Title of Invention	NOVEL TECHNIQUE FOR HYPERSONIC DRAG CONTROL USING HEAT ADDITION IN THE SHOCK LAYER
Abstract	It is an object of this invention to develop a novel passive flow control technique for bodies in hypersonic flight wherein the shock layer around the bodies in flight at hypersonic Mach numbers is modified in-flight, by controlling the amount of heat energy released into the shock layer of the body, consequently controlling the aerodynamic drag. In the present invention the aerodynamic drag of the bodies in flight are controlled using non-intrusive passive devices that require no additional power. Further, suitable material coatings are developed for bodies in flight at hypersonic Mach numbers for controlled heat release into the shock layer during flight.

Title of Invention

NOVEL TECHNIQUE FOR HYPERSONIC DRAG CONTROL USING HEAT ADDITION IN THE SHOCK LAYER

Abstract

It is an object of this invention to develop a novel passive flow control technique for bodies in hypersonic flight wherein the shock layer around the bodies in flight at hypersonic Mach numbers is modified in-flight, by controlling the amount of heat energy released into the shock layer of the body, consequently controlling the aerodynamic drag. In the present invention the aerodynamic drag of the bodies in flight are controlled using non-intrusive passive devices that require no additional power. Further, suitable material coatings are developed for bodies in flight at hypersonic Mach numbers for controlled heat release into the shock layer during flight.

Full Text	BACKGROUND FIELD OF THE INVENTION The present invention relates to flight vehicles where hypersonic drag is reduced by modifying the shock layer of the flight. DISCUSSION OF PRIOR ART Several active and passive techniques are used in order to modify the drag associated with a vehicle in flight. Examples of these techniques include the use of aerospike counter flowing jets, upstream energy additions, alteration of the flow field near the stagnation region etc. In the method wherein an aerospike is mounted at the nose [1] of the space plane, the bow shock is pushed away from the surface of the body. Another technique based on a similar concept involves the injection of gas from the stagnation point [2] to establish a fluid spike for drag reduction. Deposition of energy upstream of ' the stagnation point [3] changes the flow encountered by the vehicle to reduce drag. A marginal reduction in the drag force has been observed by techniques that utilize stepped afterbodies [4]. These techniques are employed with the objective of reducing wave drag. Enhancement in drag reduction during the use of aerospike by external burning has been observed [5]. This method alludes to the deposition of energy in the shock layer being a possible technique of wave drag reduction. The above methods do not reduce aerodynamic drag by controlled heat energy release in the shock layer of the body. SUMMARY OF THE INVENTION It is an object of this invention to develop a novel passive flow control technique for i ■I bodies in hypersonic flight wherein: • The shock layer around the bodies in flight at hypersonic Mach numbers is modified inflight, by controlling the amount of heat energy released into the shock layer of the body, consequently controlling the aerodynamic drag. • The aerodynamic drag of the bodies in flight are controlled using non-intrusive passive devices that require no additional power. • Suitable material coatings are developed for bodies in flight at hypersonic Mach numbers for controlled heat release into the shock layer during flight. BRIEF DESCRIPTION OF DRAWINGS Fig. 1 shows the schematic diagram of the proposed invention. Fig. 2 shows the variation of the aerodynamic drag with and without controlled energy addition in the shock layer. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention proposes a novel technique for flow control for bodies in hypersonic flight. By controlling the amount of heat energy released into the shock layer of the body, aerodynamic drag can be modified. One possible way for depositing energy is to induce the energy release reaction ahead of the vehicle within the shock layer. A passive technique is proposed for triggering energy release reactions in the shock layer ahead of the body using an appropriate energy release coating on the surface of the body of vehicle traveling at hypersonic Mach numbers. The energy release reactions are triggered at high enthalpy (3MJ/kg) conditions prevailing over the body that is in flight. The schematic diagram of the proposed invention is shown in figure 1. A non-intrusive special heat energy release coating (part no.3) is applied on the body (part 1) that is undertaking hypersonic flight. Once the appropriate temperature conditions are attained during flight controlled heat lenergy is released into the shock layer (part 2). Because of .r this energy addition the fluiii dynamics of the stagnating flow in fi^ont of the body is altered. Subsequent modifications in the shock layer hypersonic flow mechanics result in aerodynamic drag. The variation of the aerodynamic drag with and without controlled energy addition in the shock layer is shown in Fig.2.The thickness of the layer, material of the layer, nature of coating on the body, static temperature and pressure of the flow at the altitude where aerodynamic drag reduction is required are some of the critical design parameters that govern the effectiveness of the present invention. A 60 degree apex angle blimt cone model, equipped with stagnation point heat transfer sensors for heat transfer rate measurement and accelerometer force balance for force measurement, is used for high enthalpy (3MJ/kg) testing in the wind tunnel. The outer surface of the blunt cone model is coated with the energy release coating. During the high enthalpy testing, the energy release coating evaporates and reacts with the dissociated gas in the shock layer. These reactions in turn deposit energy in the shock layer and reduce the strength of bow shock, ahead of the body. Because of the deposition of chemical energy in the shock layer, the bow shock gets pushed away from the body. Deposition of energy is recorded by the thermal sensor while reduction in wave drag is recorded by the accelerometer force balance. It is to be understood that this invention comprehensively covers all types of passive energy release coatings on the body during flight and any other associated or modified techniques/methods based on the current principle that is adopted in actual flight to reduce the aerodynamics drag at hypersonic Mach numbers. REFERENCES [1] Viren M, Saravanan S, ;Reddy KPJ, "Shock tunnel study of spiked aerodynamic bodies flying at hypersonic Mach number" Shock Waves Vol. 12, pp 197-204 (2002) [2] Balla Venukumar, G. Jagadeesh and K.P.J. Reddy, "Counterflow drag reduction by supersonic jet for a blunt body in hypersonic flow", Physics of fluids, 18, 118104 (2006). [3] Satheesh K. and G. Jagadeesh, "Effect of concentrated energy deposition on the aerodynamic drag of a blunt body in hypersonic flow," Physics of fluids, 19, 031701 (2007). [4] Viren Menezes, S. Kumar, Maruta, K. P. J. Reddy, and K. Takayama, "Hypersonic flow over a multi-step afterbody" Shock Waves Vol. 14, pp 421-424, (2005). [5] Reding J. P. and D. M. Jecmen, "Effects of external burning on spike-induced .r separated flows," J. Spacecraft and Rockets, 20,452 (1983). WE CLAIM 1. An apparatus for use in a supersonic flying vehicle to control the aerodynamic drag comprising: a. A non-intrusive special heat energy release coating that is applied on the body that is undertaking hypersonic flight; b. Means to release heat energy into the shock layer upon reaching appropriate conditions during flight; c. Means to alter the fluid dynamics of the stagnating flow in the front of the body; and d. Means to alter aerodynamic drag by applying modifications in the shock layer hypersonic flow mechanics. 2. An apparatus of claim 1 further comprising: a. A 60 degree apex angle blunt cone model, equipped with stagnation point heat transfer sensors for heat transfer rate measurement and accelerometer force balance for force measurement that is used for high enthalpy (3MJ/kg) testing in the wind tunnel; b. Energy release coating applied to the outer surface of the blimt cone mbdel such that during the high enthalpy testing, the energy release coating I ■ - ■ evaporates and reacts with the dissociated gas in the shock layer; c. Means to deposit energy in the shock layer and reduce the strength of bow shock, ahead of the body; d. Means to push the bow shock away from the body; e. Means to record the deposition of energy; and f. Means to record reduction in wave drag. 3. An apparatus of claim 1 wherein the energy release material coating has a thickness of ~ 50 microns and is present on the vehicle without altering the aerodynamic shape, and can be applied on the body surface during the actual flight to reduce the drag. 4. An apparatus of claini 2 wherein: a. The means to record the deposition of energy is a thermal sensor. i 5. An apparatus of claim 2 wherein: a. The means to record reduction in wave drag is the accelerometer force balance. 6. An apparatus of claim 1 wherein the vehicle selected is of any arbitrary shape and is capable of flying at hypersonic speeds. 7. An apparatus of claim 1 wherein a plurality of passive energy release coatings are provided on the body during flight. 8. A method for hypersonic aerodynamics drag reduction that can be used on any arbitrary vehicle shape flying at hypersonic speeds, comprising the steps of: a. Attaining the required temperature and pressure conditions by the vehicle in hypersonic flight; b. Automatic addition of heat energy to the shock layer in a controlled manner; and c. Alteration of the fluid dynamics around the body. 9. A method of claim 8 wherein the controlled heat energy release into the shock layer of the body, during hypersonic flight alters the flow structure within the shock layer and hence the shock structure around the vehicle ultimately resulting in substantial reductio\|n of aerodynamics drag of the vehicle during actual flight. 10. A method of claim 8 wherein the amount of drag reduction can be controlled based on the amount of heat energy released into the shock layer that in turn can be altered by the type iand thickness of heat energy release coating on the vehicle. 11. A method of claim 8 including the application of a plurality of passive energy release coatings on the body during flight.

Full Text

BACKGROUND
FIELD OF THE INVENTION
The present invention relates to flight vehicles where hypersonic drag is reduced by modifying the shock layer of the flight.
DISCUSSION OF PRIOR ART
Several active and passive techniques are used in order to modify the drag associated with a vehicle in flight. Examples of these techniques include the use of aerospike counter flowing jets, upstream energy additions, alteration of the flow field near the stagnation region etc. In the method wherein an aerospike is mounted at the nose [1] of the space plane, the bow shock is pushed away from the surface of the body. Another technique based on a similar concept involves the injection of gas from the stagnation point [2] to establish a fluid spike for drag reduction. Deposition of energy upstream of ' the stagnation point [3] changes the flow encountered by the vehicle to reduce drag. A marginal reduction in the drag force has been observed by techniques that utilize stepped afterbodies [4]. These techniques are employed with the objective of reducing wave drag. Enhancement in drag reduction during the use of aerospike by external burning has been observed [5]. This method alludes to the deposition of energy in the shock layer being a possible technique of wave drag reduction. The above methods do not reduce aerodynamic drag by controlled heat energy release in the shock layer of the body.
SUMMARY OF THE INVENTION
It is an object of this invention to develop a novel passive flow control technique for
i ■I
bodies in hypersonic flight wherein:

• The shock layer around the bodies in flight at hypersonic Mach numbers is modified inflight, by controlling the amount of heat energy released into the shock layer of the body, consequently controlling the aerodynamic drag.
• The aerodynamic drag of the bodies in flight are controlled using non-intrusive passive devices that require no additional power.
• Suitable material coatings are developed for bodies in flight at hypersonic Mach numbers for controlled heat release into the shock layer during flight.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 shows the schematic diagram of the proposed invention.
Fig. 2 shows the variation of the aerodynamic drag with and without controlled energy
addition in the shock layer.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention proposes a novel technique for flow control for bodies in hypersonic flight. By controlling the amount of heat energy released into the shock layer of the body, aerodynamic drag can be modified. One possible way for depositing energy is to induce the energy release reaction ahead of the vehicle within the shock layer. A passive technique is proposed for triggering energy release reactions in the shock layer ahead of the body using an appropriate energy release coating on the surface of the body of vehicle traveling at hypersonic Mach numbers. The energy release reactions are triggered at high enthalpy (3MJ/kg) conditions prevailing over the body that is in flight.
The schematic diagram of the proposed invention is shown in figure 1. A non-intrusive special heat energy release coating (part no.3) is applied on the body (part 1) that is undertaking hypersonic flight. Once the appropriate temperature conditions are attained during flight controlled heat lenergy is released into the shock layer (part 2). Because of
.r
this energy addition the fluiii dynamics of the stagnating flow in fi^ont of the body is altered. Subsequent modifications in the shock layer hypersonic flow mechanics result in aerodynamic drag. The variation of the aerodynamic drag with and without controlled

energy addition in the shock layer is shown in Fig.2.The thickness of the layer, material of the layer, nature of coating on the body, static temperature and pressure of the flow at the altitude where aerodynamic drag reduction is required are some of the critical design parameters that govern the effectiveness of the present invention.
A 60 degree apex angle blimt cone model, equipped with stagnation point heat transfer sensors for heat transfer rate measurement and accelerometer force balance for force measurement, is used for high enthalpy (3MJ/kg) testing in the wind tunnel. The outer surface of the blunt cone model is coated with the energy release coating. During the high enthalpy testing, the energy release coating evaporates and reacts with the dissociated gas in the shock layer. These reactions in turn deposit energy in the shock layer and reduce the strength of bow shock, ahead of the body. Because of the deposition of chemical energy in the shock layer, the bow shock gets pushed away from the body. Deposition of energy is recorded by the thermal sensor while reduction in wave drag is recorded by the accelerometer force balance.
It is to be understood that this invention comprehensively covers all types of passive energy release coatings on the body during flight and any other associated or modified techniques/methods based on the current principle that is adopted in actual flight to reduce the aerodynamics drag at hypersonic Mach numbers.

REFERENCES
[1] Viren M, Saravanan S, ;Reddy KPJ, "Shock tunnel study of spiked aerodynamic bodies flying at hypersonic Mach number" Shock Waves Vol. 12, pp 197-204 (2002)
[2] Balla Venukumar, G. Jagadeesh and K.P.J. Reddy, "Counterflow drag reduction by supersonic jet for a blunt body in hypersonic flow", Physics of fluids, 18, 118104 (2006).
[3] Satheesh K. and G. Jagadeesh, "Effect of concentrated energy deposition on the aerodynamic drag of a blunt body in hypersonic flow," Physics of fluids, 19, 031701 (2007).
[4] Viren Menezes, S. Kumar, Maruta, K. P. J. Reddy, and K. Takayama, "Hypersonic flow over a multi-step afterbody" Shock Waves Vol. 14, pp 421-424, (2005).
[5] Reding J. P. and D. M. Jecmen, "Effects of external burning on spike-induced
.r
separated flows," J. Spacecraft and Rockets, 20,452 (1983).

WE CLAIM
1. An apparatus for use in a supersonic flying vehicle to control the aerodynamic
drag comprising:
a. A non-intrusive special heat energy release coating that is applied on the
body that is undertaking hypersonic flight;
b. Means to release heat energy into the shock layer upon reaching
appropriate conditions during flight;
c. Means to alter the fluid dynamics of the stagnating flow in the front of the
body; and
d. Means to alter aerodynamic drag by applying modifications in the shock
layer hypersonic flow mechanics.
2. An apparatus of claim 1 further comprising:
a. A 60 degree apex angle blunt cone model, equipped with stagnation point
heat transfer sensors for heat transfer rate measurement and accelerometer
force balance for force measurement that is used for high enthalpy
(3MJ/kg) testing in the wind tunnel;
b. Energy release coating applied to the outer surface of the blimt cone mbdel
such that during the high enthalpy testing, the energy release coating
I ■ - ■
evaporates and reacts with the dissociated gas in the shock layer;
c. Means to deposit energy in the shock layer and reduce the strength of bow
shock, ahead of the body;
d. Means to push the bow shock away from the body;
e. Means to record the deposition of energy; and
f. Means to record reduction in wave drag.
3. An apparatus of claim 1 wherein the energy release material coating has a
thickness of ~ 50 microns and is present on the vehicle without altering the

aerodynamic shape, and can be applied on the body surface during the actual flight to reduce the drag.
4. An apparatus of claini 2 wherein:
a. The means to record the deposition of energy is a thermal sensor.
i
5. An apparatus of claim 2 wherein:
a. The means to record reduction in wave drag is the accelerometer force balance.
6. An apparatus of claim 1 wherein the vehicle selected is of any arbitrary shape and is capable of flying at hypersonic speeds.
7. An apparatus of claim 1 wherein a plurality of passive energy release coatings are provided on the body during flight.
8. A method for hypersonic aerodynamics drag reduction that can be used on any arbitrary vehicle shape flying at hypersonic speeds, comprising the steps of:
a. Attaining the required temperature and pressure conditions by the vehicle
in hypersonic flight;
b. Automatic addition of heat energy to the shock layer in a controlled
manner; and
c. Alteration of the fluid dynamics around the body.
9. A method of claim 8 wherein the controlled heat energy release into the shock
layer of the body, during hypersonic flight alters the flow structure within the
shock layer and hence the shock structure around the vehicle ultimately resulting
in substantial reductio|n of aerodynamics drag of the vehicle during actual flight.

10. A method of claim 8 wherein the amount of drag reduction can be controlled
based on the amount of heat energy released into the shock layer that in turn can
be altered by the type iand thickness of heat energy release coating on the vehicle.
11. A method of claim 8 including the application of a plurality of passive energy
release coatings on the body during flight.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=8/zSPfkZvPjDItepfIzhIw==&loc=egcICQiyoj82NGgGrC5ChA==

« Previous Patent

Next Patent »

Patent Number

272722

Indian Patent Application Number

1583/CHE/2007

PG Journal Number

18/2016

Publication Date

29-Apr-2016

Grant Date

21-Apr-2016

Date of Filing

20-Jul-2007

Name of Patentee

INDIAN INSTITUTE OF SCIENCE

Applicant Address

BANGALORE 560 012KARNATAKA

Inventors:

#	Inventor's Name	Inventor's Address
1	MR KULKARNI VINAYAK NARAYAN	#347 BRAHMIN GALLI KASBA PETH BARSHI DISTRICT: SOLAPUR MAHARASTRA 413411
2	DR. GOPALKRISHNA MAHADEVA HEGDE	#198, 3RD CROSS II-BLOCK HMT LAYOUT VIDYARANYAPURA BANGALORE 560 097
3	DR. GOPALAN JAGADEESH	#763/37, 15TH B MAIN ROAD GOKULA I STAGE I PHASE BANGALORE 560 054
4	PROF. ELANGANNAN ARUNAN	EV-202 VIJNANAPURA CAMPUS INDIAN INSTITUTE OF SCIENCE QUARTERS
5	PROF. KALIDEVAPURA POLA REDDY JAGANNATHA REDDY	#8, II CROSS HMT LAYOUT MATHIKERE BANGALORE 560054

PCT International Classification Number

F42B10/62; B64C21/00; F42B10/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA