The specific impulse of solid rocket motors is much lower than that of liquid rocket motors due to limitations in solid propellant formulations. Inspired by the nuclear thermal rockets, the concept of helium injected solid–gas hybrid rocket motors (SGHRMs) is innovatively proposed and its thrust performance is numerically investigated in the present study. The injected helium is regarded as a working medium with strong expansion capacity, and the high-temperature combustion gas of the solid propellant is used as a heat source to heat the helium. Then, the mixed gas including the combustion gas and helium flows through the nozzle producing high boost thrust. Results show that the maximum specific impulse gain is up to 4.92%, and by adjusting the helium injection ratio from 0 to 2:1, the thrust regulation range of 100%–303% is achieved. When the helium is injected from the motor head, mixed gas with various helium fraction exhibits stratified flow characteristics. Hence, the mechanism of specific impulse gain can be elucidated by one-dimensional internal ballistics analysis. That is, mixed gas with a low helium mass fraction can significantly stimulate velocity gain with a slight reduction in total temperature, thereby increasing the specific impulse. However, mixed gas with a high helium mass fraction significantly reduces the total temperature, leading to a decreased expansion ability and a corresponding drop in the specific impulse. Finally, competition between mixed gases with various helium fractions determines the specific impulse gain level of SGHRMs.

1.
R. L.
Sackheim
, “
Overview of United States rocket propulsion technology and associated space transportation systems
,”
J. Propul. Power
22
(
6
),
1310
1332
(
2006
).
2.
Xinhuanet
, “
China launches commercial Gravity-1 rocket from sea
” (
2024
). See https://www.newsgd.com/node_1299786306/6b4c4fc466.shtml.
3.
P.
Nowakowski
,
A.
Okninski
,
M.
Pakosz
et al, “
Development of small solid rocket boosters for the ILR-33 sounding rocket
,”
Acta Astronaut.
138
,
374
383
(
2017
).
4.
L.
David
,
N.
Gelii
, and
M.
George
, “
Energetic performances of solid composite propellants
,”
Cent. Eur. J. Energetic Mater.
8
(
1
),
25
38
(
2011
).
5.
B.
D'Andrea
,
F.
Lillo
,
A.
Faure
et al, “
A new generation of solid propellants for space launchers
,”
Acta Astronaut.
47
(
2–9
),
103
112
(
2000
).
6.
J.-F.
Guery
,
I.-S.
Chang
,
T.
Shimada
et al, “
Solid propulsion for space applications: An updated roadmap
,”
Acta Astronaut.
66
(
1–2
),
201
219
(
2010
).
7.
D. B.
Lempert
,
H. N.
Nechiporenko
, and
S. I.
Soglasnova
, “
Energetic possibilities of compositions basing on polynitrogene high-enthalpy compounds
,”
Phys. Comb. Explos.
45
(
2
),
58
67
(
2009
).
8.
A.
Davenas
, “
Development of modern solid propellants
,”
J. Propul. Power
19
(
6
),
1108
1128
(
2003
).
9.
D.
Trache
,
T. M.
Klapötke
,
L.
Maiz
et al, “
Recent advances in new oxidizers for solid rocket propulsion
,”
Green Chem.
19
(
20
),
4711
4736
(
2017
).
10.
R. A.
Gabrielli
and
G.
Herdrich
, “
Review of nuclear thermal propulsion systems
,”
Prog. Aerosp. Sci.
79
,
92
113
(
2015
).
11.
S. H.
Nam
,
P.
Venneri
,
Y.
Kim
et al, “
Preliminary conceptual design of a new moderated reactor utilizing an LEU fuel for space nuclear thermal propulsion
,”
Prog. Nucl. Energy
91
,
183
207
(
2016
).
12.
S. K.
Borowski
and
R. R.
Corban
, “
Nuclear thermal rocket/vehicle design options for future NASA missions to the moon and mars
,” Paper No. AIAA-93-4170 (
1995
).
13.
D.
Nikitaeva
and
L. D.
Thomas
, “
Seeded hydrogen in nuclear thermal propulsion engines
,”
J. Spacecr. Rockets
57
(
5
),
907
917
(
2020
).
14.
D.
Altman
, “
Hybrid rocket development history
,” Paper No. AIAA-91-2515 (
1991
).
15.
K.
Ramohalli
and
J.
Yi
, “
Hybrids revisited
,” Paper No. AIAA-90-1962 (
1990
).
16.
J.
Zheng
,
X.
Liu
,
P.
Xu
et al, “
Development of high pressure gaseous hydrogen storage technologies
,”
Int. J. Hydrogen Energy
37
(
1
),
1048
1057
(
2012
).
17.
B.-G
.
Sun
,
D.-S.
Zhang
, and
F.-S.
Liu
, “
Analysis of the cost-effectiveness of pressure for vehicular high-pressure gaseous hydrogen storage vessel
,”
Int. J. Hydrogen Energy
37
(
17
),
13088
13091
(
2012
).
18.
J.
Yamabe
,
T.
Awane
, and
S.
Matsuoka
, “
Elucidating the hydrogen-entry-obstruction mechanism of a newly developed aluminum-based coating in high-pressure gaseous hydrogen
,”
Int. J. Hydrogen Energy
40
(
32
),
10329
10339
(
2015
).
19.
C.
San Marchi
,
B. P.
Somerday
, and
K. A.
Nibur
, “
Development of methods for evaluating hydrogen compatibility and suitability
,”
Int. J. Hydrogen Energy
39
(
35
),
20434
20439
(
2014
).
20.
B. J.
McBride
and
S.
Gordon
, “
Computer program for calculation of complex chemical equilibrium compositions and applications
,” Paper No. NASA-RP-1311 (
1996
).
21.
E. W.
Lemmon
,
I. H.
Bell
,
M. L.
Huber
et al, “NIST Standard Reference Database 23: Reference Fluid Thermodynamic and Transport Properties-REFPROP,” Version 10.0, Natl Std. Ref. Data Series (NIST NSRDS) (
National Institute of Standards and Technology
,
Gaithersburg
,
2018
).
22.
F. R.
Menter
, “
Two-equation eddy-viscosity turbulence models for engineering applications
,”
AIAA J.
32
(
8
),
1598
1605
(
1994
).
23.
N.
Bai
,
W.
Fan
, and
R.
Zhang
, “
A mixing enhancement mechanism for a hydrogen transverse jet coupled with a shear layer for gas turbine combustion
,”
Phys. Fluids
35
(
4
),
045111
(
2023
).
24.
J. C.
Traineau
,
P.
Hervat
, and
P.
Kuentzmann
, “
Cold-flow simulation of a two-dimensional nozzle less solid rocket motor
,” in
AIAA/ASME/SAE/ASEE 22nd Joint Propulsion Conference
(
AIAA
,
Huntsville, AL
,
1986
).
You do not currently have access to this content.