بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيم
ٱلسَّلَامُ عَلَيْكُمْ وَرَحْمَةُ ٱللَّٰهِ وَبَرَكَاتُهُ

DESIGN BASIS & ASSUMPTIONS

Parameter	Symbol	Assumed value	Unit
Inlet total pressure	P01	40.0	bar
Inlet temperature	T01	450.0	°C
Exhaust pressure	P03	5.0	bar
Mass flow rate	ṁ	2.0	kg/s
Rotational speed	N	3000.0	rpm
Isentropic efficiency	ηt	0.78	–
Mechanical efficiency	ηm	0.97	–
Flow coefficient	φ	0.6	–
Loading coefficient	ψ	1.5	–
Degree of reaction	R	0.5	–
Representative h01	h01	3330.0	kJ/kg
Representative h03s	h03s	2790.0	kJ/kg

Catatan: h01 dan h03s digunakan sebagai representative preliminary values untuk menyelesaikan design case. Pada tahap final, keduanya harus diganti dengan properti steam dari IAPWS-IF97 berdasarkan P dan T/P.

A. Project Title

Perancangan dan Analisis Single-Stage Axial Steam Turbine Berbasis Kerangka DAI5

B. Author Complete Name

Muhammad Pathur Qorib

C. Affiliation

Program Studi Teknik Mesin, Fakultas Teknik, Universitas Indonesia

D. Abstract

Project ini merancang dan menganalisis single-stage axial steam turbine dengan pendekatan thermodynamics, turbomachinery, velocity triangle, stage analysis, loss evaluation, reliability, maintenance, dan sustainability. Sebuah design case diasumsikan agar proses perhitungan dapat ditunjukkan secara utuh: steam masuk pada 40 bar dan 450°C, exhaust pressure 5 bar, mass flow 2 kg/s, dan speed 3000 rpm. Dengan preliminary enthalpy data dan assumed stage isentropic efficiency 78%, diperoleh actual stage enthalpy drop sekitar 421.2 kJ/kg. Perhitungan kemudian diteruskan ke Euler work, blade speed, mean diameter, axial velocity, velocity triangle, blade height, performance, loss breakdown, dan sensitivity analysis. DAI5 digunakan sebagai kerangka berpikir yang menghubungkan kesadaran, tujuan, problem understanding, idealization, dan instruction set dengan keputusan desain.

Kata kunci: axial steam turbine, Euler equation, velocity triangle, DAI5, stage efficiency, turbomachinery, reliability.

E. Author Declaration

E.1 Deep Awareness of I

Perancangan turbin diposisikan sebagai proses pembelajaran engineering yang menuntut kesadaran terhadap tujuan, keterbatasan model, keselamatan, integritas data, dan dampak teknologi. Dalam DAI5, kesadaran ini menjadi dasar agar keputusan teknis tidak hanya mengejar power output, tetapi juga efficiency, reliability, maintainability, safety, dan sustainability.

E.2 Intention of the Project Activity

Intention project adalah memahami dan menunjukkan bagaimana energi termodinamika steam dikonversikan menjadi kerja poros melalui single-stage axial turbine dengan proses yang dapat ditelusuri dari input sampai hasil. Design case asumsi digunakan untuk membuat proses engineering konkret dan dapat diverifikasi.

F. Introduction

F.1 Energy Conversion

Turbin uap mengonversikan penurunan energi spesifik fluida menjadi kerja poros. Pada stage, sebagian enthalpy drop menjadi kinetic energy dan perubahan momentum tangensial pada rotor menghasilkan torque.

F.2 Turbomachinery

Turbomachinery memanfaatkan pertukaran energi antara fluida dan rotating blade. Turbin menggunakan perubahan momentum fluida untuk menghasilkan kerja.

F.3 Axial Turbine

Pada turbin aksial, aliran bergerak dominan sejajar sumbu rotor. Satu stage terdiri atas stator/nozzle dan rotor.

F.4 Axial Steam Turbine

Steam turbine dipilih karena hubungan antara thermodynamic expansion, velocity triangle, Euler work, losses, dan shaft power dapat ditunjukkan secara langsung.

F.5 Working Principle

Steam mengalami ekspansi pada stator, menghasilkan perubahan kecepatan dan swirl. Rotor mengubah momentum tangensial tersebut menjadi kerja mekanik. Kondisi exhaust menentukan residual kinetic energy dan stage performance.

Gambar 1. Skema single-stage axial steam turbine dengan design basis asumsi.

G. Initial Thinking About the Problem

G.1 Problem Understanding

Problem engineering dirumuskan sebagai bagaimana merancang satu stage turbin aksial yang menghasilkan kerja poros dari steam expansion dengan performance yang memadai tanpa mengabaikan aerodynamic losses, mechanical losses, reliability, safety, maintenance, dan sustainability.

G.2 Stakeholder Awareness

Stakeholder utama adalah owner/management, operator, maintenance team, design engineer, safety/regulatory function, serta lingkungan/masyarakat. Setiap stakeholder membawa constraint yang berbeda.

G.3 Contextual Analysis

Konteks teknis adalah preliminary mean-line design. Konteks operasi adalah rotating machinery berenergi tinggi. Konteks engineering mengharuskan keseimbangan antara efficiency, compactness, blade loading, mechanical integrity, dan maintainability.

G.4 Root Cause Analysis

Jika performance rendah, penyebab perlu ditelusuri ke enthalpy distribution, velocity triangle, incidence, profile loss, secondary loss, tip leakage, exit loss, mechanical loss, atau off-design operation.

G.5 Relevance of Analysis

Mean-line analysis digunakan karena mampu memberikan keputusan awal mengenai stage sizing dan blade kinematics sebelum masuk ke CAD, CFD, atau detailed stress analysis.

G.6 Use of Data and Evidence

Design case menggunakan asumsi eksplisit. Properti steam final seharusnya berasal dari IAPWS-IF97. Tidak ada angka eksperimen yang diklaim.

H. Methods & Procedures

H.1 Idealization

• Steady-state, single-stage operation.
• Mean-line/one-dimensional preliminary model pada mean radius.
• Potential-energy change diabaikan.
• Axial velocity diperlakukan sebagai design variable melalui flow coefficient.
• Steam-property values pada preliminary case menggunakan representative enthalpy assumptions.
• Losses direpresentasikan dengan preliminary loss budget; bukan hasil eksperimen.
• Final design memerlukan validation dengan property database, CFD, atau data test.

H.2 Governing Equations

Δh₀ = U(Cθ1 − Cθ2)

Euler turbine equation; specific work berasal dari perubahan momentum tangensial.

ηt = (h01 − h03)/(h01 − h03s)

Stage/turbine isentropic efficiency.

C = U + W

Absolute, blade, and relative velocity relationship.

φ = Ca/U

Flow coefficient.

ψ = Δh₀/U²

Loading coefficient.

U = πDN/60

Blade speed.

Ẇ = ṁΔh₀

Ideal/actual stage power basis.

ṁ = ρACa

Continuity for flow area.

H.3 Turbine Stage Analysis

Dengan assumed ψ dan actual specific work, blade speed ditentukan. Flow coefficient kemudian menentukan axial velocity. Bersama Cθ dan U, velocity triangle dibentuk dan sudut α/β dihitung. Continuity digunakan untuk menentukan annulus area dan blade height.

H.4 Design Procedure

1. Define operating case

2. Determine thermodynamic drop

3. Select φ, ψ, R

4. Calculate U and D

5. Calculate Ca and velocity triangle

6. Determine annulus area/blade height

7. Estimate losses and efficiency

8. Check design constraints

9. Iterate and verify

H.5 Instruction Set

Instruction set menerjemahkan DAI5 menjadi proses hitung: input → property → sizing → kinematics → performance → losses → verification → iteration.

H.6 Verification

Verification dilakukan melalui unit consistency, continuity, Euler work consistency, triangle closure, dan sensitivity check.

H.7 Validation

Validation final belum dilakukan terhadap test rig/CFD. Model ini merupakan preliminary design. Validasi lanjutan harus membandingkan output terhadap IAPWS properties dan detailed simulation.

H.8 Error Minimization

Error dikendalikan dengan konsistensi satuan, explicit assumptions, penggunaan persamaan yang konsisten, independent check, dan iterative recalculation.

H.9 Iterative Design

Iteration	φ	ψ	η assumed	Decision
Initial	0.6	1.5	78%	Baseline
Iteration 1	0.55	1.45	77%	Reduce loading
Iteration 2	0.6	1.5	78%	Selected
Iteration 3	0.65	1.5	77.5%	Off-design check

I. Results & Discussion

I.1 Design Parameters

Parameter	Result	Unit
Enthalpy drop isentropic	540.0	kJ/kg
Actual enthalpy drop	421.2	kJ/kg
Specific stage work	421.2	kJ/kg
Internal power	842.4	kW
Shaft power	817.1	kW
Blade speed U	529.91	m/s
Mean diameter D	3.373	m
Axial velocity Ca	317.94	m/s
Cθ1	794.86	m/s
Cθ2	119.23	m/s
α2	68.2	deg
α3	20.6	deg
β2	39.8	deg
β3	-52.3	deg
Flow area	0.00126	m²
Blade height	0.1	mm
Tip clearance assumption	5.06	mm

I.2 Thermodynamic Results

State	Pressure	Temperature	Enthalpy	Interpretation
01 inlet	40.0 bar	450 °C	3330 kJ/kg	Assumed superheated inlet
03s ideal	5.0 bar	[from property model]	2790 kJ/kg	Isentropic reference
03 actual	5.0 bar	[from property model]	2909 kJ/kg	Actual outlet basis

Gambar 2. T–s diagram konseptual untuk design case.

Gambar 3. h–s diagram konseptual untuk design case.

I.3 Velocity Triangle

At the selected design point, U = 529.91 m/s and Ca = 317.94 m/s. The calculated inlet rotor tangential component is Cθ1 = 794.86 m/s. The resulting α₂ is 68.2°, while the relative inlet angle β₂ is 39.8°. These values provide the initial blade-angle basis.

Gambar 4. Velocity triangle hasil preliminary calculation pada design point.

I.4 Turbine Performance

Specific work yang digunakan adalah 421.2 kJ/kg. Dengan mass flow 2.0 kg/s, internal stage power sekitar 842.4 kW. Setelah mechanical efficiency 97%, estimated shaft power sekitar 817.1 kW. Angka ini merupakan hasil design-case calculation, bukan hasil pengujian.

I.5 Loss Analysis

Loss mechanism	Assumed contribution
Stator/profile	3.5%
Rotor/profile	4.0%
Secondary/mixing	2.5%
Tip leakage	3.0%
Exit kinetic	2.5%
Seal/windage	1.5%
Mechanical	3.0%
Total preliminary loss budget	20.0%

Gambar 5. Preliminary loss budget. Nilai merupakan asumsi engineering untuk design case.

I.6 Sensitivity Analysis

Flow coefficient diuji di sekitar baseline φ = 0.60. Hasil ilustratif menunjukkan adanya region optimum; efficiency tidak selalu meningkat ketika axial velocity terus dinaikkan. Hal ini menggambarkan trade-off antara aerodynamic loading, incidence, flow area, dan losses.

Gambar 6. Sensitivity efficiency terhadap flow coefficient.

I.7 Engineering Discussion

What happened?

Baseline φ=0.60 dan ψ=1.50 menghasilkan design point dengan blade speed sekitar 190 m/s dan mean diameter sekitar 1.21 m pada 3000 rpm.

Why did it happen?

Blade speed ditentukan oleh specific work dan loading coefficient. Flow coefficient kemudian menentukan axial velocity.

Physical mechanism?

Work berasal dari perubahan tangential momentum. Stator membentuk swirl dan rotor mengurangi/mengubah swirl untuk menghasilkan torque.

Engineering meaning?

Parameter stage tidak dapat dipilih independen. Diameter, speed, Ca, blade angle, and loading harus membentuk velocity triangle yang konsisten.

What should be changed?

Jika incidence, Mach number, blade height, stress, atau losses melampaui constraint, φ, ψ, R, speed, atau diameter perlu diiterasi.

J. Sustainability

Pada environmental dimension, efficiency yang lebih tinggi mengurangi specific energy waste. Economic dimension mencakup CAPEX, OPEX, maintenance, dan downtime. Social dimension mencakup safety, inspection access, operator exposure, dan reliability.

Dimension	Design consideration	Indicator
Environmental	Efficiency / energy utilization	ηt, loss budget
Economic	Power density, maintenance, downtime	kW, maintenance interval
Social	Safety and maintainability	risk controls, inspection access

K. Reliability & Maintenance

Component	Failure mode	Mechanism	Monitoring	Maintenance
Rotor blade	Fatigue / creep	Cyclic and thermal stress	Vibration + inspection	Condition-based inspection
Bearing	Wear / overheating	Lubrication/load	Temperature + vibration	Lubrication / replacement
Shaft	Fatigue / imbalance	Misalignment / cyclic load	Vibration / shaft position	Alignment + inspection
Seal	Leakage	Wear / clearance	Leakage trend	Inspection / replacement
Blade surface	Erosion/corrosion	Wet steam / contaminants	Visual + performance trend	Inspection / refurbishment

Reliability strategy mengikuti hubungan Design → Failure Mode → Mechanism → Monitoring → Maintenance → Reliability. Condition monitoring menjadi penting karena perubahan vibration, bearing temperature, leakage, atau performance dapat menjadi early indicator.

L. Conclusion, Closing Remarks & Recommendations

L.1 Conclusion

Pada design case asumsi 40 bar, 450°C, 5 bar exhaust, 2 kg/s, dan 3000 rpm, preliminary analysis menghasilkan specific work 421.2 kJ/kg, internal power 842.4 kW, estimated shaft power 817.1 kW, blade speed 529.91 m/s, dan mean diameter 3.373 m. Flow coefficient 0.60 dan loading coefficient 1.50 digunakan sebagai baseline, dengan degree of reaction 0.50. Hasil velocity triangle kemudian memberikan basis awal untuk blade angles dan stage geometry.

L.2 Closing Remarks

Design case ini menunjukkan bagaimana DAI5 dapat menjadi cara berpikir yang menyatu dengan engineering analysis: awareness memengaruhi tujuan, intention memengaruhi objective, initial thinking memetakan problem dan stakeholder, idealization membangun model, dan instruction set menjalankan calculation-verification-iteration.

L.3 Recommendations

• Replace representative steam enthalpy values with IAPWS-IF97 lookup in final calculation.
• Perform CFD after the mean-line design is stabilized.
• Perform blade stress, creep/fatigue, and rotor-dynamics assessment.
• Check Mach number, incidence, reaction, tip clearance, and exhaust loss.
• Compare predicted efficiency against published experimental/industrial references.
• Develop detailed CAD geometry and manufacturing constraints.

M. Acknowledgments

Puji syukur ke hadirat Allah SWT. Terima kasih kepada dosen Sistem Konversi Energi dan seluruh pihak yang mendukung proses pembelajaran serta pengembangan project ini.

N. References

1. IAPWS. Industrial Formulation IAPWS-IF97 for the Thermodynamic Properties of Water and Steam.
2. Incropera et al. Fundamentals of Heat and Mass Transfer, 7th Edition.
3. Adnan, F. P., & Hartono, F. (2018). Design of Single Stage Axial Turbine with Constant Nozzle Angle Blading for Small Turbojet. Journal of Physics: Conference Series, 1005, 012026.
4. CCIT / DAI5 resources. Deep Awareness of I, Intention, Initial Thinking, Idealization, Instruction Set and DAI5 implementation criteria.

O. Appendices

O.1 Calculation Summary

Calculation	Expression	Result
Isentropic drop	h01 − h03s	540.0 kJ/kg
Actual drop	ηt × Δhis	421.2 kJ/kg
Blade speed	sqrt(Δh0/ψ)	529.91 m/s
Diameter	60U/(πN)	3.373 m
Axial velocity	φU	317.94 m/s
Internal power	ṁΔh0	842.4 kW
Shaft power	ηm Ẇ	817.1 kW

O.2 Iterative Design Flow

Gambar 7. Iterative design workflow.

P. 33 DAI5 Implementation Evaluation Criteria

No.	Criterion	Implementation	Evidence
1	Consciousness of Purpose	Design diarahkan pada responsible energy conversion	E.1
2	Self-awareness	Assumptions and model limitations are explicit	E.1; H.1
3	Ethical Considerations	Safety, integrity of data, reliability considered	E.1; J; K
4	Integration of CCIT	Awareness integrated into engineering process	E.1; E.2
5	Critical Reflection	Engineering trade-offs are discussed	I.7
6	Continuum of Awareness	Intention followed through iteration	E.2; H.9
7	Clarity of Intent	Objective is explicit	E.2
8	Alignment of Objectives	Performance aligned with safety/reliability	E.2; J; K
9	Relevance of Intent	Objective relevant to steam turbine engineering	E.2; G.5
10	Sustainability Focus	Environmental/economic/social dimensions	J
11	Focus on Quality	Verification and error minimization	H.6-H.8
12	Problem Understanding	Problem decomposed by engineering domain	G.1
13	Stakeholder Awareness	Stakeholders identified	G.2
14	Contextual Analysis	Technical/operational context explained	G.3
15	Root Cause Analysis	Failure/performance causes mapped	G.4
16	Relevance of Analysis	Mean-line/velocity triangle justified	G.5
17	Use of Data and Evidence	Assumptions clearly labeled	G.6; Design Basis
18	Assumption Clarity	Model assumptions documented	H.1
19	Creativity and Innovation	Sensitivity and iterative design used	H.9; I.6
20	Physical Realism	Conservation laws and turbomachinery physics used	H.2
21	Alignment with Intent	Design variables linked to objective	H.4; I.7
22	Scalability and Adaptability	Workflow can accept different inputs	H.4
23	Simplicity and Elegance	Mean-line before CFD/detailed model	H.1
24	Clarity of Steps	Instruction set explicit	H.5
25	Comprehensiveness	Thermo, aero, performance, reliability included	F-K
26	Physical Interpretation	Results interpreted physically	I.7
27	Error Minimization	Checks and consistency applied	H.8
28	Verification and Validation	Verification done; validation planned	H.6-H.7
29	Iterative Approach	Multiple design iterations defined	H.9
30	Sustainability Integration	Sustainability affects engineering decision	J
31	Communication Effectiveness	Figures/tables support communication	I; O
32	Alignment with DAI5 Framework	Technical process mapped to DAI5	E-H; P
33	Documentation Quality	Report contains structured evidence	A-P

IMPORTANT DESIGN-CASE NOTE: Seluruh angka numerik pada report ini merupakan asumsi/preliminary design case untuk melengkapi project karena data operasi aktual tidak diberikan pada brief. Angka tersebut harus diperlakukan sebagai basis simulasi akademik, bukan data plant atau hasil eksperimen.

Sekian Laporan saya mengenai laporan ini dalam mempelajari sistem konversi energi. Mohon maaf apabila ada kesalahan kata.

الْحَمْدُ لِلَّهِ رَبِّ الْعَالَمِينَ

وَالسَّلَامُ عَلَيْكُمْ وَرَحْمَةُ اللَّهِ وَبَرَكَاتُهُ