
Citation:Satish Hiremath, Anand M Raikar. CFD Analysis Of Delta Wing Body Configurations At Lower Angle Of Attack. Int J Aeronautics Aerospace Res. 2021;08(02):258-261. doi: dx.doi.org/10.19070/2470-4415-2100033
Copyright: Satish Hiremath© 2020. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.
Abstract
The delta wing is a wing plan form in the form of a triangle. It is named for its similarity in shape to the Greek letter delta
(Δ). The first practical uses of delta wing came in the form of so-called "tailless delta", i.e. without the horizontal tail plane.
As the angle of attack increases, the leading edge of the wing generates a vortex which energizes the flow, giving the delta
a very high stall angle.Pure delta-wings fell out of favour somewhat due to their undesirable characteristics, notably flow
separation at high angles of attack, high drag at low altitudes, low wing loading and poor maneuverability. The design of
modern light weight fighter that can cruise supersonically, maneuver transonically and has a post stall capability requires additional
highly swept area ahead of the main wing called strake or leading edge extension (LEX) which lead to some of the
variations in delta wing such as tailed delta, cropped delta, double delta, cranked arrow and ogival delta.
The present project work investigates the flow field over a typical cropped delta and double deltawing body configuration
at low angles of attack (α) from 0 to 15 degrees with an increment of step 3. Delta wing with sweep angle of 60 degrees
and double delta wing with a sweep of 55/60 degrees having a beveled leading edge are modeled and simulated at Mach
number 0.4 and at a Reynolds number (Re) of 2.7x104]. The flow simulations are carried out by the unstructured hybrid
meshes comprising of tetrahedral and prism elements created by ICEMCFD. The meshes are refined adequately to resolve
the boundary layer flow. The flow simulations are carried out by ANSYS FLUENT. The aerodynamic characteristics of
both the wing body configurations are compared to find which is to be more effective. The computed data obtained is also
compared with the available experimental data.
2.Introduction
3.Literature Review
4.Dimensional analysis and Similitude
5.Design procedure of gating and runners
6.Experimental Procedures
7. Conclusion
8. References
Keywords
C: Wing Chord; S: Wing Reference; b: Wing Span; λ: Taper Ratio; - A: Aspect Ratio.
Introduction
The delta wing body configuration consists of a delta wing along
with the fuselage so called as body.Pure delta-wingsfell out of
favour somewhat due to their undesirablecharacteristics, notably
flow separation at high angles of attack and high drag at low altitudes[
1]. In order to overcome these undesirable characteristics
there were some variations in delta wing design and geometry.
They are
• Tailed delta:adds a conventional tailplane (with horizontal tail
surfaces), to improve handling (MiG-21).
• Cropped delta: tip is cut off. This helps avoid tip drag at high
angles of attack (F-16).
• Compound delta, double delta or cranked arrow: the inner part
of the wing has a very high sweepback, while the outer part has
less sweepback, to create the high-lift vortex in a more controlled
fashion, reduce the drag and thereby allow for landing the delta at
acceptably slow speed[4]. (Saab Draken fighter and High Speed
Civil Transport).
• Ogee delta (ogival delta): with a smooth 'ogee' curve joining the
two parts rather than an angle.
Scope
The present project is based on the computational analysis of
flow over delta wing body configurations (cropped delta and double
delta) at lower angle of attack ofa typical fighter aircraft.
Design and analysis of wing body configuration is important for overall aerodynamic performance of an aircraft [3]. We have
undertaken this study of flow characteristics over a wing body
configuration through CFD simulation and the objectives in this
analysis are as follows:
• Study the aerodynamic parameters such as lift coefficient and
drag coefficient i.e,( CL and CD).
• Calculate the L/D ratio for both the wing body configurations.
• Compare the two wing body configurations to find which is to
be more effective.
The analysis of steady flow is done for a semi half span of wing
body configuration at sea level and at Reynolds number of 2x105.
The analysis is done for five low angles of attack i.e , from 3 to
15 degrees with a step increment of three at a subsonic mach
number of 0.5 . Also the scope of this project is to get hands on
experience in using the following software tools:
• Modeling of the geometry using CATIA V5R20.
• Meshing of the geometry using ANSYS ICEM CFD.
• Analysis of the flow using ANSYS FLUENT.
The solution obtained for both the wing body configurations are
compared to find which is to be more effective. Also the obtained
results are compared with the available experimental data.
Problem Formulation
As we have studied earlier and also seen in the literature that double
delta wing body configuration not only increases the lifting
area of the wing, but also creates its own leading edge vortices
which help to stabilize the flow field over main wing[2]. Therefore
double delta wing body configuration produces more lift and is
more stable than a cropped delta wing.
In this present work we have made an effort to study the flow
characteristics over the double delta having sweep of [2] 55/60
degrees2 where there is less difference between the sweep and the
strake angle and the cropped delta wing having a sweep angle of
60 degrees with a beveled leading edge are modeled and simulated
at Mach number 0.4 and at a Reynolds number (Re) of 2x105. A
detailed study has been done at one subsonic Mach number 0.4
for 6 angles of attack from 0 to 15 for both the wing body configurations.
The results obtained are compared with each other to
find which is to be more effective from the design point of view.
Boundary Conditions
There are a number of common boundary types.
INLET
Inflow: Transported variables specified on the boundary, either
by a predefined profile by doing an initial 1-d, fully-developedflow
calculation.
Stagnation (or reservoir): Total pressure and total temperature
(in compressible flow) or total head (in incompressible flow)
fixed. usually inflow condition for compressible flow.
OUTLET
Outflow: Zero normal gradient for all variables.
Pressure: As for outflow, except fixed value of pressure; usual
outlet condition in compressible flow if the exit is subsonic.
Radiation (or convection): Prevent wave-like motions from reflecting
at outflow boundaries by solving a simplified first-order
wave equation with outward-directed wave velocity.
WALL:
Non-slip wall: The default case for solid boundaries (zero velocity
relative to wall stress computed by viscous-stress or wallfunction
expressions).
Slip wall: Only the velocity component normal to the wall vanishes.
Used if it is not necessary to resolve a thin boundary layer
on an unimportant wall boundary.
Geometric Modelling
The modelling of geometry of both the wing body configurations
is done using CATIA V5 R20 as follows:
CASE 1: CROPPED DELTA WING
• Planform : cropped delta
• Aspect ratio : 4
• Leading edge sweep : 60 deg
• Trailing edge sweep : 0 deg
• Taper ratio : 0.18
• Twist : 0 deg
• Root chord : 153
• Semi span of model : 75.256
( All dimensions are in mm)
CASE 2: DOUBLE DELTA WING BODY
• Planform : double delta
• Aspect ratio : 3.8
• Leading edge sweep : 60 deg
• Strake angle : 55 deg
• Trailing edge sweep : 0 deg
• Taper ratio : 0.203
• Twist : 0 deg
• Root chord : 39
• Semi span of model : 75.26
( All dimensions are in mm)
Mesh Generation
The model made in CATIA is imported to ANSYS ICEM CFD
in “.stl” format. A tetrahedral mesh is generated in the following
sequence.
• A hemispherical domain is created using ‘Sphere’ option and its
cap is created using ‘Simple surface’.
• The domain is segmented into regions and are named appropriately
as INLET, OUTLET and WALL.
• The model is segmented into body, wing upper, wing lower, side
lower and faces using ‘Segment surface’ in order to obtain a clean and quality mesh.
• The curves are extracted from the surface and extra curves are
deleted.
• Under the part mesh setup the element size is set to 30 which
yields 15,00,000 elements and the type of element is chosen to
result in a tetrahedral mesh.
• Thus the tetrahedral mesh is generated as shown below.
Results And Discussion
Cropped Delta Wing Body
Case 2: Double Delta Wing Body
From the graph of lift curve we can conclude that double delta
wing body is more efficient in producing lift than a cropped one
since the lift curve slope of double delta wing body is greater than
a cropped delta wing body.
Lift to drag ratio of Cropped Delta wing body is
Lift to drag ratio of Double Delta wing body is
As well as lift to drag ratio of double delta is 9.3 which is more
than a cropped delta which has lift to drag ratio of 6.6
Therefore double delta wing body configuration is more effective than a cropped delta wing.
Figure 1. Double delta wing body ( lower surface).
Figure 2. Cropped delta wing body ( upper surface).
Figure 3. Cropped delta wing body ( lower surface).
Figure 4. Segmented model with domain without cap.
Figure 5. Segmented domain with cap.
Figure 6. Meshed model of double delta wing body with domain.
Figure 7. Meshed model of double delta wing body with domain.
Figure 8.
Figure 9.
Figure 10. Comparison of lift curve of both the wing body configurations.
Figure 11. Comparison of drag curve for both the wing body configurations.
Figure 12. Comparison of drag polar for both the wing body configurations.
References
- Saha S, Majumdar B. Modeling and simulation on double delta wing. International Journal of Advanced Computer Research. 2013 Mar 1;3(1):201.
- Christopher J, Petter K. MODELING OF UNSTEADY AERODYNAMIC CHARACTERISTCS OF DELTA WINGS. ICAS 2002.
- Russell H, Williams RG. Cross Flow Over Double Delta Wings. CSA ENGINEERING INC PALO ALTO CA; 1994 Feb 1.
- Pirzadeh SZ. Vortical flow prediction using an adaptive unstructured grid method. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER; 2003 Mar 1.
