Continuous variation of propellant flow and thrust by application of liquid foam flow theory to injection orific

Morrell, G.

English

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July 24, I962 G. MORRELL 3,045,424 
METHOD FOR CONTINUOUS VARIATION OF PROPELLANT 
FLOW AND THRUST IN PROPULSIVE DEVICES 
Filed Feb. 24, 1960 2 Sheets-Sheet 1 
INVENTOR 
GERALD MORRELL 
https://ntrs.nasa.gov/search.jsp?R=19700031051 2020-03-17T02:08:43+00:00Z
Jdy 24, 1962 G. MORRELL 3,cr(a5,1%24 
METHOD FOR CONTINUOUS VARIATION OF PROPELLANT 
FLOW AND THRUST IN PROPULSIVE DEVICES 
Filed Feb. 24, 1960 2 Sheets-Sheet 2 
WENTOR 
GERALD MORWEBk 
3,045,424 United States Patent OfZice ,, , , , 
I I lAE A ~ A  method has the ability t o  modulate thrust in a continuous 
","-..J,-#-T 
METHOD FOR CONTINU OF PRO. manner. 
PELLANT FLOW AND PULSIVE A still additional object of the invention is a new 
n m ~ . c  method for thrust variation of liquid propellant devices, 
--. ---- 
Gerald Morrell, Middleburg Heights, Ohio, assignor to 5 which method is insensitive t o  vibration.- 
the United States of America as  represented by the Other objects and many of the attendant advantages 
Administrator of the National Aeronautics and Space of this invention will be readily appreciated as the same . - -  Administration 
Filed Feb. 24,1960, Ser. No. 10,812 becomes better understood by reference to  the following 
3 Claims. (Cl. 60-35.3) detailed description when considered in connection with 
(Granted under Title 35, U.S. Code (1952), sec. 266) the drawings wherein: FIG. 1 represents a schematic flow diagram of a rocket 
The invention described herein may be manufactured system. 
and used by or for the Government of the United States FIG. 2 is a partially-sectioned pictorial view of the 
of America for governmental purposes without the Pay- foaming device used in the system shown in FIG. 1. 
ment of any royalties thereon or therefor. 15 Referring now to the drawings, wherein like reference 
This invention pertains to a new and novel method characters designate like o r  corresponding parts through- 
for the thrust variation of propellant propulsive devices out the two views, there is shown in FIG. 1 a typical 
6y modulation of the propellant flow through density rocket fuel system using the novel foam control of the 
control. oxidant and the fuel. By way of example, the system 
Continuous thrust variation in rocket engines; in other 20 utilizes an ammonia-white fuming nitric acid mixture with 
words, throttling, is especially desirable for piloted air- helium used as a pressurizing and foaming gas. Of 
craft applications. In guided missiles, the use of a course, any combination of fuel and oxidant may be 
single powerplant, for both boost and sustainer opera- used other than those specifically disclosed for the pur- 
tion, would be possible also by continuous thrust varia- pose of explaining the system in FIG. l. Ammonia is 
tion. Another application of this theory in  another field 25 stored in tank 11 which is kept under pressure by means 
of application would be vernier thrust control near cut- of helium gas admitted through the three-ay vent valve 
off. 13. The ammonia under pressure flows from the tank 11 
Currently, rocket thrust variation is accomplished by through the flow meter 1 4  and before the amrnonia 
using multiple fixed thrust cylinders, each operating a t  reaches the foaming device 16, lithium is added in the 
fixed flow, such cylinders being continuously turned on 30 flow line from the lithium holder 15. This flow-line 
and off. Additionally, there are mechanical devices for addition of lithium metal to the ammonia causes spon- 
opening and closing injector orifices and methods for taneous ignition when the ammonia and nitric acid reach 
controlling pump speed in turbopump units. As can be the combustor. From the lithium holder 15, the am- 
seen, the flow control of these devices makes use of area monia is passed to the foaming device 16. Also admitted 
and velocity variations. 33 to the foaining device 16 is the helium gas necessary to 
The main disadvantage of the prior methods is that cause the foam. The helium gas is admitted &rough 
they have an inability to provide continuous thrust varia- the vent valve 18 and then passes through a check valve 
tion. Additionally, most of the prior methods add exces- 17  on into the foaming device 16. The foamed ammonia 
sive weight to the rocket structure. Additional disad- then passes from the foaming device 116 through a flow 
vantages found in these devices are their lack of relia- 40 control valve 1 9  into the rocket combustor. As will be 
bility and repeatability due to  vibrations, dynamic in- seen, the oxidant or nitric acid in this example goes 
stability, and changes in clearances. through the same process as did the ammonia except for 
This invention applies flow theory of liquid foams to the omission of lithium in the flow line. The acid is 
the rocket engine injection process. By foaming the stored in tank 12, which is kept under pressure by heli- 
propellants and thereby changing their bulk densities, 45 um gas being admitted through the three-way vent valve 
it is possible to vary rocket thrust continuously. Thus, 13. The acid, which is under the pressure of the helium 
by applying the foam-flow theory t o  the injector orifice gas, leaves the tank 1 2  and flows through a flowmeter 14 
of a rocket engine, the reduction in the propellant flow on into the foaming device 1 6  wherein it is caused to 
becomes a function of the ratio of the flow rates of the foam by the admission of helium gas into the device. 
inert gas and the propellant. As can be seen, the rate of 50 The helium gas is admitted through the vent valve 18 and 
propellant flow through the injector orifice will decrease then flows through a check valve 17 on into the foaming 
as the foaming of the incoming propellant stream is in- device 16. After leaving the foaming device 16, the 
creased. By the simple variance of the inert gas flow, foamed acid passes through a flow control valve 19 into 
the flow rate of the propellant through the orifice can the rocket combustor 21. 
readily be varied. Naturally, as the flow rate of propel- 55 Referring now to FIG. 2 wherein the foaming device 
lant is varied, the thrust of the engine will vary propor- 1 6  is shown, it  is seen that the foaming gas is admitted 
tionately. through the pipe 22, which is actually the flow line from 
Thus, an object of this invention is la new method for the gas storage tank. Attached to the inlet pipe 22, by 
thrust variation of liquid propellant devices wherein the welding or other conventiohal means (not shown), is a 
propellant flow is modulated through density control. 60 perforated tube 23. The perforated tube 23 is mounted 
An additional object of this invention is a new method concentrically within T-joint 27 by thread means 30 on 
for thrust variation of liquid propellant devices where inlet pipe 22 and is secured in place by a lock nut 26. 
the propellant density is modulated by foam formation. The liquid is admitted through the arm 24 of the joint 27 
A further object of the invention is a new method for and is caused to foam by the gas that is emitted through 
thrust variation of liquid propellant devices, which 65 the perforations in the tube 23. The final foamed liquid 
method has mechanical simplicity. leaves the device through the arm 25 of the +-joint 27. 
Another object of the invention is a new method for It is to be noted that the tube 23 is fitted into the T- 
thrust variation of liquid propellant devices, which joint 27 so that the tube axis coincides with the through 
method embraces flow rate mechanical structures. axis of the T-joint. By so injecting a gas into a liquid 
A still further object of the invention is a new method 70 stream through a multiplicity of small orifices, a foam is 
for thrust variation of liquid propellant devices, which thus produced, having a substantially smaller apparent 
3,0411,484 
3 4 
density than the unmodified liquid. Greatest efficiency device which method comprises injecting an inert gas 
is obtained by using an insoluble gas, but the action is into a propellant causing said propellant to foam and 
not prevented by partial solubility. By varying the subsequently using said foamed propellant to power said 
mount of helium gas flowing into the foaming device, propulsive device whereby the thrust produced by said 
the consistency of the foam will be caused to vary. Thus, 5 propulsive device varies proportionately to the amount 
as more helium gas is injected, a greater foaming action ~f foaming action. 
occurs resulting in a decrease of the propellant flow to 2. A method for varying the thrust of a liquid propel- 
the injector. lant propulsive device which method comprises injecting 
Alterna(ive to the particular method described herein, an inert gas into a propellant causing said propellant to 
the foaming could be accomplished at the outlet of the 10 foam and subsequently feeding the foamed propellant 
storage vessel or at the entrance or exit of a turbopump. into said propulsive device whereby the quantity of pro- 
Mso, the herein disclosed method could be used to con- pellant entering said propulsive device decreases as the 
brol the Bow to a gas generator which drives a turbo- foaming action increases. 
pump set. An additional adaptation of the foam theory 3. A method for varying the thrust of a liquid propel- 
would be to generate the foam in situ in a solid propel- 15 lant propulsive device which method comprises storing 
nant rocket during the liquid curing stage whereby it the fuel and oxidizer components under pressure of an 
would be possible to pre-program thrust variations in inert gas, feeding said fuel and oxidizer to said propul- 
such devices. sive device, injecting an inert gas into said fuel and 
Obviously, many modifications and variations of the oxidizer being fed thereby causing said fuel and oxidizer 
present invention are possible in the light of the above 20 to foam prior to the fuel and oxidizer entering said 
teacGgs. It is, therefore, to be understood that within propulsive device, whereby the quantity of fuel and 
the scope of the attendant claims the invention may be oxidizer entering said propulsive device decreases as the 
practiced othepwise &an as specifically described. foaming action increases. 
m a t  is claimed is: 
1. A method for varying the thrust of a propulsive 25 No references cited. 


Method for continuous variation of propellant flow and thrust in propulsive devices Patent

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