Imperial College London


Faculty of EngineeringDepartment of Mechanical Engineering

Chair in Thermofluids



+44 (0)20 7594 7032p.aleiferis




Ms Serena Dalrymple +44 (0)20 7594 7029




615City and Guilds BuildingSouth Kensington Campus






BibTex format

author = {Hamzehloo, A and Aleiferis, P},
doi = {10.1016/j.ijheatfluidflow.2019.01.017},
journal = {International Journal of Heat and Fluid Flow},
pages = {309--334},
title = {LES and RANS Modelling of Under-Expanded Jets with Application to Gaseous Fuel Direct Injection for Advanced Propulsion Systems},
url = {},
volume = {76},
year = {2019}

RIS format (EndNote, RefMan)

AB - A density-based solver with the classical fourth-order accurate Runge-Kutta temporal discretization scheme wasdeveloped and applied to study under-expanded jets issued through millimeter-size nozzles for applications in highpressuredirect-injection (DI) gaseous-fuelled propulsion systems. Both large eddy simulation (LES) and ReynoldsaveragedNavier-Stokes (RANS) turbulence modelling techniques were used to evaluate the performance of the newcode. The computational results were compared both quantitatively and qualitatively against available data from theliterature. After initial evaluation of the code, the computational framework was used in conjunction with RANSmodelling (k-ω SST) to investigate the effect of nozzle exit geometry on the characteristics of gaseous jets issued frommillimeter-size nozzles. Cylindrical nozzles with various length to diameter ratios, namely 5, 10 and 20, in addition toa diverging conical nozzle, were studied. This study is believed to be the first to provide a direct comparison betweenRANS and LES within the context of nozzle exit profiling for advanced high-pressure injection systems with theformation of under-expanded jets. It was found that reducing the length of the straight section of the nozzle by 50%resulted in a slightly higher level of under-expansion (~2.6% higher pressure at the nozzle exit) and ~1% higher massflow rate. It was also found that a nozzle with 50% shorter length resulted in ~6% longer jet penetration length. At aconstant nozzle pressure ratio (NPR), a lower nozzle length to diameter ratio resulted in a noticeably higher jetpenetration. It was found that with a diverging conical nozzle, a fairly higher penetration length could be achieved if anunder-expanded jet formed downstream of the nozzle exit compared to a jet issued from a straight nozzle with the sameNPR. This was attributed to the radial restriction of the flow and consequently formation of a relatively smallerreflected shock angle. With the conical
AU - Hamzehloo,A
AU - Aleiferis,P
DO - 10.1016/j.ijheatfluidflow.2019.01.017
EP - 334
PY - 2019///
SN - 0142-727X
SP - 309
TI - LES and RANS Modelling of Under-Expanded Jets with Application to Gaseous Fuel Direct Injection for Advanced Propulsion Systems
T2 - International Journal of Heat and Fluid Flow
UR -
UR -
VL - 76
ER -