Wind Turbine Simulator — Lab Practice 1

Type: Tutorial Audience: Engineering students using the simulator for the first time Goal: By the end of this tutorial, you will have launched the Wind Turbine Simulator, recorded measurements at different wind speeds, compared all three blade profiles, and observed how the grid load affects turbine output — connecting the simulation directly to real wind energy concepts.

Overview

This tutorial guides you through a structured hands-on session with the Wind Turbine Simulator at:

https://instrumentationandcontrol.net/wind-turbine-simulator.php

The simulator models a small horizontal-axis wind turbine with a rotor diameter of 0.5 m operating in air at standard density (ρ = 1.225 kg/m³). It computes rotor speed, wind power, useful power output, tip speed ratio, and power coefficient in real time, and displays the results on live charts and an animated P&ID-style diagram.

You will complete five steps:

1. Identify all panels, instruments, and controls before starting
2. Run the turbine at default conditions and observe the instruments and animation
3. Vary wind speed and record the relationship between wind speed and available power
4. Compare all three blade profiles at the same wind speed
5. Sweep the grid load from fully connected to disconnected and observe the effect on voltage and power output

No prior experience with the simulator is required. You should be comfortable with basic concepts of power, rotational speed, and what a wind turbine does. All engineering concepts introduced in the steps are explained as you go.

Understanding the Interface

Before starting the simulator, take a few minutes to locate every element on the page. You will interact with all of them during this tutorial.

Test Controls (left panel)

The left panel contains all the controls that set the operating conditions of the turbine.

The measurement instruments in the right panel are only active while the simulation is running. They display dashes or zero when the turbine is stopped.

Measurement Instruments (right panel, active when running)

All instruments include ±1–2% random measurement noise, simulating the behaviour of real instruments. Do not be alarmed by small fluctuations — this is intentional.

Charts (lower panel)

Two charts display recorded data and update as you record points:

• Nu vs n — useful power (W) plotted against rotational speed (rpm). Shows how output power changes with rotor speed.
• Cp vs λ — power coefficient plotted against tip speed ratio. A horizontal reference line at Cp = 0.593 marks the Betz limit — the theoretical maximum fraction of wind power that any wind turbine can extract.

SVG Diagram (centre panel)

An animated P&ID-style illustration shows the turbine blades rotating, the tower, the generator, and the connection to the grid. Measurement readouts are overlaid directly on the diagram and update in real time while the simulation is running.

Audio

When the simulation is running, a low-pass filtered noise signal plays through your browser's audio output, simulating the combined sound of wind and rotor. Your browser must have received a user gesture (such as a button click) before audio will play.

Step 1 — Getting Familiar with the Interface

Before touching any controls, complete this orientation checklist. Locate and identify each element on the page:

• [ ] Wind Speed slider — note its current position and the 4–14 m/s scale
• [ ] Pitch Angle slider — note its current position and the 0–90° scale
• [ ] Grid Connection slider — note that 0% is fully connected and 100% is fully disconnected
• [ ] Blade type selector — confirm the three options: Straight, 40°, Aero
• [ ] START / STOP button — not pressed yet
• [ ] Record and Clear Data buttons
• [ ] Eight instrument readouts — confirm they show dashes or zero (turbine is stopped)
• [ ] Nu vs n chart — confirm it is empty
• [ ] Cp vs λ chart — locate the horizontal Betz limit line at 0.593
• [ ] SVG diagram — confirm the blades are stationary

Once you have located every element, you are ready to proceed.

Step 2 — Your First Run

In this step you will start the turbine with a known set of conditions and observe how all parts of the interface respond.

Set the starting conditions

Adjust the controls to the following values before pressing START:

55° is the optimum pitch angle for the Straight blade profile. At this angle the blade extracts the maximum fraction of wind power for this blade type.

Start the turbine

Press the START button.

What you should see immediately:

• The SVG blades begin rotating. Rotation speed increases over the first few seconds as the rotor accelerates to steady state.
• The audio output becomes audible — a low, broadband wind/rotor noise.
• The instrument readouts become active and display fluctuating values.

What you should see at steady state (allow 5–10 seconds):

Nv is the wind power — the total kinetic energy flux through the rotor swept area, computed as: Nv = ρ · π · (D² - d_hub²) / 4 · c³ / 2. This value depends only on wind speed and rotor geometry, not on what the turbine does with it. Nu is always less than Nv because no turbine can extract all the available wind power.

Record your first data point

Press ● Record to start recording, then ■ Stop rec. after a moment. A data point will appear on both charts. Note its position on the Cp vs λ chart relative to the Betz limit line.

Leave the turbine running and proceed to the next step.

Step 3 — Effect of Wind Speed

Wind power scales with the cube of wind speed: Nv = ρ · π · (D² - d_hub²) / 4 · c³ / 2. Doubling wind speed multiplies available power by eight. In this step you will verify this relationship by recording data at three different wind speeds.

Keep the blade type as Straight, pitch angle at 55°, and grid connection at 0%. Only move the Wind Speed slider.

Procedure

Press Clear Data to remove any existing chart data.

Move the Wind Speed slider to each value in the table below. At each position, wait 5–10 seconds for steady state, then press ● Record followed immediately by ■ Stop rec. to capture one data point.

What to observe

After recording all three points:

• Look at the Nu vs n chart. The three points should form a curve rising steeply from left (low wind) to right (high wind). This curvature reflects the cubic relationship between wind speed and power.
• Look at the Cp vs λ chart. The three points should cluster near the same Cp value — the Straight blade's characteristic Cp_max of approximately 0.28. The tip speed ratio λ also stays near the Straight blade's optimum of approximately 2.5, because both n and c change together.

The cubic relationship

To check the cubic scaling, compare your recorded Nv values at 4 m/s and 8 m/s. The ratio of wind speeds is 8/4 = 2. The expected ratio of wind powers is 2³ = 8. Your measured Nv at 8 m/s should be approximately eight times the value at 4 m/s.

The ±1–2% instrument noise means your recorded values will not match the theoretical ratio exactly. A result within 10–15% of the expected ratio is entirely normal.

Step 4 — Blade Comparison Experiment

The three blade profiles — Straight, 40°, and Aero — have different aerodynamic designs. Each has its own maximum power coefficient and the tip speed ratio at which that maximum occurs. In this step you will test all three profiles under identical conditions and compare their performance on the Cp vs λ chart.

Reference values (from turbine specifications):

Procedure

Press Clear Data to start with an empty chart.

Fix the following common conditions for all three tests:

For each blade type, follow these steps:

1. Select the blade type using the selector.
2. Set the pitch angle to the β_opt value for that blade (see table above).
3. Wait 5–10 seconds for steady state.
4. Press ● Record, then ■ Stop rec. to save the point.

Run order:

What to observe on the Cp vs λ chart

After recording all three tests, the chart should show three clearly separated points:

• Straight — lowest Cp (~0.28), lowest λ (~2.5). The rotor spins relatively slowly.
• 40° — intermediate Cp (~0.38), intermediate λ (~3.8). The rotor spins faster.
• Aero — highest Cp (~0.46), highest λ (~5.8). The rotor spins fastest for the same wind speed.

All three points should sit well below the Betz limit line at 0.593. No real turbine can reach the Betz limit because it would require extracting all kinetic energy from the wind — which would mean bringing the airflow to a complete stop, which is physically impossible.

Why does blade design matter?

The Aero profile has a more refined aerodynamic cross-section that generates more lift and less drag at the optimum operating angle than the Straight or 40° profiles. This allows it to extract a larger fraction of available wind power (higher Cp) and to do so at a higher rotor speed relative to wind speed (higher λ). In real wind turbine design, blade aerodynamics represent a significant fraction of overall system cost and are engineered to achieve high Cp across a wide range of wind speeds.

Step 5 — Grid Load Effect

So far, you have kept the grid connection at 0% (fully connected, low resistance). In this step, you will use the Aero blade at its optimal conditions and progressively disconnect the load, observing how generator voltage and useful power respond.

Set optimal conditions

Configure the simulator as follows:

Press START if the turbine is not already running. Wait for steady state.

Procedure

Press Clear Data. Then move the Grid Connection slider in steps from 0% to 100%, pausing at each position to allow the instruments to settle (approximately 5 seconds). Record the values at each step:

What to observe

As you move the grid slider from 0% toward 100%:

• Rg increases — a higher slider value corresponds to higher load resistance, reducing current draw.
• U increases — with less current flowing, the terminal voltage rises toward the generator's open-circuit voltage.
• Nu decreases — less current means less electrical power delivered to the load, even though voltage is higher. The power delivered to a resistance is Nu = U² / Rg; as Rg grows faster than U², total power falls.
• n increases slightly — with less electrical load on the generator, the rotor experiences less counter-torque and spins slightly faster.
• Cp changes — the turbine's operating point shifts because the rotor speed changes the tip speed ratio λ, moving the operating point away from the optimum.

At 100% grid disconnection, the generator is effectively open-circuit. Rg is very high (∞ Ω), U reaches its maximum, but Nu drops close to zero because almost no current flows. This is the no-load condition.

In real wind turbines, sudden loss of grid connection is a fault condition that must be handled by the protection system. The rotor, no longer loaded by the generator, can accelerate to dangerously high speeds. Real turbines detect grid loss and apply aerodynamic or mechanical brakes automatically. The simulator does not model blade over-speed protection — it is simplified for educational purposes.

What You Have Learned

By completing this tutorial, you have directly observed the following wind energy engineering fundamentals:

The central concept linking all five steps is the power coefficient Cp — the fraction of available wind power that the turbine converts to useful electrical output. Cp depends on blade design, pitch angle, and operating tip speed ratio. The Betz limit (0.593) is an absolute upper bound; all real turbines operate below it, and maximising Cp across a wide range of wind conditions is the primary goal of wind turbine aerodynamic design.

Next Steps

• Try operating each blade at a pitch angle significantly away from its β_opt — for example, the Aero blade at β = 60° — and observe how Cp falls when the blade stalls or feathers
• Set wind speed to its minimum (4 m/s) and try to find the pitch angle that maximises Nu for each blade type by adjusting β manually
• Repeat the blade comparison at c = 14 m/s and compare Nv with your earlier recordings to confirm the cubic scaling holds across blade types
• Investigate the Nu vs n chart: at constant wind speed, vary the grid connection slowly and trace how the useful power versus rotor speed curve is swept

Information and Definitions

Wind Power (Nv)

Wind power (Nv) is the total kinetic power carried by the wind through the rotor swept area. It represents the upper bound of energy available to the turbine before any conversion losses. The formula is:

Nv = ρ · π · (R² - r_hub²) / 2 · c³

Where:

• ρ — air density (kg/m³)
• R — rotor radius (m)
• r_hub — hub radius (m), equal to d_hub / 2
• c — wind speed (m/s)

The most important feature of this equation is the cubic relationship between wind speed and available power. Doubling the wind speed increases available wind power by a factor of eight (2³ = 8). This makes wind speed by far the most influential variable in wind turbine performance — small increases in wind speed yield disproportionately large gains in power output. It also means that a turbine produces very little at low wind speeds and reaches its rated power relatively quickly as speed increases.

Useful Power (Nu)

Useful power (Nu) is the mechanical power actually extracted from the wind by the rotor and delivered to the generator shaft. It is the fraction of wind power that the rotor captures:

Nu = Cp · Nv

Where Cp is the power coefficient (dimensionless). Since Cp is always less than 1, the useful power is always less than the available wind power. The simulator displays Nu in watts (W) on the main power readout. All other losses — generator, electrical, bearing friction — occur after this point and are not modelled.

Power Coefficient (Cp)

The power coefficient (Cp) is a dimensionless number that describes how efficiently a rotor extracts kinetic energy from the wind. It is defined as the ratio of useful mechanical power extracted to the total wind power passing through the rotor swept area:

Cp = Nu / Nv

Cp is not a fixed property of a turbine. It varies continuously with the tip speed ratio (λ), pitch angle (β), and blade profile. Each combination of blade and operating condition produces a different Cp value. The theoretical maximum value of Cp is the Betz limit (0.593). Real turbines achieve values well below this. In this simulator, the maximum achievable Cp values are:

• Straight blade: 0.28
• 40° blade: 0.38
• Aero blade: 0.46

The Cp vs λ chart shows how Cp changes as the turbine speed varies relative to wind speed, revealing the optimal operating region.

Betz Limit (0.593)

The Betz limit is the theoretical maximum fraction of wind power that any rotor can extract from the wind. Its value is 16/27, approximately 0.593 (59.3%). It was first derived by Albert Betz in 1919 using classical momentum theory applied to an ideal actuator disc.

The physical argument is as follows. For the rotor to extract energy, it must slow the wind down. However, if the wind were slowed to zero, the air would pile up behind the rotor and no further air would flow through. Betz showed that the maximum power extraction occurs when the wind is slowed to exactly one-third of its upstream speed as it passes through the rotor. At that condition, the ratio of extracted power to available wind power equals 16/27.

This limit applies to all rotor designs regardless of the number of blades, blade shape, or rotational speed. No wind turbine — real or theoretical — can convert more than 59.3% of the kinetic energy in the wind into shaft power. Real turbines achieve Cp values of 0.35 to 0.50, which already approach this limit closely.

Tip Speed Ratio (TSR, λ)

The tip speed ratio (λ, lambda) is the ratio of the speed of the blade tips to the free-stream wind speed:

λ = ω · R / c

Where:

• ω — rotor angular velocity (rad/s), equal to 2π · n / 60
• R — rotor radius (m)
• c — wind speed (m/s)

TSR is the primary dimensionless operating variable of a wind turbine. It determines how much the airflow is disturbed by successive blade passes. At very low TSR, the blades move slowly and much of the wind passes through unused. At very high TSR, the blades spin so fast that they act like a solid disc, creating excessive drag and turbulence.

Each blade profile has an optimal TSR (λ_opt) where the power coefficient Cp reaches its maximum. The Cp vs λ chart in the simulator plots this relationship and makes the optimum clearly visible.

Optimal TSR (λ_opt)

The optimal tip speed ratio (λ_opt) is the specific λ value at which a given blade profile achieves its maximum power coefficient. Operating at λ_opt keeps the aerodynamic angle of attack close to optimal across the full blade span, minimising drag and maximising lift-to-drag ratio.

Each blade profile in the simulator has a different λ_opt:

The more aerodynamically refined the blade, the higher its optimal TSR and the higher its peak Cp. Aerodynamic blades require the tips to move faster than the wind to develop sufficient lift. Straight blades, which rely more on drag than lift, perform best at lower tip speeds.

Pitch Angle (β)

The pitch angle (β, beta) is the angle between the blade chord line and the plane of rotor rotation. Adjusting pitch angle changes the aerodynamic angle of attack of the blade relative to the oncoming airflow, which directly affects the lift and drag forces acting on it.

At the optimal pitch angle (β_opt), the blade produces the best lift-to-drag ratio at the design wind speed and TSR, maximising Cp. Moving away from β_opt — either increasing or decreasing β — reduces Cp by either stalling the blade (too high an angle of attack, causing flow separation) or feathering it (too low, reducing lift generation).

In the simulator, each blade profile has a recommended β_opt. The pitch angle slider allows the student to observe how Cp degrades as pitch deviates from its optimal value, and to understand why real variable-pitch turbines actively adjust β as wind speed changes.

Blade Profile Types

The simulator provides three blade profiles representing increasing levels of aerodynamic refinement:

Straight blade — A flat, untwisted blade with no aerodynamic profiling. Power extraction relies primarily on drag forces rather than lift. This profile is simple to manufacture but has a low maximum power coefficient (Cp_max = 0.28) and operates at low tip speed ratios (λ_opt = 2.5). It represents early or low-cost turbine designs.

40° blade — A twisted blade with a fixed 40° pitch angle geometry. The twist improves the angle of attack distribution along the blade span and introduces some lift contribution. Performance is intermediate (Cp_max = 0.38, λ_opt = 3.8). This profile represents a mid-range design suitable for educational and small-scale applications.

Aero blade — An aerodynamically optimised blade with an airfoil cross-section, designed to generate strong lift along its full length. This profile achieves the highest power coefficient (Cp_max = 0.46) at a high tip speed ratio (λ_opt = 5.8), approaching modern large-scale wind turbine blade design principles.

Rotational Speed (n)

Rotational speed (n) is the number of complete revolutions the rotor makes per minute (rpm). It is the primary controlled variable in wind turbine operation. Rotational speed is linked to wind speed and tip speed ratio by:

n = λ · c / R · (60 / 2π)

At a fixed wind speed, increasing the rotor speed increases the TSR. To maximise power output, the rotor should spin at the speed that achieves λ_opt. In practice, wind speed varies continuously, so the target rotational speed must be adjusted accordingly. The Nu vs n chart in the simulator illustrates how useful power varies with speed for a given wind condition, showing the speed at which power peaks.

Grid Load Resistance (Rg)

The grid load resistance (Rg, in ohms) represents the electrical load connected to the generator output. In the simulator, the grid switch has two states:

• Disconnected (open circuit) — Rg is effectively infinite (∞ Ω). No current flows, so no electrical torque opposes the rotor. The turbine spins freely under aerodynamic torque, tending towards runaway speed.
• Connected (closed circuit) — Rg is a finite resistance. Current flows through the load, creating a counter-torque in the generator that acts as a brake on the rotor. The rotor reaches equilibrium where aerodynamic torque equals generator braking torque.

Lowering Rg (increasing the electrical load) increases the braking torque, slowing the rotor. This shifts the operating point on the Nu vs n chart. Selecting a Rg value that places the rotor at its λ_opt for the current wind speed is how maximum power extraction is achieved in practice.

Generator Voltage (U)

Generator voltage (U, in volts) is the electromotive force produced by the generator. For a permanent magnet generator — the type represented in this simulator — voltage is proportional to rotational speed:

U = K_emf · n

Where K_emf is the generator's voltage constant (V per rpm), a fixed property of the generator design. When the grid is connected, the load current is:

I = U / (R_int + Rg)

Where R_int is the internal resistance of the generator windings. The electrical power delivered to the load is:

P_elec = I² · Rg

In the simulator, the voltmeter displays U in real time. Watching U respond to changes in wind speed or load resistance provides a direct illustration of how generator output tracks rotor speed.

Air Density (ρ)

Air density (ρ, rho) is the mass of air per unit volume, expressed in kilograms per cubic metre (kg/m³). At standard conditions — sea level, 15 °C, and 101.325 kPa — air density is approximately 1.225 kg/m³. This is the value used in the simulator.

Air density appears as a direct multiplier in the wind power formula. Denser air carries more kinetic energy for the same wind speed. In practice, air density decreases with altitude and increases with lower temperatures, which affects turbine performance at real sites. A turbine installed at high altitude will produce less power than the same turbine at sea level, even under identical wind conditions.

Swept Area

The swept area is the area of the disc traced by the rotating blades. Because the blades are mounted on a hub of finite diameter, the rotor does not sweep a full circle — it sweeps an annular area (a ring):

A = π · (R² - r_hub²)

Where:

• R — rotor radius from the centre of rotation to the blade tip (m)
• r_hub — hub radius (m), equal to d_hub / 2

The hub at the centre displaces air but does not sweep it, so the inner area is excluded. Swept area appears directly in the wind power formula: a larger rotor intercepts more wind and produces more power. Doubling the rotor radius quadruples the swept area and, everything else equal, quadruples the available wind power.

Nu vs n Chart

The Nu vs n chart (useful power versus rotational speed) shows how the mechanical power extracted by the rotor varies as the rotor speed changes, for a given wind speed and blade configuration. It takes the shape of a curve that rises from zero at standstill, reaches a clear maximum at the optimal operating speed, then falls as speed increases further and the TSR moves away from λ_opt.

The peak of this curve identifies the optimal rotational speed for maximum power extraction at the current wind condition. By adjusting the grid load resistance Rg (and observing where the operating point sits on this curve), the student can understand the concept of maximum power point tracking (MPPT) — the strategy used in real wind turbine controllers to continuously seek the peak of this curve as wind speed varies.

Cp vs λ Chart

The Cp vs λ chart (power coefficient versus tip speed ratio) is the fundamental aerodynamic performance map of a wind turbine rotor. It is independent of wind speed and rotor size — it characterises the blade profile itself.

The chart shows that Cp is low at very low TSR (blades too slow, much wind passes unused), rises to a maximum at λ_opt, then falls at high TSR (blades too fast, excessive drag and turbulence). The height of the Cp peak and the sharpness of the curve around it vary with blade profile:

• Straight blades produce a broad, low peak.
• Aero blades produce a taller, narrower peak centred at higher TSR.

The current operating point (the λ and Cp calculated from live readings) is shown on the chart. Observing this point move as wind speed, load, or pitch angle changes connects the abstract curve to real turbine behaviour.

Measurement Noise

All physical instruments introduce some degree of uncertainty into their readings. Sources include electrical interference, sensor resolution limits, turbulence in the measured flow, mechanical vibration, and analogue-to-digital conversion rounding. The simulator replicates this behaviour by adding ±1 to 2% random noise to all displayed readings at each update cycle.

The underlying physics calculations are exact. Only the displayed values fluctuate. This means that the true operating point is always slightly different from any individual reading. When recording data, it is good practice to average several readings rather than relying on a single value — exactly as engineers do with real instruments. The noise also explains why charts may appear slightly scattered rather than perfectly smooth.

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Frequently Asked Questions

Q1 Why does Cp never reach the Betz limit of 0.593?

A1 The Betz limit is a theoretical ceiling derived from ideal actuator-disk theory: it assumes a perfect, lossless rotor with no swirl, no tip losses, no drag, and an infinitely thin disk spanning the entire swept area. Real blades — and the models used in this simulator — fall short for several reasons. Lift-generating profiles produce tip vortices that bleed energy at each blade tip. The blade chord creates profile drag. The wake behind the rotor spins in the opposite direction, wasting rotational kinetic energy. The simulator models these losses through a Gaussian-shaped Cp(λ) curve: even at the ideal tip speed ratio, each blade profile has a physical ceiling well below 0.593. The Aero blade reaches a maximum Cp of approximately 0.46; the Straight blade peaks at around 0.28. The Betz line is drawn on the chart purely as a reference to show how much room for improvement a real blade still has.

Q2 What happens to power output when I disconnect the grid (set to ∞ Ω)?

A2 Setting the grid resistance to ∞ Ω opens the electrical circuit: no current flows, so no electrical power is delivered to any external load. At the same time, the simulator models the loss of generator braking torque — without an electrical load to resist it, the rotor loses its operating point and drops to a fraction of its optimal tip speed ratio. The turbine effectively freewheels at very low rotational speed, moving the operating point far to the left on the Cp(λ) curve and collapsing the power coefficient. Both Nu (useful power) and the terminal voltage U fall sharply. This condition represents a grid-loss or turbine-trip scenario. To restore full power output, move the grid slider back into the connected region (green pill indicator).

Q3 Why does the Aero blade produce more power than the Straight blade?

A3 The three blade profiles differ in their aerodynamic efficiency and the tip speed ratio at which they perform best. The Straight blade is a flat-plate profile: it generates lift but also substantial drag, and it reaches peak Cp of about 0.28 at a low optimal TSR (λ ≈ 2.5). The Aero blade is a cambered aerofoil: its higher lift-to-drag ratio allows it to sustain attached flow at much higher tip speeds, achieving a peak Cp of about 0.46 at an optimal TSR of λ ≈ 5.8. Because the available wind power (Nv) is the same for all blades at the same wind speed, the Aero blade converts a larger fraction of that power into useful output. The 40° blade sits between the two, with a peak Cp of about 0.38 at λ ≈ 3.8. Selecting the Aero blade at its optimal pitch angle and grid load will always give the highest readings for Nu and Cp on the instrument panel.

Q4 What is the tip speed ratio (TSR) and why does it matter?

A4 The tip speed ratio (λ) is the ratio of the blade-tip velocity to the incoming wind speed: λ = ω · R / c, where ω is the rotor angular velocity in rad/s, R is the rotor radius (0.3075 m in the simulator), and c is the wind speed in m/s. If λ is too low, the blades are moving too slowly — much of the wind passes through the rotor plane without being intercepted, and energy is wasted. If λ is too high, the blades sweep through the air so rapidly that they create a near-solid disc, blocking airflow and generating turbulent wakes that reduce lift. Each blade profile has a narrow band of λ where its Cp is close to maximum; this is the optimal TSR. The yellow TSR instrument on the dashboard lets you monitor this value in real time. To push λ higher, reduce the grid resistance (which increases rotor speed); to push it lower, increase resistance or reduce wind speed.

Q5 Why does wind power increase so sharply with wind speed?

A5 The kinetic power available in the wind passing through the rotor's swept area follows a cubic relationship with wind speed: Nv = ½ · ρ · A · c³, where ρ is air density (1.225 kg/m³), A is the net swept area, and c is wind speed in m/s. The cubic exponent means that doubling the wind speed increases the available power by a factor of eight (2³ = 8). In the simulator you can observe this directly: increase the wind speed from 4 m/s to 8 m/s and watch the Nwind display jump by roughly eight times. This sensitivity to wind speed is why wind resource assessment — identifying sites with consistently higher mean wind speeds — is so important in real turbine siting. A site with 10% higher average wind speed has approximately 33% more extractable annual energy than a site at the lower speed.

Q6 What does the pitch angle (β) control, and what happens at extreme values?

A6 The pitch angle (β) sets the angle between the blade chord line and the plane of rotation. It controls the effective angle of attack at which the wind strikes the blade surface, directly influencing how much lift and drag the blade generates. Each blade profile has an optimal pitch angle where Cp is highest: 55° for the Straight blade, 40° for the 40° blade, and 30° for the Aero blade. The simulator applies a Gaussian penalty to Cp whenever β deviates from this optimum — the further the deviation, the steeper the power drop. At β = 0° or β = 90° (the extremes of the slider), the blade is either fully feathered into the wind or broadside to it; in both cases, useful lift collapses and Cp falls close to zero. In real turbines, active pitch control is used to maintain the optimal angle at low-to-rated wind speeds and to feather the blades beyond rated speed in order to shed excess power and prevent mechanical overload.

Q7 The instruments show slightly different values each second — is the simulator broken?

A7 The simulator is working as designed. Random noise is added to every displayed reading at each update cycle to replicate the behaviour of real field instruments. Wind speed readings vary by ±1.0%, rotor speed and TSR by ±1.5%, terminal voltage by ±1.8%, and the useful power and Cp readings by ±2.0%. In a real plant, these fluctuations arise from electrical interference on signal cables, turbulence in the wind, transmitter quantisation, and measurement uncertainty in the sensors themselves. A process operator learns to read the mean value from a fluctuating display rather than reacting to individual samples. If you need a stable value for comparison purposes, use the Record function: it captures a snapshot at regular intervals, and the averaged trend across several recorded points gives a more reliable picture of the true operating condition.

Q8 How do I use the Record function to compare blade types systematically?

A8 The Record button captures one data point every six simulation ticks (approximately every two seconds while the simulator is running) and adds each row to the data table and scatter charts. To make a controlled comparison between blade types, follow this procedure. First, set a fixed wind speed, pitch angle, and grid resistance. Start the simulator and click Record; after ten to fifteen seconds, click Stop rec. to freeze that series. Next, switch to a different blade using the blade selector buttons — the blade type is saved with each recorded row — then click Record again under the same conditions and collect a second series. Repeat for the third blade. The Cp vs λ chart will overlay all three series as separate coloured scatter plots, labelled by blade type and pitch angle, alongside the Betz limit reference line. The n vs Nu chart shows the same data as rotor speed against useful power. This side-by-side view makes it straightforward to compare peak Cp values and the TSR at which each blade achieves them. Use Clear data to reset the charts before starting a new comparison run.