The document discusses turbomachinery, which includes pumps and turbines. A turbopump in a rocket engine consists of a pump that delivers fuel or oxidizer to the thrust chamber. Turbomachinery transfers energy between a flowing fluid and rotating elements, resulting in pressure and momentum changes. They are used for power generation, aircraft propulsion, and vehicular propulsion. Turbomachines are classified based on energy transfer, flow direction, fluid condition, and shaft position. The main components include a rotating element carrying vanes, stationary guide vanes, an input/output shaft, and a housing. Design challenges include complex static and rotating parts dealing with thermal transients and high blade speeds.

1. Turbomachinery
Merchant Bilal A 1
Kalsekar Polytechnic
Address
Mechanical Department, 2nd
year (inst.code-1608)
1bmerchant96@yahoo.in
Abstract— A turbopump in a rocket engine consists of a pump
that delivers fuel or oxidizer to the thrust chamber where the
propellants are brought to react and increase in temperature.
Since the combustion process takes place under constant
pressure, the chamber pressure is the net result of the
turbopump system. Turbomachinery for liquid rocket propulsion
shares many of the design features and challenges found in gas
turbines. To an even greater extent than in jet-engines used for
aircraft the emphasis is on delivering very high power in a small
machine. Pumps and turbines are classical subjects of
engineering and are in wide spread use in many areas.
Keywords—Turbomacine, stator, rotor, dynamic, impeller, etc.
I. INTRODUCTION
The turbomachine has been defined differently by different
authors, though these definitions are similar and nearly
equivalent. According to Daily [1], the turbomachine is a
device in which energy exchange is accomplished by
hydrodynamic forces arising between a moving fluid and the
rotating and stationary elements of the machine. According to
Wislicenus [2], a turbomachine is characterized by dynamic
energy exchange between one or several rotating elements and
a rapidly moving fluid. Binder [3] states that a turbomachine is
characterized by dynamic action between a fluid and one or
more rotating elements. A definition to include the spirit of all
the preceding definitions would be: A turbomachine is a
device in which energy transfer occurs between a flowing
fluid and a rotating element due to dynamic action resulting
in a change in pressure and momentum of the fluid.
Mechanical energy transfer occurs into or out of the
turbomachine, usually in steady flow. Turbomachines include
all those types that produce large-scale power and those that
produce a head or pressure, such as centrifugal pumps and
compressors.
Fig. 1
II. USES OF TURBOMACHINES
The turbomachine is used in several applications, the
primary ones being electrical power generation, aircraft
propulsion and vehicular propulsion for civilian and military
use. The units used in power generation are steam, gas and
hydraulic turbines, ranging in capacity from a few kilowatts to
several hundred and even thousands of megawatts, depending
on the application. Here, the turbomachine drives the
alternator at the appropriate speed to produce power of the
right frequency. In aircraft and heavy vehicular propulsion for
military use, the primary driving element has been the gas
turbine.
III. CLASSIFICATION OF TUBOMACHINES
Turbomachines are classified into five basic types on the
basis of the following,
a. Energy transfer
i. Power generating turbo machines-Turbines
ii. Power absorbing turbo machines-Pumps
b. Direction of flow
i. Axial Flow
ii. Radial Flow
iii. Mixed Flow
iv. Tangential Flow
c. Condition of fluid
i. Impulse type (constant pressure)-Pelton
wheel turbine
ii. Reaction type (variable pressure)- Francis
turbine
d. Position of rotating shaft
i. Horizontal shaft – Steam turbines
ii. Vertical shaft – Kaplan water turbines
iii. Inclined shaft – Modern bulb micro- hydel
turbines
IV. COMPONENTS OF TURBOMACHINES
The principal components of a turbomachine are: (i) A
rotating element carrying vanes operating in a stream of fluid,
(ii) A stationary element or elements which generally act as
guide vanes or passages for the proper control of flow
direction and the energy conversion process, (iii) an input
and/or an output shaft, and (iv) a housing (Fig. 2). The rotating
element carrying the vanes is also known by the names rotor,
runner, impeller, etc., depending upon the particular
application. Energy transfer occurs only due to the exchange
of momentum between the flowing fluid and the rotating

2. elements; there may not be even a specific boundary that the
fluid is not permitted to cross.
Fig. 2
V. MECHANICAL DRAWBACK
The mechanical design is highly complex both in static and
rotating parts. The main difficulty in the static parts is the
severe thermal transients encountered on start and stop
transients. Parts designed for burst become thick walled due to
high pressures suffer from the thermal gradients encountered
during transients. This causes a conflict in the designs that are
hard to solve and demands a lot of work and design
experience. In order to be efficient and have high power
output the blades must move at high speed.
VI. BLADE VIBRATION
Blade vibration is most definitely one of the major design
concerns for the turbine. Blade vibration problems in general
constitute the probably largest source of difficult problems late
in the design project.
Fig. 3
VII. RECENT DEVELOPMENT AND TRENDS
By 1940, single turbine units with a power capacity of
100,000 kilowatts were common. Ever-larger turbines (with
higher efficiencies) have been constructed during the last half
of the century, largely because of the steadily rising cost of
fossil fuels. This required a substantial increase in steam
generator pressures and temperatures. Some units operating
with supercritical steam at pressures as high as 34,500
kilopascals gauge and at temperatures of up to 650 °C were
built before 1970. Reheat turbines that operate at lower
pressures (between 17,100 to 24,100 kilopascals gauge) and
temperatures (540–565 °C) are now commonly installed to
assure high reliability. Steam turbines in nuclear power plants,
which are still being constructed in a number of countries
outside of the United States, typically operate at about 7,580
kilopascals gauge and at temperatures of up to 295 °C to
accommodate the limitations of reactors. Turbines that exceed
one-million-kilowatt output require exceptionally large, highly
alloyed steel blades at the low pressure end.
Fig. 4
VIII. CONCLUSION
Turbomachinery has its application more in conventional
machine having adequate efficiency and performance. Thus
they have their various applications in displacement of fluid,
electricity generation, etc.
REFERENCES
[1] Daily, J.W., Hydraulic Machinery, Part 13, Engineering
Hydraulics, Ed. H. Rouse, Wiley, 1950.
[2] Wislicenus, G.F., Fluid Mechanics of Turbomachinery, McGraw-
Hill, 1947.
[3] Binder, R.C., Advanced Fluid Mechanics, Vol. I, Prentice-Hall,
1958.