The drag induced in a aerospace vehicle due to air is tabulated and studied also the drag reduction using aerospike is studied using cfd.

1. DRAG
REDUCTION
USING
AEROSPIKE
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2. PRESENTATION OUTLINE
 AIM
 INTRODUCTION
 LITERATURE SURVEY
 CFD ANALYSIS OF AEROSPIKE
 RESULTS
 CONCLUSIONS
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3. AIM
 The main aim of this very brief study is to understand the
phenomena of aerodynamic drag reduction in aerospace vehicles
(missiles) using fixed body aero spikes.
 CFD study has been carried out using Fluent to study the flow
phenomena ahead of a missile nose-cone for supersonic
flow(M=6 & 0.75).
 Aero spike are protrusions ahead of a missile nose-cone which
replaces the strong bow shock with a system of weaker shocks
along with creating a zone of recirculation flow ahead of the fore
body thus reducing both drag and aerodynamic heating.
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4. BALLISTIC MISSILE TRAJECTORY
LOSSES:
1.GRAVITATIONAL PULL – nothing can be done
2.AERODYNAMIC DRAG – can be minimized

5. DRAG
TYPES CAUSES
SKIN FRICTION DRAG VISCOSITY OF AIR
PERSSURE DRAG and
WAVE DRAG
SHAPE OF FOREBODY
BASE DRAG EXHAUST AND WAKE
Minuteman
Main contributors to drag in missile:
Topol-M Trident
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6. NEED FOR THE USE OF BLUNT
NOSE IN SUPERSONIC MISSILES
 Considering only aerodynamics, sharp and pointed nose are
most beneficial in supersonic flight.
 But the available space in a cone or a wedge shaped nose is
limited.
 Therefore it is not practicable for the integration of avionic or
a seeker.
 The functionality of the device for seeking a target might be
increased which is often of advantage in particular for highly
agile flying objects.
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7. METHOD TO REDUCE
WAVE DRAG
 Aero-spike
 Air-spike
 Flame spike
 Pulse jet
 Laser beam
 Microwaves
 Chromium coating
 Cavitations
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8. AEROSPIKE
 A well known concept of reducing the
wave drag while keeping a blunt nose
in supersonic flight is the aero spike
concept
 The thin antenna-like structure
mounted on the nose cone is the aero-
spike.
 Slight variations of the initial design
include cones, spheres or disks that are
additionally mounted on the tip of the
rod.
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9. Different Aerospike Configurations
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10. HOW AEROSPIKE REDUCES DRAG?
 A detached bow shock stands out in front of the
aerospike and remains away from the dome.
 As the flow behind the bow shock expands around
the aerospike, a weak compression is formed at its
base.
 The wake flow caused by the aero spike and the
nearly stagnant flow near the dome creates the
conically-shaped recirculation region.
 Recirculating region is separated from the inviscid
flow within the bow shock by a flow separation
shock.
 Within the recirculating region the pressure and
temperature is reduced.
 Drag reduction of 50% is achieved.

11. Meshing in Gambit
 2-D Analysis
 Mapped Structured Mesh
 The zone specified are
 Pressure far-field
 Wall
 Pressure outlet
 Axis
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12. Problem definition in FLUENT
Define the problem as,
 Solver -Pressure based
 Formulation -Implicit
 Space -2D
 Time -Steady
 Viscous -Two-equation SST-k-omega model
 Enable the Energy equation
 The fluid type used is Air defined as ideal gas
 Operating pressure= 0 Pa

13. Inputs to Pressure Far-Field Zone
 The reference values are taken from internal database based on
average trajectory profile for long range aerospace vehicles.
 The input values are
 Static Gauge Pressure – 11111 Pa
 Mach no-0.75M
 Temperature - 216 k
 The fluid is air. The motion type is stationary.
 Wall boundary condition – no slip condition.
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14. EFFECT OF AEROSPIKE for M=6.0
Hemisphere Aerospike l/d=0.5 Aerospike l/d=1.0

15. Actual Mach No. contour at M=6
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16. Static Pressure Contours
M=0.75

17. Static Temperature Contours
M=0.75

18. Velocity (Mach No. )Contours
M=0.75

19. Results & Conclusion
 The coefficient of drag has been found for each case. From the results, it is proved that the use of
aerospike reduces the drag significantly.
 The increase in length to diameter ratio the drag reduces
Configuration Total Force
(Pressure+ Viscous)
Hemisphere 1295.8 N
Aerospike (l/d=1) 1230.7 N
Aerospike (l/d=1.5) 1206.4 N
Configuration Total Force
(Pressure+ Viscous)
Cd
Blunt Body 10192 N 0.84
Hemisphere 3526 N 0.32
Aerospike (l/d=1) 3109 N 0.2796
M=6
M=0.75
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20. Reason for Reduction in drag and
Temperature
 Flow recirculation occurs which reduces the pressure
and temperature along the length of the spike and the
nosecone.
 In addition to the aerodynamic drag reduction, heat
transfer was also reduced as the length of the spike
increases.
 Spike lengths larger than some critical length were not
effective due to the detachment of the shock structure
from the point of the spike and its reformation as a
strong normal shock just upstream of the body.

21. References
1. MEHTA, R.C. Numerical heat transfer study over spiked-blunt body at Mach 6.80, AIAA
paper 2000-0344, January 2000.
2. BODONOFF, S.N. and VAS, I.E. Preliminary investigations of spiked bodies at hypersonic
speeds, J Aerospace Sciences, 1959, 26, (2), pp
3. CRAWFORD D.H. Investigation of the flow over a spiked-nose hemisphere 65-74.
4. FUJITA, M. and KUBOTA, H. Numerical simulation of flow field over a spiked-nose,
Computational Fluid Dynamics J, 1992, 1, (2), pp 187195.
5. GUENTHER, R.A. and REDING, J.P. Fluctuating pressure environment of a drag reduction
spike, J Spacecraft and Rockets, 1977, 44, (12), pp 705-710. cylinder at a Mach number of
6.8, NASA TN D-118, December Fluid Mechanics, 1960, 8, (4), pp 584-592.
6. HUTT, G.R. and HOWE, A.J. Forward facing spike effects on bodies of different cross
section in supersonic flow, Aeronaut J, 1989, 93, (6), pp 229-234.
7. KALIMUTHU, R., MEHTA, R.C. and RATHAKRISHANN, E. Blunt body drag reduction
using aerospike and aerodisk at Mach 6, in the proceedings of International Conference on
High Speed Trans-atmospheric Air & Space Transportation, Hyderabad, India, June 2007.