noc20-ae13-lec35_Lecture-35: Performance/cycle analysis: Turboshaft, and Propfan
Okay. So, we. Have started. Discussing, about the. Turboprop. Engine then now we are going to move to that turbos opting, in and, then. We. Will continue, with the some of the other parts. But let's, look, at the, turbo. Cept, because. What we have finished, like, the comparison, with the turboprop. With the turbo. Fan. And. Now we are going to look at the turbo. Shaft so. This. Is also going to be a small section, this. Also kind. Of engine, is a form of gas turbine, which. Is optimized, to produce a produce. Sub. Power other than jet thrust so, this produces. Shaft. Power not, the jet thrust, generally. A turboshaft, engine is made up of two major components, one. Is the. Gas. Generator. Another. Component, is the power. Section. So. The. Gas generator consists. Of one or more compressor. Combustor chamber. Or. Turbine, and the, power section, actually, consists. Of an, additional. Turbine or, a gear, reduction, system. And the shaft output, so. There. Are a different, example. Of turbo shaft. Manufacturer. Like. One is the biggest is pratt & whitney they, have PT 6 and 56. Pt6a. These are the engines then. Ge also manufacture, some of this like, it, has a. 61-62. Then. Also. So, that power this aircraft, so the engine is. The. 700. Or CT. 7 these are the Indian. Then. Also Allison. Indian, company, like. Coming Rolls. Royce all. These, answers the Soviet also. They also manufacture. This, kind of turboshaft. Engine just. To look. At the, analysis. Of a turboshaft, engine let's see if we look at a, single. Pull engine then. The ingenuity, the schematic, will look like this. We, have a. Like. Then, there is a. Turbine. Sitting, there, then. You, have the, load. So, this is an single. Spool. Turbo. Shaft. Schematic. So. One can think a. -. There. Is the combustion chamber. And. Then three. This. Is four. Five. So. You. Can see this the, load is driven by the same gas generator, Sept, or. Given, by the free turbine. So. This is a single spool, configuration. And. The. Similar. One. We can. So. The, TS diagram if we plot, of the. Same engine it. Will look like starting. From here, it will go there and, then. From there. It. Will come here so. This is 3. Here. The PA is, P naught 2, equals. To P 5, this. Is 5. This. Is 4. So. That's. The, and. If. We look at so. It. Has them. We. Can. Single. Pool engine. So. This is some analysis. Would be quite similar to, turboprop. Now. What. We can do the single. Pool engine. Spool. Engine we can look at the turbine. The. Turbine. Drives both the compressor, and the load so. Assuming. Full expansion in the turbine so. The shaft. Power would. Be 1 plus F minus, B ETA. MTW. T minus, WC, by ETA. MC where, F is the fuel air ratio B, is the bleed ratio and the, mechanical efficiency is, ETA. Empty, compressor. Efficiency is, ETA MC now. The shaft, which drives a load, it. Could be the, load which means let us say for example the, rotor of the helicopter. Experiences. Some of the mechanical, losses due to friction. So. The W load would be e TM, w, shaft. So. Then. We. Can find out the P load would. Be m. Dot a, w. Load so. That's, how we can get it now. Similarly. Like. A single. Spool, we. Can have, an to. Spool turbo shaft also and, there is a different, station number, and if. You draw the th. Diagram similarly. Here, this. Is where from where it goes like that so. This. Is 3, this is, 4. And. This. Is 5. This. Is, 6. P. A P. Naught 2 P. 6. So. Now. The twin spool also now. If you look at the. Gas. Generator. Turbine. So. If, you have the gas generator turbine. So, that point provides. Sufficient. Energy to draw the compressor. Thus. The. Outlet, temperature is, obtained from the energy balance and, how. Do we get it is. A simple. Similar. Analysis. That we have done it, is WC, by ETA, MC. So. That. Gives her t naught v is T naught 4, minus. CP C. T. Naught 3 minus, T naught to. CP. T, ETA. MC, e, TM. T 1 plus F minus B and, similarly. We. Get P naught 5 is P, naught 4. 1. Minus. T. Naught 4 minus, T naught 4 by. ETA. TT naught 4. So. Now. Free. Power, turbine. The. Free power turbine, if we look at the, gases, are. Basically. Have a complete, expansion. And. To the ambient pressure so, the power delivered, to the load would, be P, load is. M. Dot a 1 plus f -, B. ETA. M CP. Ft. T, naught 5 1. Minus, P a by, P. Naught 5. Gamma. T minus 1 by gamma T, so. That's. How the, analysis. Actually. Holds. For. Turbo. Shaft. Engine. Now. So. That's how you, can have single pool or double spool, turbo. SEP imeem, the detail other component. Detail analysis we can carry out in the similar fashion that we have done for turboprop, or any other, turbine. Engines now, that will move to the, one which is is. Propeller. Fan. Okay. So. This is a modern. Type, of aircraft, engine related to concept, of both the turboprop, enter, both, so. That somehow uses. Both the concept, of turboprop. Plus. Turbofan. So. That sort of a combination but. Distinct, from both the. Engine uses a gas turbine to drive a unshielded. Propellant, like a turboprop, but. The propeller itself, is designed, with. A large, number, of. Short. Highly. To state to, state blades similar. To the turbofan, engine. For. This reason the propeller, fan, has been variously, described, as this. Could be called as. Unducted. Fan. You, behave or. Call. Open. Rotors. Which, is our or. It. Could be called ultra. High.
Bypass. That. Is you HB. Turbo. Fan. So. This, could be also said like that now. It. Has. A small, diameter highly. Loaded multiple. Bladed variable pitch popular.i. Propulsor. Having. Swept wide, quad blades, so. Propeller, friend is designed. To operate with a turbine, engine and using a single stage reduction, gear so. It has in. Reduction. Gear. That. Results, in high performance so, the performance is high, so. The design is sort. Of intended, to offer the performance, of a turbofan with the fuel economy of turboprop. So. Most common arrangement of propeller fan is a to spool gas generator, to. Spool. Gas. Generator. And, after. Located gearbox, diving a.push are found, so. With. Apt. Look. At it. Gearbox. Driving. A. Push. Are fun. So. These fan produces, the majority, of the thrust. It. Has number of blade which is greater than the propeller, of turboprops, but. Less. Than those of fan in the turbofan. Similarly. Da. So. One. Can see. Like. There. Are also some, historical. Things. There, is a history, behind this kind of things so. Like. Some. Old. Like. Here is an example, of open rotor, so. This, is. Like. This is a G. Introduced. This unducted. G36. This. Is an, apt. Mounted. Open rated fan system, with. Two rows of counter-rotating. Composite, fan blades. So. This was in 1980s, it is of the, pusher configuration. The. Core was based on GF not for military target and so. Exhaust gases were discharged, through a seven stage LP. Turbine. Each stage ring was designed to move freely, so. The turbine rotor driver on propeller, while the other propeller, is connected. To the on earth. Turbine. Stator and all this. So. The, total the in, effect that power turbine has 14, stages which, you can see here. Now. The. Other. One which, one. Can see. Is also. The, one which is shown here. Which. Is inducted. Fan in md80. Okay. So. This, is another. One. Which is. Example. Of that. Nature. So. Pratt. And Whitney engine, one. Can see, also. There. Are I, mean. Other engine manufacturer, which. Also, they. Produce some engines of this. Kind of propeller, fan and they. Are in. To. Some extent, like this, is another one which is pattern. Hundred five seventy, eight DX. Which. Is. Nineteen. Eighty, this. Also, having. A reduction, gearbox between, LP turbine and the propeller blades. So. Now. The. Some. Progress, been, made so. This is our. Twenty, seven propeller, fam so this was developed by USS, R, so. This is even conventional ill note with prop propeller. Fan blades, in front. So. It, is used for propelling a in, 70, aircraft, so. This. Was used for in 70. Aircraft. So. Typically. If. You look at the classification, of the propeller from there are two different types one is the tractor type so if I look, the prop. Fan. Then. There could be. Tractor. Type, or. It. Could be. To. Shut type so. These are the two different. Category. Which can be possible, and. The. Tractor. Type, propeller. Fan is similar to so this is one of the. Kind. Like it. Could be saying the tractor. Time, or. You. Can say puller. Type so. This is an similar. To forward fan with the fan placed. So. This is again. The tractor. Fan. Can. Have, two. Different kind. One. Is the single. And. Another. Is the counter, contra, contra-rotating, or. Counter-rotating. Whatever it is so. The. Example. Of. Contra. Rotating, is. This. One, you. Can see this is the contra, rotating, so. That. Is what is shown there this forward rotor has eight. Bladed, while the rear is six plated and the. Pusher, type if. One has to see this is a pusher, type typical, arrangement of the turbofan. Where. It. Is similar to the apt fan where. The fan is coupled. To the, turbine, it is always, of the contra. Rotating type. So. The. Two fan rows are. Driven. By free turbine this type would, be more elegant, as the engine would be placed behind the, rear. Pressure, bulkhead. In the fuselage, minimizing. The noise it. Also allow an aerodynamically, clean, wing. Now. One. Can. Compare. This. Like. Between. Turbo. Prop. Turbo. Fan. And. Propeller. Fan. So. If you compare, that propeller. Fan engines have the best known. Propulsion, efficiency. Sindelle. Single. Rotation propeller, engines. Have propulsion, efficiency around, eighty percent where, contra-rotating, can, go up to ninety percent so. Main feature or propeller, fan. Engine. Versus. Both turboprop. And turboshaft. Are. Quite. Significant. So. Also.
We Can see that. Like. For. Example we. Can go here, and see this comparison, between. All these turboprop. Turbofan. And this. You. Have. This. But. You. Can see the, propeller, fan number of blades, compared. To turbofan, lays but more, than these diameter. Is smaller, power. Is larger, blade, type Swift. Maximum. Thickness thinner, tip, speed, supersonic. Bypass. Ratio is 25, propulsion. Efficiency higher. Es. FC is, there. Mach number is around point seven, six eight seven cruising. Altitude, is 11000 but, open rotor play. Some. Post, some technological challenges. Which. Like, like. The open rotor kind of configuration. Like. Noise and. Vibration. Like. Then. Structural. Re-enforcement. Of. Fuselage. And. Wings. So. Your. Worthiness. Your. Worthiness. Consideration. Engine. Installation. And mounting. Gearbox. Cooling. And. Reliability. Then. Design. Of. Efficient. Counter. Rotating. Components. So. These, are some of the challenges. With. Then. Competing technologies. Because. Obviously. That, is another. Competing. Technologies. So. The current, technology. Engine is, improving. On an average 1%. Per year which means that traditional, turbofan, engine available in 2020, are. Likely. To be at least 11 percent, more efficient than 2010. Production so. That's an, major. Technological, breakthrough. Then. We, can another. Is the slower. Aircraft. Operating. Speed. Operating. Speeds. So. These, are the some. Of these challenges, with out there and you can see these so. The, other thing what what is also possible, that on. This. There, is a possibility of, this. Is a three, spool, configuration. So. That is also possible this, is the unducted 3 spool configuration. And you. Have all these, kind. Of I mean. This is just an example that this is also possible, and you, can have a th, diagram for, these and, you can similarly look at the analysis, so. For example, a. 2. To. 2. To 11. Goes. 3. This. Is 11, this, is a. 0. To. Zero. Four. So. This is zero five zero. Six. Seven. Eight. So. Nine. So. This. One is. Zero, it is. This. Is Delta. H. This, is Alpha. Delta H. Now. This. One would be 9s. And. Here. One. Can have. This, goes right there, so. This is, zero, one zero and. That. Also. Connect. To e, and. This. Is 12. Ok, so these are the different, portion, now, one can do this analysis, which. Could be quite. Sort, of straightforward, so, one, has to look at first the. Intake. Which. Is this is probably the last one, that, we would like to discuss, on turbofan, and that would pretty much, finishes. The so, if you have the let's say the flight. Speed. Which. Is given, you, and. Then. Ambient. Condition, ta ta. Then. You can find out gamma, RT a, then. At the intake, you can find out the Mach number, you buy a. So. You get the T naught 2 which. Is the relationship, using that. M. Square and, P. Naught 2 so. We have done this so many time bus, probably. So, diffuser or intake efficiency. Minus. 1 by 2 m, square gamma. C by gamma C minus 1. Now. Intermediate. Compressor, so. Inter. Mediate. Compressor. Which. Is 2 2 3 so. Here P naught 3 is P naught 2 into, PI I, PC. So. And. T. Naught 3 equals 2 T naught 2, 1. Plus PI, I PC. To. The power gamma C minus 1 divided, by ETA I PC. Now. Hi. H. PC or high. Pressure compressor, which is 3 to 4. So. P naught 4 would be P naught 3 into, PI H PC. Similarly. T naught 4 would be T naught 3. 1. Plus PI, H PC. Gamma. C minus one by gamma Z. ETA. HPC. Combustion. Chamber which is four to five. Where. P, not v is P, naught 4, into. 1 minus, Delta P. You see and, it. Is 1 minus B. Into. CPCC. T. Naught 5 minus, CP, CT not 4, divided. By ETA B QR, minus. CPCC. T. Naught 5. Then. HP. T that's. 5 to 6, so. Energy, balance, for higher pressure, pull. From. Where we get CPC. T. Naught 4 minus, t naught 3, 1. Plus F minus b c. Ph, t. Naught 5 minus, T naught 6. So. Here. We. Are assuming, the, transmission. Efficiency or, the mechanical, efficiency of, the shaft on all these, to. Be 100 percent so. From here we get T naught 6. Minus. F 1. Plus. F minus. V/c. Ph. T. Naught 4 minus, t naught 6 and. P. Naught 6 by P naught 5 which. Is 1 by ETA. HP, t 1. Minus t gnostics, by t naught 5. Which. Will be gamma, h by gamma h minus 1, then. Intermediate. Mediate. Pressure. Turbine, or i. PT. Which, is 6 2 7 again. Energy balance, would give us, T, naught 6 minus, CPC, by 1. Plus CP, h t, naught 3 minus, t naught 2, so. We get the pressure by, P naught 6. 1. Minus, 1 by IP, t. Tea, not seven, by T not, six. Gamma. H by gamma H minus one so. We get from. Here we. Get P not seven. From. Here we get P. Not six, then. You. DF or unducted. Fan. So. Here, T not, ten is T not to, so. P not ten would be PA 1, plus gamma C minus 1 by 2 m square. Minus. 1 so. P not one, is spin, not 1, into PI u DF, so. T. Not won t, not 10. 1. Plus pi u DF. Gamma. C minus 1 divided. By ETA u, DF. So. What we get t, 12 by T not. 11. PA. By P. Not 11. Gamma, C minus 1 by gamma C so. From here we get t 12, so. Unducted. Friend, it would be root over up to. CPC. T. Not 11, minus t 12 so. That's, what we get, and. Once. You get that then. We. Have free, turbine. Which. Is 7 to 8 and. What. Nozzle. Which. Is 8 to 9 so. From here we will write t 9 s equals, to P.
Not 7 by PA. Gamma. H minus, gamma H which, gets out 9 s and, then. Temperature, drop in free turbine node between not 7 minus, T naught 8. ETA. F T, t. Not 7, minus, T naught 8 s. Equals. To ETA, F T into. Alpha. Into. T not 7, minus, T 9 s. So. We get T not 8. We, get do. Not 8s. So. From here we get the pressure ratio. Which. Is T naught 7 by T naught a is gamma, H by gamma H minus 1 so. That gives us, V. Naught 8 and. Then. The. Nozzle exit velocity. Would be 2 CP, h, ETA. N into. T. Naught 8 minus, T. 9s. Now. So. The thrust would. Give, us m dot, 1. Plus if. U. N minus, u. So. That you, get then. Finally, energy. Balance would, give us beta CPC. T. Naught 11, minus T naught 10 equal, to ETA, M unducted. Fan, 1. Plus AP p. H. T. Naught 7 minus, t naught 8, so. From here we'll get. Beta and then. The thrust for which is obtained, throught tu, DF is. Beta m. Dot. UE. UDF. Minus. U, so. The total thrust. Would. Be total, u DF plus T, n, so. And. The. Power, would be. Unducted. Power, would be you. Into, t, UD. F. So. That's. How you, can get and then. Finally. You. Can find out the propulsive. Efficiency. Which. Is T, into, u and. The. Total. Equivalent. Power, is. P. T. Total. Into, u. So. This, is T, into u into. 0.5. M dot into. U. M, minus. U, square plus. Beta. You, undocked. It Fran - you square so. Then you can get the propulsive, efficiency, so. That's. How you. Also can analyze the three spool engine and that's. Pretty. Much. Kind. Of talks. About this turboprop. Turbo, shaft and, turbofan, engines and. Analyses. You have seen already this turbine by cycles how the analysis is carried out so now you'd be able to carry out the similar kind of analysis, so we'll stop the discussion here and continue, in the next session in the other topics.