A wave disk engine or wave disk generator is a type of

pistonless rotary engine A pistonless rotary engine is an internal combustion engine that does not use pistons in the way a reciprocating engine does. Designs vary widely but typically involve one or more rotors, sometimes called rotary pistons. Although many different ...

being developed at

Michigan State University Michigan State University (Michigan State, MSU) is a public university, public Land-grant university, land-grant research university in East Lansing, Michigan. It was founded in 1855 as the Agricultural College of the State of Michigan, the fi ...

and Warsaw Institute of Technology. The engine has a spinning disk with curved blades. Once fuel and air enter the engine, the rotation of the disk creates shockwaves that compress the mixture. When ignited, the burning mixture expands, pushing against the blades, causing them to spin. The spinning of the disk itself opens and closes intake and exhaust ports. The proposed concept was called a radial internal combustion wave rotor.

Background

Wave rotors utilize

shock waves In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a med ...

to transfer energy between a high-energy fluid to a low-energy fluid, thereby increasing both temperature and pressure of the low-energy fluid (also called pressure wave machines or pressure exchangers).

Operational principles

As with all

heat engine In thermodynamics and engineering, a heat engine is a system that converts heat to mechanical energy, which can then be used to do mechanical work. It does this by bringing a working substance from a higher state temperature to a lower state ...

s, the efficiency of a wave disk engine is governed by the temperature difference between the hot and cold sides (see Carnot's theorem). Compared to a conventional piston engine (

reciprocating engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common featu ...

), a wave disk engine works at higher peak temperature, which theoretically makes it more efficient. The design also works without a cooling system, saving weight. Compared to

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating e ...

based systems, the rotational speed and the rotor-blade temperature of the wave disk engine is lower, which creates lower stress on materials, and consequently less demanding requirements for materials, leading to cheaper manufacturing and maintenance costs. Earlier wave rotor implementations were mainly

axial flow An axial compressor is a gas compressor that can continuously pressurize gases. It is a rotating, airfoil-based compressor in which the gas or working fluid principally flows parallel to the axis of rotation, or axially. This differs from othe ...

, where the

scavenging Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding be ...

process of returning hot compressed air back into the turbine is complex. The wave-disc engine uses a radial and circumferential flow, using centrifugal forces for scavenging. Curved channels provide greater length for the same disc diameter compared to straight channels, allowing the travel times of the waves to be tuned properly.

Current status

The wave-disk engine has the potential for better energy efficiency compared to conventional internal combustion engine designs and can potentially save weight. Possible applications include charging batteries in

hybrid vehicle A hybrid vehicle is one that uses two or more distinct types of power, such as submarines that use diesel when surfaced and batteries when submerged. Other means to store energy include pressurized fluid in hydraulic hybrids. The basic princip ...

s, which could reduce weight by about .Shock wave puts hybrid engines in a spin
Helen Knight, New Scientist, 15 March 2011, Accessed March 2011 It promises to be up to 60% efficient, 30% lighter, and 30% cheaper to manufacture than an equivalent conventional piston engine, and to reduce

emissions Emission may refer to: Chemical products * Emission of air pollutants, notably: **Flue gas, gas exiting to the atmosphere via a flue ** Exhaust gas, flue gas generated by fuel combustion ** Emission of greenhouse gases, which absorb and emit rad ...

by 90%.

and Warsaw Institute of Technology researchers claim to have a prototype wave-disk engine and electricity generator that could replace current backup generator technology of plug-in electric hybrid vehicles. The research team is led by Associate Professor of Mechanical Engineerin
Norbert Müller
and has been given $2.5 million funding from the

United States Department of Energy The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United Stat ...

ARPA-E ARPA-E, or Advanced Research Projects Agency–Energy is a United States government agency tasked with promoting and funding research and development of advanced energy technologies. It is modeled after the Defense Advanced Research Projects Agenc ...

program. Müller's team hoped to have a vehicle-sized 25 kilowatt (33 hp) wave disc engine/generator ready by the end of 2011. As of January 2013, the project is looking into commercialization of the technology. Research continues at Columbia University in 2017

References

External links

Numerical investigation of the Wave Disk Micro-Engine concept - International Journal of Gas Turbine, Propulsion and Power Systems December 2008, Volume 2, Number 1Shockwave Engine: Wave Disk Engine
ARPA-E site for Michigan State University, U.S. Department of Energy
Directory:Wave Disk Engine
PESWiki * *
A Review of Wave Rotor Technology and Its Applications
Akbari and Nalim, Department of Mechanical Engineering, Purdue School of Engineering and Technology, Indianapolis, IN, USA. Published in Journal of Engineering for Gas Turbines and Power OCTOBER 2006, Vol. 128 / 719. Accessed March 2012 {{Machine configurations, state=uncollapsed Pistonless rotary engine Emerging technologies Proposed engines