An example of an engine used in the generation of electricity is shown in Figure 1. The engine, known as a gas turbine engine, comprises a compressor 10 which compresses air drawn in through an air inlet 11. The compressed air is heated in a heat exchanger 12, taking advantage of the hot exhaust gases of the engine. The heated compressed air is mixed with fuel from a fuel inlet 13 and is burnt in a combustion chamber 14 where the volume of gas significantly increases causing the velocity at which the gas is moving to also significantly increase. The fast moving gas is directed through a turbine 15 which is caused to rotate and the excess hot gas is exhausted via heat exchanger 12. The rotation of turbine 15 drives a shaft 16 which is connected to compressor 10 and provides the power for compression of the air within compressor 10. The shaft is also connected to a generator 17 which generates electricity.

The above described gas turbine engine suffers from the disadvantage that such turbine engines are most efficient and effective on a large scale and do not adapt well to being scaled down to small applications such as generating electricity for single domestic premises or recharging car batteries in a hybrid car.

Preferred embodiments of the present invention seek to overcome the above described disadvantages of the prior art.

According to an aspect of the present invention there is provided an engine comprising: a housing having at least one inlet and at least one exhaust outlet ; a compression fan adapted to rotate in a first sense to cause compression of a fuel and air mixture ; and a reaction member mounted substantially coaxially with said compression fan and comprising a plurality of vanes, wherein the reaction member is adapted to receive said compressed fuel and air mixture from said compression fan and in use said fuel and air mixture is burnt between said vanes and gases produced by said burning are vectored to cause said reaction member to rotate in a second sense opposite to said first sense.

By providing a compressor which feeds a fuel and air mixture directly into a reaction member, the advantage is provided that because the compression fan and reaction member are rotating in opposite senses, the relative velocity of the fuel air mixture entering the reaction member is approximately equal to the outer rim velocity of the compression fan added to the reaction member velocity at the same radius. This high entry velocity when diffused within the reaction member results in a higher compression ratio than could be achieved by the compression fan alone. When the air/fuel mixture is burnt, the force of the expanding combustion gases as they escape tangentially from the reaction member act directly upon the reaction member giving efficient conversion of the energy of combustion of the fuel air mix to rotational energy of the reaction member. For example such an engine can be used to generate electricity on a single domestic scale or used to recharge batteries in a hybrid car. Engines which are typically used for such purposes at present include the internal combustion engine, generally of the petrol or diesel type. The above described invention provides the advantage over these types of engine that there is no conversion of the linear motion of pistons in to the rotary motion of a drive shaft with the inherent losses in energy which will occur. Furthermore there is no requirement for a continuously operating ignition timing mechanism or complex water cooling system which also reduces the energy losses of the engine of the present invention.

In a preferred embodiment said fuel and air mixture are further compressed within said reaction member.

By further compressing the fuel and air mixture the advantage is provided that the engine has a higher output per unit size of engine.

In a preferred embodiment said further compression occurs by diffusion of said mixture within said reaction member.

In another preferred embodiment said further compression occurs by ram compression of said mixture within said reaction member.

In a preferred embodiment said compression fan discharges said mixture in a direction substantially tangential to a circle defined by the rotation of vane tips of the vanes of the compression fan.

Because the mixture is discharged from the compression fan substantially tangentially to the fan, the radial component of the velocity of the mixture at that point is minimised.

Therefore the mass flow that will pass through the engine can be reduced and the unit can be produced with lower output thereby increasing the number of potential applications.

In another preferred embodiment said fuel and air mixture is received within said reaction member at a velocity relative to the reaction member substantially equal to the sum of the velocities of the compression fan vane tips and the reaction member at substantially the same radius.

In a preferred embodiment the engine further comprises at least one turbine member for driving said compression fan.

In another preferred embodiment, at least one said turbine member is driven by exhaust gases from said reaction member.

In a preferred embodiment, said fuel and air mixture is mixed prior to entry into the engine through the or each inlet.

By mixing the fuel and air prior to entry into the engine the advantage is provided that when the fuel air mixture is burnt in the reaction member it is already thoroughly mixed, thereby burning with maximum efficiency. In particular the mixing occurs prior to the compression fan and as the fuel and air pass through the compression fan, the reaction member (before passing through the flame grid) and through the flame grid itself.

In a preferred embodiment, the cross-sectional area, measured in a circumferential direction, of the space defined by two adjacent vanes, increases as the radial distance from the axis of the reaction member increases, to a maximum substantially half way along the length of said vanes, and then decreases as said radial distance further increases.

By initially increasing and then decreasing the space between each pair of vanes of the reaction member as the distance from the centre of the reaction member increases, the advantage is provided that each section of the reaction member, which is defined by an adjacent pair of vanes, acts in a similar manner to a ram-jet. That is, that as the fuel air mixture is forced at high velocity from the compression fan into the reaction member it is caused to slow down by the increasing volume between two vanes, which in turn increases the pressure of the fuel air mix. At the point when the air fuel mix is slowed down sufficiently to sustain combustion, the fuel air mixture is burnt and the hot expanding combustion gases continue through the passage area between adjacent vanes which vector or direct the combustion gases through a nozzle formed by the now converging adjacent vanes. The direction of the expelled gas is tangential to the reaction member radius thereby causing the tangential jet reaction which rotates the reaction member in the second sense.

In a preferred embodiment said reaction member further comprises a flame grid.

By providing the reaction member with a flame grid the advantage is provided that the grid acts as a bluff body, which causes the velocity of the fuel air mix immediately behind the flame grid to be less than the flame speed relative to the flame grid. As a result, the combustion of the fuel air mix can be controlled at the flame grid.

In a preferred embodiment the flame grid is located at a position along the vanes where the cross-sectional area defined by adjacent vanes, is at its greatest.

By providing the flame grid at the point of greatest cross- sectional area between the vanes, i. e. approximately half way along the length of the vanes, the advantage is provided that the fuel air mix is burnt at the point of slowest gas speed and as a result highest pressure. The decrease in speed and increase in gas pressure results from the increase in cross- sectional area between the vanes.

In a preferred embodiment said vanes are adapted to reduce a cross-sectional area, measured in a circumferential direction, of the space defined by two adjacent vanes, decreases as the radial distance from the axis of the reaction member increases, to a minimum cross-sectional area, thereby substantially defining the flame front, before increasing.

In a preferred embodiment the reaction member further comprises at least one outer supporting member which supports said vanes along at least some of their length.

By providing at least one supporting member for the vanes the advantage is provided that the tendency for the vanes to flex or vibrate is reduced or eliminated.

In a preferred embodiment said reaction member comprises two said outer supporting members attached to said vanes along opposing edges of said vanes.

In another preferred embodiment said vanes are supported substantially along their whole length.

By providing supporting members along the entire length of both sides of the vanes the advantage is provided that the reaction member becomes enclosed and as a result a maximum reaction force from the combustion of the fuel air mix is applied to the reaction member.

In a preferred embodiment said outer supporting members extend to at least partially cover the compression fan. By extending the outer supporting member to shroud the compression fan more efficient transfer of fuel and air mixture is provided between the compression fan and the reaction member.

In a preferred embodiment said vanes at their smallest radial distance from the axis of the reaction member are at an angle substantially tangential to the outer radius of the compression fan.

By starting the vanes at approximately a tangent to the compression fan the advantage is provided that the fuel air mixture exiting the compression fan enters the reaction member with least resistance from the vanes.

In a preferred embodiment, said housing has at least one further inlet, adapted to allow a flow of cooling air to be entrained between said housing and said reaction member.

In another preferred embodiment, said reaction member has further vanes extending outside of the supporting members of the reaction member, and adapted to provide the flow of cooling air.

In a preferred embodiment, said further vanes are adapted to provide said flow of air at a pressure substantially equivalent to a pressure of combustion products of the burning of the fuel and air mixture immediately adjacent a maximum radius of said reaction member Preferred embodiments of the present invention will now be described, by way of example only, and not in any limitative sense, with reference to the accompanying drawings in which: Figure 1 is a schematic cross-sectional view of a gas turbine engine of the prior art; Figure 2 is a cross-section view of an engine of a first embodiment of the present invention ; Figure 3 is a cross-sectional view, along the line A-A, of the engine of Figure 2; Figure 4 is a cross-sectional view of an engine of a second embodiment of the present invention; Figure 5 is a cross-sectional view of the engine of Figure 4; and Figure 6 is a cross-sectional view of an engine of a third embodiment of the present invention.

Referring to Figures 2 and 3 an engine 30 comprises a housing 32 having inlets 34 therein. Engine 30 also has a compression fan 36 coaxially mounted with reaction member 38. Compression fan 36 is mounted on and fixed with respect to hollow axle 40 and reaction member 38 is mounted on and fixed with respect to axle 42.

Mounted within axle 40 is a further axle (or free spindle) 44.

Free spindle 44 is free to rotate relative to axle 40 and compression fan 36, and relative to axle 42 and reaction member 38, by virtue of its mounting on first bearing assemblies 46 and second bearing assemblies 48. Axle 42 is mounted on bearings 50.

Casing 32 extends around reaction member 38 to form volute 52 and extends to form a further volute which extends around nozzle ring 53. Adjacent to nozzle ring 53 is turbine wheel 54 which is connected to compression fan 36 via axle 40. The engine 30 further comprises exhausts 56.

Reaction member 38 comprises vanes 60, flame grid 62 and supporting members in the form of side casings 64. Adjacent pairs of vanes 60 define sections 66 which are themselves divided by flame grid 62 into diffusion zones 68 and combustion zones 70. Each vanes 60 may be divided into two sections, 60a and 60b, on either side of the flame grid 62. The compression fan 36 has vanes 72 which have vane tips 74.

The operation of the engine 30 shown in Figures 2 and 3 will now be described. It will be appreciated that Figure 2 is a view along the line B-B in Figure 3.

A mixture of fuel and air enters engine 30 via inlets 34. The mixture is drawn into compression fan 36 which causes an increase in the pressure of the mixture. From the compression fan 36 the mixture is directed towards the reaction member 38.

The rotation of the compression fan 36 causes the vane tips 74 of vanes 72 to define a circle (which as shown in Figure 3 approximates to the outer rim of the compression fan). The mixture is directed by the compression fan substantially tangential to this circle. Because the compression fan 36 is rotating in a first sense or direction D (as shown in Figure 4) and the reaction member 38 is rotating in a second sense or opposite direction E, the velocity of the fuel and air mixture entering-the reaction member 38, relative to the reaction member 38, is approximately the sum of the external rim velocity of the compression fan 36 and the internal rim velocity of the reaction member 36.

The reaction member 38, which encloses the compression fan 36, receives the mixture into the diffusion zone 68 between adjacent pairs of vanes 60. The geometry of the diffusion zone 68 is designed to receive the mixture at high velocity and efficiently exchange that velocity for pressure. For example, if the mixture is travelling at subsonic speeds, as the mixture enters the reaction member 38 it firstly enters the diffusion zones 68 between adjacent pairs of vanes 60. As the mixture moves radially outwards through the reaction member 38, the volume into which the mixture is moving increases, due to the radial divergence of the vanes 60. This increase in volume is exaggerated as the side casings 64 of the reaction member 38 diverge from the point of entry of the mixture. This increase in volume causes the velocity at which the mixture is travelling to reduce, which in turn increases the pressure of the mixture. Alternatively, (and not shown in the Figures) if the mixture is travelling at supersonic speeds, as the mixture enters the reaction member 38 it firstly enters the diffusion zones 68 between adjacent pairs of vanes 60. As the mixture moves radially outwards through the reaction member 38, the volume into which the mixture is moving decreases, due to the geometry of the vanes 60. This decrease in volume causes an increase in the pressure of the mixture.

This increase in pressure continues until the mixture reaches the flame grid 62. The grid 62 consists of a perforated sheet of a material which can withstand the temperatures experienced within the reaction member 38. The flame grid 62 acts as a bluff body. As the mixture passes through the perforations it is caused to increase its velocity relative to the velocity of the mixture immediately before flame grid 62. Once through the perforations in the flame grid the mixture becomes turbulent and decreases its velocity thereby filling the space immediately behind the material (non-perforated part) of the flame grid 62. Flame grid 62 marks a boundary at which combustion of the fuel air mixture occurs. The combustion takes place in the turbulent zone immediately behind the flame grid and is maintained there by the flame grid as a result of the increase in the velocity of the mixture as it passes through the perforations. This increased velocity must be greater than the flame speed of the fuel air mixture in order to retain the flame front at the flame grid 62.

The combustion of the mixture causes a rapid increase in the gaseous volume contained within the combustion zone 70 of each section 66 of reaction member 38. These gases continue through the combustion zones 70 and upon exit from the reaction member 38 apply a reaction force at a radius to the axis of the reaction member 38 turning it in an opposite direction (or sense) to the direction of movement of compression fan 36.

As the radial distance from the flame grid 62 of the reaction member 38 increases, the geometry of the combustion zone 70 is designed to suit the expanding combustion gases. The distance between the side casings 64 may be varied or the curvature of the vane 60 may be varied or a combination of both so as to control and direct the combustion gases to the exit of the combustion zone 70 of the reaction member 38 where the reaction force is generated. The curvature of the vanes 60 and the shape of the sides casings 64 are such that they create nozzles at the exit of the combustion zones 70. These nozzles are sized so as to optimise the velocity of the gases as they exit the reaction member 38. Furthermore, the nozzles are angled, by curvature of the vanes 60 so as to cause the gases to exit at an optimum angle thereby applying an optimum torque to the reaction member.

By using the compression fan to force the fuel air mixture into the section 66 of reaction member 38 at high velocity, and then initially increasing and then decreasing the volume within each section 66 and causing the combustion of the fuel air mixture adjacent the flame grid 62, approximately half way along each section 66, this causes each section to act in a similar manner to a ram-jet resulting in a efficient conversion of the combustion energy into mechanical energy.

The external surfaces of reaction member 38 are cooled by air drawn in through air inlets 58. The cooling air is entrained into the gas stream at the maximum radius of the reaction member 38.

The combusted gases from the reaction member 38 and entrained cooling air are directed via volute 52 and nozzle ring 53 towards turbine wheel 54. The velocity of the gases causes turbine wheel 54 to rotate before the excess gas is exhausted through exhaust 56. The rotation of turbine wheel 54 causes the rotation of axle 40 which is connected to compression fan 36. It is therefore the exhaust gases turning turbine wheel 54 which result in the compression of the fuel air mixture by compression fan 36.

In order to start engine 30, axle 42 is rotated. This can occur by the application of electrical power to the generator attached to axle 42, the generator thereby acting as an electric motor and causing the axle 42 to turn. Alternatively, another starter motor can be used to cause the rotation of axle 42. The resulting rotation of axle 42 causes the rotation of reaction member 38 which draws the fuel air mixture through inlets 34. Once the velocity of the fuel air mixture exiting the reaction member 38 is marginally greater than the flame speed of the mixture, the mixture is ignited. The combustion gases are directed through the turbine which drives the turbine wheel 54 which drives the compression fan 36. The speed of the reaction member 38 is then adjusted so that the flame flashes back and settles on flame grid 62. Once this has occurred the reaction member 38 will now drive the generator continuously whilst the air/fuel mixture is available.

The engine runs efficiently under a continuous load, but is not designed to provide power against a varying load. This type of engine is therefore most suitable for electricity generating and could for example be used in an electric car. The engine can be used to generate electricity to recharge batteries whilst the vehicle is moving. Although there are power losses from the conversion of mechanical to electrical energy, the efficient nature in which the engine runs make these power losses acceptable. The engine is able to run so efficiently as a result of its lack of reciprocating parts and the use of air cooling which negates the requirement for a water pump and heat exchanger with their associated losses in engine efficiency.

Referring to figures 4 and 5, in which parts common to the embodiment of figures 2 and 3 are denoted by like reference numerals but increased by 100, an engine 130 has a compression fan 136 and a reaction member 138. A side casing 164 extends, at 176, to partially enclose compression fan 136. By enclosing the compression fan within the reaction member, the transfer of the fuel and air mixture is more efficient.

The reaction member 138 also has further vanes 178, which assist the entrainment of the cooling air, actively drawing it into the engine. As an alternative to the frame grid 62 (in Figures 2 and 3), the vanes 160 are thickened at 180 so as to reduce the cross-sectional area, measured in a circumferential direction, of the space defined by two adjacent vanes, until the point were the frame front is to be ideally located, and then the cross-sectional area rapidly increases again. This shape has the effect of acting as a single bluff-body as opposed to the multiple bluff-body resulting from the flame grid. The fuel air mixture increases its velocity as cross-sectional area between the vanes decreases. The space between the vanes is reduced so as to increase the velocity of the fuel such that it is faster than the flame speed of the fuel/air mixture and thus the flame front is maintained at this location.

Referring to Figure 6, in which parts common to the embodiment of figures 4 and 5 are denoted by like reference numerals but increased by 100, reaction member 238 has further vanes 278.

The length and location of these further vanes specifically compresses the cooling air to a pressure approximately equal to the pressure of the combustion gases resulting from the burning of the fuel air mixture as they leave the reaction member 238.

Attached, in Annexes I and II, are set point calculations for the temperatures and pressures throughout the process and an engine efficiency is also calculated. The calculations in Annexe I are based on the assumption that the secondary compression, occurring in between the first sections 60a of vanes 60 in reaction member 38, is a ram compression. The calculations in Annexe II are based on the assumption that the secondary compression is diffusion compression.

It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only, and not in any limitative sense, and that various alterations and modification are possible without departure from the scope of the invention as defined by the appended claims.

TanJet Engine. Set Point Calculations.

It is assumed that petrol fuel is vaporised and mixed with air at a ratio of 22 : 1 prior to the impeller. The temperature of combustion will be in the region of 21800K and cooling air is entrained after the tangential jet reaction. A mass flow of 0. 25Kg/sec is assumed. Ratio of specific heats is taken as 1.333 for air/fuel mixture and a CpGAS value of 1.150 KJ/Kg. K 1/Compression. (Impeller) <BR> <BR> A slip factor of 0.835 is catenated for a 12 vane impetter. The impeller peripheral<BR> speed U1 is 460als ; Inlet temperature is 288bk ; Inlet pressure is 1.01 bar. An isentropic efficiency of 81% is assumed (ie 90% impeller x 90% diffuser) over the whole compression process.

Mass flow of air/fuel mix ; mmix:= 0.25. kg. sec Ratio of specific heats; γ:= 1.333 Specific heat (gas); CpGAs:= 1150. joule<BR> kg x K Slip factor; #:= 0.835 Compressor efficiency; compressor:= 0.90 Inlet temperature ; T1:= 288.K Inlet pressure; P1 : = 1.01 x 105 . Pa Compressor rim velocity; U1 := 460 . m sec Temperature cfter impetier Ideal temperature after impeller T 2 = T1-h [(T2--Tl) X Ncompressor] T 2 = 426. 276K Pressure after impeller, Compressor power required ; Powercom := mmix x CpGAS X (T2-T1) Powercom = 4.417 x 104 watt 2/ Compression. (Diffuser) Air/fuel mixture leaves the compressor and enters the reaction wheel diffusion zone at a combined velocity of U1 + U2 and the velocity prior to combustion is U3 relative to the reaction wheel. The velocity of the mixture entering the diffuser is higher due to the rotation of the reaction wheel in the opposite direction to the impeller. An isentropic efficiency of 81% is assumed for the whole of the compression process. (ie 90% impeller x 90% diffuser) Inner rim velocity ; u2= 150 m sec Velocity prior to combustion; U3 := 75 . m sec Diffuser efficiency; #diffuser := 0.90 Temperature after diffusion : T3 = 563. 222K Ideal temperature after diffusion; T_3 := T2 + [ (T3-T2) x #diffuser] T_3 = 551.063 K Pressure after diffusion ; P3<BR> Diffusion pressure ratio; = 2.426<BR> P2<BR> P3<BR> O/all pressure ratio; = 11.655<BR> P1 Power required from reaction Powerram := mmix x CpGAS x (T3 - T2) wheel for ram compression ; <BR> <BR> <BR> .Powerram = 3.495 x 104 watt 3/Temperature of Combustion, A combustion efficiency of 95% is assumed and the pressure drop is 5% of pressure P3. The calorific value of petrol fuel is 43 MJ/Kg and the afr is 22:1. <BR> <BR> joule<BR> Air/fuel ratio ; afr := 22 Fuel calorific value; Fuelcv:= 43 x 106 x<BR> kg<BR> Combustionefficiency #combustion : = 0.95<BR> Energy supplied; Heatin := mmix x Fuelcv x #combustion Heatin = 4.642 x 105 joule<BR> afrsec<BR> Heatin<BR> Temperature after Combustion; T4 := T3 + T4 = 2.178 x 103 K<BR> mmix x CpGAS Pressure after combustion ; P4 =. P3 x (1.--0. 05) P4 1. 118 x 106Pa 4r Tangential Reaction.

The hot pressurised gas is to partially expand through the tangential nozzles, the reaction from which, will cause the reaction wheel to rotate and provide useful output power. The power output reaction factor is adjusted iterativefy to ensure that enough energy is left in the fluid to power the turbine. (The power output represents the useful shaft power output+ the ram diffuser effort (section 2) + the cooling air delivery effort (section 5).) An isentrop efficiency of 90% is assumed for the reaction nozzles.

Nozzle efficiency ; reaction.-o. 90 Power output reaction factor ; RFpower : = c 4835 Power out; Powerout := RFpower x Heatin Powerout = 2.244 x 105 watt (Power out is shaft power + ram diffuser effort + cooling air delivery effort.) Temperature prior to reaction; T4 = 2.178 x 10³ K <BR> <BR> Powerout<BR> Temp' after reaction; T5 := T4 - T5 = 1.397 x 10³ K<BR> mmix x CpGAS Temperature drop; T4 - T5 = 780.671 K <BR> <BR> (T4 - T5)<BR> Ideal temp' after reaction; T_5 := T4 - T_5 = 1.31 x 103 K 'n reaction Pressure before reacTiont P4 = 1. 11S x 106Pa Pressure after reaction ; 5/ReactionVheel Cooling.

The hot pressurised gas is contained within the walls of the rotating reaction wheel Cooling air is delivered across the walls by radial vanes attached to the out side of the reaction wheel. The vanes act like an impeller and are designed to deliver the cooling air at the same pressure as the hot combustion gases after partial expansio through the nozzles. This cooling air is entrained by the high velocity of the primary combustion gases emerging at the reaction radius. The total mass flow is estimated at 2.75 times the initial mass flow because an AFR of 60.5 : 1 (2. 75 x 22) would give a cooler combustion temperature of 11500iC. The cooling air entering the system is at 2889t and the CD value is 1.005 KJ/Kg. K. Ratio of specific heats for air is taken as 1.4 Total mass flow ; (after reaction wheel) Assuming that the outer vanes on the reaction wheel are similar in configuration to the impeller then the slip factor will be the same and the caEculation will be similar to section one. The efficiency be lower, say 80% Mass flow; mcoolair := mtotal - mmix Cool air vanes efficiency; #vanes := 0.80 Ratio of spec' heats; γair : = 1. 4 Inlet temperature ; T1 : = 288 x K <BR> <BR> Specific heat (air); CpAIR := 1005. joule Inlet pressure; P1 = 1.01 x 105 . Pa<BR> kg x K Pressure after vanes; Pvtips := P5 Pvtips = 1.464 x 105 Pa Slip factor; # := 0.835 Ideal ! temperature after vanes ; 1'air-1 lait r Tvtips : = Tl x--Ttips = 320. 208 K i emperature after vanes ; TVtips = T1 + 0 (_vtips T1) 1 L rivanes j tips= 328. 26K 'vanes Vanes rim velocity ; L(Ti'tips-Tl Y CpAIRJ m Uye es : = I-'-Uvalles = i a see o sec Cooling air delivery effort ; Powervanes := mcoolair x CpAIR x (Tvtips - T1) Powervanes = 1.77 x 104 watt Temperature after entrainment of cooling air with gas, (mmi ; x CpGAS x T5) + (mcoolair x CpAIR x Tvtips)] (ncoolair x CpAiR) + (mmx x CpQAs) T5s== 750. 865 K 6/Turbine The gas is to expand further through the turbine. The power required at the turbine is to match the power required for the compressor. (This is accomplished by adjustment of the power output reaction factor.) An isentropic efficiency of 85% is assumed for a turbine with constant mass flow.

Final press'is same P6 : = pi Turbine efficiency ; Turbine : =0. 85 as initial press'; mtotal = 0.688 kg P5 = 1.464 x 105 Pa sec Ideal temp'after expansion ; Temp' after expansion; T6 := T5e - [(T5e - T_6) x #turbine] T6 = 694.366 K Turbine power output; Powerturb := mtotal x CpGAs x (T5e - T6) Powerturb = 4.467 x 104 watt Compressor power required ; Poxvercom = 4. 417 x 104watt Engine efficiency ; (PowerOutP°>erram-P°wervanes) Xoall : = Eoall = 37.007 % Heatin <BR> <BR> <BR> Shaft power output; Powerout-,Poweram - Powervanes = 1.718 x 105 watt Turbine/compressor power ratio ; Powerturb =1. 01. 1 Powercom TanJet Engine. Set Point Calculations.

It is assumed that petrol fuel is vaporised and mixed with air at a ratio of 22 : 1 prior to the impeller. The temperature of combustion will be in the region of 2175°K and cooling air is entrained after the tangentiai jet reaction. A mass flow of 0. 25Kg/sec is assumed. Ratio of specific heats is taken as 1. 333 for air/fuel mixture and a CpGas value of 1,150 KJ/Kg.K 1/Compression. (Impeller) A slip factor of 0.835 is calculated for a 12 vane impeller. The impeller'peripheral speed U1 is 460m/s; Inlet temperature is 2880K ; Inlet pressure is 1.01 bar. An isentropic efficiency of 81% is assumed (ie 90% impeller x 90% diffuser) over the whole compression process kg<BR> Mass flow;mmix := 0.25 x sec Ratio of spec'heats ; y : = 1. 333 Specific heat (gas); CpGAS := 1150 x joule<BR> kg x K Slip factor ; # : = 0.835 Compressor efficiency ; #compressor :=0.90 Inlet temperature; T1 := 288 x K Inlet pressure ; p1 := 1.01 x 105 x Pa Compressor rim velocity ; U1 := 460 x m sec Temperature after impeller ; <BR> Ideal temperature after impeller; T_2 := T1 + [(T2 - T1) x #compressor] T_2 = 426.276 K Pressure after impel'er, Compressor power required ; Powercom := mmix x CpGAS x (T2 - T1) Powercom = 4.417 x] 04 wa. t 2/Compression. (Diffuser) Air/fuel mixtureleaves the conipressor and enters the reaction wheeldiffusion zone at a combined velocity of U1 + U2 relative to the diffuser. The velocity of the mixture entering the diffuser is higher due to the rotation of the reaction wheel in the opposite direction to the impeller. An isentropic efficiency of 81% is assumed (ie 90% impeller x 90% diffuser) over the whole compression proçess.

Inner rim velocity ; U2 := 150 x m sec Compression efficiency ; compression : =o. 8i Temp'after diffusion ; Ideal temp' after diffusion; T_3 := T1 + [(T3 - T1) x #compression] T_3 = 506.843 K Pressure after diffusion ; p"<BR> Diffusion pressure ratio ;-L=2<BR> P3 O/ail pressure ratio; = 9.609 P1 Effort req'd from reaction<BR> wheel for diffusion ; Powerram := mmix x CpGAS x (T3 - T2) <BR> Powerram = 3.35 x 104 watt 3/Temperature of Combustion.

A combustion efficiency of 95% is assumed and the pressure drop is 5% of pressure P3. The calorific value of petrol fuel is 43 MJ/kg and the afr is 22:1.

Air/fuel ratio ; afr : = Fuel calorific value; Fuelcv := 43 x 106 x joule<BR> kg<BR> Combustionefficiency #combustion := 0.95<BR> mmixx Fuelcv x #combustion joule<BR> Energy supplied; Heatin := Heatin = 4.642 x 105<BR> afr sec<BR> Temperature after Combustion; T4 := T3 + Heatin T4 = 2.173 x 10³ K<BR> mmix x CpGAS<BR> Pressure after combustion ; P4 := P3 x (1 - 0.05) P4 = 9.219 x 105 Pa<BR> 4/Tangential Reaction.

The hot pressurised gas is to partially expand through the tangential nozzles, the reaction from which, will cause the reaction wheel to rotate and provide useful output power. The power output reaction factor is adjusted iteratively to ensure that enough energy is left in the fluid to power the turbine. (The power output represents the useful shaft power output _ the ram diffuser effort (section 2) + the cooling air delivery effort (section 5).) An isentropic efficiency of 90% is assumed for the reaction nozzles.

Nozzle efficiency; #reaction := 0.9 Power output reaction factor ; RFpower := 0.45 Power out PowerOut := RFpower x Heatin Powerout = 2.0S9 x 105 watt (Power out is shaft power +ram dirfuser effort + cooling air delivery effort.) Temperature prior to reaction; T4 = 2.173 x 10³ K Temp' after reaction; T5 := T4 - T5 = 1.446 x 103 K mmix x CpGAS Temperature drop ; T4 - T5 = 703.976 K Ideal temp' after reaction; T_5 := T4 - (T4 - T5) T_5 = 1.365 x 103 K #reaction Pressure before reaction ; P4 = 9.219 x 105 Pa Pressure after reaction ; 5/ReactionWneel Coolinq.

The hot pressurised gas is contained within the walls of the rotating reaction wheel. Cooling air is delivered across the walls by radial vanes attached to the out side of the reaction wheel. The vanes act like an impeller and are designed to deliver the cooling air at the same pressure as the hot combustion gases after partial expansion through the nozzles. This cooling air is entrained by the high velocity of the primary combustion gases emerging at the reaction radius. The cooling air entering the system is at 2880K and the CD value is 1. 005 KJ/Kg. K Ratio of specific heats is taken as 1. 4 for air Tota ! mass flow ; (guessed) (after reaction wheel) kg<BR> mtotal := 3 x mmix mtotal = 0.75 sec Assuming that the outer vanes on the reaction wheel are similar in configeration to<BR> the impellor then the slip factor will be the same and the calculation will be similar to section one. The efficiency will be lower, say 80% Mass flow; mair := mtotal - mmix Cool air vanes efficiency; #vanes := 0.80 Ratio of spec'heats ; γair := 1.4 Inlet temperature; T1 := 288 x K Specific heat (air) ; CpAIR= 1005x joule Inlet pressure; ; Pl =. o] x 105xPa<BR> kg K Pressure after vanes ; pvtips := p5 pvtips = 1.436 x 105pa Slip factor ; # : = 0. 835 Ideal temperature after vanes ; 7air-1 % air T-T ("S r_V2PpS = rl X (-p] ips = 3l8 467lÇ Temperature after vanes ; _ 1 vtips Tl +---------Ivttps = 326. 0b4K ) vanes Vanes rim velocity ; TVanes _ lTis-'l X CpAIR y ; anes = ? 14. 097 in aCY seo o sec Cooling air delivery effort; Powervanes : = mair x CpAIRx (Tps-Ti) Power vanes = 1.914 x 10 watt Temperature after entramment of cooling air with gas ; [(mmix X CpGAS X T5) + (mair x CLAIR x TvtipS)]<BR> T5e : _<BR> (mair x CpAir) + (mmix CpGAS) , T5e = 733.729K 6/Turbine.<BR> <P>The gas is to expand further through the turbine. The power required at the<BR> turbine is to match the power required for the compressor. (This is accomplished<BR> by adjustment of the power output reaction factor.) An isentropic efficiency of 85% is assumed for the turbine.

Final press'is same p6 : =p1 as initial press'; Turbine efficiency ; #Turbine : = 0. 85 kg 5<BR> mtota = 0. 75 g Ps = 1.436 x 105Pa<BR> sec Ideal temp'after expansion ; Temp' after expansion ; T6 : = T5e - [(T5e-T_6) x #turbinee] T6 = 681. 235K Turbine power output ; Powerturb : = mtotal x CpGAS x (T5e-T6) <BR> <BR> 4<BR> Power = 4.528 x 10 watt Compressor power required ; Powercom = 4.417 x 104watt.

(Powerout-Powerram-Powervanes)<BR> Engine efficiency ; Eo<BR> Heats Eoall = 31.352% 5 5haft power oUTpUt ; Powerout-Powerram-Powervanes = 1.563 x 10 watt <BR> Turbine/compressor power ratio Powerturb = 1. 025 Powercom