Thermal Analysis of a Jet Deflector Subjected to Liquid Engine Jet Exhaust in a Static Test

Abstract

The survivability of a jet deflector encountering severe heating conditions due to the direct impingement of exhaust gases from a liquid engine is analyzed. Using engineering methods the thermal environments and temperature history are estimated. The cooling of the jet deflector using a water stream into the exhaust stream through spray nozzles located upstream from the deflector to reduce the exhaust temperature is considered. Since the major source of heating of the jet deflector is by convection, the convective heating due to jet impingement is evaluated. A flow field from the exhaust of the liquid engine is generated using a finite-volume-based Navier–Stokes computational fluid dynamics solver. For evaluating convective heat transfer coefficient, engineering methods are used based on the flow-field data generated. The theoretical flow-field data generated do not account for jet water mixing. To account for the water jet effect, an energy balance method is used to estimate the jet temperature and a one-dimensional thermal response analysis is carried out using in-house design code. The computed temperature data are compared with the measured temperature data and the survivability of the jet deflector is assured.

ACKNOWLEDGMENTS

The authors acknowledge the support and guidance received from Shri R. Swaminathan (Rtd), ARD, ADTG, and also Dr. George Joseph (Rtd), GD ADTG for his support and valuable reviews.

NOMENCLATURE

Cd	=	specific heat of deflector, J/kg-K
Cj	=	specific heat of jet, J/kg-K
Cv	=	specific heat of vapor, J/kg-K
Cw	=	specific heat of water, J/kg-K
hx	=	local heat transfer coefficient of film, W/m2-K
kd	=	thermal conductivity of the deflector, W/m-K
kj	=	thermal conductivity of the jet, W/m-K
L	=	latent heat of evaporation of water, J/kg
M	=	local Mach number
Me	=	nozzle exit jet Mach number
mj	=	mass flow rate of jet, kg/s
mw	=	mass flow rate of water, kg/s
Po	=	total pressure, bar
R	=	nozzle exit radius, m
T	=	temperature, K
t	=	time, s
Tb	=	boiling temperature, K
Te	=	nozzle exit jet temperature K
Ti	=	initial temperature, K
Tj	=	temperature of jet, K
Tm	=	temperature of jet after mixing, K
To	=	total temperature, K
VX	=	jet velocity parallel to the surface, m/s
X	=	distance along the plate surface, m
y	=	distance in thickness direction of deflector, m

Greek Symbols

μ	=	viscosity, Ns/m2
ϵ	=	emissivity
λ	=	mixing ratio
ρd	=	density of deflector, kg/m3
ρj	=	density of jet, kg/m3
σ	=	Stefan–Boltzmann constant

Additional information

Notes on contributors

Parameswaran Anoop

Parameswaran Anoop received his M.Tech. degree from Kerala University in 2003. He is working in the Aerodynamic Heating and Thermal Analysis Division of Vikram Sarabhai Space Centre. He is involved in the TPS design and analysis of launch and reentry vehicles.

Chakkedath Unnikrishnan

Chakkedath Unnikrishnan received his M.Tech. and Ph.D. from IIT Madras. He is currently working in the Aerodynamics R&D Division of Vikram Sarabhai Space Centre in the area of computational fluid dynamics. He has authored many research papers in international/national journals and conferences.

Balachandran Sundar

Balachandran Sundar received his M.Tech. from Anna University, Chennai. He is working in the Aerodynamic Heating and Thermal Analysis Division of Vikram Sarabhai Space Centre. Presently, he is the Head of the Aerodynamic Heating and Analysis section. He has contributed for external TPS design of launch and reentry vehicles.

M. Joseph Chacko

M. Joseph Chacko received his M.Sc. degree at Sardar Patel University, Gujarat, in 1982. He received his Ph.D. from Mahatma Gandhi University in 2012. He is working in Vikram Sarabhai Space Centre. Presently, he is the Head of the Aerodynamic Heating and Analysis Division. He has contributed in heat transfer studies for space applications. He has co-authored research papers in international journals.