Recuperative heat exchangers in the exhaust nozzle of an aero engine

BY:MOHAMMED FAZIL CHALILContact: +919947117403engfazil92@gmail.com

10/20/20151RECUPERATIVE HEAT EXCHANGERS IN THE EXHAUST NOZZLE OF AN AERO ENGINE

ILM COLLEGE OF ENGINEERING AND TECHNOLOGY, METHALA, PERUMBAVOOR

1engfazil92@gmail.com

ABSTRACT10/20/20152

EU initiated an action for the design and construction of efficient and environmentally friendly engines(EEFAE) .

Major European Gas turbine industries MTU proposed a new technology on the basis of alternate thermo dynamic cycle- basis of this cycle is the adoption of the recuperation part with heat exchangers installed in exhaust nozzle of aircraft engines.

The benefits of this technique is focused on reduced pollutants and decreased fuel consumption.Need for safer, cleaner and more affordable civil aero engines are found to be great importance.

INTRODUCTION10/20/20153Ultimate demand of lower fuel consumption (issues raised by international environmental committee) has led aero engine manufacturers to pioneer in new advanced engines to face competitive future of civil transport.

MTU aero engines have developed the concept of intercool recuperative aero engine (IRA).

Basic idea is to use less conventional , more efficient and thermodynamic cycle for aircraft engines based on recuperation.

Recuperative engine. The heat exchangers are installed in the exhaust nozzleTHE CONCEPT OF RECUPERATIVE ENGINE :10/20/20154

Side view of the heat exchanger (left) and a hot gas pass through a characteristic passage of the heat exchanger (right).HEAT EXCHANGER10/20/20155

Meridional view of the exhaust nozzle of the recuperative engineRECUPERATIVE EXHAUST NOZZLE10/20/20156

THE IDEOLOGY IN SHORT:

CombustionchamberGas turbineHeat exchangersAt nozzle

Compressor

Hot exhaust enthalpy to preheat the compressor air.10/20/20157 TO

ATMOSPHERE

THE CONSTRUCTION OF A MODEL OF THE EXHAUST NOZZLE:

1:1 model of the quarter of the nozzle operating at laboratory conditions was constructed.

A 1:1 model of the heat exchanger10/20/20158

Views of the test-rig. Left: the exhaust nozzle together with the outlet section. Middle: inlet section of the exhaust nozzle. Right: The heat exchanger installation inside the nozzle.Whole construction was integrated in a wind tunnel.

Computational Fluid Dynamics modelling was done.10/20/20159

MASS FLOW THROUGH EACH HEAT EXCHANGER:

One major aspect of heat exchanger installation is the mass distribution in the frontal area.By installation of exchangers unbalanced distribution of the mass flow for each heat exchanger is found which increases the pressure drop.

Heat exchangerMass flow percentageNet mass flow rate (kg/s)1(horizontally placed)17.41.25227.11.96337.92.734(vertically placed along the meridion line)17.61.27

Mass flow distribution through the heat exchangers:10/20/201510

Heatexchanger 1 Heatexchanger 2 Heat exchanger 3CFD results10.24%39.68%50.09%Measurements21.04%33.00%45.96%

Comparison of CFD calculated values with the experiment one:

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Comparison of the calculated and measured average values of the total and static pressure and of the total and static pressure drop in the measurement stations. For each diagram, the first value corresponds to the inlet, the second and the third to the stations 1, 2 and the fourth to the outlet.10/20/201512

OPTIMIZATION OF THE INSTALLATION:

Performed only by means of CFD modelling.

The fig. Shows the regions inside the exhaust nozzle where the optimization should be focussed on.

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Achievements with the new configuration is summarized as follows:

Separation located at the last heat exchanger minimized by connecting ramp.

original geometry new geometry10/20/201514

The cavity located before the first heat exchanger minimized by designing new geometry

Original geometry New geometry 10/20/201515

The new geometry of the first heat exchanger modified to obtain better distribution of flow field downstream of the heat exchanger.

Original geometry New geometry10/20/201516

Cone geometry placed after the entire shaft also redesigned to prevent creation of large recirculation region( found during CFD Modelling and during measurements.)

Recirculation region

Minimized10/20/201517

CONCLUSION

Alternative technology for the improvement of aero engine thermodynamic cycle has been presented.

Using heat exchangers at the nozzle engines hot gas enthalpy is directed to the compressor in order to pre-heat the compressor air.

In order to ensure an optimum operation of the engine, the pressure losses due to the existence of the heat exchangers has been investigated both experimentally and computationally.

Optimization is performed on the basis of experimental and CFD analysis. Necessary changes brought in the geometry of the exhaust nozzle and the heat exchanger alignment.

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The optimization has been mainly focused on the minimization of the recirculation regions together with the examination of alternative setups of the heat exchangers in order to have a better mass flow distribution through them, an action which surely leads to lower values for the pressure losses.

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THANKS FOR YOUR ATTENTION!10/20/201522