Flywheel energy storage system development in India

•  Prof Asim Tewari IIT Bombay
• Dr.Vivek Agarwal IIT Bombay
• Prof Tiwari IIT Guwahati

IIT Guwahati Vetomac Rotordynamics Vibration 2025 Lab visits

 

1. RPM indicator = Testo brand
2. Flux sensor = Metravi GM197
3. Power amplifier = CAN automotion AMC
4. Current sources for injection = Chroma programmable AC current source
5. Voltage and FLux sensor = LEM
6. Laser alignment maching = AVV-711

AMB literature survey notes 0400:600

 18122025

1. When shaft stiffness is less than the bearing stiffness, equivalent stiffness is positive and the poles will occur in the stable complex pairs. This can be checked only with the integrated flexible model
2. Uses 5.15 to check the static values of rotational poles
3. Cant use 5.17 to check the rotating case. It is only for free free system.

Applications of modern gyro technology, The RAS , 12 Jan 1977

 The effect of modern tech on Gyros , S G Smith

Gyroscope can be strapped down gyro or gimbaled gyro

Strap down gyros are rigidly mounted to aircraft, it requires digital computers to solve for the roll

Accuracy requirement for gyros:

• 0.01° per hour drift is allowed in the presence fo  400° per sec rolls
• Dynamic range must be 1x10^8,no units given

Single axis rate sensor : Spring restrained, single gimbal mounted rotating wheel.

Types of rate sensors:

1. gyroscope
2. gas jet rate sensor
3. vibrating wire sensor
4. tuning fork
5. magneto hydrodynamic sensor

Gas jet rate:

• deflection of a laminar flow of gas when  the case of the instrument is rotated
• jet is maintained by the piezo pump
• gas jet rate is measured by hot wire
• extreme rugged ness, low cost
• major disadvantage: transit time of the gas causes low frequency of response
• has onlyt 0.1°/s sensitivity and 1% linearity

Acoustic padding and combustor resonance

1. The triangle foam on the acoustic panels for noise absorption: The triangle height determines what is the frequency being absorbed, the triangle foam material determines the absorption factor
2. The  flame in the combustor tube excites multiple frequencies. The frequency corresponding to quarter wave length of the combustor tube will be amplified because of resonance from the combustor tube. 

Orifice type flow meter

How to Build a Low-Cost Orifice Plate Mass Flow Meter for Compressed Air (0.07–0.2 kg/s) – Completely DIY in India

If you need to measure compressed air mass flow in the range 0.07 to 0.2 kg/s (roughly 250–700 m³/hr at 6 bar) in a 1-inch pipeline, and you cannot afford a ready-made thermal/Coriolis meter (₹1.5–3 lakh), here is a proven, fully fabricable orifice-plate-based solution that costs only ₹25,000–₹30,000.

Service Conditions

• Fluid: Dry compressed air
• Mass flow range: 0.07 – 0.2 kg/s
• Pipe size: 1 inch Schedule 40 (ID = 27.3 mm)
• Max gauge pressure: 5 bar → ~6 bar(a)
• Max temperature: 60 °C

Step-by-Step Design Calculations

1. Selection of β ratio

Chosen β = 0.50 (best compromise between accuracy and pressure loss)

Orifice bore d = 0.5 × 27.3 = 13.65 mm → 13.6 mm (easy to machine)

2. Expected Differential Pressure

Density at 6 bar(a), 60 °C ≈ 6.27 kg/m³

Using ISO 5167-2 formula →

• At 0.2 kg/s → ΔP ≈ 11.2 kPa ≈ 1140 mmWC
• At 0.07 kg/s → ΔP ≈ 140 mmWC

This range is perfectly measurable with commonly available Indian DP transmitters.

3. Final Orifice Plate Specification

Parameter	Value
Pipe ID (Sch 40)	27.3 mm
Orifice bore (d)	13.6 ± 0.02 mm
β ratio	0.50
Plate thickness	3–4 mm
Material	SS304
Taps	Corner taps
Bevel	45° on downstream side
Permanent pressure loss	≈ 55% of ΔP (≈ 600 mmWC max)

Fabrication Drawing (Give This to Any Local Workshop)

• Plate size: 80 mm OD circular or 50×50 mm square with handle tab
• Centre hole: 13.6 mm reamed
• Downstream face: 45° bevel
• Upstream face: polished (Ra < 0.4 µm)
• Weld two 6 mm SS nipples on pipe for corner taps

Recommended Instruments (Easily Available in India – 2025 prices)

Parameter	Make & Model	Range	Approx Price
Differential Pressure	WIKA A-10 / Waaree / Galaxy	0–2000 mmWC	₹9,000–12,000
Cheap mechanical option	Galaxy Magnehelic type	0–2000 mmWC	₹3,500–5,000
Gauge Pressure	WIKA 233.50 / H Guru	0–10 bar	₹1,200–2,000
Temperature	Pt-100 RTD or bimetallic	0–100 °C	₹800–1,500

Field Calculation Formula (Mass Flow)

Mass flow (kg/s) = 0.000178 × √(ΔP in mmWC) × √(P_abs in bar × 288/(T+273))

You can put this formula in Excel or display live value using Arduino + 4-20 mA DP transmitter.

Total Estimated Cost (India – Nov 2025)

• Orifice plate + welding: ₹4,000
• DP transmitter: ₹10,000
• Pressure & temperature gauges: ₹3,000
• Tubing, valves, manifold: ₹5,000
• Optional display/logging: ₹4,000
• Total: ₹25,000 – ₹30,000 only

Is Thermal Mass Flow Meter Easier to DIY?

Absolutely NOT.

• You still need to buy the sensing element (₹15,000–40,000)
• Complex electronics & calibration required
• Not truly DIY

Orifice plate + DP cell + P&T compensation is the cheapest, most robust and 100% locally fabricable solution in India.

Lecture notes on aerodynamics